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Sample records for brazilian tropical savanna

  1. Legacy phosphorus and no tillage agriculture in tropical oxisols of the Brazilian savanna.

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    Rodrigues, Marcos; Pavinato, Paulo Sergio; Withers, Paul John Anthony; Teles, Ana Paula Bettoni; Herrera, Wilfrand Ferney Bejarano

    2016-01-15

    Crop production in the Brazilian Cerrado is limited by soil phosphorus (P) supply without large inputs of inorganic P fertilizer, which may become more costly and scarce in the future. Reducing dependency on fertilizer P requires a greater understanding of soil P supply in the highly weathered soils in this important agricultural region. We investigated the impact of no tillage (NT) and conventional tillage (CT) agriculture on accumulated (legacy) soil P and P forms in four long-term sites. Compared to the native savanna soils, tilled soils receiving regular annual P fertilizer inputs (30-50 kg P ha(-1)) increased all forms of inorganic and organic P, except highly recalcitrant P associated with the background lithology. However, 70-85% of the net added P was bound in moderately labile and non-labile forms associated with Fe/Al oxyhydroxides rather than in plant available forms. Under NT agriculture, organic P forms and labile and non-labile inorganic P forms were all significantly (Pagriculture. The contribution of organic P cycling in these tropical soils increased after conversion to agriculture and was proportionally greater under NT. The results highlight the large amounts of unutilized legacy P present in Brazil's Cerrado soils that could be better exploited to reduce dependency on imports of finite phosphate rock. No tillage agriculture confers a positive albeit relatively small benefit for soil P availability and overall soil function. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Tropical savannas and dry forests.

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    Pennington, R Toby; Lehmann, Caroline E R; Rowland, Lucy M

    2018-05-07

    In the tropics, research, conservation and public attention focus on rain forests, but this neglects that half of the global tropics have a seasonally dry climate. These regions are home to dry forests and savannas (Figures 1 and 2), and are the focus of this Primer. The attention given to rain forests is understandable. Their high species diversity, sheer stature and luxuriance thrill biologists today as much as they did the first explorers in the Age of Discovery. Although dry forest and savanna may make less of a first impression, they support a fascinating diversity of plant strategies to cope with stress and disturbance including fire, drought and herbivory. Savannas played a fundamental role in human evolution, and across Africa and India they support iconic megafauna. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. The biodiversity cost of carbon sequestration in tropical savanna

    OpenAIRE

    Abreu, Rodolfo C. R.; Hoffmann, William A.; Vasconcelos, Heraldo L.; Pilon, Natashi A.; Rossatto, Davi R.; Durigan, Giselda

    2017-01-01

    Tropical savannas have been increasingly viewed as an opportunity for carbon sequestration through fire suppression and afforestation, but insufficient attention has been given to the consequences for biodiversity. To evaluate the biodiversity costs of increasing carbon sequestration, we quantified changes in ecosystem carbon stocks and the associated changes in communities of plants and ants resulting from fire suppression in savannas of the Brazilian Cerrado, a global biodiversity hotspot. ...

  4. The biodiversity cost of carbon sequestration in tropical savanna.

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    Abreu, Rodolfo C R; Hoffmann, William A; Vasconcelos, Heraldo L; Pilon, Natashi A; Rossatto, Davi R; Durigan, Giselda

    2017-08-01

    Tropical savannas have been increasingly viewed as an opportunity for carbon sequestration through fire suppression and afforestation, but insufficient attention has been given to the consequences for biodiversity. To evaluate the biodiversity costs of increasing carbon sequestration, we quantified changes in ecosystem carbon stocks and the associated changes in communities of plants and ants resulting from fire suppression in savannas of the Brazilian Cerrado, a global biodiversity hotspot. Fire suppression resulted in increased carbon stocks of 1.2 Mg ha -1 year -1 since 1986 but was associated with acute species loss. In sites fully encroached by forest, plant species richness declined by 27%, and ant richness declined by 35%. Richness of savanna specialists, the species most at risk of local extinction due to forest encroachment, declined by 67% for plants and 86% for ants. This loss highlights the important role of fire in maintaining biodiversity in tropical savannas, a role that is not reflected in current policies of fire suppression throughout the Brazilian Cerrado. In tropical grasslands and savannas throughout the tropics, carbon mitigation programs that promote forest cover cannot be assumed to provide net benefits for conservation.

  5. A MODIS-Based Energy Balance to Estimate Evapotranspiration for Clear-Sky Days in Brazilian Tropical Savannas

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    Yadvinder S. Malhi

    2012-03-01

    Full Text Available Evapotranspiration (ET plays an important role in global climate dynamics and in primary production of terrestrial ecosystems; it represents the mass and energy transfer from the land to atmosphere. Limitations to measuring ET at large scales using ground-based methods have motivated the development of satellite remote sensing techniques. The purpose of this work is to evaluate the accuracy of the SEBAL algorithm for estimating surface turbulent heat fluxes at regional scale, using 28 images from MODIS. SEBAL estimates are compared with eddy-covariance (EC measurements and results from the hydrological model MGB-IPH. SEBAL instantaneous estimates of latent heat flux (LE yielded r 2= 0.64 and r2 = 0.62 over sugarcane croplands and savannas when compared against in situ EC estimates. At the same sites, daily aggregated estimates of LE were r 2 = 0.76 and r2 = 0.66, respectively. Energy balance closure showed that turbulent fluxes over sugarcane croplands were underestimated by 7% and 9% over savannas. Average daily ET from SEBAL is in close agreement with estimates from the hydrological model for an overlay of 38,100 km2 (r2 = 0.88. Inputs to which the algorithm is most sensitive are vegetation index (NDVI, gradient of temperature (dT to compute sensible heat flux (H and net radiation (Rn. It was verified that SEBAL has a tendency to overestimate results both at local and regional scales probably because of low sensitivity to soil moisture and water stress. Nevertheless the results confirm the potential of the SEBAL algorithm, when used with MODIS images for estimating instantaneous LE and daily ET from large areas.

  6. MARKET OF NON-WOOD FOREST PRODUCTS FROM BRAZILIAN SAVANNA

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    Sandra Regina Afonso

    2009-10-01

    Full Text Available In this article, we analyze the main non-wood forest products from Brazilian savanna. We studied the behavior and the growth rates of production and prices of almond of babaçu, oil of copaiba, fiber of buriti, leaf of jaborandi, bark of barbatimão, bark of angico, fruit of mangaba, almonds of pequi, from 1982 to 2005. All the products exhibited decreasing production, with exception of the oil of copaiba and almonds of pequi, which showed positive growth rates: 12.9% and 8.5%, respectively. The analysis of prices for most products was not significant, except for barks of barbatimão and angico, and almonds of pequi, which showed positive trends: 10.9%, 6.7%, and 4.6%, respectively. We believe that results were not significant due to the severe variations of the Brazilian currency in the period. We conclude that pequi is the main product from savanna and that oil of copaiba has the biggest increase in the production because most of the production comes from the whole Brazilian Amazon region.

  7. Seasonal variation of ground spiders in a Brazilian Savanna

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    Marina Farcic Mineo

    2010-06-01

    Full Text Available The Brazilian Savanna Ecoregion (Cerrado is one of the richest biomes in the world, with a characteristic highly seasonal climate a dry season between May and September and a rainy season from October through April. Ground-dwelling spiders from three Cerrado phytophysiognomies, "campo cerrado", "cerrado" and "cerrad��o", were sampled using pitfall traps during two years, totaling 111 species and 3,529 individuals. The abundance of individuals and species richness was higher during the wet season. Fifty-eight species were captured exclusively during that period, whereas only nineteen were restricted to the dry season. Only two species were found in all samples. The number of juveniles was higher than the number of adults in all phytophysiognomies and in all species during both seasons. The highest abundance was registered in October and the lowest in April. Overall sex ratio was male-biased in all vegetation types sampled. Distinct climate variables affected the abundance of spiders depending on sex, age and vegetal physiognomy where they were sampled. This study involved the longest sampling of spider abundance and diversity on the ground of a Brazilian Savanna.

  8. Environmental determinants of tropical forest and savanna distribution: A quantitative model evaluation and its implication

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    Zeng, Zhenzhong; Chen, Anping; Piao, Shilong; Rabin, Sam; Shen, Zehao

    2014-07-01

    The distributions of tropical ecosystems are rapidly being altered by climate change and anthropogenic activities. One possible trend—the loss of tropical forests and replacement by savannas—could result in significant shifts in ecosystem services and biodiversity loss. However, the influence and the relative importance of environmental factors in regulating the distribution of tropical forest and savanna biomes are still poorly understood, which makes it difficult to predict future tropical forest and savanna distributions in the context of climate change. Here we use boosted regression trees to quantitatively evaluate the importance of environmental predictors—mainly climatic, edaphic, and fire factors—for the tropical forest-savanna distribution at a mesoscale across the tropics (between 15°N and 35°S). Our results demonstrate that climate alone can explain most of the distribution of tropical forest and savanna at the scale considered; dry season average precipitation is the single most important determinant across tropical Asia-Australia, Africa, and South America. Given the strong tendency of increased seasonality and decreased dry season precipitation predicted by global climate models, we estimate that about 28% of what is now tropical forest would likely be lost to savanna by the late 21st century under the future scenario considered. This study highlights the importance of climate seasonality and interannual variability in predicting the distribution of tropical forest and savanna, supporting the climate as the primary driver in the savanna biogeography.

  9. Bistability, Spatial Interaction, and the Distribution of Tropical Forests and Savannas

    NARCIS (Netherlands)

    Staal, Arie; Dekker, Stefan C.; Xu, Chi; Nes, van Egbert H.

    2016-01-01

    Recent work has indicated that tropical forest and savanna can be alternative stable states under a range of climatic conditions. However, dynamical systems theory suggests that in case of strong spatial interactions between patches of forest and savanna, a boundary between both states is only

  10. Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper (Schinus terebinthifolius).

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    Stevens, Jens T; Beckage, Brian

    2009-10-01

    * Fire disturbance can mediate the invasion of ecological communities by nonnative species. Nonnative plants that modify existing fire regimes may initiate a positive feedback that can facilitate their continued invasion. Fire-sensitive plants may successfully invade pyrogenic landscapes if they can inhibit fire in the landscape. * Here, we investigated whether the invasive shrub Brazilian pepper (Schinus terebinthifolius) can initiate a fire-suppression feedback in a fire-dependent pine savanna ecosystem in the southeastern USA. * We found that prescribed burns caused significant (30-45%) mortality of Brazilian pepper at low densities and that savannas with more frequent fires contained less Brazilian pepper. However, high densities of Brazilian pepper reduced fire temperature by up to 200 degrees C, and experienced as much as 80% lower mortality. * A cellular automaton model was used to demonstrate that frequent fire may control low-density populations, but that Brazilian pepper may reach a sufficient density during fire-free periods to initiate a positive feedback that reduces the frequency of fire and converts the savanna to an invasive-dominated forest.

  11. New Native Rhizobia Strains for Inoculation of Common Bean in the Brazilian Savanna

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    Fábio Martins Mercante

    Full Text Available ABSTRACT Maximization of biological nitrogen fixation in the common bean (Phaseolus vulgaris L. crop depends on the genetic characteristics related to the plant, the symbiotic efficiency of rhizobia, and environmental factors. The objective of this study was to evaluate the performance of rhizobia selected beforehand from Cerrado (Brazilian tropical savanna soils in Mato Grosso do Sul. The experiments were conducted in 2007 in the municipalities of Aquidauana, Anaurilândia, Campo Grande, and Dourados, all located in the state of Mato Grosso do Sul. All procedures established followed the current recommendations of the Brazilian Ministry of Agriculture (Ministério de Agricultura, Pecuária e Abastecimento – MAPA, in accordance with the “official protocol for assessing the feasibility and agronomic efficiency of strains, and inoculant technologies linked to the process of biological nitrogen fixation in legumes”. The program for selection of rhizobia for inoculation in bean plants resulted in identification of different strains with high symbiotic efficiency, competitiveness, and genetic stability, based on the Embrapa Agropecuária Oeste collection of multifunctional microorganism cultures. In previous studies, 630 isolates of Rhizobium were evaluated. They were obtained from nodules of leucaena (380 or dry beans (250 from 87 locations, including 34 municipalities in Mato Grosso do Sul. Three of them stood out from the others: CPAO 12.5 L2, CPAO 17.5 L2, and CPAO 56.4 L2. Inoculation of these strains in bean plants demonstrated economic viability and high potential for obtaining a more effective inoculant suitable for trading purposes.

  12. Long range lateral root activity by neo-tropical savanna trees.

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    Leonel da S. L. Sternberg; Sandra Bucci; Augusto Franco; Guillermo Goldstein; William A. Hoffman; Frederick C. Meinzer; Marcelo Z. Moreira; Fabian. Scholz

    2004-01-01

    The extent of water uptake by lateral roots of savanna trees in the Brazilian highlands was measured by irrigating two 2 by 2 m plots with deuterium-enriched water and assaying for the abundance of deuterium in stem water from trees inside and at several distances from the irrigation plots. Stem water of trees inside the irrigation plots was highly enriched compared to...

  13. Disaggregating tree and grass phenology in tropical savannas

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    Zhou, Qiang

    Savannas are mixed tree-grass systems and as one of the world's largest biomes represent an important component of the Earth system affecting water and energy balances, carbon sequestration and biodiversity as well as supporting large human populations. Savanna vegetation structure and its distribution, however, may change because of major anthropogenic disturbances from climate change, wildfire, agriculture, and livestock production. The overstory and understory may have different water use strategies, different nutrient requirements and have different responses to fire and climate variation. The accurate measurement of the spatial distribution and structure of the overstory and understory are essential for understanding the savanna ecosystem. This project developed a workflow for separating the dynamics of the overstory and understory fractional cover in savannas at the continental scale (Australia, South America, and Africa). Previous studies have successfully separated the phenology of Australian savanna vegetation into persistent and seasonal greenness using time series decomposition, and into fractions of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil (BS) using linear unmixing. This study combined these methods to separate the understory and overstory signal in both the green and senescent phenological stages using remotely sensed imagery from the MODIS (MODerate resolution Imaging Spectroradiometer) sensor. The methods and parameters were adjusted based on the vegetation variation. The workflow was first tested at the Australian site. Here the PV estimates for overstory and understory showed best performance, however NPV estimates exhibited spatial variation in validation relationships. At the South American site (Cerrado), an additional method based on frequency unmixing was developed to separate green vegetation components with similar phenology. When the decomposition and frequency methods were compared, the frequency

  14. Palaeovegetation dynamics of an ecotone forest-savanna in southern Brazilian Amazon during the late Pleistocene and Holocene based on carbon isotopes of soil organic matter

    International Nuclear Information System (INIS)

    Pessenda, L.C.R.; Gouveia, S.E.M.; Freitas, H.A. de; Bendassoli, J.A.; Gomes, B.M.; Aravena, R.; Ribeiro, A.S.; Boulet, R.

    2002-01-01

    This study was carried out in the Brazilian southern Amazon region (Rondonia state and Humaita, southern Amazon state). Carbon isotope data on soil organic matter have been collected along an ecosystem transect of about 750 km that includes a savanna, a wooded savanna (cerrado), a tropical semideciduous forest (cerradao), a forest transition type and a tropical forest. The main objective is to evaluate the expansion-regression dynamics of these vegetation units in relation to climate changes during the Late Pleistocene (Late Glacial) and Holocene. Large ranges in δ 13 values were observed in soil organic matter collected from profiles in the savanna (-27 to -14 per mille and forest regions (-26 to -19 per mille) reflecting changing distribution of 13 C-depleted C 3 forest and 13 C enriched C 4 savanna vegetation in response to climate change. 14 C data of humin fraction and buried charcoal indicate that the organic matter in these soils is at least 17,000 years BP at 300-cm depth. In this period, the entire ecosystem transect are characterized by δ 13 C soil depth profiles, generated typically by C 3 plants (forest), inferring a humid climate in the southern Amazon region after the end of last glaciation. 13 C data also indicate that C 4 plants (grasses) have influenced significantly the vegetation at the transitional forest and the cerrado sites of southern Rondonia state and two distinct points in the forest ecosystem in the southern Amazon state. These typical C 4 type isotopic signatures probably reflect a drier climate during about 9000-8000 yr BP to 3000 yr BP and the savanna and wooded savanna expansion in distinct points of the transect. The 13 C records representing the 3000 yr show an expansion of the forest, due to a climatic improvement, in areas previously occupied by savanna vegetation. This study adds to the mounting evidence that extensive forested areas existed in the Amazon during the last glacial and that savanna vegetation expanded in response

  15. Functional Connectivity of Precipitation Networks in the Brazilian Rainforest-Savanna Transition Zone

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    Adera, S.; Larsen, L.; Levy, M. C.; Thompson, S. E.

    2016-12-01

    In the Brazilian rainforest-savanna transition zone, vegetation change has the potential to significantly affect precipitation patterns. Deforestation, in particular, can affect precipitation patterns by increasing land surface albedo, increasing aerosol loading to the atmosphere, changing land surface roughness, and reducing transpiration. Understanding land surface-precipitation couplings in this region is important not only for sustaining Amazon and Cerrado ecosystems, but also for cattle ranching and agriculture, hydropower generation, and drinking water management. Simulations suggest complex, scale-dependent interactions between precipitation and land cover. For example, the size and distribution of deforested patches has been found to affect precipitation patterns. We take an empirical approach to ask: (1) what are the dominant spatial and temporal length scales of precipitation coupling in the Brazilian rainforest-savanna transition zone? (2) How do these length scales change over time? (3) How does the connectivity of precipitation change over time? The answers to these questions will help address fundamental questions about the impacts of deforestation on precipitation. We use rain gauge data from 1100 rain gauges intermittently covering the period 1980 - 2013, a period of intensive land cover change in the region. The dominant spatial and temporal length scales of precipitation coupling are resolved using transfer entropy, a metric from information theory. Connectivity of the emergent network of couplings is quantified using network statistics. Analyses using transfer entropy and network statistics reveal the spatial and temporal interdependencies of rainfall events occurring in different parts of the study domain.

  16. Trait shifts associated with the subshrub life-history strategy in a tropical savanna.

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    Giroldo, A B; Scariot, A; Hoffmann, W A

    2017-10-01

    Over the past 10 million years, tropical savanna environments have selected for small growth forms within woody plant lineages. The result has been the evolution of subshrubs (geoxyles), presumably as an adaptation to frequent fire. To evaluate the traits associated with the shift from tree to subshrub growth forms, we compared seed biomass, germination, survival, resprouting, biomass allocation, and photosynthesis between congeneric trees and subshrubs, and quantified phylogenetic conservatism. Despite large differences in adult morphology between trees and subshrub species, the differences are modest in seedlings, and most of the variation in traits was explained by genus, indicating considerable phylogenic conservatism. Regardless, tree seedlings invested more heavily in aboveground growth, compared to subshrubs, which is consistent with the adult strategy of savanna trees, which depend on a large resistant-fire stem. Subshrub seedlings also invest in greater non-structural carbohydrate reserves, likely as an adaptation to the high fire frequencies typical of tropical savannas. The modest differences as seedlings suggest that selective pressures during early development may not have contributed substantially to the evolution of the subshrub growth form and that the distinct allocation and life history must arise later in life. This is consistent with the interpretation that the subshrub growth form arose as a life-history strategy in which maturity is reached at a small stem size, allowing them to reproduce despite repeated fire-induced topkill. The convergent evolution of subshrubs within multiple tree lineages reaffirms the importance of fire in the origin and diversification of the flora of mesic savannas.

  17. BRS 369RF and BRS 370RF: Glyphosate tolerant, high-yielding upland cotton cultivars for central Brazilian savanna

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    Camilo de Lelis Morello

    2015-12-01

    Full Text Available BRS 369RF and BRS 370RF were developed by the EMBRAPA as a part of efforts to create high-yielding germplasm with combinations of transgenic traits. BRS 369RF and BRS 370RF are midseason cultivars and have yield stability, adaptation to the central Brazilian savanna, good fiber quality and tolerance to glyphosate herbicide.

  18. The magnitude and persistence of soil NO, N20, CH4, and C02 fluxes from burned tropical savanna in Brazil

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    Mark Poth; Iris Cofman Anderson; Heloisa Sinatora Miranda; Antonia Carlos Miranda; Philip J. Riggan

    1995-01-01

    Among all global ecosystems, tropical savannas are the most severely and extensively affected by anthropogenic burning. Frequency of fire in cerrado, a type of tropical savanna covering 25% of Brazil, is 2 to 4 years. In 1992 we measured soil fluxes of NO, N20, CH4, and C02 from cerrado sites that had...

  19. The spectral changes of deforestation in the Brazilian tropical savanna.

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    Trancoso, Ralph; Sano, Edson E; Meneses, Paulo R

    2015-01-01

    The Cerrado is a biome in Brazil that is experiencing the most rapid loss in natural vegetation. The objective of this study was to analyze the changes in the spectral response in the red, near infrared (NIR), middle infrared (MIR), and normalized difference vegetation index (NDVI) when native vegetation in the Cerrado is deforested. The test sites were regions of the Cerrado located in the states of Bahia, Minas Gerais, and Mato Grosso. For each region, a pair of Landsat Thematic Mapper (TM) scenes from 2008 (before deforestation) and 2009 (after deforestation) was compared. A set of 1,380 samples of deforested polygons and an equal number of samples of native vegetation have their spectral properties statistically analyzed. The accuracy of deforestation detections was also evaluated using high spatial resolution imagery. Results showed that the spectral data of deforested areas and their corresponding native vegetation were statistically different. The red band showed the highest difference between the reflectance data from deforested areas and native vegetation, while the NIR band showed the lowest difference. A consistent pattern of spectral change when native vegetation in the Cerrado is deforested was identified regardless of the location in the biome. The overall accuracy of deforestation detections was 97.75%. Considering both the marked pattern of spectral changes and the high deforestation detection accuracy, this study suggests that deforestation in Cerrado can be accurately monitored, but a strong seasonal and spatial variability of spectral changes might be expected.

  20. Pleistocene climatic changes drive diversification across a tropical savanna.

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    Potter, Sally; Xue, Alexander T; Bragg, Jason G; Rosauer, Dan F; Roycroft, Emily J; Moritz, Craig

    2018-01-01

    Spatial responses of species to past climate change depend on both intrinsic traits (climatic niche breadth, dispersal rates) and the scale of climatic fluctuations across the landscape. New capabilities in generating and analysing population genomic data, along with spatial modelling, have unleashed our capacity to infer how past climate changes have shaped populations, and by extension, complex communities. Combining these approaches, we uncover lineage diversity across four codistributed lizards from the Australian Monsoonal Tropics and explore how varying climatic tolerances interact with regional climate history to generate common vs. disparate responses to late Pleistocene change. We find more divergent spatial structuring and temporal demographic responses in the drier Kimberley region compared to the more mesic and consistently suitable Top End. We hypothesize that, in general, the effects of species' traits on sensitivity to climate fluctuation will be more evident in climatically marginal regions. If true, this points to the need in climatically marginal areas to craft more species-(or trait)-specific strategies for persistence under future climate change. © 2017 John Wiley & Sons Ltd.

  1. Satellite observations for describing fire patterns and climate-related fire drivers in the Brazilian savannas

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    Verola Mataveli, Guilherme Augusto; Siqueira Silva, Maria Elisa; Pereira, Gabriel; da Silva Cardozo, Francielle; Shinji Kawakubo, Fernando; Bertani, Gabriel; Cezar Costa, Julio; de Cássia Ramos, Raquel; Valéria da Silva, Viviane

    2018-01-01

    In the Brazilian savannas (Cerrado biome) fires are natural and a tool for shifting land use; therefore, temporal and spatial patterns result from the interaction of climate, vegetation condition and human activities. Moreover, orbital sensors are the most effective approach to establish patterns in the biome. We aimed to characterize fire, precipitation and vegetation condition regimes and to establish spatial patterns of fire occurrence and their correlation with precipitation and vegetation condition in the Cerrado. The Cerrado was first and second biome for the occurrence of burned areas (BA) and hotspots, respectively. Occurrences are higher during the dry season and in the savanna land use. Hotspots and BA tend to decrease, and concentrate in the north, but more intense hotspots are not necessarily located where concentration is higher. Spatial analysis showed that averaged and summed values can hide patterns, such as for precipitation, which has the lowest average in August, but minimum precipitation in August was found in 7 % of the Cerrado. Usually, there is a 2-3-month lag between minimum precipitation and maximum hotspots and BA, while minimum VCI and maximum hotspots and BA occur in the same month. Hotspots and BA are better correlated with VCI than precipitation, qualifying VCI as an indicator of the susceptibility of vegetation to ignition.

  2. Alien plant invasions in tropical and sub-tropical savannas: patterns, processes and prospects

    Czech Academy of Sciences Publication Activity Database

    Foxcroft, L. C.; Richardson, D. M.; Rejmánek, M.; Pyšek, Petr

    2010-01-01

    Roč. 12, č. 12 (2010), s. 3913-3933 ISSN 1387-3547 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60050516 Keywords : savannas * plant invasions * world Subject RIV: EF - Botanics Impact factor: 3.474, year: 2010

  3. Three new species of the killifish genus Melanorivulus from the central Brazilian Cerrado savanna (Cyprinodontiformes, Aplocheilidae

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    Wilson J.E.M. Costa

    2017-01-01

    Full Text Available Three new species are described from the Neotropical region comprising the Cerrado savannas of the central Brazilian plateaus, which is among the most important biodiversity centres in the world. These species are considered closely related to M. dapazi from the same region, with which they share the presence of a rudimentary interarcual cartilage and a dark reddish brown distal margin on the male anal fin. The group comprising M. dapazi and the three new species is here named as the M. dapazi species group. Melanorivulus ignescens sp. n., from the upper Rio Araguaia basin, is distinguished from all other species of the M. dapazi group by the anal-fin colour pattern in males; M. flavipinnis sp. n. and M. regularis sp. n. from the Rio Paraguai basin are distinguished from all other congeners of the M. dapazi group by the colour pattern of the caudal fin and number of scales in the longitudinal series, respectively. All the new species are further unambiguously diagnosed by unique combinations of morphological characters, including meristic and morphometric data, and colour patterns. This study reinforces the importance of using live colour patterns to diagnose species and species groups of the genus Melanorivulus, but also indicates that osteological characters may be informative for species diagnosis. This study confirms the high diversity of species of Melanorivulus in the central Brazilian Cerrado plateaus already reported in previous studies, indicating that endemic species are often restricted to short segments of a single river drainage.

  4. Antioxidant activity and phenolic content of leaf infusions of Myrtaceae species from Cerrado (Brazilian Savanna

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    L. K. Takao

    Full Text Available Abstract There is considerable interest in identifying new antioxidants from plant materials. Several studies have emphasized the antioxidant activity of species belonging to the Myrtaceae family. However, there are few reports on these species from the Cerrado (Brazilian savanna. In this study, the antioxidant activity and phenolic content of 12 native Myrtaceae species from the Cerrado were evaluated (Blepharocalyx salicifolius, Eugenia bimarginata, Eugenia dysenterica, Eugenia klotzschiana, Hexachlamys edulis, Myrcia bella, Myrcia lingua, Myrcia splendens, Myrcia tomentosa, Psidium australe, Psidium cinereum, and Psidium laruotteanum. Antioxidant potential was assessed using the antioxidant activity index (AAI by the DPPH method and total phenolic content (TPC by the Folin–Ciocalteu assay. There was a high correlation between TPC and AAI values. Psidium laruotteanum showed the highest TPC (576.56 mg GAE/g extract and was the most potent antioxidant (AAI = 7.97, IC50 = 3.86 µg·mL−1, with activity close to that of pure quercetin (IC50 = 2.99 µg·mL−1. The extracts of nine species showed IC50 of 6.24–8.75 µg·mL−1. Most species showed TPC and AAI values similar to or higher than those for Camellia sinensis, a commonly consumed tea with strong antioxidant properties. The results reveal that the analyzed Myrtaceae species from the Cerrado possess high phenolic contents and antioxidant activities. Thus, they are a potential source of new natural antioxidants.

  5. Nutritional composition and protein value of the baru (Dipteryx alata Vog.) almond from the Brazilian Savanna.

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    Fernandes, Daniela C; Freitas, Jullyana B; Czeder, Ludmila P; Naves, Maria Margareth V

    2010-08-15

    The almond of the baru tree (Dipteryx alata Vog.), a native species of the Brazilian Savanna, is used in the gastronomy of the central western region of the country. There is relatively little information about the chemical composition and nutritional value of the baru almond, which was the motivation for this research. The baru almonds had high lipid (397-437 g kg(-1)) and protein (238-281 g kg(-1)) contents. There were differences in the amino acid score (AAS = 83-103%) and limiting amount of sulfur amino acids, depending on the origin of the almond. The protein value of the baru almond was higher than that of the peanut according to the relative net protein ratio (RNPR(Baru) = 74%, RNPR(Peanut) = 66%) and the protein digestibility-corrected amino acid score (PDCAAS). The baru almond also had high iron (mean 48.1 mg kg(-1)), zinc (mean 46.6 mg kg(-1)) and dietary fibre (mean 115.8 g kg(-1)) contents in relation to Dietary Reference Intakes. The baru almond has a high nutrient density and high content of quality protein. Furthermore, the lipid and protein contents and amino acid profile of the baru almond are representative of edible seeds and similar to those of true nuts. This almond can be used as a complementary source of protein and as an excellent option for a healthy diet. Copyright (c) 2010 Society of Chemical Industry.

  6. Floristic and phytosociological analysis of palm swamps in the central part of the Brazilian savanna

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    Isa Lucia de Morais Resende

    2013-03-01

    Full Text Available We analyzed the floristics and phytosociology of three palm swamps in the municipality of Bela Vista de Goiás, located in the state of Goiás, Brazil, in the central part of the Brazilian savanna (Cerrado. The floristic surveys were conducted monthly from May 2008 to April 2009, and 310 species were recorded (seven bryophytes, 15 ferns and 288 angiosperms. Bryophytes belonged to five genera and five families; ferns belonged to nine genera and nine families; and angiosperms belonged to 134 genera and 45 families. The angiosperm families with the highest species richness were Poaceae, Cyperaceae, Asteraceae, Eriocaulaceae, Xyridaceae, Lentibulariaceae, Melastomataceae, Rubiaceae and Fabaceae. The palm swamps were divided into three zones of increasing humidity: edge, middle and core. The number of species was higher in the middle than at the edge and the core. The families with the highest cover values were Cyperaceae, Melastomataceae, Arecaceae and Poaceae. Although the palm swamps had been disturbed to varying degrees, those disturbances did not affect the flora in the middle or the core. Floristic similarity was high between these two zones within a given palm swamp and low between the edges of different palm swamps.

  7. Where Does The Carbon Go? Carbon Dynamics And Fire of a North Australian Tropical Savanna

    Science.gov (United States)

    Hutley, L. B.; Beringer, J.; Tapper, N. J.; Cernusak, L.

    2007-12-01

    The role of fire as one of the primary natural carbon cycling mechanisms is a key issue in considering global change feedbacks. In north Australia, the dominant ecosystem is tropical savanna and for mesic savannas within 100 km of the northern coastline, fire, storms and cyclones all impact carbon stocks. Fire is the most frequent disturbance agent as fires burn with a near annual frequency in these systems. We aimed to determine the annual net ecosystem productivity (NEP) from these savannas and the impact of fire on productivity. We established a long-term eddy covariance flux tower at Howard Springs, Australia and present here 5 years of data from 2001 to 2005. Fire has direct impacts through emissions but also has indirect effects through the loss of productivity due to reduced functional leaf area index and the carbon costs of rebuilding the canopy. The impact of fire on the canopy latent energy exchange was evident for 40 days while the canopy was rebuilt; however, the carbon balance took approximately 70 days to recover. The annual fire free NEP at Howard Springs was estimated at -4.3 t C ha-1 y-1 with a range of -3.5 to -5.1 t C ha-1 y-1 across years. We calculated the average annual indirect fire effect as 0.7 t C ha-1 y-1 using a neural network model approach and estimated average emissions of fine and coarse fuels as 1.6 t C ha-1 y-1. This allowed us to calculate a net biome production of 2.0 t C ha-1 y-1. We then partitioned this remaining sink and suggest that most of this can be accounted for by woody increment (1.2 t C ha-1 y-1) and shrub encroachment (0.5 t C ha-1 y-1). Given the consistent sink at this site, even under an almost annual fire regime, there may be management options to increase carbon sequestration by reducing fire frequency.

  8. Changes in diversity, abundance, and structure of soil bacterial communities in Brazilian Savanna under different land use systems.

    Science.gov (United States)

    Rampelotto, Pabulo Henrique; de Siqueira Ferreira, Adão; Barboza, Anthony Diego Muller; Roesch, Luiz Fernando Wurdig

    2013-10-01

    The Brazilian Savanna, also known as "Cerrado", is the richest and most diverse savanna in the world and has been ranked as one of the main hotspots of biodiversity. The Cerrado is a representative biome in Central Brazil and the second largest biome in species diversity of South America. Nevertheless, large areas of native vegetation have been converted to agricultural land including grain production, livestock, and forestry. In this view, understanding how land use affects microbial communities is fundamental for the sustainable management of agricultural ecosystems. The aim of this work was to analyze and compare the soil bacterial communities from the Brazilian Cerrado associated with different land use systems using high throughput pyrosequencing of 16S rRNA genes. Relevant differences were observed in the abundance and structure of bacterial communities in soils under different land use systems. On the other hand, the diversity of bacterial communities was not relevantly changed among the sites studied. Land use systems had also an important impact on specific bacterial groups in soil, which might change the soil function and the ecological processes. Acidobacteria, Proteobacteria, and Actinobacteria were the most abundant groups in the Brazilian Cerrado. These findings suggest that more important than analyzing the general diversity is to analyze the composition of the communities. Since soil type was the same among the sites, we might assume that land use was the main factor defining the abundance and structure of bacterial communities.

  9. Relationship Between Edaphic Factors and Vegetation in Savannas of the Brazilian Midwest Region

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    Michellia Pereira Soares

    2015-06-01

    Full Text Available The Brazilian savanna is a mosaic of phytophysiognomies influenced by edaphic and topographic factors that range from the occurrence of fires to anthropic disturbance. The goal of this study was a comparative analysis between two cerrado areas in southeastern Goiás, relating the floristic composition and structure of the vegetation to soil properties to better understand the physiognomic characteristics of the region. Twenty-five 20 × 20 m plots were used. All plants with circumference at breast height of more than 15 cm were measured. Soil samples collected at a depth of 0-20 cm were subjected to physical and chemical analyses. Canonical correspondence analysis (CCA was used to detect possible correlations between the soil properties and species abundance and distribution. The density and total basal area were 1,647 ind/ha and 15.57 m2/ha, respectively, in Ouroana. At this site, 107 species were sampled. In Montes Claros de Goiás, the density and total basal area were 781 ind/ha and 17.62 m2/ha, and 120 species were sampled. The soil texture of Ouroana was sandy and significantly different from the medium to clayey texture of Montes Claros. The soils of both areas are dystrophic, however, more fertile in Montes Claros and aluminum-toxic in Ouroana. The species of vegetation were distributed according to soil fertility levels. The CCAs grouped species according to soil properties that defined location and abundance as well as the phytophysiognomies of the studied areas.

  10. Late Glacial Tropical Savannas in Sundaland Inferred From Stable Carbon Isotope Records of Cave Guano

    Science.gov (United States)

    Wurster, C. M.; Bird, M. I.; Bull, I.; Dungait, J.; Bryant, C. L.; Ertunç, T.; Hunt, C.; Lewis, H. A.; Paz, V.

    2008-12-01

    During the Last Glacial Period (LGP), reduced global sea level exposed the continental shelf south of Thailand to Sumatra, Java, and Borneo to form the contiguous continent of Sundaland. However, the type and extent of vegetation that existed on much of this exposed landmass during the LGP remains speculative. Extensive bird and bat guano deposits in caves throughout this region span beyond 40,000 yr BP, and contain a wealth of untapped stratigraphic palaeoenvironmental information. Stable carbon isotope ratios of insectivorous bird and bat guano contain a reliable record of the animal's diet and, through non-specific insect predation, reflect the relative abundance of major physiological pathways in plants. Various physiological pathways of carbon fixation in plants yield differing stable carbon isotope ratios. Stable carbon isotope values of C3 plants are lower than C4 vegetation due to different enzymatic discriminations of the heavy isotope through the carbon fixing pathways. In tropical locales, grasses nearly always follow the C4 photosynthetic pathway, whereas tropical rainforest uses C3 photosynthesis, providing a proxy for vegetation and therefore climate change in the past. Here we discuss four guano stable-isotope records, based on insect cuticle and n-alkane analysis, supplemented by pollen analysis. All sites suggest a C3 dominated ecosystem for the Holocene, consistent with the wet tropical forest vegetation present at all locations. Two sites from Palawan Island, Philippines, record stable carbon isotope values of guano that document a drastic change from C3 (forest) to C4 (savanna) dominated ecosystems during the Last Glacial Maximum (LGM). A third location, at Niah Great Cave, Malaysia, indicates C3-dominant vegetation throughout the record, but does display variation in stable carbon isotope values likely linked to humidity changes. A fourth location, Batu Caves in Peninsular Malaysia, also indicates open vegetation during the LGM. Vegetation

  11. High spatial resolution mapping of land cover types in a priority area for conservation in the Brazilian savanna

    Science.gov (United States)

    Ribeiro, F.; Roberts, D. A.; Hess, L. L.; Davis, F. W.; Caylor, K. K.; Nackoney, J.; Antunes Daldegan, G.

    2017-12-01

    Savannas are heterogeneous landscapes consisting of highly mixed land cover types that lack clear distinct boundaries. The Brazilian Cerrado is a Neotropical savanna considered a biodiversity hotspot for conservation due to its biodiversity richness and rapid transformation of its landscape by crop and pasture activities. The Cerrado is one of the most threatened Brazilian biomes and only 2.2% of its original extent is strictly protected. Accurate mapping and monitoring of its ecosystems and adjacent land use are important to select areas for conservation and to improve our understanding of the dynamics in this biome. Land cover mapping of savannas is difficult due to spectral similarity between land cover types resulting from similar vegetation structure, floristically similar components, generalization of land cover classes, and heterogeneity usually expressed as small patch sizes within the natural landscape. These factors are the major contributor to misclassification and low map accuracies among remote sensing studies in savannas. Specific challenges to map the Cerrado's land cover types are related to the spectral similarity between classes of land use and natural vegetation, such as natural grassland vs. cultivated pasture, and forest ecosystem vs. crops. This study seeks to classify and evaluate the land cover patterns across an area ranked as having extremely high priority for future conservation in the Cerrado. The main objective of this study is to identify the representativeness of each vegetation type across the landscape using high to moderate spatial resolution imagery using an automated scheme. A combination of pixel-based and object-based approaches were tested using RapidEye 3A imagery (5m spatial resolution) to classify the Cerrado's major land cover types. The random forest classifier was used to map the major ecosystems present across the area, and demonstrated to have an effective result with 68% of overall accuracy. Post

  12. Monitoring the Distribution and Dynamics of an Invasive Grass in Tropical Savanna Using Airborne LiDAR

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    Shaun R. Levick

    2015-04-01

    Full Text Available The spread of an alien invasive grass (gamba grass—Andropogon gayanus in the tropical savannas of Northern Australia is a major threat to habitat quality and biodiversity in the region, primarily through its influence on fire intensity. Effective control and eradication of this invader requires better insight into its spatial distribution and rate of spread to inform management actions. We used full-waveform airborne LiDAR to map areas of known A. gayanus invasion in the Batchelor region of the Northern Territory, Australia. Our stratified sampling campaign included wooded savanna areas with differing degrees of A. gayanus invasion and adjacent areas of native grass and woody tree mixtures. We used height and spatial contiguity based metrics to classify returns from A. gayanus and developed spatial representations of A. gayanus occurrence (1 m resolution and canopy cover (10 m resolution. The cover classification proved robust against two independent field-based investigations at 500 m2 (R2 = 0.87, RMSE = 12.53 and 100 m2 (R2 = 0.79, RMSE = 14.13 scale. Our mapping results provide a solid benchmark for evaluating the rate and pattern of A. gayanus spread from future LiDAR campaigns. In addition, this high-resolution mapping can be used to inform satellite image analysis for the evaluation of A. gayanus invasion over broader regional scales. Our research highlights the huge potential that airborne LiDAR holds for facilitating the monitoring and management of savanna habitat condition.

  13. Shifts in functional traits elevate risk of fire-driven tree dieback in tropical savanna and forest biomes.

    Science.gov (United States)

    Pellegrini, Adam F A; Franco, Augusto C; Hoffmann, William A

    2016-03-01

    Numerous predictions indicate rising CO2 will accelerate the expansion of forests into savannas. Although encroaching forests can sequester carbon over the short term, increased fires and drought-fire interactions could offset carbon gains, which may be amplified by the shift toward forest plant communities more susceptible to fire-driven dieback. We quantify how bark thickness determines the ability of individual tree species to tolerate fire and subsequently determine the fire sensitivity of ecosystem carbon across 180 plots in savannas and forests throughout the 2.2-million km(2) Cerrado region in Brazil. We find that not accounting for variation in bark thickness across tree species underestimated carbon losses in forests by ~50%, totaling 0.22 PgC across the Cerrado region. The lower bark thicknesses of plant species in forests decreased fire tolerance to such an extent that a third of carbon gains during forest encroachment may be at risk of dieback if burned. These results illustrate that consideration of trait-based differences in fire tolerance is critical for determining the climate-carbon-fire feedback in tropical savanna and forest biomes. © 2015 John Wiley & Sons Ltd.

  14. The long term recovery of heat and moisture fluxes to the atmosphere following fire in Australia's tropical savanna

    Science.gov (United States)

    Tapper, N.; Beringer, J.; Hutley, L.; Coutts, A.

    2003-04-01

    Fire is probably the greatest natural and anthropogenic environmental disturbance in Australia's tropical savannas, with the vast area burned each year (up to 250,000 km^2) likely to increase with predicted regional climate change. Globally savanna ecosystems cover 11.5% of the global landscape (Scholes and Hall 1996). As much as 75% of this landscape burns annually (Hao et al., 1990), accounting for more than 40% of all global biomass consumed (Hao and Ward 1993). These landscape-scale fires undoubtedly have massive impacts on regional water, energy and carbon dioxide exchanges and as a result may have important feedbacks to the atmosphere and regional climate. Fire may influence climate directly through the emission of smoke and trace gases from burning, but there are other important impacts of fire that may affect the atmosphere. Fire and the subsequent fire scars are likely to radically alter the surface energy budgets of tropical savannas through reduced surface albedo, increased available energy for partitioning into the convective fluxes, and increased substrate heat flux. The aerodynamic and biological properties of the ecosystem may also change, affecting surface-atmosphere coupling. There is a clear potential to influence atmospheric motion and moist convection at a range of scales. Potential fire scar impacts such as those mentioned above have previously been largely ignored and are the focus of the Savanna Fire Experiment (SAFE). Tower measurements of radiation, heat, moisture and CO_2 fluxes above burned and unburned savanna near Darwin, Australia, were initiated in August 2001 to observe the impacts of fire and fire scarring on flux exchange with the atmosphere, along with the longer term post-fire recovery of fluxes. Intensive field campaigns were mounted in the dry (fire) seasons of both 2001 and 2002, with flux recovery observed into the each of the subsequent monsoon seasons. Results and an early analysis of the time series of heat and moisture

  15. On the relative role of fire and rainfall in determining vegetation patterns in tropical savannas: a simulation study

    Science.gov (United States)

    Spessa, Allan; Fisher, Rosie

    2010-05-01

    Tropical savannas cover 18% of the world's land surface and are amongst the most productive terrestrial systems in the world. They comprise 15% of the total terrestrial carbon stock, with an estimated mean net primary productivity (NPP) of 7.2 tCha-1yr-1 or two thirds of NPP in tropical forests. Tropical savannas are the most frequently burnt biome, with fire return intervals in highly productive areas being typically 1-2 years. Fires shape vegetation species composition, tree to grass ratios and nutrient redistribution, as well as the biosphere-atmosphere exchange of trace gases, momentum and radiative energy. Tropical savannas are a major source of emissions, contributing 38 % of total annual CO2 from biomass burning, 30% CO, 19 % CH4 and 59 % NOx. Climatically, they occur in regions subject to a strongly seasonal ‘wet-dry' regime, usually under monsoonal control from the movement of the inter-tropical convergence zone. In general, rainfall during the prior wet season(s) determines the amount of grass fuel available for burning while the length of the dry season influences fuel moisture content. Rainfall in tropical savannas exhibits high inter-annual variability, and under future climate change, is projected to change significantly in much of Africa, South America and northern Australia. Process-based simulation models of fire-vegetation dynamics and feedbacks are critical for determining the impacts of wildfires under projected future climate change on i) ecosystem structure and function, and ii) emissions of trace gases and aerosols from biomass burning. A new mechanistic global fire model SPITFIRE (SPread and InTensity of FIRE) has been designed to overcome many of the limitations in existing fire models set within Dynamic Global Vegetation Models (DGVMs). SPITFIRE has been applied in coupled mode globally and southern Africa, both as part of the LPJ DGVM. It has also been driven with MODIS burnt area data applied to sub-Saharan Africa, while coupled to the

  16. Spatial Patterns of Fire Recurrence Using Remote Sensing and GIS in the Brazilian Savanna: Serra do Tombador Nature Reserve, Brazil

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    Gabriel Antunes Daldegan

    2014-10-01

    Full Text Available The Cerrado is the second largest biome in Brazil after the Amazon and is the savanna with the highest biodiversity in the world. Serra Tombador Natural Reserve (STNR is the largest private reserve located in Goiás State, and the fourth largest in the Cerrado biome. The present study aimed to map the burnt areas and to describe the spatial patterns of fire recurrence and its interactions with the classes of land-cover that occurred in STNR and its surroundings in the period between 2001 and 2010. Several Landsat TM images acquired around the months of July, August and September, coinciding with the region’s dry season when fire events intensify, were employed to monitor burnt areas. Fire scars were mapped using the supervised Mahalanobis-distance classifier and further refined using expert visual interpretation. Burnt area patterns were described by spatial landscape metrics. The effects of fire on landscape structure were obtained by comparing results among different land-cover classes, and results summarized in terms of fire history and frequencies. During the years covered by the study, 69% of the areas analyzed had fire events. The year with the largest burnt area was 2004, followed by 2001, 2007 and 2010. Thus, the largest fire events occurred in a 3-year cycle, which is compatible with other areas of the Brazilian savanna. The regions with higher annual probabilities of fire recurrence occur in the buffer zone around the park. The year 2004 also had the highest number of burnt area patches (831. In contrast, the burnt area in 2007 showed the most extensive fires with low number of patches (82. The physiognomies that suffered most fires were the native savanna formations. The study also identified areas where fires are frequently recurrent, highlighting priority areas requiring special attention. Thus, the methodology adopted in this study assists in monitoring and recovery of areas affected by fire over time.

  17. SEASONAL SOIL FLUXES OF CARBON MONOXIDE IN BURNED AND UNBURNED BRAZILIAN SAVANNAS

    Science.gov (United States)

    Soil-atmosphere fluxes of carbon monoxide (CO) were measured from September 1999 through November 2000 in savanna areas in central Brazil (Cerrado) under different fire regimes using transparent and opaque static chambers. Studies focused on two vegetation types, cerrado stricto...

  18. Longitudinal Distribution of the Functional Feeding Groups of Aquatic Insects in Streams of the Brazilian Cerrado Savanna.

    Science.gov (United States)

    Brasil, L S; Juen, L; Batista, J D; Pavan, M G; Cabette, H S R

    2014-10-01

    We demonstrate that the distribution of the functional feeding groups of aquatic insects is related to hierarchical patch dynamics. Patches are sites with unique environmental and functional characteristics that are discontinuously distributed in time and space within a lotic system. This distribution predicts that the occurrence of species will be based predominantly on their environmental requirements. We sampled three streams within the same drainage basin in the Brazilian Cerrado savanna, focusing on waterfalls and associated habitats (upstream, downstream), representing different functional zones. We collected 2,636 specimens representing six functional feeding groups (FFGs): brushers, collector-gatherers, collector-filterers, shredders, predators, and scrapers. The frequency of occurrence of these groups varied significantly among environments. This variation appeared to be related to the distinct characteristics of the different habitat patches, which led us to infer that the hierarchical patch dynamics model can best explain the distribution of functional feeding groups in minor lotic environments, such as waterfalls.

  19. Temporal Dynamics and Resource Availability for Drosophilid Fruit Flies (Insecta, Diptera in a Gallery Forest in the Brazilian Savanna

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    Henrique Valadão

    2010-01-01

    Full Text Available Seasonality can cause severe bottlenecks in natural populations, even leading to local extinction. Large variation in resource availability may explain the bottlenecks, but the role of these variations is still poorly understood. The goal of this study was to analyze if temporal variations in the guild of drosophilids breeding in fruits of Mauritia flexuosa (Arecaceae can be explained by the shortage of this resource during the dry season. Fruits of M. flexuosa were collected over one year in a gallery forest located in the Central Brazilian Savanna. The drosophilid assemblage varied over time, with a lower density of species and of individuals in the dry season, when the percentage of colonized fruits was also smaller. These findings suggest that although the fruits were available during the dry season, they were underused. This way, the resource availability does not seem to regulate the community in the dry season.

  20. Temporal Dynamics and Resource Availability for Drosophilid Fruit Flies (Insect, Diptera) in a Gallery Forest in the Brazilian Savanna

    International Nuclear Information System (INIS)

    Valadao, H.; Du Vall Hay, J.; Tidon, R.

    2010-01-01

    Seasonality can cause severe bottlenecks in natural populations, even leading to local extinction. Large variation in resource availability may explain the bottlenecks, but the role of these variations is still poorly understood. The goal of this study was to analyze if temporal variations in the guild of drosophilids breeding in fruits of Mauritia flexuosa (Arecaceae) can be explained by the shortage of this resource during the dry season. Fruits of M. flexuosa were collected over one year in a gallery forest located in the Central Brazilian Savanna. The drosophilid assemblage varied over time, with a lower density of species and of individuals in the dry season, when the percentage of colonized fruits was also smaller. These findings suggest that although the fruits were available during the dry season, they were under used. This way, the resource availability does not seem to regulate the community in the dry season.

  1. On the delineation of tropical vegetation types with an emphasis on forest/savanna transitions

    NARCIS (Netherlands)

    Torello-Raventos, M.; Feldpausch, T.R.; Veenendaal, E.M.; Sykora, K.V.

    2013-01-01

    Background: There is no generally agreed classification scheme for the many different vegetation formation types occurring in the tropics. This hinders cross-continental comparisons and causes confusion as words, such as ‘forest’ and ‘savanna’ have different meanings to different people. Tropical

  2. Contribution to the discussions on the origin of the cerrado biome: Brazilian savanna

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    MHO. Pinheiro

    Full Text Available Theories that attempt to explain the origin of the cerrado biome are mostly based on the isolated action of three major factors: climate, fire and soil. Another factor that has been mentioned is that of human interference. We hypothesise that the evolutionary origin of this biome resulted from the complex interaction of climate, fire and soil, with climate being the triggering agent of this assumed interaction. Fire, as well as acid and dystrophic soils, would be factors involved in the selection of savanna species throughout climatic events, during the Tertiary and the Quaternary, e.g. Pliocene and Pleistocene. The genesis of the physiognomies that would give rise to cerrado sensu lato, rather than forest formations, could have occurred due to the strong pressure exerted by the reduction in water availability, and the selection of the species adapted to the new conditions imposed by the environment. The characteristics of cerrado sensu lato soil, originated from edaphic impoverishment caused by lixiviation and successive past fires, would remain, even after hydric availability increased following the Pleistocene glaciations.

  3. The influence of biogeographic history on the functional and phylogenetic diversity of passerine birds in savannas and forests of the Brazilian Amazon.

    Science.gov (United States)

    Almeida, Sara Miranda; Juen, Leandro; Sobral, Fernando Landa; Santos, Marcos Pérsio Dantas

    2018-04-01

    Passeriformes is the largest and most diverse avian order in the world and comprises the Passeri and Tyranni suborders. These suborders constitute a monophyletic group, but differ in their ecology and history of occupation of South America. We investigated the influence of biogeographic history on functional and phylogenetic diversities of Passeri and Tyranni in forest and savanna habitats in the Brazilian Amazon. We compiled species composition data for 34 Passeriformes assemblages, 12 in savannas and 22 in forests. We calculated the functional (Rao's quadratic entropy, FD Q ) and phylogenetic diversities (mean pairwise distance, MPD, and mean nearest taxon distance, MNTD), and the functional beta diversity to investigate the potential role of biogeographic history in shaping ecological traits and species lineages of both suborders. The functional diversity of Passeri was higher than for Tyranni in both habitats. The MPD for Tyranni was higher than for Passeri in forests; however, there was no difference between the suborders in savannas. In savannas, Passeri presented higher MNTD than Tyranni, while in forest areas, Tyranni assemblages showed higher MNTD than Passeri. We found a high functional turnover (~75%) between Passeri and Tyranni in both habitats. The high functional diversity of Passeri in both habitats is due to the high diversity of ecological traits exhibited by species of this group, which enables the exploitation of a wide variety of resources and foraging strategies. The higher Tyranni MPD and MNTD in forests is likely due to Tyranni being older settlers in this habitat, resulting in the emergence and persistence of more lineages. The higher Passeri MNTD in savannas can be explained by the existence of a larger number of different Passeri lineages adapted to this severe habitat. The high functional turnover between the suborders in both habitats suggests an ecological strategy to avoid niche overlap.

  4. Importance of Habitat Heterogeneity in Richness and Diversity of Moths (Lepidoptera) in Brazilian Savanna.

    Science.gov (United States)

    Braga, Laura; Diniz, Ivone Rezende

    2015-06-01

    Moths exhibit different levels of fidelity to habitat, and some taxa are considered as bioindicators for conservation because they respond to habitat quality, environmental change, and vegetation types. In this study, we verified the effect of two phytophysiognomies of the Cerrado, savanna and forest, on the diversity distribution of moths of Erebidae (Arctiinae), Saturniidae, and Sphingidae families by using a hierarchical additive partitioning analysis. This analysis was based on two metrics: species richness and Shannon diversity index. The following questions were addressed: 1) Does the beta diversity of moths between phytophysiognomies add more species to the regional diversity than the beta diversity between sampling units and between sites? 2) Does the distribution of moth diversity differ among taxa? Alpha and beta diversities were compared with null models. The additive partitioning of species richness for the set of three Lepidoptera families identified beta diversity between phytophysiognomies as the component that contributed most to regional diversity, whereas the Shannon index identified alpha diversity as the major contributor. According to both species richness and the Shannon index, beta diversity between phytophysiognomies was significantly higher than expected by chance. Therefore, phytophysiognomies are the most important component in determining the richness and composition of the community. Additive partitioning also indicated that individual families of moths respond differently to the effect of habitat heterogeneity. The integrity of the Cerrado mosaic of phytophysiognomies plays a crucial role in maintaining moth biodiversity in the region. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Climate-biomes, pedo-biomes and pyro-biomes: which world view explains the tropical forest - savanna boundary in South America?

    Science.gov (United States)

    Langan, Liam; Higgins, Steven; Scheiter, Simon

    2015-04-01

    Elucidating the drivers of broad vegetation formations improves our understanding of earth system functioning. The biome, defined primarily by the dominance of a particular growth strategy, is commonly employed to group vegetation into similar units. Predicting tropical forest and savanna biome boundaries in South America has proven difficult. Process based DGVMs (Dynamic global vegetation models) are our best tool to simulate vegetation patterns, make predictions for future changes and test theory, however, many DGVMs fail to accurately simulate the spatial distribution or indeed presence of the South American savanna biome which can result in large differences in modelled ecosystem structural properties. Evidence suggests fire plays a significant role in mediating these forest and savanna biome boundaries, however, fire alone does not appear to be sufficient to predict these boundaries in South America using DGVMs hinting at the presence of one or more missing environmental factors. We hypothesise that soil depth, which affects plant available water by determining maximum storage potential and influences temporal availability, may be one of these missing environmental factors. To test our hypothesis we use a novel vegetation model, the aDGVM2. This model has been specifically designed to allow plant trait strategies, constrained by trade-offs between traits, evolve based on the abiotic and biotic conditions where the resulting community trait suites are emergent properties of model dynamics. Furthermore it considers root biomass in multiple soil layers and therefore allows the consideration of alternative rooting strategies, which in turn allows us to explore in more detail the role of soil hydraulic factors in controlling biome boundary distributions. We find that changes in soil depth, interacting with fire, affect the relative dominance of tree and grass strategies and thus the presence and spatial distribution of forest and savanna biomes in South America

  6. Frequency and distribution of forest, savanna, and crop fires over tropical regions during PEM-Tropics A

    Science.gov (United States)

    Olson, Jennifer R.; Baum, Bryan A.; Cahoon, Donald R.; Crawford, James H.

    1999-03-01

    Advanced very high resolution radiometer 1.1 km resolution satellite radiance data were used to locate active fires throughout much of the tropical region during NASA's Global Tropospheric Experiment (GTE) Pacific Exploratory Mission-Tropics (PEM-Tropics A) aircraft campaign, held in September and October 1996. The spatial and temporal distributions of the fires in Australia, southern Africa, and South America are presented here. The number of fires over northern Australia, central Africa, and South America appeared to decrease toward the end of the mission period. Fire over eastern Australia was widespread, and temporal patterns showed a somewhat consistent amount of burning with periodic episodes of enhanced fire counts observed. At least one episode of enhanced fire counts corresponded to the passage of a frontal system which brought conditions conducive to fire to the region, with strong westerlies originating over the hot, dry interior continent. Regions that were affected by lower than normal rainfall during the previous wet season (e.g., northern Australia and southwestern Africa) showed relatively few fires during this period. This is consistent with a drought-induced decrease in vegetation and therefore a decreased availability of fuel for burning. Alternatively, a heavier than normal previous wet season along the southeastern coast of South Africa may have contributed to high fuel loading and an associated relatively heavy amount of burning compared to data from previous years.

  7. Assessment of irrigation performance: contribution to improve water management in a small catchment in the Brazilian savannas

    Science.gov (United States)

    Rodrigues, Lineu; Marioti, Juliana; Steenhuis, Tammo; Wallender, Wesley

    2010-05-01

    Irrigated agriculture is the major consumer of surface water in Brazil using over 70% of the total supply. Due to the growing competition for water among different sectors of the economy, sustainable water use can only be achieved by decreasing the portion of water used by the irrigated agriculture. Thus, in order to maintain yield, farmers need to irrigate more efficiently. There is little known on irrigation efficiency in Brazil. Therefore a study was carried out in the Buriti Vermelho basin to assess the irrigation performance of existing system. The experimental basin has a drainage area of 940 hectares and is located in the eastern part of the Federal District, in the Brazilian savanna region. Agriculture is the main activity. There is a dominance of red latosols. Several types of land use and crop cover are encountered in the basin. Conflicts among farmers for water are increasing. As water, in quality and quantity, is crucial to maintain the livelihood of the population in the basin, concern about risk of water lack due to climatic and land use change is in place. Once irrigation is the main water user in the basin, to increase water availability and reduce conflicts a water resource management plan has to be established. For this purpose, irrigation system performance has to be understood. The objective of this work was to assess the performance and the management of irrigation (small and big) that has been carried out by farmers in the Buriti Vermelho experimental watershed. A survey undertaken in 2007 was used to identify the irrigation systems in the basin. It was verified that irrigation is practiced by both small (area up to 6 hectare) and big farmers. Small farmers usually crop limes and vegetables and use micro-irrigation, drip, sprinkler, guns or furrow to irrigate them. Big farmers plant annual crops and use center pivot as irrigation system. In this first assessment 13 irrigation systems were evaluated: five conventional sprinklers, four drip

  8. Effectiveness of scat-detection dogs in determining species presence in a tropical savanna landscape.

    Science.gov (United States)

    Vynne, Carly; Skalski, John R; Machado, Ricardo B; Groom, Martha J; Jácomo, Anah T A; Marinho-Filho, Jader; Ramos Neto, Mario B; Pomilla, Cristina; Silveira, Leandro; Smith, Heath; Wasser, Samuel K

    2011-02-01

    Most protected areas are too small to sustain populations of wide-ranging mammals; thus, identification and conservation of high-quality habitat for those animals outside parks is often a high priority, particularly for regions where extensive land conversion is occurring. This is the case in the vicinity of Emas National Park, a small protected area in the Brazilian Cerrado. Over the last 40 years the native vegetation surrounding the park has been converted to agriculture, but the region still supports virtually all of the animals native to the area. We determined the effectiveness of scat-detection dogs in detecting presence of five species of mammals threatened with extinction by habitat loss: maned wolf (Chrysocyon brachyurus), puma (Puma concolor), jaguar (Panthera onca), giant anteater (Myrmecophaga tridactyla), and giant armadillo (Priodontes maximus). The probability of scat detection varied among the five species and among survey quadrats of different size, but was consistent across team, season, and year. The probability of occurrence, determined from the presence of scat, in a randomly selected site within the study area ranged from 0.14 for jaguars, which occur primarily in the forested areas of the park, to 0.91 for maned wolves, the most widely distributed species in our study area. Most occurrences of giant armadillos in the park were in open grasslands, but in the agricultural matrix they tended to occur in riparian woodlands. At least one target species occurred in every survey quadrat, and giant armadillos, jaguars, and maned wolves were more likely to be present in quadrats located inside than outside the park. The effort required for detection of scats was highest for the two felids. We were able to detect the presence for each of five wide-ranging species inside and outside the park and to assign occurrence probabilities to specific survey sites. Thus, scat dogs provide an effective survey tool for rare species even when accurate detection

  9. Multiple remote sensing data sources to assess spatio-temporal patterns of fire incidence over Campos Amazônicos Savanna Vegetation Enclave (Brazilian Amazon).

    Science.gov (United States)

    Alves, Daniel Borini; Pérez-Cabello, Fernando

    2017-12-01

    Fire activity plays an important role in the past, present and future of Earth system behavior. Monitoring and assessing spatial and temporal fire dynamics have a fundamental relevance in the understanding of ecological processes and the human impacts on different landscapes and multiple spatial scales. This work analyzes the spatio-temporal distribution of burned areas in one of the biggest savanna vegetation enclaves in the southern Brazilian Amazon, from 2000 to 2016, deriving information from multiple remote sensing data sources (Landsat and MODIS surface reflectance, TRMM pluviometry and Vegetation Continuous Field tree cover layers). A fire scars database with 30 m spatial resolution was generated using a Landsat time series. MODIS daily surface reflectance was used for accurate dating of the fire scars. TRMM pluviometry data were analyzed to dynamically establish time limits of the yearly dry season and burning periods. Burned area extent, frequency and recurrence were quantified comparing the results annually/seasonally. Additionally, Vegetation Continuous Field tree cover layers were used to analyze fire incidence over different types of tree cover domains. In the last seventeen years, 1.03millionha were burned within the study area, distributed across 1432 fire occurrences, highlighting 2005, 2010 and 2014 as the most affected years. Middle dry season fires represent 86.21% of the total burned areas and 32.05% of fire occurrences, affecting larger amount of higher density tree surfaces than other burning periods. The results provide new insights into the analysis of burned areas of the neotropical savannas, spatially and statistically reinforcing important aspects linked to the seasonality patterns of fire incidence in this landscape. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Phytochemical Analysis and Antifungal Activity of Extracts from Leaves and Fruit Residues of Brazilian Savanna Plants Aiming Its Use as Safe Fungicides.

    Science.gov (United States)

    Breda, Caroline Alves; Gasperini, Alessandra Marcon; Garcia, Vera Lucia; Monteiro, Karin Maia; Bataglion, Giovana Anceski; Eberlin, Marcos Nogueira; Duarte, Marta Cristina Teixeira

    2016-08-01

    The increasing demand for safe food without preservatives or pesticides residues has encouraged several studies on natural products with antifungal activity and low toxicity. In this study, ethanolic extracts from leaves and fruit residues (peel and seeds) of three Brazilian savanna species (Acrocomia aculeata, Campomanesia adamantium and Caryocar brasiliense) were evaluated against phytopathogenic fungi. Additionally, the most active extract was chemically characterized by ESI-MS and its oral acute toxicity was evaluated. Extracts from C. brasiliense (pequi) peel and leaves were active against Alternaria alternata, Alternaria solani and Venturia pirina with minimal inhibitory concentrations between 350 and 1000 µg/mL. When incorporated in solid media, these extracts extended the lag phase of A. alternata and A. solani and reduced the growth rate of A. solani. Pequi peel extract showed better antifungal activity and their ESI-MS analysis revealed the presence of substances widely reported as antifungal such as gallic acid, quinic acid, ellagic acid, glucogalin and corilagin. The oral acute toxicity was relatively low, being considered safe for use as a potential natural fungicide.

  11. Biophysical Properties of Cultivated Pastures in the Brazilian Savanna Biome: An Analysis in the Spatial-Temporal Domains Based on Ground and Satellite Data

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    Fernando M. Araújo

    2013-01-01

    Full Text Available Brazil has the largest commercial beef cattle herd in the world, with cattle ranching being particularly prominent in the 200-million ha, Brazilian neotropical moist savanna biome, known as Cerrado, one of the world’s hotspots for biodiversity conservation. As decreasing productivity is a major concern affecting the Cerrado pasturelands, evaluation of pasture conditions through the determination of biophysical parameters is instrumental for more effective management practices and herd occupation strategies. Within this context, the primary goal of this study was the regional assessment of pasture biophysical properties, through the scaling of wet- and dry-season ground truth data (total biomass, green biomass, and % green cover via the combined use of high (Landsat-TM and moderate (MODIS spatial resolution vegetation index images. Based on the high correlation found between NDVI (normalized difference vegetation index and % green cover (r = 0.95, monthly MODIS-based % green cover images were derived for the 2009–2010 hydrological cycle, which were able to capture major regional patterns and differences in pasture biophysical responses, including the increasing greenness values towards the southern portions of the biome, due to both local conditions (e.g., more fertile soils and management practices. These results corroborate the development of biophysically-based landscape degradation indices, in support of improved land use governance and natural area conservation in the Cerrado.

  12. Medium- and large-sized mammals in a steppic savanna area of the Brazilian Pampa: survey and conservation issues of a poorly known fauna.

    Science.gov (United States)

    Espinosa, C C; Galiano, D; Kubiak, B B; Marinho, J R

    2016-02-01

    The wildlife of the Brazilian Pampa is threatened by large-scale habitat loss, due in particular to the expansion of soybean cultivation and the conversion of grasslands areas into extensive areas of silviculture. It is essential to study how the mammal fauna copes with the highly fragmented, human-influenced, non-protected landscape. Our study presents the results of a survey of the large- and medium-sized mammals of a typical human-influenced steppic savanna area of the Pampa biome. The survey was conducted exclusively with the use of camera traps over a period of 16 months. The relative frequencies of species in the area were evaluated. We recorded 18 species, some of them locally threatened (Tamandua tetradactyla, Alouatta caraya, Leopardus colocolo, Leopardus geoffroyi, Leopardus wiedii, Puma yagouaroundi, Mazama gouazoubira and Cuniculus paca). Several species were found to thrive in the area; however, many species were considered rare, and undoubtedly new species could be recorded if we continued the sampling. Our results contribute to the knowledge of faunal diversity in the Pampa biome and associated habitats, warn about threats and provide support for conservation measures.

  13. Medium- and large-sized mammals in a steppic savanna area of the Brazilian Pampa: survey and conservation issues of a poorly known fauna

    Directory of Open Access Journals (Sweden)

    C. C. Espinosa

    Full Text Available Abstract The wildlife of the Brazilian Pampa is threatened by large-scale habitat loss, due in particular to the expansion of soybean cultivation and the conversion of grasslands areas into extensive areas of silviculture. It is essential to study how the mammal fauna copes with the highly fragmented, human-influenced, non-protected landscape. Our study presents the results of a survey of the large- and medium-sized mammals of a typical human-influenced steppic savanna area of the Pampa biome. The survey was conducted exclusively with the use of camera traps over a period of 16 months. The relative frequencies of species in the area were evaluated. We recorded 18 species, some of them locally threatened (Tamandua tetradactyla, Alouatta caraya, Leopardus colocolo, Leopardus geoffroyi, Leopardus wiedii, Puma yagouaroundi, Mazama gouazoubira and Cuniculus paca. Several species were found to thrive in the area; however, many species were considered rare, and undoubtedly new species could be recorded if we continued the sampling. Our results contribute to the knowledge of faunal diversity in the Pampa biome and associated habitats, warn about threats and provide support for conservation measures.

  14. Abundance and Night Hourly Dispersal of the Vesicating Beetles of the Genus Paederus (Coleoptera: Staphylinidae) Attracted to Fluorescent, Incandescent, and Black Light Sources in the Brazilian Savanna.

    Science.gov (United States)

    Lima, D C B; Costa, A A V; Silva, F S

    2015-01-01

    Paederus beetles are cosmopolitan medically important insects that cause dermatitis linearis to humans. In Brazil, despite the medical importance of these beetles, no studies focusing directly on the abundance and ecological features of harmful species exist. Therefore, this study aims at determining the abundance and the nocturnal hourly dispersal of Paederus species attracted to fluorescent, incandescent, and black light sources in the Brazilian savanna. Paederus species were captured from May to September for three consecutive years, between 2011 and 2013. The specimens were caught hourly, from 1800 to 0600 hours. Paederus beetles were attracted to incandescent, fluorescent, and black light lamps as light sources. A total of 959 individuals of five species were collected. The collected species were Paederus protensus Sharp (59.85%), Paederus columbinus Laporte de Castelnau (29.20%), Paederus mutans Sharp (7.09%), Paederus brasiliensis Erichson (3.34%), and Paederus ferus Erichson (0.52%). The black light was the most attractive source, and the darkest collecting point was the most representative for the number of individuals. The lowest catches were captured at full moon, and the highest catches were between 2200 and 0100 hours. Future investigations are needed to better understand the role of night temperature and soil humidity affecting the seasonal growth of Paederus beetle populations of northeastern Brazil. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Phenological patterns of Spodoptera Guenée, 1852 (Lepidoptera: Noctuidae) is more affected by ENSO than seasonal factors and host plant availability in a Brazilian Savanna

    Science.gov (United States)

    Piovesan, Mônica; Specht, Alexandre; Carneiro, Eduardo; Paula-Moraes, Silvana Vieira; Casagrande, Mirna Martins

    2018-03-01

    The identification of factors responsible for the population dynamics is fundamental for pest management, since losses can reach 18% of annual production. Besides regular seasonal environmental factors and crop managements, additional supra-annual meteorological phenomena can also affect population dynamics, although its relevance has been rarely investigated. Among crop pests, Spodoptera stands out due to its worldwide distribution, high degree of polyphagy, thus causing damages in several crops in the world. Aiming to distinguish the relevance of different factors shaping population dynamics of Spodoptera in an ecosystem constituted of dry and rainy seasons, the current study used circular statistics to identify phenological patterns and test if its population fluctuation is driven by El Niño-Southern Oscillation (ENSO) effect, seasonal meteorological parameters, and/or host plant availability. Samplings were done in an intercropping system, in the Brazilian Savanna, during the new moon cycles between July/2013 and June/2016. Species were recorded all year round, but demonstrated differently non-uniform distribution, being concentrated in different seasons of the year. Population fluctuations were mostly affected by the ENSO intensity, despite the contrasting seasonal meteorological variation or host plant availability in a 400-m radius. Studies involving the observation of supra-annual phenomena, although rare, reach similar conclusions in relation to Neotropical insect fauna. Therefore, it is paramount to have long-term sampling studies to obtain a more precise response of the pest populations towards the agroecosystem conditions.

  16. Knowledge and extractivism of Stryphnodendron rotundifolium Mart. in a local community of the Brazilian Savanna, Northeastern Brazil.

    Science.gov (United States)

    Feitosa, Ivanilda Soares; Albuquerque, Ulysses Paulino; Monteiro, Júlio Marcelino

    2014-09-09

    This study aims to understand how the stem bark of Stryphnodendron rotundifolium Mart. is used by a rural community in the savanna of Northeastern Brazil, associated with a preliminary assessment involving plant population structure and extractivism in the main sites of collection. A population structure study and analysis of bark extractivism was conducted in two sites: one within the forest and another at its edge. We had the intention of testing whether there are differences between these sites; since the local extractive practice is prohibited, expecting more intense extraction in the forest interior than its edge by the local fiscalization. We interviewed 120 informants who reported knowing and using the species, and also the places of extractivism. We also calculated quantitative measures of local knowledge, and the influence of gender and age on the knowledge about this species. Knowledge of the uses was evenly distributed between men and women. A total of 28 specimens were recorded at Site 1, whereas 23 were identified at Site 2, with the specimens at both sites distributed in 4-diameter classes with 4-cm intervals. Nine of the specimens found in Site 1 (32.14%) showed some sign of extraction. No specimen from Site 2 showed signs of extraction. In Site 1, the total area of stem bark removed was 43,468 cm2, and the total area of stem bark available was 33,200 cm2. In Site 2, only the available stem-bark area of 44,666 cm2 was identified because no specimens were harvested. There is no difference in knowledge of this species regarding the gender and age. Stryphnodendron rotundifolium is a key resource for the studied community. A large proportion of bark collected from the first diameter size class may affect the growth of these individuals and may influence the recruitment process. Perhaps, this effect may explain the absence of individuals in some size classes.

  17. Beneficial Effects of Ants and Spiders on the Reproductive Value of Eriotheca gracilipes (Malvaceae) in a Tropical Savanna.

    Science.gov (United States)

    Stefani, Vanessa; Pires, Tayna Lopes; Torezan-Silingardi, Helena Maura; Del-Claro, Kleber

    2015-01-01

    Predators affect plant fitness when they forage on them and reduce the action of herbivores. Our study evaluates the complementary effects of spiders and ants that visit the extrafloral nectaries of Eriotheca gracilipes (Malvaceae) on the production of fruits and viable seeds of these savanna trees. Four experimental groups were established: control group - with free access of spiders and ants; exclusion group - spiders and ants excluded; ant group - absence of spiders; and spider group - absence of ants. The presence of ants reduced the spider richness; however, the presence of spiders did not affect the ant richness. A significantly higher number of fruits per buds were found in the presence of spiders alone or spiders and ants together (control group) compared with the absence of both predators (exclusion group). The number of seeds per fruits and seed viability were higher in the control group. This is the first study showing that spiders and ants may exert a positive and complementary effect on the reproductive value of an extrafloral nectaried plant. Mostly the impact of ants and/or spiders on herbivores is considered, whereas our study reinforces the importance of evaluating the effect of multiple predators simultaneously, exploring how the interactions among predators with distinct skills may affect the herbivores and the plants on which they forage.

  18. Sorption of thiabendazole in sub-tropical Brazilian soils.

    Science.gov (United States)

    de Oliveira Neto, Odilon França; Arenas, Alejandro Yopasa; Fostier, Anne Hélène

    2017-07-01

    Thiabendazole (TBZ) is an ionizable anthelmintic agent that belongs to the class of benzimidazoles. It is widely used in veterinary medicine and as a fungicide in agriculture. Sorption and desorption are important processes influencing transport, transformation, and bioavailability of xenobiotic compounds in soils; data related to sorption capacity are therefore needed for environmental risk assessments. The aim of this work was to assess the sorption potential of TBZ in four Brazilians soils (sandy, sandy-clay, and clay soils), using batch equilibrium experiments at three pH ranges (2.3-3.0, 3.8-4.2, and 5.5-5.7). The Freundlich sorption coefficient (K F ) ranged from 9.0 to 58 μg 1-1/n  (mL) 1/n  g -1 , with higher values generally observed at the lower pH ranges (2.3-3.0 and 3.8-4.2) and for clay soils. The highest organic carbon-normalized sorption coefficients (K OC ) obtained at pH 3.8-5.7 (around the natural pH range of 4.1-5.0) for both clay soils and sandy-clay soil were 3255 and 2015 mL g -1 , respectively. The highest correlations K F vs SOM (r = 0.70) and K F vs clay content (r = 0.91) were observed at pH 3.8-4.2. Our results suggest that TBZ sorption/desorption is strongly pH dependent and that its mobility could be higher in the studied soils than previously reported in soils from temperate regions.

  19. Spatial Distribution of Aboveground Carbon Stock of the Arboreal Vegetation in Brazilian Biomes of Savanna, Atlantic Forest and Semi-Arid Woodland.

    Science.gov (United States)

    Scolforo, Henrique Ferraco; Scolforo, Jose Roberto Soares; Mello, Carlos Rogerio; Mello, Jose Marcio; Ferraz Filho, Antonio Carlos

    2015-01-01

    The objective of this study was to map the spatial distribution of aboveground carbon stock (using Regression-kriging) of arboreal plants in the Atlantic Forest, Semi-arid woodland, and Savanna Biomes in Minas Gerais State, southeastern Brazil. The database used in this study was obtained from 163 forest fragments, totaling 4,146 plots of 1,000 m2 distributed in these Biomes. A geographical model for carbon stock estimation was parameterized as a function of Biome, latitude and altitude. This model was applied over the samples and the residuals generated were mapped based on geostatistical procedures, selecting the exponential semivariogram theoretical model for conducting ordinary Kriging. The aboveground carbon stock was found to have a greater concentration in the north of the State, where the largest contingent of native vegetation is located, mainly the Savanna Biome, with Wooded Savanna and Shrub Savanna phytophysiognomes. The largest weighted averages of carbon stock per hectare were found in the south-center region (48.6 Mg/ha) and in the southern part of the eastern region (48.4 Mg/ha) of Minas Gerais State, due to the greatest predominance of Atlantic Forest Biome forest fragments. The smallest weighted averages per hectare were found in the central (21.2 Mg/ha), northern (20.4 Mg/ha), and northwestern (20.7 Mg/ha) regions of Minas Gerais State, where Savanna Biome fragments are predominant, in the phytophysiognomes Wooded Savanna and Shrub Savanna.

  20. Gaseous Nitrogen Losses from Tropical Savanna Soils of Northern Australia: Dynamics, Controls and Magnitude of N2O, NO, and N2 emissions

    Science.gov (United States)

    Werner, C.; Hickler, T.; Hutley, L. B.; Butterbach-Bahl, K.

    2014-12-01

    Tropical savanna covers a large fraction of the global land area and thus may have a substantial effect on the global soil-atmosphere exchange of nitrogen. The pronounced seasonality of hygric conditions in this ecosystem affects strongly microbial process rates in the soil. As these microbial processes control the uptake, production, and release of nitrogen compounds, it is thought that this seasonality finally leads to strong temporal dynamics and varying magnitudes of gaseous losses to the atmosphere. However, given their areal extent and in contrast to other ecosystems, still few in-situ or laboratory studies exist that assess the soil-atmosphere exchange of nitrogen. We present laboratory incubation results from intact soil cores obtained from a natural savanna site in Northern Australia, where N2O, NO, and N2 emissions under controlled environmental conditions were investigated. Furthermore, in-situ measurements of high temporal resolution at this site recorded with automated static and dynamic chamber systems are discussed (N2O, NO). This data is then used to assess the performance of a process-based biogeochemical model (LandscapeDNDC), and the potential magnitude and dynamics of components of the site-scale nitrogen cycle where no measurements exist (biological nitrogen fixation and nitrate leaching). Our incubation results show that severe nutrient limitation of the soil only allows for very low N2O emissions (0.12 kg N ha-1 yr-1) and even a periodic N2O uptake. Annual NO emissions were estimated at 0.68 kg N ha-1 yr-1, while the release of inert nitrogen (N2) was estimated at 6.75 kg N ha-1 yr-1 (data excl. contribution by pulse emissions). We observed only minor N2O pulse emissions after watering the soil cores and initial rain events of the dry to wet season transition in-situ, but short-lived NO pulse emissions were substantial. Interestingly, some cores exhibited a very different N2O emission potential, indicating a substantial spatial variability of

  1. Habitat Heterogeneity Variably Influences Habitat Selection by Wild Herbivores in a Semi-Arid Tropical Savanna Ecosystem.

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    Victor K Muposhi

    Full Text Available An understanding of the habitat selection patterns by wild herbivores is critical for adaptive management, particularly towards ecosystem management and wildlife conservation in semi arid savanna ecosystems. We tested the following predictions: (i surface water availability, habitat quality and human presence have a strong influence on the spatial distribution of wild herbivores in the dry season, (ii habitat suitability for large herbivores would be higher compared to medium-sized herbivores in the dry season, and (iii spatial extent of suitable habitats for wild herbivores will be different between years, i.e., 2006 and 2010, in Matetsi Safari Area, Zimbabwe. MaxEnt modeling was done to determine the habitat suitability of large herbivores and medium-sized herbivores. MaxEnt modeling of habitat suitability for large herbivores using the environmental variables was successful for the selected species in 2006 and 2010, except for elephant (Loxodonta africana for the year 2010. Overall, large herbivores probability of occurrence was mostly influenced by distance from rivers. Distance from roads influenced much of the variability in the probability of occurrence of medium-sized herbivores. The overall predicted area for large and medium-sized herbivores was not different. Large herbivores may not necessarily utilize larger habitat patches over medium-sized herbivores due to the habitat homogenizing effect of water provisioning. Effect of surface water availability, proximity to riverine ecosystems and roads on habitat suitability of large and medium-sized herbivores in the dry season was highly variable thus could change from one year to another. We recommend adaptive management initiatives aimed at ensuring dynamic water supply in protected areas through temporal closure and or opening of water points to promote heterogeneity of wildlife habitats.

  2. Elemental contents in exotic Brazilian tropical fruits evaluated by energy dispersive X-ray fluorescence

    Directory of Open Access Journals (Sweden)

    Oliveira Alessandra Lopes de

    2006-01-01

    Full Text Available The exotic flavor of Brazilian tropical fruits led to increased consumption. Consumers awareness regarding balanced diets, makes necessary determining nutritional composition - vitamins and minerals of the fruits ordinarily consumed. This study contributed to the evaluation of macro (K, Ca and microelements (Mn, Fe, Cu, Zn and Br in eight exotic Brazilian tropical fruits: "abiu" (Lucuma caimito Ruiz & Pav., "jenipapo" (Genipa americana L., "jambo rosa" (rose apple, Eugenia Jambos L., "jambo vermelho" (Syzygium malaccence L., Merr & Perry, "macaúba" (Acrocomia aculeata Jacq. Lood. Ex Mart., "mangaba" (Hancornia speciosa, "pitanga" (Brazilian Cherry, Eugenia uniflora L., and tamarind (Tamarindus indica L., using the Energy Dispersive X-Ray Fluorescence (EDXRF technique. "jambo vermelho" and "macaúba" presented the highest values of K concentrations, 1,558 and 1,725 mg 100 g-1, respectively. On the other hand, Ca concentrations were highest in "macaúba" (680 mg 100 g-1 and "jenipapo" (341 mg 100 g-1. The microelemental concentrations in these eight fruits ranged from: 0.9 to 2.0 mg 100 g-1 for Mn, 3.9 to 11.4 mg 100 g-1 for Fe, 0.5 to 1.0 mg 100 g-1 for Cu, 0.6 to 1.5 mg 100 g-1 for, Zn and 0.3 to 1.3 mg 100 g-1 for Br. The amounts of macro and microelements in the eight fruits analyzed were compared to other tropical fruits and it was found that some of them could be classified as rich sources for these macro and microelements.

  3. Plant Traits Demonstrate That Temperate and Tropical Giant Eucalypt Forests Are Ecologically Convergent with Rainforest Not Savanna

    Science.gov (United States)

    Tng, David Y. P.; Jordan, Greg J.; Bowman, David M. J. S.

    2013-01-01

    Ecological theory differentiates rainforest and open vegetation in many regions as functionally divergent alternative stable states with transitional (ecotonal) vegetation between the two forming transient unstable states. This transitional vegetation is of considerable significance, not only as a test case for theories of vegetation dynamics, but also because this type of vegetation is of major economic importance, and is home to a suite of species of conservation significance, including the world’s tallest flowering plants. We therefore created predictions of patterns in plant functional traits that would test the alternative stable states model of these systems. We measured functional traits of 128 trees and shrubs across tropical and temperate rainforest – open vegetation transitions in Australia, with giant eucalypt forests situated between these vegetation types. We analysed a set of functional traits: leaf carbon isotopes, leaf area, leaf mass per area, leaf slenderness, wood density, maximum height and bark thickness, using univariate and multivariate methods. For most traits, giant eucalypt forest was similar to rainforest, while rainforest, particularly tropical rainforest, was significantly different from the open vegetation. In multivariate analyses, tropical and temperate rainforest diverged functionally, and both segregated from open vegetation. Furthermore, the giant eucalypt forests overlapped in function with their respective rainforests. The two types of giant eucalypt forests also exhibited greater overall functional similarity to each other than to any of the open vegetation types. We conclude that tropical and temperate giant eucalypt forests are ecologically and functionally convergent. The lack of clear functional differentiation from rainforest suggests that giant eucalypt forests are unstable states within the basin of attraction of rainforest. Our results have important implications for giant eucalypt forest management. PMID:24358359

  4. Cost-Effectiveness of Seven Approaches to Map Vegetation Communities — A Case Study from Northern Australia’s Tropical Savannas

    Directory of Open Access Journals (Sweden)

    Stuart Phinn

    2013-01-01

    Full Text Available Vegetation communities are traditionally mapped from aerial photography interpretation. Other semi-automated methods include pixel- and object-based image analysis. While these methods have been used for decades, there is a lack of comparative research. We evaluated the cost-effectiveness of seven approaches to map vegetation communities in a northern Australia’s tropical savanna environment. The seven approaches included: (1. aerial photography interpretation, (2. pixel-based image-only classification (Maximum Likelihood Classifier, (3. pixel-based integrated classification (Maximum Likelihood Classifier, (4. object-based image-only classification (nearest neighbor classifier, (5. object-based integrated classification (nearest neighbor classifier, (6. object-based image-only classification (step-wise ruleset, and (7. object-based integrated classification (step-wise ruleset. Approach 1 was applied to 1:50,000 aerial photography and approaches 2–7 were applied to SPOT5 and Landsat5 TM multispectral data. The integrated approaches (3, 5 and 7 included ancillary data (a digital elevation model, slope model, normalized difference vegetation index and hydrology information. The cost-effectiveness was assessed taking into consideration the accuracy and costs associated with each classification approach and image dataset. Accuracy was assessed in terms of overall accuracy and the costs were evaluated using four main components: field data acquisition and preparation, image data acquisition and preparation, image classification and accuracy assessment. Overall accuracy ranged from 28%, for the image-only pixel-based approach, to 67% for the aerial photography interpretation, while total costs ranged from AU$338,000 to AU$388,180 (Australian dollars, for the pixel-based image-only classification and aerial photography interpretation respectively. The most labor-intensive component was field data acquisition and preparation, followed by image data

  5. Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

    Directory of Open Access Journals (Sweden)

    J. Lloyd

    2015-11-01

    C / N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm and potassium (Km. Both Nm and Km also increased with declining mean annual precipitation (PA, but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such as mean canopy height, area-based soil exchangeable potassium content, [K]sa , proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination. Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10. Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests – in combination with some newly conceptualised interacting effects of PA and θP also presented here – a critical role for potassium as a modulator of tropical vegetation structure and function.

  6. Multivariate analysis of effects of diurnal temperature and seasonal humidity variations by tropical savanna climate on the emissions of anthropogenic volatile organic compounds.

    Science.gov (United States)

    Liu, Chih-Chung; Chen, Wei-Hsiang; Yuan, Chung-Shin; Lin, Chitsan

    2014-02-01

    Volatile organic compounds (VOCs), particularly those from anthropogenic sources, have been of substantial concern. In this study, the influences of diurnal temperature and seasonal humidity variations by tropical savanna climate on the distributions of VOCs from stationary industrial sources were investigated by analyzing the concentrations during the daytime and nighttime in the dry and wet seasons and assessing the results by principal component analysis (PCA) and cluster analysis. Kaohsiung City in Southern Taiwan, known for its severe VOC pollution, was chosen as the location to be examined. In the results, the VOC concentrations were lower during the daytime and in the wet season, possibly attributed to the stronger photochemical reactions and increasing inhibition of VOC emissions and transports by elevating humidity levels. Certain compounds became appreciably more important at higher humidity, as these compounds were saturated hydrocarbons with relatively low molecular weights. The influence of diurnal temperature variation on VOC distribution behaviors seemed to be less important than and interacted with that of seasonal humidity variation. Heavier aromatic hydrocarbons with more complex structures and some aliphatic compounds were found to be the main species accounting for the maximum variances of the data observed at high humidity, and the distinct grouping of compounds implied a pronounced inherent characteristic of each cluster in the observed VOC distributions. Under the influence of diurnal temperature variation, selected VOCs that may have stronger photochemical resistances and/or longer lifetimes in the atmosphere were clustered with each other in the cluster analysis, whereas the other groups might consist of compounds with different levels of vulnerability to sunlight or high temperatures. These findings prove the complications in the current knowledge regarding the VOC contaminations and providing insight for managing the adverse impacts of

  7. Integration of UAV and ground-based Structure from Motion with Multi-View Stereo photogrammetry and hydrological data to quantify hillslope gully erosion processes in tropical savanna

    Science.gov (United States)

    Koci, J.; Jarihani, B.; Sidle, R. C.; Wilkinson, S. N.; Bartley, R.

    2017-12-01

    Structure from Motion with Multi-View Stereo (SfM-MVS) photogrammetry provides a cost-effective method of rapidly acquiring high resolution (sub-meter) topographic data, but is rarely used in hydrogeomorphic investigations of gully erosion. This study integrates high resolution topographic and land cover data derived from an unmanned aerial vehicle (UAV) and ground-based SfM-MVS photogrammetry, with rainfall and gully discharge data, to elucidate hydrogeomorphic processes driving hillslope gully erosion. The study is located within a small (13 km2) dry-tropical savanna catchment within the Burdekin River Basin, northeast Australia, which is a major contributor sediments and nutrients to the Great Barrier Reef World Heritage Area. A pre-wet season UAV survey covered an entire hillslope gully system (0.715 km2), and is used to derive topography, ground cover and hydrological flow pathways in the gully contributing area. Ground-based surveys of a single active gully (650 m2) within the broader hillslope are compared between pre- and post-wet season conditions to quantify gully geomorphic change. Rainfall, recorded near to the head of the gully, is related to gully discharge during sporadic storm events. The study provides valuable insights into the relationships among hydrological flow pathways, ground cover, rainfall and runoff, and spatial patterns of gully morphologic change. We demonstrate how UAV and ground-based SfM-MVS photogrammetry can be used to improve hydrogeomorphic process understanding and aid in the modelling and management of hillslope gully systems.

  8. Diameter distribution in a Brazilian tropical dry forest domain: predictions for the stand and species.

    Science.gov (United States)

    Lima, Robson B DE; Bufalino, Lina; Alves, Francisco T; Silva, José A A DA; Ferreira, Rinaldo L C

    2017-01-01

    Currently, there is a lack of studies on the correct utilization of continuous distributions for dry tropical forests. Therefore, this work aims to investigate the diameter structure of a brazilian tropical dry forest and to select suitable continuous distributions by means of statistic tools for the stand and the main species. Two subsets were randomly selected from 40 plots. Diameter at base height was obtained. The following functions were tested: log-normal; gamma; Weibull 2P and Burr. The best fits were selected by Akaike's information validation criterion. Overall, the diameter distribution of the dry tropical forest was better described by negative exponential curves and positive skewness. The forest studied showed diameter distributions with decreasing probability for larger trees. This behavior was observed for both the main species and the stand. The generalization of the function fitted for the main species show that the development of individual models is needed. The Burr function showed good flexibility to describe the diameter structure of the stand and the behavior of Mimosa ophthalmocentra and Bauhinia cheilantha species. For Poincianella bracteosa, Aspidosperma pyrifolium and Myracrodum urundeuva better fitting was obtained with the log-normal function.

  9. Carbon emission as a function of energy generation in hydroelectric reservoirs in Brazilian dry tropical biome

    International Nuclear Information System (INIS)

    Ometto, Jean P.; Cimbleris, André C.P.; Santos, Marco A. dos; Rosa, Luiz P.; Abe, Donato; Tundisi, José G.; Stech, José L.; Barros, Nathan; Roland, Fábio

    2013-01-01

    Most energy generation globally is fueled by coal and oil, raising concerns about greenhouse gas emissions. Hydroelectric reservoirs are anthropogenic aquatic systems that occur across a wide geographical extent, and, in addition to their importance for energy production, they have the potential to release two important greenhouse gases (GHGs), carbon dioxide and methane. We report results from an extensive study of eight hydroelectric reservoirs located in central and southeastern tropical Brazil. In the Brazilian dry tropical biome reservoirs, emissions (in tons of CO 2 Eq. per MW h) varied from 0.01 to 0.55, and decreased with reservoir age. Total emissions were higher in the reservoir lake when compared to the river downstream the dam; however, emissions per unit area, in the first kilometer of the river after the dam, were higher than that in the reservoir. The results showed, despite higher carbon emissions per energy production in the youngest reservoirs, lower emission from hydroelectric reservoirs from the studied region in relation to thermo electrical supply, fueled by coal or fossil fuel. The ratio emission of GHG per MWh produced is an important parameter in evaluating the service provided by hydroelectric reservoir and for energy planning policies. - Highlights: ► Hydroelectric reservoirs construction is growing worldwide. ► The effect of hydropower reservoir in the carbon cycle is dependent on environment characteristics. ► Carbon emissions per energy production are higher in the youngest tropical savannah reservoirs. ► Methane emissions decrease with reservoir age in tropical savannah reservoirs. ► In general, the effect of hydropower in the carbon cycle is lower than other energy sources

  10. SOIL EMISSIONS OF N2O, NO AND CO2 IN BRAZILIAN SAVANNAS: EFFECTS OF VEGETATION TYPE, SEASONALITY, AND PRESCRIBED FIRES

    Science.gov (United States)

    Using closed chamber techniques, soil fluxes of NO, N20 and C02 were measured from September 1999 through October 2000 in savanna areas in central Brazil (Cerrado) subjected to prescribed fires. Our studies focused on two vegetation types, cerrado stricto sensu (20-50% canopy cov...

  11. Biological screening of Brazilian medicinal plants

    Directory of Open Access Journals (Sweden)

    Tânia Maria de Almeida Alves

    2000-06-01

    Full Text Available In this study, we screened sixty medicinal plant species from the Brazilian savanna ("cerrado" that could contain useful compounds for the control of tropical diseases. The plant selection was based on existing ethnobotanic information and interviews with local healers. Plant extracts were screened for: (a molluscicidal activity against Biomphalaria glabrata, (b toxicity to brine shrimp (Artemia salina L., (c antifungal activity in the bioautographic assay with Cladosporium sphaerospermum and (d antibacterial activity in the agar diffusion assay against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Pseudomonas aeruginosa. Forty-two species afforded extracts that showed some degree of activity in one or more of these bioassays.

  12. Trophic structure of a fish community in Bananal stream subbasin in Brasília National Park, Cerrado biome (Brazilian Savanna, DF

    Directory of Open Access Journals (Sweden)

    Mariana Schneider

    2011-01-01

    Full Text Available The aim of this study was to determine the trophic structure of the fish community in the Bananal stream subbasin, which belongs to a well-preserved Cerrado area (Brazilian Savanna in Brasília National Park, Brazil. We also evaluated the influence of environmental variations in the diet of fish species. Four samples were taken in each 30 m long established transect, two in the rainy season and two in the dry season. A total of 1,050 stomachs of the 13 most abundant species were analyzed. A total of 36 food items were consumed, where 24 were autochthonous, 8 allochthonous, and 4 of undetermined origin. Non-metric multidimensional scaling (NMDS analysis, in addition to the results of frequency of occurrence and abundance charts, was used to determine four groups of feeding guilds: detritivores, omnivores (tending toward herbivory and invertivory, invertivores and piscivores. Around 69% of the volume of resources consumed was allochthonous, which proves the importance of the resources provided by riparian vegetation. The contribution of autochthonous and allochthonous items in the diet differed due to seasonality for Aspidoras fuscoguttatus, Astyanax sp., Characidium xanthopterum, Hyphessobrycon balbus, Kolpotocheirodon theloura, Moenkhausia sp., Phalloceros harpagos, and Rivulus pictus. Despite the Cerrado climate characteristics, there was no significant influence of season on the fish diet. The absence of seasonal variation and the predominance of allochthonous items in the fish diet are probably associated with the presence of riparian vegetation, which acts as a transition area in the Cerrado biome and provides resources for the aquatic fauna. This work shows the importance of studies in non-disturbed areas considered here as a source of information concerning the biology of fish species and as a guide for direct conservation policies on the management of aquatic resources, recovery of damaged areas and determination of priority areas for

  13. Floristics and biogeography of vegetation in seasonally dry tropical regions

    DEFF Research Database (Denmark)

    Dexter, K.G.; Smart, B.; Baldauf, C.

    2015-01-01

    To provide an inter-continental overview of the floristics and biogeography of drought-adapted tropical vegetation formations, we compiled a dataset of inventory plots in South America (n=93), Africa (n=84), and Asia (n=92) from savannas (subject to fire), seasonally dry tropical forests (not...... similar vegetation formations (e.g. savannas) are floristically highly dissimilar. Neotropical moist forest, savanna and seasonally dry tropical forest are floristically distinct, but elsewhere there is no clear floristic division of savanna and seasonally dry tropical forest, though moist and dry...... of the ecology, biology and conservation of savannas and seasonally dry tropical forests may be difficult....

  14. Tropical Atlantic Contributions to Strong Rainfall Variability Along the Northeast Brazilian Coast

    Directory of Open Access Journals (Sweden)

    G. A. Hounsou-gbo

    2015-01-01

    Full Text Available Tropical Atlantic (TA Ocean-atmosphere interactions and their contributions to strong variability of rainfall along the Northeast Brazilian (NEB coast were investigated for the years 1974–2008. The core rainy seasons of March-April and June-July were identified for Fortaleza (northern NEB; NNEB and Recife (eastern NEB; ENEB, respectively. Lagged linear regressions between sea surface temperature (SST and pseudo wind stress (PWS anomalies over the entire TA and strong rainfall anomalies at Fortaleza and Recife show that the rainfall variability of these regions is differentially influenced by the dynamics of the TA. When the Intertropical Convergence Zone is abnormally displaced southward a few months prior to the NNEB rainy season, the associated meridional mode increases humidity and precipitation during the rainy season. Additionally, this study shows predictive effect of SST, meridional PWS, and barrier layer thickness, in the Northwestern equatorial Atlantic, on the NNEB rainfall. The dynamical influence of the TA on the June-July ENEB rainfall variability shows a northwestward-propagating area of strong, positively correlated SST from the southeastern TA to the southwestern Atlantic warm pool (SAWP offshore of Brazil. Our results also show predictive effect of SST, zonal PWS, and mixed layer depth, in the SAWP, on the ENEB rainfall.

  15. No Evidence of Habitat Loss Affecting the Orchid Bees Eulaema nigrita Lepeletier and Eufriesea auriceps Friese (Apidae: Euglossini) in the Brazilian Cerrado Savanna.

    Science.gov (United States)

    Silva, D P; De Marco, P

    2014-12-01

    Habitat loss, landscape fragmentation, and agriculture intensification constitute the main threats to bees. As the organisms responsible for almost one third of the food produced worldwide, there are growing concerns on bees' response to human-related disturbances. Among all bee groups, orchid bees (Apidae: Euglossini) compose an interesting group to test landscape-related hypotheses. In here, we tested the effect of landscape features (amount of anthropic areas and isolation) on the probability of occurrence and the abundances of both Eulaema nigrita Lepeletier and Eufriesea auriceps Friese in the Cerrado savanna. In general, we did not observe any effect of landscape features on the probability of occurrence and abundances of both species in our sampling sites. Given their potential high dispersal abilities, these bee species may be less sensitive to fragmented landscapes or even positively affected by the increase of anthropic habitats. Since we sampled many E. nigrita specimens in highly preserved Cerrado savanna areas, we believe that at least for this biome, this species may not be a good indicator of landscape disturbance.

  16. Climate change effects on the geographic distribution of specialist tree species of the Brazilian tropical dry forests.

    Science.gov (United States)

    Rodrigues, P M S; Silva, J O; Eisenlohr, P V; Schaefer, C E G R

    2015-08-01

    The aim of this study was to evaluate the ecological niche models (ENMs) for three specialist trees (Anadenanthera colubrina, Aspidosperma pyrifolium and Myracrodruon urundeuva) in seasonally dry tropical forests (SDTFs) in Brazil, considering present and future pessimist scenarios (2080) of climate change. These three species exhibit typical deciduousness and are widely distributed by SDTF in South America, being important in studies of the historical and evolutionary processes experienced by this ecosystem. The modeling of the potential geographic distribution of species was done by the method of maximum entropy (Maxent).We verified a general expansion of suitable areas for occurrence of the three species in future (c.a., 18%), although there was reduction of areas with high environmental suitability in Caatinga region. Precipitation of wettest quarter and temperature seasonality were the predictor variables that most contributed to our models. Climatic changes can provide more severe and longer dry season with increasing temperature and tree mortality in tropics. On this scenario, areas currently occupied by rainforest and savannas could become more suitable for occurrence of the SDTF specialist trees, whereas regions occupied by Caatinga could not support the future level of unsustainable (e.g., aridity). Long-term multidisciplinary studies are necessary to make reliable predictions of the plant's adaptation strategies and responses to climate changes in dry forest at community level. Based on the high deforestation rate, endemism and threat, public policies to minimize the effects of climate change on the biodiversity found within SDTFs must be undertaken rapidly.

  17. Nutrient budgets (C, N and P and trophic dynamicsof a Brazilian tropical estuary: Barra das Jangadas

    Directory of Open Access Journals (Sweden)

    Carlos E. D Noriega

    2011-06-01

    Full Text Available This paper focuses on the nutrient dynamics of a tropical estuary on the northeastern Brazilian coast, studied using the LOICZ biogeochemical budgeting protocol. We describe the methodology and assumptions underlying this model. Input data (monthly for rainfall, evaporation, river discharge, and concentrations of salt, phosphorus and nitrogen were obtained during field campaigns in the Barra das Jangadas Estuary (BJE over a 5 years period (1999 to 2003. Mass balance results indicate large inputs of nutrients to the system. The model shows that the seasonal variation of the Net Ecosystem Metabolism (NEM indicates that the system passes from a stage of organic matter liquid production and mineralization during the dry season (-0.5 mmoles C m-2 d-1 to liquid mineralization during the rainy season (-19 mmoles C m-2 d-1. We suggest that the system varies slightly between autotrophy and heterotrophy during the year due to the rainfall regime, human activities in the basin (density population and sugarcane plantations, and associated DIP riverine loads. High per capita loads of N and P indicate a high population density and high runoff. The application of flux balance modeling was useful to understand the nutrient dynamics of this typical small tropical estuaryEste trabalho se focalizou na dinâmica de nutrientes de um estuário tropical na costa nordeste brasileira, usando o protocolo LOICZ de balanços biogeoquímicos. Nós descrevemos a metodologia e os pressupostos subjacentes a este modelo. Os dados de entrada (precipitação e evaporação mensal, vazão do rio, e as concentrações de sal, fósforo e nitrogênio foram obtidos durante as campanhas de campo no estuário de Barra das Jangadas - Brasil durante um período de 5 anos (1999 a 2003. Os resultados indicam grandes entradas de nutrientes ao sistema. O modelo mostrou que a variação sazonal do Metabolismo do Ecosistema (NEM indica que o sistema passa de uma fase de produção de l

  18. Effects of vegetation burning on the atmospheric chemistry of the Venezuelan savanna

    International Nuclear Information System (INIS)

    Sanhueza, E.

    1991-01-01

    Biomass burning in tropical savanna and rainforest regions is an important factor in the chemical composition of the atmosphere. On the global scale, burning of savanna grass procedures three to four times greater emission of trace gases than deforestation processes of tropical rainforest. As part of a comprehensive study of the Venezuelan savanna atmosphere, measurements of gases and particles, chemical composition of rain, and biogenic soil emission were made during burning and nonburning periods at several rural savanna sites. A review of the most significant findings is presented in this chapter, and their regional and global implications are discussed

  19. A Landscape-Scale, Applied Fire Management Experiment Promotes Recovery of a Population of the Threatened Gouldian Finch, Erythrura gouldiae, in Australia's Tropical Savannas.

    Directory of Open Access Journals (Sweden)

    Sarah Legge

    Full Text Available Fire is an integral part of savanna ecology and changes in fire patterns are linked to biodiversity loss in savannas worldwide. In Australia, changed fire regimes are implicated in the contemporary declines of small mammals, riparian species, obligate-seeding plants and grass seed-eating birds. Translating this knowledge into management to recover threatened species has proved elusive. We report here on a landscape-scale experiment carried out by the Australian Wildlife Conservancy (AWC on Mornington Wildlife Sanctuary in northwest Australia. The experiment was designed to understand the response of a key savanna bird guild to fire, and to use that information to manage fire with the aim of recovering a threatened species population. We compared condition indices among three seed-eating bird species--one endangered (Gouldian finch and two non-threatened (long-tailed finch and double-barred finch--from two large areas (> 2,830 km2 with initial contrasting fire regimes ('extreme': frequent, extensive, intense fire; versus 'benign': less frequent, smaller, lower intensity fires. Populations of all three species living with the extreme fire regime had condition indices that differed from their counterparts living with the benign fire regime, including higher haematocrit levels in some seasons (suggesting higher levels of activity required to find food, different seasonal haematocrit profiles, higher fat scores in the early wet season (suggesting greater food uncertainty, and then lower muscle scores later in the wet season (suggesting prolonged food deprivation. Gouldian finches also showed seasonally increasing stress hormone concentrations with the extreme fire regime. Cumulatively, these patterns indicated greater nutritional stress over many months for seed-eating birds exposed to extreme fire regimes. We tested these relationships by monitoring finch condition over the following years, as AWC implemented fire management to produce the 'benign

  20. A Landscape-Scale, Applied Fire Management Experiment Promotes Recovery of a Population of the Threatened Gouldian Finch, Erythrura gouldiae, in Australia's Tropical Savannas.

    Science.gov (United States)

    Legge, Sarah; Garnett, Stephen; Maute, Kim; Heathcote, Joanne; Murphy, Steve; Woinarski, John C Z; Astheimer, Lee

    2015-01-01

    Fire is an integral part of savanna ecology and changes in fire patterns are linked to biodiversity loss in savannas worldwide. In Australia, changed fire regimes are implicated in the contemporary declines of small mammals, riparian species, obligate-seeding plants and grass seed-eating birds. Translating this knowledge into management to recover threatened species has proved elusive. We report here on a landscape-scale experiment carried out by the Australian Wildlife Conservancy (AWC) on Mornington Wildlife Sanctuary in northwest Australia. The experiment was designed to understand the response of a key savanna bird guild to fire, and to use that information to manage fire with the aim of recovering a threatened species population. We compared condition indices among three seed-eating bird species--one endangered (Gouldian finch) and two non-threatened (long-tailed finch and double-barred finch)--from two large areas (> 2,830 km2) with initial contrasting fire regimes ('extreme': frequent, extensive, intense fire; versus 'benign': less frequent, smaller, lower intensity fires). Populations of all three species living with the extreme fire regime had condition indices that differed from their counterparts living with the benign fire regime, including higher haematocrit levels in some seasons (suggesting higher levels of activity required to find food), different seasonal haematocrit profiles, higher fat scores in the early wet season (suggesting greater food uncertainty), and then lower muscle scores later in the wet season (suggesting prolonged food deprivation). Gouldian finches also showed seasonally increasing stress hormone concentrations with the extreme fire regime. Cumulatively, these patterns indicated greater nutritional stress over many months for seed-eating birds exposed to extreme fire regimes. We tested these relationships by monitoring finch condition over the following years, as AWC implemented fire management to produce the 'benign' fire regime

  1. Neglected tropical diseases in Brazilian children and adolescents: data analysis from 2009 to 2013.

    Science.gov (United States)

    Brandão, Eduardo; Romero, Sebastián; da Silva, Maria Almerice Lopes; Santos, Fred Luciano Neves

    2017-11-03

    Neglected tropical diseases (NTDs) prevail in conditions of poverty and contribute to the maintenance of social inequality. Out of the NTDs prioritized by the Brazilian Ministry of Health, four parasitic infections require mandatory notification: acute Chagas disease, leishmaniasis, malaria, and schistosomiasis. Data on the behaviour of these NTDs in the young population are currently limited. This study seeks to analyse the epidemiological aspects of these parasitic infections in children and adolescents in Brazil. A retrospective exploratory ecological study was conducted. A spatial analysis of the cases reported between 2009 and 2013 in individuals aged between 0 and 19 years that were notified through the Health Notification Aggravation Information System (SINAN) was performed. In total, 64,567 cases of cutaneous and visceral leishmaniasis, malaria, schistosomiasis, and acute Chagas disease were recorded in the SINAN database, representing a rate of 20.15 cases per 100,000 inhabitants. The average age of the cases was 12.2 years and 62.32% were male. Four hundred and three deaths related to these obligatorily reported parasites were recorded, indicating a case fatality rate of 0.62%. Visceral leishmaniasis and acute Chagas disease had the highest rates of lethality. A heterogeneous spatial distribution of the studied parasites was observed. The number of cases and the lethality rate described in this study show that these diseases still represent a serious problem for public health in Brazil. This points to the need to encourage new research and the reformulation of social, economic, and public health policies aimed at ensuring better health and living conditions for all individuals, especially those among the populations considered vulnerable, as is the case of the young.

  2. Land use policies and deforestation in Brazilian tropical dry forests between 2000 and 2015

    Science.gov (United States)

    Dupin, Mariana G. V.; Espírito-Santo, Mário M.; Leite, Marcos E.; Silva, Jhonathan O.; Rocha, André M.; Barbosa, Rômulo S.; Anaya, Felisa C.

    2018-03-01

    Tropical Dry Forests (TDFs) have been broadly converted into pastures and crops, with direct consequences to biodiversity, ecosystem services, and social welfare. Such land use and cover changes (LUCC) usually are strongly influenced by government environmental and development policies. The present study aimed at analyzing LUCC in Brazilian TDFs between 2000 and 2015, using the north of Minas Gerais state (128 000 km2) as a case study. We evaluated the potential biophysical and social-economic drivers of TDF loss, natural regeneration and net area change at the county level. Further, we determined the effects of these LUCC variables on socioeconomic indicators. We identified a considerable change in TDF cover, expressed as 9825 km2 of deforestation and 6523 km2 of regeneration, which resulted in a net loss of 3302 km2. The annual rate of TDF cover change was -1.2%, which is extremely high for a vegetation type that is protected as part of the Atlantic Rain Forest biome since 1993. TDF deforestation was directly affected by county area and by the increase in cattle density, and inversely affected by terrain declivity, indicating that land conversion is mostly driven by cattle ranching in flat regions. TDF regeneration was directly affected by county area and inversely affected by the increase in population density and terrain declivity. LUCC variables did not affect welfare indicators, undermining claims from rural sectors that TDF protection would cause a socioeconomic burden for northern Minas Gerais. Our results highlight the importance of naturally regenerating secondary forests to the maintenance of ecosystem integrity and its services, which are frequently neglected in conservation strategies. Hegemonic macroeconomic policies affecting TDFs have been deeply rooted in deforestation for commodities production, and need urgent review because they cause long-term environmental impacts without evidence of welfare gains.

  3. Runoff and soil erosion for an undisturbed tropical woodland in the Brazilian Cerrado

    Science.gov (United States)

    Oliveira, Paulo Tarso S.; Nearing, Mark; Wendland, Edson

    2015-04-01

    The Brazilian Cerrado is a large and important economic and environmental region that is experiencing major loss of its natural landscapes due to pressures of food and energy production, which has caused large increases in soil erosion. However the magnitude of the soil erosion increases in this region is not well understood, in part because scientific studies of surface runoff and soil erosion are scarce or nonexistent in undisturbed Cerrado vegetation. In this study we measured natural rainfall-driven rates of runoff and soil erosion for an undisturbed tropical woodland classified as "cerrado sensu stricto denso" and bare soil to compute the Universal Soil Loss Equation (USLE) cover and management factor (C-factor) to help evaluate the likely effects of land use change on soil erosion rates. Replicated data on precipitation, runoff, and soil loss on plots (5 x 20 m) under bare soil and cerrado were collected for 55 erosive storms occurring in 2012 and 2013. The measured annual precipitation was 1247.4 mm and 1113.0 mm for 2012 and 2013, resulting in a rainfall erosivity index of 4337.1 MJ mm ha-1 h-1 and 3546.2 MJ mm ha-1 h-1, for each year respectively. The erosive rainfall represented 80concentrated in the wet season, which generally runs from October through March. In the plots on bare soil, the runoff coefficient for individual rainfall events (total runoff divided by total rainfall) ranged from 0.003 to 0.860 with an average value and standard deviation of 0.212 ± 0.187. Moreover, the runoff coefficient found for the bare soil plots (~20infiltration capacity. In forest areas the leaf litter and the more porous soil tend to promote the increase of infiltration and water storage, rather than rapid overland flow. Indeed, runoff coefficients ranged from 0.001 to 0.030 with an average of less than 1under undisturbed cerrado. The soil losses measured under bare soil and cerrado were 15.68 t ha-1yr-1 and 0.24 t ha-1 yr-1 in 2012, and 14.82 t ha-1 yr-1, 0.11 t ha-1

  4. Fire-free land use in pre-1492 Amazonian savannas.

    Science.gov (United States)

    Iriarte, José; Power, Mitchell J; Rostain, Stéphen; Mayle, Francis E; Jones, Huw; Watling, Jennifer; Whitney, Bronwen S; McKey, Doyle B

    2012-04-24

    The nature and scale of pre-Columbian land use and the consequences of the 1492 "Columbian Encounter" (CE) on Amazonia are among the more debated topics in New World archaeology and paleoecology. However, pre-Columbian human impact in Amazonian savannas remains poorly understood. Most paleoecological studies have been conducted in neotropical forest contexts. Of studies done in Amazonian savannas, none has the temporal resolution needed to detect changes induced by either climate or humans before and after A.D. 1492, and only a few closely integrate paleoecological and archaeological data. We report a high-resolution 2,150-y paleoecological record from a French Guianan coastal savanna that forces reconsideration of how pre-Columbian savanna peoples practiced raised-field agriculture and how the CE impacted these societies and environments. Our combined pollen, phytolith, and charcoal analyses reveal unexpectedly low levels of biomass burning associated with pre-A.D. 1492 savanna raised-field agriculture and a sharp increase in fires following the arrival of Europeans. We show that pre-Columbian raised-field farmers limited burning to improve agricultural production, contrasting with extensive use of fire in pre-Columbian tropical forest and Central American savanna environments, as well as in present-day savannas. The charcoal record indicates that extensive fires in the seasonally flooded savannas of French Guiana are a post-Columbian phenomenon, postdating the collapse of indigenous populations. The discovery that pre-Columbian farmers practiced fire-free savanna management calls into question the widely held assumption that pre-Columbian Amazonian farmers pervasively used fire to manage and alter ecosystems and offers fresh perspectives on an emerging alternative approach to savanna land use and conservation that can help reduce carbon emissions.

  5. Analysis of the Spatial Relationship between Cattle and Wild Ungulates across Different Land-Use Systems in a Tropical Savanna Landscape

    Directory of Open Access Journals (Sweden)

    Geoffrey W. Kinga

    2018-01-01

    Full Text Available In many African savanna landscapes, domestic and wild herbivores cooccur across different land-use systems, but the role of land-use in shaping their spatial relationship is poorly understood. We evaluated the spatial relationship between cattle and wild herbivores categorized by body sizes and feeding habits across different land-use types, namely, private ranches (PR, transitional lands (TRL, and pastoral grazing areas (PGA, in Laikipia County, Kenya. Cattle and wild herbivores spatial distribution data were obtained from Kenya’s Department of Resources Survey and Remote Sensing (DRSRS. Spatial relationships between cattle and different wild herbivore guilds were analyzed using Ripley’s bivariate K12 function. In PR, wild herbivore guilds showed significant attraction to cattle at short distances. In TRL, wild grazers, mixed feeders, megaherbivores, and medium-sized ungulates exhibited significant attraction to cattle. Additionally, repulsion was observed between cattle and browsers at short distances under this land-use system. In PGA, wild grazers, mixed feeders, and megaherbivores repelled strongly with cattle at short distances while browsers and medium-sized ungulates were significantly attracted to cattle. Cattle and wild herbivores were more randomly and independently distributed in PR than in TRL and PGA. These spatial relationships imply better coexistence between cattle and wild herbivores in PR than in TRL and PGA.

  6. Restoring tropical forests on bauxite mined lands: lessons from the Brazilian Amazon

    Science.gov (United States)

    John A. Parrotta; Oliver H. Knowles

    2001-01-01

    Restoring self-sustaining tropical forest ecosystems on surface mined sites is a formidable challenge that requires the integration of proven reclamation techniques and reforestation strategies appropriate to specific site conditions, including landscape biodiversity patterns. Restorationists working in most tropical settings are usually hampered by lack of basic...

  7. Paleohydrology of tropical South America and paleoceanography of the tropical Atlantic as deduced from two new sediment cores on the Brazilian continental slope

    Science.gov (United States)

    Nace, T.; Baker, P. A.; Dwyer, G. S.; Silva, C. G.; Hollander, D. J.; Rigsby, C. A.; Giosan, L.; Burns, S. J.

    2011-12-01

    Paleoclimate/paleoceanographic reconstructions of the Amazon Basin, Brazilian Nordeste, and western equatorial Atlantic have been undertaken on two new sediment cores located on the Brazilian continental slope (Core CDH-5 at 1708 mbsl, 4N, 48W, 32m long, ~30 ka record; Core CDH-86 at 3708 mbsl, 0N/S, 44W, 30m long, ~100ka record). High-resolution XRF analyses of Fe, Ti, and Ca are used to define the paleohydrologic history of the adjacent continent at both sites. Large and abrupt excursions of Ti/Ca ratios are observed in both cores, but are significantly better defined in the southern core, representative of Nordeste conditions. In this core there are a total of 9 Ti/Ca excursions, the oldest recovered dating to ~98ka. These excursions correlate well with Heinrich events from the North Atlantic. High-resolution stable oxygen isotopic analysis and Mg/Ca paleothermometry undertaken on the near-surface-dwelling planktic foraminiferal species Globierinoides ruber provide a picture of paleoceanographic forcings in the western equatorial Atlantic. The northern and southern cores respectively exhibit rapid warming of ~3C and ~3.5C between the last glacial maximum and the early Holocene. Furthermore, in almost all cases, during the last glacial stage, there was a 0.5C to 2C warming of the western equatorial Atlantic during the periods of high Ti/Ca ratios that correlate with Heinrich events. Thus, as observed in some previous studies, the western equatorial Atlantic was warm and the adjacent southern tropical continent was wet at the same time that the high-latitude North Atlantic was cold. The largely accepted paradigm is that Northern hemisphere cold events result in a southward migration of the Intertropical Convergence Zone (ITCZ), contributing to drier conditions at the northern extent of the ITCZ annual range (Cariaco Basin) and increased precipitation in the southern tropics of South America. The ITCZ appears to have been influenced by millennial variability of

  8. Challenges and opportunities in land surface modelling of savanna ecosystems

    Directory of Open Access Journals (Sweden)

    R. Whitley

    2017-10-01

    Full Text Available The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs, which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model

  9. N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

    Directory of Open Access Journals (Sweden)

    C. Werner

    2014-11-01

    Full Text Available Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil–atmosphere exchange of nitrous oxide (N2O, nitric oxide (NO and dinitrogen (N2 is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture under controlled soil temperatures (ST and soil moisture (SM we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2. Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (−2 h−1; 2O-N m−2 h−1 or in the case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m−2 h−1 and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m−2 h−1 were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4–99.3% of total N lost, although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%. N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha−1 yr−1 (N2O, 0.68 kg N ha−1 yr−1 (NO and 6.65 kg N ha−1 yr−1 (N2. The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events

  10. N2O, NO, N2 and CO2 emissions from tropical savanna and grassland of northern Australia: an incubation experiment with intact soil cores

    Science.gov (United States)

    Werner, C.; Reiser, K.; Dannenmann, M.; Hutley, L. B.; Jacobeit, J.; Butterbach-Bahl, K.

    2014-11-01

    Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil-atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (soil uptake was observed. Substantial NO (max: 306.5 μg N m-2 h-1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m-2 h-1) were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4-99.3% of total N lost), although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%). N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha-1 yr-1 (N2O), 0.68 kg N ha-1 yr-1 (NO) and 6.65 kg N ha-1 yr-1 (N2). The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events compared to the total annual emissions was found to be of importance for NO emissions

  11. Organomineral Interactions and Herbicide Sorption in Brazilian Tropical and Subtropical Oxisols under No-Tillage.

    Science.gov (United States)

    Bonfleur, Eloana J; Kookana, Rai S; Tornisielo, Valdemar L; Regitano, Jussara B

    2016-05-25

    We evaluated the effects of the soil organic matter (SOM) composition, distribution between soil aggregates size, and their interactions with the mineral phase on herbicide sorption (alachlor, bentazon, and imazethapyr) in tropical and subtropical Oxisols under no-till systems (NT). Using soil physical fractionation approach, sorption experiments were performed on whole soils and their aggregates. SOM chemistry was assessed by CP/MAS (13)C NMR. The lower sorption observed in tropical soils was attributed to the greater blockage of SOM sorption sites than in subtropical soils. When these sites were exposed upon physical fractionation, sorption of the three herbicides in tropical soils increased, especially for imazethapyr. High amounts of poorly crystallized sesquioxides in these soils may have contributed to masking of sorption sites, indicating that organomineral interactions may lead to blockage of sorption sites on SOM in tropical soils.

  12. Insect-plant interactions: new pathways to a better comprehension of ecological communities in Neotropical savannas.

    Science.gov (United States)

    Del-Claro, Kleber; Torezan-Silingardi, Helena M

    2009-01-01

    The causal mechanisms shaping and structuring ecological communities are among the most important themes in ecology. The study of insect-plant interactions in trophic nets is pointed out as basic to improve our knowledge on this issue. The cerrado tropical savanna, although extremely diverse, distributed in more than 20% of the Brazilian territory and filled up with rich examples of multitrophic interactions, is underexplored in terms of biodiversity interaction. Here, this ecosystem is suggested as valuable to the study of insect-plant interactions whose understanding can throw a new light at the ecological communities' theory. Three distinct systems: extrafloral nectary plants or trophobiont herbivores and the associated ant fauna; floral herbivores-predators-pollinators; and plants-forest engineers and associated fauna, will serve as examples to illustrate promising new pathways in cerrado. The aim of this brief text is to instigate young researchers, mainly entomologists, to initiate more elaborated field work, including experimental manipulations in multitrophic systems, to explore in an interactive way the structure that maintain preserved viable communities in the Neotropical savanna.

  13. The Size But not the Symmetry of the Wings of Eulaema nigrita Lepeletier (Apidae: Euglossini) is Affected by Human-Disturbed Landscapes in the Brazilian Cerrado Savanna.

    Science.gov (United States)

    Pinto, N S; Silva, D P; Rodrigues, J G; De Marco, P

    2015-10-01

    Among other human-related activities, habitat loss and fragmentation are currently ranked as the most important environmental features affecting the persistence of animal and plant populations in landscapes, as well as the maintenance of ecological processes and services. Since these processes are also capable of affecting the ontogenetic development of species inhabiting those landscapes, here we measured the wing veins of male Eulaema nigrita Lepeletier (Apidae: Euglossini) bees in order to evaluate whether the bees sampled in agriculture (AG) areas suffer higher fluctuating asymmetry (FA) than those sampled in Cerrado (CE) areas in the Brazilian state of Goiás. We believe that individuals sampled in CE areas would be less asymmetric than those sampled in AG areas, given a potential higher exposure of these specimens to environmental stresses (mostly pesticides). However, we did not observe a significant trend in the FA measures we obtained, although three wing measures were bigger for bees from CE areas. The lack of significant effects of FA may be related to inherent bionomic features of E. nigrita. For instance, given their high individual dispersal abilities, the individuals we analyzed may have developed in different areas than those where they were sampled. Their generalist feeding behavior may also have given them a higher resistance to environmental perturbations, buffering the normal development of immatures even in areas with local high environmental stress. Nonetheless, higher death rates of individuals from anthropic areas may also have killed the developing immatures of E. nigrita before they reached adulthood consequently equalizing our sampled estimates.

  14. Light hydrocarbon emissions from African savanna burnings

    International Nuclear Information System (INIS)

    Bonsang, B.; Lambert, G.; Boissard, C.C.

    1991-01-01

    A study was undertaken in West Africa to determine the background mixing ratio of nonmethane hydrocarbons (NMHC) during the dry season and to measure the composition of savanna burnings. The experiment was conducted from 13 to 22 January 1989 in the experimental station located at the border of the tropical rainforest and savanna. Samples were collected during aircraft flights at 2,400 m in the free troposphere, at 400 m in the haze layer and in a smoke plume at 200 m altitude. Samples representing the ground-level evolution of the local background were collected at 10 m altitude. Fire samples were collected at a short distance from the fires during the intensive experiments. Results are presented in tables and indicate that the effect of NMHC produced by biomass burning on the tropospheric photochemistry is limited to a few species, namely, C 2 -C 4 alkenes

  15. Notas sobre a composição arbóreo-arbustiva de uma fisionomia das savanas de Roraima, Amazônia Brasileira Notes on the woody composition of a vegetation physionomy of the Roraima's savannas, Brazilian Amazonia

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    Reinaldo Imbrozio Barbosa

    2005-06-01

    Full Text Available Foi realizado um inventário florístico das espécies arbóreo-arbustivas presentes em uma das unidades de vegetação que compõem a paisagem de savanas do Estado de Roraima, extremo norte da Amazônia brasileira. Esta unidade é caracterizada por ser densamente colonizada por ninhos do cupim Cornitermes ovatus Emerson. Foram observadas 29 espécies (15 famílias botânicas em três localidades utilizadas para a amostragem. O total de espécies, por localidade, variou de 12 a 20. As espécies mais abundantes foram Byrsonima verbascifolia (L. DC. e Mimosa microcephala Humb. & Bonpl. ex Willd. (subarbustivas, Byrsonima cf. intermedia A. Juss. e Randia formosa (Jack. K. Schum. (arbustivas e, Byrsonima crassifolia (L. H.B.K. e Curatella americana L. (arbóreas. Oito espécies são comuns às três localidades. A diversidade medida pelo Índice de Shannon (H' foi baixa para todos os locais amostrados (A floristic inventory of woody species was carried out in one of the vegetation units that compose the savannas landscape of the Roraima State, northernmost of Brazilian Amazonia. This unit is characterized by dense colonization of nests of termites Cornitermes ovatus Emerson. Twenty nine woody species were observed (15 botany families in three localities used for sampling. The total of species varied from 12 to 20 by locality. The most abundant species were Byrsonima verbascifolia (L. DC. and Mimosa microcephala Humb. & Bonpl. ex Willd. (dwarf shrubs, Byrsonima cf. intermedia A. Juss. and Randia formosa (Jack. K. Schum. (shrubby and, Byrsonima crassifolia (L. H.B.K. and Curatella americana L. (arboreal. Eight species are common to all localities. Diversity measured by the Index of Shannon (H' was low for all the areas sampled (<0.90 indicating high specimens concentration in few species. The Index of Sørensen indicated similarities (± 0.60 among studied areas, suggesting a group of landscapes with common plant diversity, representing a same

  16. Soil physical conditions in Nigerian savannas and biomass production

    International Nuclear Information System (INIS)

    Salako, F.K.

    2004-01-01

    Nigeria is located in the tropical zone, with a vast area having savanna vegetation. This is a region that is itself diverse, necessitating a classification into derived savanna, southern Guinea savanna and northern Guinea savanna. These classifications reflect environmental characteristics such as length of growing period, which for instance is 151-180 days for the northern Guinea savanna, 181-210 days for the southern Guinea savanna and 211-270 days for the derived savanna/coastal savanna. The major soils found in the various agro-ecological zones have coarse-textured surface soil, and are low in organic matter and chemical fertility. Although, yields can be improved by addition of inorganic and organic fertilizer, this can only be sustained and assured with high soil physical qualities. Soil physical qualities can be sustained at a high level with conservation tillage and soil conservation measures. Tillage is physical manipulation of the soil. Thus, the most profound effect of tillage is in relation to soil physical properties. For socio-economic and cultural reasons, manual tillage is still widely practiced in Africa as farming is largely at subsistence level. However, there are now a number of commercial farms especially for cash crop production in many parts of Africa. Many of these are located in locations which were hitherto reserved as forest and a need for sustainable production in pertinent to maintain ecological balance. Soils with coarse texture are not often sensitive to some physical parameters while some physical parameters are more relevant in a given study than others. Sustainable crop production researches in the tropics have focused on the role of planted fallows and their spatial arrangement (e.g., as in alley cropping) for many decades. Application of soil physics in the area of food production and environmental management still lags behind other sub-disciplines of soil science, particularly soil fertility in the tropics. A great challenge is

  17. Diversidade genética de pitayas nativas do cerrado com base em marcadores RAPD Genetic diversity of native pitaya native from brazilian savannas with basis on RAPD markers

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    Keize Pereira Junqueira

    2010-09-01

    Full Text Available As pitayas do Cerrado vegetam naturalmente sobre maciços rochosos de arenito ou quartzito, troncos de árvores e em solos arenosos de campos rupestres de Minas Gerais, Bahia, Goiás, Distrito Federal, Tocantins, Rio de Janeiro e Bahia, havendo fortes evidências de que a região central do Brasil seja o maior centro de dispersão das pitayas, tendo em vista a grande diversidade fenotípica observada em acessos coletados. Objetivou-se realizar o estudo da diversidade genética de 13 acessos de pitayas mantidos na coleção de germoplasma da Embrapa Cerrados por meio de marcadores moleculares RAPD (Random Amplified Polymorphic DNA. O DNA genômico de cada acesso foi extraído, e quatorze iniciadores decâmeros foram utilizados para a obtenção de marcadores moleculares RAPD, que foram convertidos em matriz de dados binários, a partir da qual foram estimadas as distâncias genéticas entre os acessos com base no complemento do coeficiente de similaridade de Nei e Li (1979 e realizadas análises de agrupamento e de dispersão gráfica. Foram obtidos 162 marcadores RAPD, perfazendo uma média de 11,57 marcadores por primer. Do total de marcadores, 154 (95,06% foram polimórficos. As distâncias genéticas variaram entre 0,088 e 0,848, sendo que os maiores valores observados se referem a distância entre o acesso de Unaí-MG e o acesso Seleção Embrapa Cerrados. O acesso que mais se diferenciou dos demais foi "Unaí-MG", que apresentou uma distância genética média de 0,675 em relação aos demais acessos. A alta distância genética verificada é devido ao fato de os referidos acessos não pertencerem à mesma espécie. Os agrupamentos dos acessos de pitaya pouco se relacionaram com a origem geográfica dos mesmos. A grande diversidade genética das pitayas encontradas no Cerrado permite incluir esse Bioma no centro de diversidade e abre boas perspectivas para maiores estudos acerca do potencial dessa frutífera.Brazilian savanna pitayas

  18. Properties of Arboreal Ant and Ground-Termite Nests in relation to Their Nesting Sites and Location in a Tropical-Derived Savanna

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    B. C. Echezona

    2012-01-01

    Full Text Available Ecosystem engineers such as ants and termites play an important role in the fertility of tropical soils. Physicochemical analyses were thus carried out on some arboreal ant nests collected from mango (Mangifera indica, bush mango (Irvingia gabonensis, kola (Cola nitida, newbouldia plant (Newbouldia laevis, and oil bean plant (Pentaclethra macrophylla and on ground nest of termite, Odontotermes sudanensis Sjost. (Isoptera: Termitidae in Nigeria. Arboreal nests, particularly those of M. indica, were significantly richer in the chemical constituents sampled, compared to those of ground-termite nests or adjacent unaffected soils. Available water capacity of nests from M. indica (60.0% was significantly higher than those of other sites or locations sampled. While biogenic structures were sandy-loamy in texture, their corresponding adjacent soils were either sandy or sandy-loamy. Soils worked by ants and termites had greater proportions of silt-sized (17.9 versus 9.7 and clay-sized (19.2 versus 9.3 to the detriment of coarse-sized particles (51.2 versus 60.9 and fine-sand-sized particles (11.7 versus 20.1 relative to the adjacent soils. Generally, biogenic structures were about 348% richer in P than their corresponding adjacent soils; an attribute, which holds a strong promise in bioremediation and biofortification of soils especially during amendment.

  19. Impact of livestock on a mosquito community (Diptera: Culicidae) in a Brazilian tropical dry forest

    OpenAIRE

    Santos,Cleandson Ferreira; Borges,Magno

    2015-01-01

    AbstractINTRODUCTION: This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil.METHODS: Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models.RESULTS: Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition.CO...

  20. Management impacts on fire occurrence: A comparison of fire regimes of African and South American tropical savannas in different protected areas.

    Science.gov (United States)

    Alvarado, Swanni T; Silva, Thiago Sanna Freire; Archibald, Sally

    2018-07-15

    Humans can alter fire dynamics in grassland systems by changing fire frequency, fire seasonality and fuel conditions. These changes have effects on vegetation structure and recovery, species composition, and ecosystem function. Understanding how human management can affect fire regimes is vital to detect potential changes in the resilience of plant communities, and to predict vegetation responses to human interventions. We evaluated the fire regimes of two recently protected areas in Madagascar (Ibity and Itremo NPA) and one in Brazil (Serra do Cipó NP) before and after livestock exclusion and fire suppression policies. We compare the pre- and post-management fire history in these areas and analyze differences in terms of total annual burned area, density of ignitions, burn scar size distribution, fire return period and seasonal fire distribution. More than 90% of total park areas were burned at least once during the studied period, for all parks. We observed a significant reduction in the number of ignitions for Ibity NPA and Serra do Cipó NP after livestock exclusion and active fire suppression, but no significant change in total burned area for each protected area. We also observed a seasonal shift in burning, with fires happening later in the fire season (October-November) after management intervention. However, the protected areas in Madagascar had shorter fire return intervals (3.23 and 1.82 years) than those in Brazil (7.91 years). Our results demonstrate that fire exclusion is unattainable, and probably unwarranted in tropical grassland conservation areas, but show how human intervention in fire and vegetation patterns can alter various aspects of the fire regimes. This information can help with formulating realistic and effective fire management policies in these valuable conservation areas. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Impact of livestock on a mosquito community (Diptera: Culicidae in a Brazilian tropical dry forest

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    Cleandson Ferreira Santos

    2015-08-01

    Full Text Available AbstractINTRODUCTION: This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil.METHODS: Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models.RESULTS: Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition.CONCLUSIONS: This is the first study to evaluate the impact of cattle removal on Culicidae community structure in Brazil and demonstrates the importance of assessing ecological parameters such as community species composition.

  2. Impact of livestock on a mosquito community (Diptera: Culicidae) in a Brazilian tropical dry forest.

    Science.gov (United States)

    Santos, Cleandson Ferreira; Borges, Magno

    2015-01-01

    This study evaluated the effects of cattle removal on the Culicidae mosquito community structure in a tropical dry forest in Brazil. Culicidae were collected during dry and wet seasons in cattle presence and absence between August 2008 and October 2010 and assessed using multivariate statistical models. Cattle removal did not significantly alter Culicidae species richness and abundance. However, alterations were noted in Culicidae community composition. This is the first study to evaluate the impact of cattle removal on Culicidae community structure in Brazil and demonstrates the importance of assessing ecological parameters such as community species composition.

  3. TDDFT calculations and photoacoustic spectroscopy experiments used to identify phenolic acid functional biomolecules in Brazilian tropical fruits in natura

    Science.gov (United States)

    Lourenço Neto, M.; Agra, K. L.; Suassuna Filho, J.; Jorge, F. E.

    2018-03-01

    Time-dependent density functional theory (TDDFT) calculations of electronic transitions have been widely used to determine molecular structures. The excitation wavelengths and oscillator strengths obtained with the hybrid exchange-correlation functional B3LYP in conjunction with the ADZP basis set are employed to simulate the UV-Vis spectra of eight phenolic acids. Experimental and theoretical UV-Vis spectra reported previously in the literature are compared with our results. The fast, sensitive and non-destructive technique of photoacoustic spectroscopy (PAS) is used to determine the UV-Vis spectra of four Brazilian tropical fresh fruits in natura. Then, the PAS along with the TDDFT results are for the first time used to investigate and identify the presence of phenolic acids in the fruits studied in this work. This theoretical method with this experimental technique show to be a powerful and cheap tool to detect the existence of phenolic acids in fruits, vegetables, cereals, and grains. Comparison with high performance liquid chromatography results, when available, is also carried out.

  4. Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations

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    ROBSON B. DE LIMA

    2017-08-01

    Full Text Available ABSTRACT Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005 generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005 is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

  5. Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations.

    Science.gov (United States)

    Lima, Robson B DE; Alves, Francisco T; Oliveira, Cinthia P DE; Silva, José A A DA; Ferreira, Rinaldo L C

    2017-01-01

    Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005) generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005) is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

  6. Spatio-Temporal Distribution of Bark and Ambrosia Beetles in a Brazilian Tropical Dry Forest.

    Science.gov (United States)

    Macedo-Reis, Luiz Eduardo; Novais, Samuel Matos Antunes de; Monteiro, Graziela França; Flechtmann, Carlos Alberto Hector; Faria, Maurício Lopes de; Neves, Frederico de Siqueira

    2016-01-01

    Bark and the ambrosia beetles dig into host plants and live most of their lives in concealed tunnels. We assessed beetle community dynamics in tropical dry forest sites in early, intermediate, and late successional stages, evaluating the influence of resource availability and seasonal variations in guild structure. We collected a total of 763 beetles from 23 species, including 14 bark beetle species, and 9 ambrosia beetle species. Local richness of bark and ambrosia beetles was estimated at 31 species. Bark and ambrosia composition was similar over the successional stages gradient, and beta diversity among sites was primarily determined by species turnover, mainly in the bark beetle community. Bark beetle richness and abundance were higher at intermediate stages; availability of wood was the main spatial mechanism. Climate factors were effectively non-seasonal. Ambrosia beetles were not influenced by successional stages, however the increase in wood resulted in increased abundance. We found higher richness at the end of the dry and wet seasons, and abundance increased with air moisture and decreased with higher temperatures and greater rainfall. In summary, bark beetle species accumulation was higher at sites with better wood production, while the needs of fungi (host and air moisture), resulted in a favorable conditions for species accumulation of ambrosia. The overall biological pattern among guilds differed from tropical rain forests, showing patterns similar to dry forest areas. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

  7. Diversity of Archaea in Brazilian savanna soils.

    Science.gov (United States)

    Catão, E; Castro, A P; Barreto, C C; Krüger, R H; Kyaw, C M

    2013-07-01

    Although the richness of Bacteria and Fungi in Cerrado' soils has been reported, here we report, for the first time, the archaeal community in Cerrado's soils. DNA extracted from soil of two distinct vegetation types, a dense subtype of sensu strict (cerrado denso) and riverbank forest (mata de galeria), was used to amplify Archaea-specific 16S rRNA gene. All of the fragments sequenced were classified as Archaea into the phylum Thaumarchaeota, predominantly affiliated to groups I.1b and I.1c. Sequences affiliated to the group I.1a were found only in the soil from riverbank forest. Soils from 'cerrado denso' had greater Archaea richness than those from 'mata de galeria' based on the richness indexes and on the rarefaction curve. β-Diversity analysis showed significant differences between the sequences from the two soil areas studied because of their different thaumarchaeal group composition. These results provide information about the third domain of life from Cerrado soils.

  8. [Paths taken by Dr. Jorge Clarke Bleyer in the fields of tropical medicine and Brazilian prehistory].

    Science.gov (United States)

    Bleyer Martins Costa, Terezinha de Jesus Thibes

    2003-01-01

    This research note presents a preliminary evaluation of the life history of Georg Carl Adolf Bleyer, physician, hygienist and naturalist who played a crucial role in the institution of public health in Santa Catarina and was a pioneer in tropical medicine, anthropology and archeology of Brazil. Adolpho Lutz was one of the main partners in Brazil of this equally multifacted physician who published important articles in German journals. His most thorough study was important to the history of the disciplines which which he worked; it provides the basis for understanding the conditions of medical and scientific practice in places far from the urban centers of southeastern Brazil that dominate the historiography of medicine and science.

  9. Spatial pattern analysis and demography of two tropical trees in the Brazilian Caatinga

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    Maira Fontes Manzan

    2014-12-01

    Full Text Available Aspidosperma pyrifolium (Apocynaceae and Caesalpinia pyramidalis (Fabaceae share the same habitat in the Brazilian Caatinga domain. In this paper, we investigate the intra and inter-species interactions between these two plants using spatial pattern analysis among cohorts. The results showed that the adult trees of each species present higher densities at distances shorter than 9 m to 12 m. However, due to seed dispersal via autochory, we expected a more aggregate density for C. pyramidalis than A. pyrifolium as the later disperses seeds through anemochory. Difference in spatial aggregation among cohorts was not observed and therefore the results contradict the expectations of the Janzen-Connell hypothesis. It is likely that this is associated with anthropogenic factors in the past such as fire, animal husbandry and logging. Using a bivariate analysis of the neighborhood density, we also confirmed the significant coexistence between the two species. This coexistence could be explained by the process of positive interspecific interactions, such as facilitation, which is common in semi-arid regions under stressful conditions.

  10. Responses of tropical legumes from the Brazilian Atlantic Rainforest to simulated acid rain.

    Science.gov (United States)

    Andrade, Guilherme C; Silva, Luzimar C

    2017-07-01

    We investigated the morphological and anatomical effects of simulated acid rain on leaves of two species native to the Brazilian Atlantic Rainforest: Paubrasilia echinata and Libidibia ferrea var. leiostachya. Saplings were subjected to acid rain in a simulation chamber during 10 days for 15 min daily, using H 2 SO 4 solution pH 3.0 and, in the control, deionized water. At the end of the experiment, fragments from young and expanding leaves were anatomically analyzed. Although L. ferrea var. leiostachya leaves are more hydrophobic, rain droplets remained in contact with them for a longer time, as in the hydrophilic P. echinata leaves, droplets coalesce and rapidly run off. Visual symptomatology consisted in interveinal and marginal necrotic dots. Microscopic damage found included epicuticular wax flaking, turgor loss and epidermal cell shape alteration, hypertrophy of parenchymatous cells, and epidermal and mesophyll cell collapse. Formation of a wound tissue was observed in P. echinata, and it isolated the necrosis to the adaxial leaf surface. Acid rain increased thickness of all leaf tissues except spongy parenchyma in young leaves of L. ferrea var. leiostachya, and such thickness was maintained throughout leaf expansion. To our knowledge, this is the first report of acidity causing increase in leaf tissue thickness. This could represent the beginning of cell hypertrophy, which was seen in visually affected leaf regions. Paubrasilia echinata was more sensitive, showing earlier symptoms, but the anatomical damage in L. ferrea var. leiostachya was more severe, probably due to the higher time of contact with acid solution in this species.

  11. INVENTORY OF MOSQUITOES (DIPTERA: CULICIDAE IN CONSERVATION UNITS IN BRAZILIAN TROPICAL DRY FORESTS

    Directory of Open Access Journals (Sweden)

    Cleandson Ferreira SANTOS

    2015-06-01

    Full Text Available In Brazil, most studies of the Culicidae family are concentrated in rainforest regions. As such, there is a lack of knowledge regarding the diversity of Culicidae in regions with different climatic and vegetational characteristics. The aim of this study was to compile an inventory of Culicidae in protected areas of the semi-arid region of the state of Minas Gerais, Brazil, in order to better understand the diversity of the family within this region. The study was conducted across four protected areas in the northern region of the state, in tropical dry forest (TDF fragments. Sampling methods included Shannon trap and CDC light trap, as well as active collection. A total of 11,219 mosquito specimens were collected between August 2008 and July 2012, belonging to 11 genera and 45 species; 15 new records for the state of Minas Gerais were registered, as well as 26 new records for semi-arid regions within the state. The high number of new Culicidae records in this region demonstrates the importance of inventory studies for increasing the knowledge of culicid biodiversity in Minas Gerais, and in particular within semi-arid regions of the state.

  12. INVENTORY OF MOSQUITOES (DIPTERA: CULICIDAE) IN CONSERVATION UNITS IN BRAZILIAN TROPICAL DRY FORESTS.

    Science.gov (United States)

    Santos, Cleandson Ferreira; Silva, Alex Chavier; Rodrigues, Raquel Andrade; de Jesus, Jamilli Sanndy Ramos; Borges, Magno Augusto Zazá

    2015-01-01

    In Brazil, most studies of the Culicidae family are concentrated in rainforest regions. As such, there is a lack of knowledge regarding the diversity of Culicidae in regions with different climatic and vegetational characteristics. The aim of this study was to compile an inventory of Culicidae in protected areas of the semi-arid region of the state of Minas Gerais, Brazil, in order to better understand the diversity of the family within this region. The study was conducted across four protected areas in the northern region of the state, in tropical dry forest (TDF) fragments. Sampling methods included Shannon trap and CDC light trap, as well as active collection. A total of 11,219 mosquito specimens were collected between August 2008 and July 2012, belonging to 11 genera and 45 species; 15 new records for the state of Minas Gerais were registered, as well as 26 new records for semi-arid regions within the state. The high number of new Culicidae records in this region demonstrates the importance of inventory studies for increasing the knowledge of culicid biodiversity in Minas Gerais, and in particular within semi-arid regions of the state.

  13. Analyzing the edge effects in a Brazilian seasonally dry tropical forest.

    Science.gov (United States)

    Arruda, D M; Eisenlohr, P V

    2016-02-01

    Due to the deciduous nature of dry forests (widely known as seasonally dry tropical forests) they are subject to microclimatic conditions not experienced in other forest formations. Close examinations of the theory of edge effects in dry forests are still rare and a number of questions arise in terms of this topic. In light of this situation we examined a fragment of the dry forest to respond to the following questions: (I) Are there differences in canopy cover along the edge-interior gradient during the dry season? (II) How does the microclimate (air temperature, soil temperature, and relative humidity) vary along that gradient? (III) How does the microclimate influence tree species richness, evenness and abundance along that gradient? (IV) Are certain tree species more dominant closer to the forest edges? Regressions were performed to address these questions. Their coefficients did not significantly vary from zero. Apparently, the uniform openness of the forest canopy caused a homogeneous internal microclimate, without significant differentiation in habitats that would allow modifications in biotic variables tested. We conclude that the processes of edge effect commonly seen in humid forests, not was shared with the dry forest assessed.

  14. Seasonality in the dung beetle community in a Brazilian tropical dry forest: Do small changes make a difference?

    Science.gov (United States)

    Medina, Anderson Matos; Lopes, Priscila Paixão

    2014-01-01

    Dung beetle (Coleoptera: Scarabaeoidea: Scarabaeinae) activity is influenced by rainfall seasonality. We hypothesized that rainfall might also play a major role in regulating the community structure of this group. In this study, we describe seasonal changes in the richness, composition, and structure of the Scarabaeinae community in a Brazilian tropical dry forest. A fragment of arboreal Caatinga was sampled using baited pitfall traps during the early dry season (EDS), late dry season (LDS), early wet season (EWS), and middle wet season (MWS). We compared the dung beetle community in each season in relationship to species richness, rank-dominance, curves, and composition. We collected 1352 Scarabaeinae individuals , belonging to 15 species. Dichotomius aff. laevicollis Felsche (Coleoptera: Scarabaeidae) was the dominant species, representing 73.89% of the individuals. There were no seasonal changes in the rank dominance curves; all had a single dominant species and a few species with low abundance, typical for arid areas. Estimated richness was highest in MWS, followed by EWS. Dry-season samples (EDS and LDS) had lower richness, with no significant difference between the dry seasons. Although species richness increased as the habitat became wetter, the difference between the wet and dry seasons was small, which differs completely from the findings of other studies in Neotropical dry forests, where almost all species cease activities in the dry season. Species composition changes were found in non-metric multidimensional scaling and sustained by analysis of similarity. All the seasons had pairwise differences in composition, with the exception of EDS and MWS, which indicates that the dung beetle community in this fragment requires more than three months of drought to trigger changes in species composition; this is probably due to small changes in the forest canopy. There was no difference in composition between EDS and MWS. As in other tropical dry forests, although

  15. Mayfly diversity in the brazilian tropical headwaters of Serra do Cipó

    Directory of Open Access Journals (Sweden)

    Michael Goulart

    2005-11-01

    Full Text Available The objectives of this study were to evaluate spatial and seasonal distribution, assemblage structure and substrate associations of mayfly nymphs in five lotic ecosystems in the headwaters of the Doce River and São Francisco River watersheds, Brazil. Samples were taken in 24 sampling stations during rainy and dry seasons in 1998. In total, 7,066 organisms were collected, belonging to 27 genera and 6 families of Ephemeroptera. The dominant taxa were Americabaetis, Paracloeodes, Leptohyphes and Hagenulus. During the rainy period, the São Francisco River watershed showed higher taxonomic richness, diversity and evenness, while in the dry period, the taxonomic richness was higher in Doce River watershed. No significant differences were found in the taxonomic richness, diversity, evenness and density of mayfly assemblages between the two studied sampling periods. The results suggested that the diversity of the mayfly assemblages in tropical headwaters of Serra do Cipó would be probably due to ecosystem and watershed characteristics.Os objetivos foram avaliar a distribuição espaço-temporal, estrutura de assembléias e associações de ninfas de Ephemeroptera com substratos em 5 ecossistemas lóticos nas nascentes das bacias dos rios Doce e São Francisco, Brasil. As amostragens foram realizadas em 24 estações, nos períodos de chuvas e seca de 1998. No total, 7,066 organismos foram coletados, pertencentes a 27 gêneros e 6 famílias. Os taxa dominantes foram Americabaetis, Paracloeodes, Leptohyphes e Hagenulus. No período de chuvas foram observados maiores valores dos indices de riqueza taxonômica, diversidade e equitabilidade na bacia do rio São Francisco, enquanto que no período de seca, a riqueza taxonômica foi maior na bacia do rio Doce. Não foram encontradas diferenças significativas dos valores dos indices de riqueza, equitabilidade, diversidade e densidade de ninfas de Ephemeroptera entre os dois períodos estudados. Os

  16. Determinación de la actividad lignocelulolítica en sustrato natural de aislamientos fúngicos obtenidos de sabana de pastoreo y de bosque secundario de sabana inundable tropical Determination of lignocellulolytic activity in a natural substrate of native fungi strains obtained from savanna and of secondary forest from a tropical flooded savanna

    Directory of Open Access Journals (Sweden)

    Martha Lucía Ortiz Moreno

    2010-12-01

    integrated samples. A lignolytic strain (005L Verticillium spp. and 72 cellulolytic strains were obtained. A comparison of soil usages (savanna grazing and secondary forest showed no correlation between the number of obtained genera and soil characteristics. Selection of the strains to be evaluated in a dry-grass natural substrate (Brachiaria spp. was carried out by quantification of lignolytic and cellulolytic activity. Two strains with high exoglucanase activity (055C and 061C Penicillium spp. and a strain with high endoglucanase activity (019C Trichoderma spp. relative to the Trichoderma viride control were selected and evaluated in the natural substrate in consortia formed by one lignolytic and one cellulolytic. The test showed that the enzymatic activity of the selected strains increased in the substrate grass, surpassing that of the positive controls (Pleurotus ostreatus for lignin and T. viride for cellulose for both consortia. The use of the consortia is therefore recommended for the development of soil conditioning biofertilizers, especially that formed by the 005L (Verticillium spp. and 055C (Penicillium spp. strains with high lignolytic and cellulolytic activity.

  17. STRUCTURE OF MICROBIAL COMMUNITIES IN NATIVE AND CONVERTED SAVANNA AREAS OF CENTRAL BRAZIL

    Science.gov (United States)

    Brazilian savannas (Cerrado) have suffered drastic changes in land use with major conversion of native areas to agriculture since 1960. Burning, both due to natural conditions and as a human-induced practice, is a common event during the dry season (April to September) and plays ...

  18. Hydraulic lift in a neotropical savanna: experimental manipulation and model simulations

    Science.gov (United States)

    Fabian G. Scholz; Sandra J. Bucci; William A. Hoffmann; Frederick C. Meinzer; Guillermo Goldstein

    2010-01-01

    The objective of this study was to assess the magnitude of hydraulic lift in Brazilian savannas (Cerrado) and to test the hypothesis that hydraulic lift by herbaceous plants contributes substantially to slowing the decline of water potential and water storage in the upper soil layers during the dry season. To this effect, field observations of soil water content and...

  19. BRS Deméter: nova cultivar de cevada cervejeira irrigada para o Cerrado do Brasil Central BRS Deméter: new malting barley cultivar for irrigated Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Renato Fernando Amabile

    2008-09-01

    Full Text Available BRS Deméter é uma cultivar de cevada dística (duas fileiras de grãos de ampla adaptação, sob irrigação, ao Cerrado do Brasil Central. Apresenta potencial produtivo de grãos acima de 5.000 kg ha-1, estabilidade de produção e alta qualidade industrial malte-cervejeira. A cultivar atende às demandas do produtor por rendimento competitivo e às da indústria malteira por alta qualidade cervejeira.BRS Deméter is a spring, two-rowed barley, widely adapted to irrigated areas of the savanna, in Central Brazil. It presents production stability and high malting quality, with yield potential above 5,000 kg ha-1. It fulfills both the farmer and malting industry expectations regarding competitive yield and brewing quality.

  20. Biome-specific effects of nitrogen and phosphorus on the photosynthetic characteristics of trees at a forest-savanna boundary in Cameroon.

    Science.gov (United States)

    Domingues, Tomas Ferreira; Ishida, F Yoko; Feldpausch, Ted R; Grace, John; Meir, Patrick; Saiz, Gustavo; Sene, Olivier; Schrodt, Franziska; Sonké, Bonaventure; Taedoumg, Herman; Veenendaal, Elmar M; Lewis, Simon; Lloyd, Jon

    2015-07-01

    Photosynthesis/nutrient relationships of proximally growing forest and savanna trees were determined in an ecotonal region of Cameroon (Africa). Although area-based foliar N concentrations were typically lower for savanna trees, there was no difference in photosynthetic rates between the two vegetation formation types. Opposite to N, area-based P concentrations were-on average-slightly lower for forest trees; a dependency of photosynthetic characteristics on foliar P was only evident for savanna trees. Thus savanna trees use N more efficiently than their forest counterparts, but only in the presence of relatively high foliar P. Along with some other recent studies, these results suggest that both N and P are important modulators of woody tropical plant photosynthetic capacities, influencing photosynthetic metabolism in different ways that are also biome specific. Attempts to find simple unifying equations to describe woody tropical vegetation photosynthesis-nutrient relationships are likely to meet with failure, with ecophysiological distinctions between forest and savanna requiring acknowledgement.

  1. Terrestrial Carbon Fluxes from Deforestation in the Brazilian Amazon and Cerrado Regions Predicted from MODIS Satellite Data and Ecosystem Modeling

    Science.gov (United States)

    Klooster, S.; Potter, C.; Genovese, V.

    2008-12-01

    The NASA-CASA (Carnegie Ames Stanford Approach) simulation model based on satellite observations of monthly vegetation cover from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to estimate tropical forest and savanna (Cerrado) carbon pools for the Brazilian Amazon region over the period 2000-2004. Adjustments for mean age of forest stands were carried out across the region, resulting in a new mapping of aboveground biomass pools based on MODIS satellite data. Yearly maps of newly deforested lands from the Brazilian PRODES (Programa de calculo do desflorestamento da Amazonia ) project were combined with these NASA-CASA biomass predictions to generate seasonal budgets of potential carbon and nitrogen trace gas losses from biomass burning events. Simulations of plant residue and soil carbon decomposition were conducted in the NASA-CASA model during and following deforestation events to track the fate of aboveground biomass pools that were cut and burned each year across the region.

  2. Impact of savanna conversion to oil palm plantations on C stocks dynamics and soil fertility

    Science.gov (United States)

    Quezada, Juan Carlos; Guillaume, Thomas; Buttler, Alexandre; Ruegg, Johanna

    2017-04-01

    Large-scale expansion of oil palm cultivation on forested land in South-East Asia during the last decades lead to high negative environmental impacts. Because rainforests store high amount of C, their conversion to oil palm plantations results in large net CO2 emissions. Oil palm cultivation in tropical ecosystems such as savanna that store less C than forests is seen as an alternative to reduce greenhouse gas emissions of future oil palm development. While this option is more and more frequently mentioned, few data are available on the effective gain in C storage. Furthermore negative impact on soil organic carbon and soil fertility could offset gains of C storage in oil palm biomass. Here, we present results on aboveground and belowground C stocks and soil nutrient dynamics over a full rotation cycle of oil palm plantations established on tropical savanna grasslands. Three natural savanna grasslands as reference sites and 9 oil palm plantations ranging from two to twenty-seven years old were selected in the Llanos in Colombia. Oxisols were sampled down to 70 cm in each management zones of oil palm plantations (weeded circle, interrow, frond piles and harvesting path). Taking advantages of a shift from C4 to C3 vegetation, we quantified savanna-derived soil organic carbon (SOC) decomposition and oil palm-derived SOC stabilization rates and how they were affected by management practices (mineral fertilization, organic amendments, etc.). Results show that, in opposite to forest conversion, C storage increases when savannas are converted to oil palm plantations. Because soil C storage was very low in natural conditions, SOC changes had little effects on overall C storage. Substitution of savanna-derived SOC by oil palm-derived SOC was very fast in the topsoil and highest under frond pile and weeded circle where C and nutrients inputs are highest. However, stabilization of oil palm-derived SOC compensated loss of savanna-derived SOC rather than increased SOC stocks

  3. Disentangling how landscape spatial and temporal heterogeneity affects Savanna birds.

    Directory of Open Access Journals (Sweden)

    Bronwyn Price

    Full Text Available In highly seasonal tropical environments, temporal changes in habitat and resources are a significant determinant of the spatial distribution of species. This study disentangles the effects of spatial and mid to long-term temporal heterogeneity in habitat on the diversity and abundance of savanna birds by testing four competing conceptual models of varying complexity. Focussing on sites in northeast Australia over a 20 year time period, we used ground cover and foliage projected cover surfaces derived from a time series of Landsat Thematic Mapper imagery, rainfall data and site-level vegetation surveys to derive measures of habitat structure at local (1-100 ha and landscape (100-1000s ha scales. We used generalised linear models and an information theoretic approach to test the independent effects of spatial and temporal influences on savanna bird diversity and the abundance of eight species with different life-history behaviours. Of four competing models defining influences on assemblages of savanna birds, the most parsimonious included temporal and spatial variability in vegetation cover and site-scale vegetation structure, suggesting savanna bird species respond to spatial and temporal habitat heterogeneity at both the broader landscape scale and at the fine-scale. The relative weight, strength and direction of the explanatory variables changed with each of the eight species, reflecting their different ecology and behavioural traits. This study demonstrates that variations in the spatial pattern of savanna vegetation over periods of 10 to 20 years at the local and landscape scale strongly affect bird diversity and abundance. Thus, it is essential to monitor and manage both spatial and temporal variability in avian habitat to achieve long-term biodiversity outcomes.

  4. Disentangling how landscape spatial and temporal heterogeneity affects Savanna birds.

    Science.gov (United States)

    Price, Bronwyn; McAlpine, Clive A; Kutt, Alex S; Ward, Doug; Phinn, Stuart R; Ludwig, John A

    2013-01-01

    In highly seasonal tropical environments, temporal changes in habitat and resources are a significant determinant of the spatial distribution of species. This study disentangles the effects of spatial and mid to long-term temporal heterogeneity in habitat on the diversity and abundance of savanna birds by testing four competing conceptual models of varying complexity. Focussing on sites in northeast Australia over a 20 year time period, we used ground cover and foliage projected cover surfaces derived from a time series of Landsat Thematic Mapper imagery, rainfall data and site-level vegetation surveys to derive measures of habitat structure at local (1-100 ha) and landscape (100-1000s ha) scales. We used generalised linear models and an information theoretic approach to test the independent effects of spatial and temporal influences on savanna bird diversity and the abundance of eight species with different life-history behaviours. Of four competing models defining influences on assemblages of savanna birds, the most parsimonious included temporal and spatial variability in vegetation cover and site-scale vegetation structure, suggesting savanna bird species respond to spatial and temporal habitat heterogeneity at both the broader landscape scale and at the fine-scale. The relative weight, strength and direction of the explanatory variables changed with each of the eight species, reflecting their different ecology and behavioural traits. This study demonstrates that variations in the spatial pattern of savanna vegetation over periods of 10 to 20 years at the local and landscape scale strongly affect bird diversity and abundance. Thus, it is essential to monitor and manage both spatial and temporal variability in avian habitat to achieve long-term biodiversity outcomes.

  5. Deciphering the distribution of the savanna biome

    CSIR Research Space (South Africa)

    Lehmann, CER

    2011-07-01

    Full Text Available to rainfall. We identified three continental divergences in the limits of savanna that could not be explained by environment. Climate and soils do not have a deterministic effect on the distribution of savanna. Over the range of savanna, some proportion...

  6. Trophic interactions among invertebrates in termitaria in the African savanna : a stable isotope approach

    NARCIS (Netherlands)

    De Visser, Sarah N.; Freymann, Bernd P.; Schnyder, Hans

    2008-01-01

    1. Termites (Isoptera) in tropical savannas are known as ecosystem engineers, affecting the spatial and temporal distribution of water, carbon, cations, and nutrients through their mound structures. Their mounds, however, also offer habitation to diverse taxa and feeding guilds of other

  7. Are community-based forest enterprises in the tropics financially viable? Case studies from the Brazilian Amazon

    Science.gov (United States)

    Shoana Humphries; Thomas P. Holmes; Karen Kainer; Carlos Gabriel Goncalves Koury; Edson Cruz; Rosana de Miranda Rocha

    2012-01-01

    Community-based forest management is an integral component of sustainable forest management and conservation in the Brazilian Amazon, where it has been heavily subsidized for the last ten years. Yet knowledge of the financial viability and impact of community-based forest enterprises (CFEs) is lacking. This study evaluates the profitability of three CFEs in the...

  8. Human impacts in African savannas are mediated by plant functional traits.

    Science.gov (United States)

    Osborne, Colin P; Charles-Dominique, Tristan; Stevens, Nicola; Bond, William J; Midgley, Guy; Lehmann, Caroline E R

    2018-05-28

    Tropical savannas have a ground cover dominated by C 4 grasses, with fire and herbivory constraining woody cover below a rainfall-based potential. The savanna biome covers 50% of the African continent, encompassing diverse ecosystems that include densely wooded Miombo woodlands and Serengeti grasslands with scattered trees. African savannas provide water, grazing and browsing, food and fuel for tens of millions of people, and have a unique biodiversity that supports wildlife tourism. However, human impacts are causing widespread and accelerating degradation of savannas. The primary threats are land cover-change and transformation, landscape fragmentation that disrupts herbivore communities and fire regimes, climate change and rising atmospheric CO 2 . The interactions among these threats are poorly understood, with unknown consequences for ecosystem health and human livelihoods. We argue that the unique combinations of plant functional traits characterizing the major floristic assemblages of African savannas make them differentially susceptible and resilient to anthropogenic drivers of ecosystem change. Research must address how this functional diversity among African savannas differentially influences their vulnerability to global change and elucidate the mechanisms responsible. This knowledge will permit appropriate management strategies to be developed to maintain ecosystem integrity, biodiversity and livelihoods. © 2018 The Authors New Phytologist © 2018 New Phytologist Trust.

  9. Nutrient dynamics and plant assemblages of Macrotermes falciger mounds in a savanna ecosystem

    Science.gov (United States)

    Muvengwi, Justice; Ndagurwa, Hilton G. T.; Nyenda, Tatenda; Mbiba, Monicah

    2016-10-01

    Termites through mound construction and foraging activities contribute significantly to carbon and nutrient fluxes in nutrient-poor savannas. Despite this recognition, studies on the influence of termite mounds on carbon and nitrogen dynamics in sub-tropical savannas are limited. In this regard, we examined soil nutrient concentrations, organic carbon and nitrogen mineralization in incubation experiments in mounds of Macrotermes falciger and surrounding soils of sub-tropical savanna, northeast Zimbabwe. We also addressed whether termite mounds altered the plant community and if effects were similar across functional groups i.e. grasses, forbs or woody plants. Mound soils had significantly higher silt and clay content, pH and concentrations of calcium (Ca), magnesium (Mg), potassium (K), organic carbon (C), ammonium (NH4+) and nitrate (NO3-) than surrounding soils, with marginal differences in phosphorus (P) and sodium (Na) between mounds and matrix soils. Nutrient enrichment increased by a factor ranging from 1.5 for C, 4.9 for Mg up to 10.3 for Ca. Although C mineralization, nitrification and nitrification fraction were similar between mounds and matrix soils, nitrogen mineralization was elevated on mounds relative to surrounding matrix soils. As a result, termite mounds supported unique plant communities rich and abundant in woody species but less diverse in grasses and forbs than the surrounding savanna matrix in response to mound-induced shifts in soil parameters specifically increased clay content, drainage and water availability, nutrient status and base cation (mainly Ca, Mg and Na) concentration. In conclusion, by altering soil properties such as texture, moisture content and nutrient status, termite mounds can alter the structure and composition of sub-tropical savanna plant communities, and these results are consistent with findings in other savanna systems suggesting that increase in soil clay content, nutrient status and associated changes in the plant

  10. Microbial Diversity in Cerrado Biome (Neotropical Savanna Soils.

    Directory of Open Access Journals (Sweden)

    Alinne Pereira de Castro

    Full Text Available The Cerrado, the largest savanna region in South America, is located in central Brazil. Cerrado physiognomies, which range from savanna grasslands to forest formations, combined with the highly weathered, acidic clay Cerrado soils form a unique ecoregion. In this study, high-throughput sequencing of ribosomal RNA genes was combined with shotgun metagenomic analysis to explore the taxonomic composition and potential functions of soil microbial communities in four different vegetation physiognomies during both dry and rainy seasons. Our results showed that changes in bacterial, archaeal, and fungal community structures in cerrado denso, cerrado sensu stricto, campo sujo, and gallery forest soils strongly correlated with seasonal patterns of soil water uptake. The relative abundance of AD3, WPS-2, Planctomycetes, Thermoprotei, and Glomeromycota typically decreased in the rainy season, whereas the relative abundance of Proteobacteria and Ascomycota increased. In addition, analysis of shotgun metagenomic data revealed a significant increase in the relative abundance of genes associated with iron acquisition and metabolism, dormancy, and sporulation during the dry season, and an increase in the relative abundance of genes related to respiration and DNA and protein metabolism during the rainy season. These gene functional categories are associated with adaptation to water stress. Our results further the understanding of how tropical savanna soil microbial communities may be influenced by vegetation covering and temporal variations in soil moisture.

  11. Spatial patterns of DOC concentration and DOM optical properties in a Brazilian tropical river-wetland system

    Science.gov (United States)

    Dalmagro, Higo J.; Johnson, Mark S.; de Musis, Carlo R.; Lathuillière, Michael J.; Graesser, Jordan; Pinto-Júnior, Osvaldo B.; Couto, Eduardo G.

    2017-08-01

    The Cerrado (savanna) and Pantanal (wetland) biomes of Central Western Brazil have experienced significant development activity in recent decades, including extensive land cover conversion from natural ecosystems to agriculture and urban expansion. The Cuiabá River transects the Cerrado biome prior to inundating large areas of the Pantanal, creating one of the largest biodiversity hot spots in the world. We measured dissolved organic carbon (DOC) and the optical absorbance and fluorescence properties of dissolved organic matter (DOM) from 40 sampling locations spanning Cerrado and Pantanal biomes during wet and dry seasons. In the upper, more agricultural region of the basin, DOC concentrations were highest in the rainy season with more aromatic and humified DOM. In contrast, DOC concentrations and DOM optical properties were more uniform for the more urbanized middle region of the basin between wet and dry seasons, as well as across sample locations. In the lower region of the basin, wet season connectivity between the river and the Pantanal floodplain led to high DOC concentrations, a fourfold increase in humification index (HIX) (an indicator of DOM humification), and a 50% reduction in the spectral slope (SR). Basin-wide, wet season values for SR, HIX, and FI (fluorescence index) indicated an increasing representation of terrestrially derived DOM that was more humified. Parallel factor analysis identified two terrestrially derived components (C1 and C2) representing 77% of total fluorescing DOM (fDOM). A third, protein-like fDOM component increased markedly during the wet season within the more urban-impacted region.

  12. Morphological and functional diversity of primary producers group in savannas

    International Nuclear Information System (INIS)

    Medina, E.

    1996-01-01

    (mutual symbiosis) affect the availability of nutritious, and in consequence the productive capacity of savannas. Although there is a theoretical mark to explain the mechanisms that allow the coexistence of similar species in tropical savannas, the specific echo-physiologic properties are still ignored, even for the most dominant species. The advance in the diversity-function study of tropical savannas requires ambitious programs in order to characterize the way how the different primary producer species make use of the available environmental resources [es

  13. Leaf anatomical traits of non-arboreal savanna species along a gradient of tree encroachment

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Souza Pinheiro

    2017-10-01

    Full Text Available ABSTRACT In the Brazilian savanna (Cerrado of Brazil, fire suppression has transformed typical savanna formations (TS into forested savanna (FS due to the phenomenon of encroachment. Under encroachment, non-arboreal plants begin to receive less light due to greater tree density and canopy closure. Here we aim to evaluate if leaf anatomical traits of non-arboreal species differ according to the degree of tree encroachment at the Assis Ecological Station - São Paulo, Brazil. To this end, we evaluated leaf tissue thickness and specific leaf area (SLA in representative non-arboreal species occurring along a gradient of tree encroachment. Leaves of TS species showed a trend towards xeromorphism, with traits reported to facilitate survival under high luminosity, such as thick leaves, thick epidermis and mesophyll, and low SLA. In contrast, FS species exhibited mesomorphic leaves, with thin mesophyll and high SLA, which are able to capture diffuse light in denser environments. Thus, non-arboreal understory species with mesomorphic leaf traits should be favored in environments with denser vegetation in contrast to typical savanna species. The results suggest that typical non-arboreal savanna species would not survive under tree encroachment due to the low competitiveness of their leaf anatomical strategies in shady environments.

  14. Sobrevivência e crescimento de seis espécies arbóreas submetidas a quatro tratamentos em área minerada no cerrado Survival and growth of six tree species under four treatments on a mined areain the Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Lucas de Carvalho Ramos Silva

    2008-08-01

    Full Text Available Entre as várias atividades antrópicas desenvolvidas no Cerrado, a mineração é uma das que provocam significativos danos. A regeneração natural da vegetação em áreas mineradas é extremamente lenta e, portanto, a intervenção em lavras esgotadas faz-se necessária. O presente trabalho objetiva avaliar a sobrevivência e o crescimento de mudas de seis espécies arbóreas, submetidas a quatro tratamentos, usadas na revegetação de uma cascalheira em Brasília-DF. Os quatro tratamentos consistiram da combinação da utilização de cobertura morta sobre as covas e/ou o plantio de árvores em substrato coberto por Stylosanthes spp. Um tratamento controle, localizado em área adjacente não minerada, foi estabelecido para efeitos comparativos. Os resultados indicam que as mudas arbóreas implantadas na área minerada apresentaram maior sobrevivência e crescimento do que as mesmas espécies plantadas na área controle não minerada. Na área minerada não foram verificadas diferenças significativas no desenvolvimento das espécies em função dos tratamentos aplicados - cobertura morta sobre covas e/ou estrato herbáceo sobre a superfície minerada.Among many human activities developed in areas of Brazilian savanna, mining is one that causes significative damage to the environment. Natural sucession on such sites is extremely slow and therefore revegetation works are necessary. This work aims to evaluate survival and growth of six tree species under four treatments grown on an exploited gravel mine in the Brazilian Federal District. The four treatments were drawn from the combination of mulching around tree seedlings and the establishment of Stylosanthes spp on the area surface. A control was established on a nearby unexploited for comparison reason. Results show a higher survival rate and growth of tree seedlings established on the exploited site than on the control-site which kept intact soil. There were no significant differences for

  15. Nutrient and Light Limitations on Grass Productivity in a Southern African Savanna

    Science.gov (United States)

    Ries, L. P.; Shugart, H. H.; Caylor, K. K.; Okin, G. S.; Kgope, B.

    2006-12-01

    Despite the ubiquity of sub-tropical savannas throughout the earth, limitations of savanna productivity are understudied relative to other terrestrial systems. In particular, there has been little attention on the role of phosphorus (P) in savanna productivity and structure. This study examined the role of increased nitrogen (N) and P in grass productivity in a woodland savanna in Botswana. We added aqueous forms of N and P individually and together to selected grasses. During the following growing season we measured foliar nutrient concentrations, aboveground biomass productivity and photosynthetic response at various levels of incident photosynthetically active radiation to estimate the productivity response. As expected, we observed an increase in foliar P concentrations in P and N+P treatments. However, there was no increase in foliar N for any treatments. We also observed a significant increase in net carbon assimilation and Amax for all treatments relative to the control grasses. Despite a higher rate of leaf level carbon assimilation in the N treatment, the aboveground biomass production was smaller than that of the N+P treatment. These results suggest that the aboveground productivity of these woodland savanna grasses is limited by both N and P. Additionally, under constant CO2 availability, photosynthesis appears to be limited by nutrients for light levels greater than 500 μmol m-2s-1. This research will help broaden our understanding of the biogeochemical processes that govern savanna productivity. Ultimately, these data can be used to model canopy productivity and ecological succession of savannas under scenarios in which bush encroachment and desertification may alter light and nutrients availability.

  16. Using paleoecological data to define main vegetation dynamics along the savanna-forest ecotone in Colombia: implications for accurate assessment of human impacts

    NARCIS (Netherlands)

    Berrio, J.C.; Wouters, H.; Hooghiemstra, H.; Carr, A.S.; Boom, A.; Randall, R.W

    2012-01-01

    n recent decades there has been increasing interest, from scientists of many disciplines, in the origins and dynamics of tropical savanna-forest boundaries. These boundaries are rarely present as a smooth gradient from tropical forests to scattered trees and open grassland (Bond and Parr 2010);

  17. The new research centre of the Brazilian Petroleum Company in Rio de Janeiro, Brazil: The achievements in the thermal performance of air-conditioned buildings in the tropics

    Energy Technology Data Exchange (ETDEWEB)

    Brandao, Rafael; Marcondes, Monica Pereira; De Benedetto, Gisele S.; Goncalves, Joana Carla Soares; Duarte, Denise Helena Silva; Ramos, Jose Ovidio [Laboratorio de Conforto Ambiental e Eficiencia Energetica (LABAUT), Departamento de Tecnologia da Arquitetura (AUT), Faculdade de Arquitetura e Urbanismo, Universidade de Sao Paulo (FAUUSP), Sao Paulo, Brasil, Rua do Lago, 876, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil)

    2008-07-01

    The study on the thermal performance of the air-conditioned buildings of the new research centre of the Brazilian Petroleum Company, in the tropical climate of Rio de Janeiro, was part of a bigger research and consultancy project involving environmental issues. The architectural design was the subject of a national competition in 2004, encompassing over 100,000 m{sup 2}. According to the design brief, out of the 10 buildings of the new research centre, 7 have to be either completely or partially air-conditioned, due to specific occupation requirements. The challenge for better thermal performance was related to systems' energy efficiency, to the introduction of natural ventilation and to the notion of adaptive comfort, which were verified with the support of thermal dynamic simulations. At the early stages of the assessments, the potential for natural ventilation in the working spaces considering the mixed-mode strategy achieved 30% of occupation hours. However, the development of the design project led to fully air-conditioned working spaces, due to users' references regarding the conventional culture of the office environment. Nevertheless, the overall architectural approach in accordance to the climatic conditions still showed a contribution to the buildings' energy efficiency. (author)

  18. Propriedades químicas de um Neossolo Quartzarênico sob diferentes sistemas de manejo no Cerrado mato-grossense Soil chemical properties in a Typic Quartzipisamment under different management systems in Brazilian savanna in Mato Grosso State, Brazil

    Directory of Open Access Journals (Sweden)

    Leidivan Almeida Frazão

    2008-05-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de diferentes usos da terra e sistemas de manejo do solo, nas características químicas de um Neossolo Quartzarênico, no Cerrado de Mato Grosso. Os tratamentos estudados foram: cerrado nativo; uma pastagem de baixa produtividade com 22 anos de implantação; plantio convencional com 1 e 4 anos de uso e diferentes sucessões de culturas; e plantio direto com 5 anos de implantação. Foram determinados os teores de carbono e nitrogênio, pH, acidez potencial, capacidade de troca de cátions (CTC, fósforo disponível, bases trocáveis e saturação por bases do solo. Os valores mais baixos de pH, fósforo disponível, potássio, cálcio e magnésio foram observados nas áreas sob cerrado e pastagem, e a menor concentração de carbono no solo sob pastagem refletiu menor CTC do solo. A aplicação do calcário nos tratamentos com plantio convencional e direto favorece o aumento das concentrações de cálcio e magnésio no solo. Nesses sistemas, a saturação por bases (V% do solo é mais elevada nas áreas com maior tempo de implantação (4 e 5 anos. Embora o Neossolo Quartzarênico possua limitações para o cultivo, em razão de sua baixa fertilidade natural, se adequadamente manejado, este solo apresenta potencial para o cultivo agrícola.The objective of this work was to evaluate the effect of different land uses and soil management systems, on chemical characteristics of a Typic Quartzipisamment in the savanna (Cerrado of Mato Grosso State, Brazil. The treatments studied were: native cerrado; pasture with low productivity for 22 years; conventional tillage with one and four years and different crop successions; and no-tillage for five years. Soil carbon and nitrogen, pH, potential acidity, cation exchange capacity (CEC, available phosphorus, exchangeable bases and base saturation were determined. The cerrado and pasture treatments had the lowest pH, available phosphorus, calcium and magnesium

  19. Spatial and temporal distribution of tropical biomass burning

    Science.gov (United States)

    Hao, Wei Min; Liu, Mei-Huey

    1994-12-01

    A database for the spatial and temporal distribution of the amount of biomass burned in tropical America, Africa, and Asia during the late 1970s is presented with a resolution of 5° latitude × 5° longitude. The sources of burning in each grid cell have been quantified. Savanna fires, shifting cultivation, deforestation, fuel wood use, and burning of agricultural residues contribute about 50, 24, 10, 11, and 5%, respectively, of total biomass burned in the tropics. Savanna fires dominate in tropical Africa, and forest fires dominate in tropical Asia. A similar amount of biomass is burned from forest and savanna fires in tropical America. The distribution of biomass burned monthly during the dry season has been derived for each grid cell using the seasonal cycles of surface ozone concentrations. Land use changes during the last decade could have a profound impact on the amount of biomass burned and the amount of trace gases and aerosol particles emitted.

  20. Tropical Sex in a European Country: Brazilian Women’s Migration to Italy in the Frame of International Sex Tourism

    Directory of Open Access Journals (Sweden)

    Adriana Piscitelli

    2007-09-01

    Full Text Available In Fortaleza, which is one of the main cities linked to sex tourism in the Northeast of Brazil, young low income women leave the country with or invited by sex tourists. While some indeed engage themselves in the sex industry in Europe, others leave it when marrying European men. Focusing on the universe of integrants of couples integrated women from the Northeast from Brazil and Italian men, this paper addresses the differentiations that acquire centrality when these relationships, formed in an ambiguous terrain where sexuality, economic interest and romance intermingle, are contextualized in Italy. I analyze the cultural, political and economic implications of that migration. The study discusses the relationship between gender and economic negotiations in those couples, reflecting on the meanings acquired by “tropical sexuality” in the migration to that Northern country.

  1. Tropical sex in a European country: Brazilian women's migration to Italy in the frame of international sex tourism

    Directory of Open Access Journals (Sweden)

    Adriana Piscitelli

    2008-01-01

    Full Text Available In Fortaleza, which is one of the main cities linked to sex tourism in the Northeast of Brazil, young low income women leave the country with or invited by sex tourists. While some indeed engage themselves in the sex industry in Europe, others leave it when marrying European men. Focusing on the universe of integrants of couples integrated women from the Northeast from Brazil and Italian men, this paper addresses the differentiations that acquire centrality when these relationships, formed in an ambiguous terrain where sexuality, economic interest and romance intermingle, are contextualized in Italy. I analyze the cultural, political and economic implications of that migration. The study discusses the relationship between gender and economic negotiations in those couples, reflecting on the meanings acquired by "tropical sexuality" in the migration to that Northern country.

  2. Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds

    Directory of Open Access Journals (Sweden)

    PEREIRA R. C.

    2002-01-01

    Full Text Available Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1 -- 0.08% dry weight. This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.

  3. Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds

    Directory of Open Access Journals (Sweden)

    R. C. PEREIRA

    Full Text Available Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1 -- 0.08% dry weight. This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.

  4. Greenhouse gas emissions from Savanna ( Miombo ) woodlands ...

    African Journals Online (AJOL)

    Natural vegetation represents an important sink for greenhouse gases (GHGs); however, there is relatively little information available on emissions from southern African savannas. The effects of clearing savanna woodlands for crop production on soil fluxes of N2O, CO2 and CH4 were studied on clay (Chromic luvisol) and ...

  5. Malaria in the State of Amazonas: a typical Brazilian tropical disease influenced by waves of economic development

    Directory of Open Access Journals (Sweden)

    Vanderson Souza Sampaio

    2015-06-01

    Full Text Available In Brazil, more than 99% of malaria cases are reported in the Amazon, and the State of Amazonas accounts for 40% of this total. However, the accumulated experience and challenges in controlling malaria in this region in recent decades have not been reported. Throughout the first economic cycle during the rubber boom (1879 to 1912, malaria was recorded in the entire state, with the highest incidence in the villages near the Madeira River in the Southern part of the State of Amazonas. In the 1970s, during the second economic development cycle, the economy turned to the industrial sector and demanded a large labor force, resulting in a large migratory influx to the capital Manaus. Over time, a gradual increase in malaria transmission was observed in peri-urban areas. In the 1990s, the stimulation of agroforestry, particularly fish farming, led to the formation of permanent Anopheline breeding sites and increased malaria in settlements. The estimation of environmental impacts and the planning of measures to mitigate them, as seen in the construction of the Coari-Manaus gas pipeline, proved effective. Considering the changes occurred since the Amsterdam Conference in 1992, disease control has been based on early diagnosis and treatment, but the development of parasites that are resistant to major antimalarial drugs in Brazilian Amazon has posed a new challenge. Despite the decreased lethality and the gradual decrease in the number of malaria cases, disease elimination, which should be associated with government programs for economic development in the region, continues to be a challenge.

  6. Performance of tropical legumes grown as understory of a eucalypt plantation in a seasonally dry area of the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    Maria Luiza F. Nicodemo

    2015-09-01

    Full Text Available Nine tropical legumes were grown outside the canopy and in the understory of an 8-year-old Eucalyptus grandis stand in order to assess their seasonal production and forage quality for 4 evaluation periods. Incident photosynthetically active radiation in the understory was 18% of that outside the canopy. In the understory, production of Lablab purpureus, Centrosema schiedeanum, Clitoria ternatea, Pueraria phaseoloides, Alysicarpus vaginalis, Aeschynomene villosa, Estilosantes Campo Grande (Stylosanthes capitata + S. macrocephala, Calopogonium mucunoides and Arachis pintoi was <1 kg/ha/d for most samples. Even considering this low production, the large area available for animal production in forest plantations might justify the interest in legumes because of their high nutritive value. Lablab purpureus produced the greatest amount of dry matter in the understory in the establishment phase (12.1 kg/ha/d, but did not persist. It could be a suitable candidate for a cover legume species mixture to provide early growth. Centrosema schiedeanum developed rapidly and showed a high capacity for ground cover (>70% and persistence, and had high nitrogen concentration, thus demonstrating good potential for protecting soils and promoting nutrient cycling in forest plantations. Another species with potential is A. pintoi, which established slowly but towards the end of the experiment showed moderate to high understory ground cover.Keywords: Dry matter production, forage quality, shade, silvopastoral system.DOI: 10.17138/TGFT(3151-160

  7. Breeding sites of drosophilids (Diptera in the Brazilian Savanna. I. Fallen fruits of Emmotum nitens (Icacinaceae, Hancornia speciosa (Apocynaceae and Anacardium humile (Anacardiaceae Sítios de criação de drosofilídeos (Diptera no bioma Cerrado. I. Frutos caídos de Emmotum nitens (Icacinaceae, Hancornia speciosa (Apocynaceae e Anacardium humile (Anacardiaceae

    Directory of Open Access Journals (Sweden)

    Francisco Roque

    2009-06-01

    Full Text Available In this study, drosophilids that bred in fruits of three common plant species of the Brazilian Savanna were investigated: Emmotum nitens, Hancornia speciosa and Anacardium humile, along with the temporal and spatial distribution of these insects among fruits obtained from six individuals of E. nitens. Fallen fruits were collected in natural environments, placed on moist sand in individual containers and all drosophilids that emerged from these resources during 15 days were collected, counted and identified. From 3,651 fruits collected (3,435 of E. nitens, 179 of A. humile and 37 of H. speciosa 4,541 flies emerged and were classified into 19 species of Drosophilidae. Their distribution was unequal among the three resources, also over time, and among the six individuals of E. nitens. Such fluctuations probably reflect the availability of resources in time and space and probably the action of selective factors such as larval competition.Neste estudo, são investigados os drosofilídeos que se criam em frutos de três espécies de plantas comuns do Cerrado brasileiro: Emmotum nitens, Hancornia speciosa e Anacardium humile, juntamente com a distribuição temporal e espacial desses insetos entre os frutos obtidos de seis indivíduos de E. nitens. Frutos recolhidos sobre a serrapilheira, em ambientes naturais, foram mantidos no laboratório e os drosofilídeos que deles emergiram foram contados e identificados. Dos 3.651 frutos coletados (3.435 de E. nitens, 179 de A. humile e 37 de H. speciosa emergiram 4.541 drosofilídeos, classificados em 19 espécies. A distribuição dessas espécies foi desigual entre os três tipos de recursos, ao longo do tempo, e também entre os seis indivíduos de E. nitens. Essas flutuações refletem a disponibilidade dos recursos no tempo e no espaço, e provavelmente a ação de forças seletivas como a competição entre as larvas.

  8. The Brazilian Developments on the Regional Atmospheric Modeling System (BRAMS 5.2): An Integrated Environmental Model Tuned for Tropical Areas

    Science.gov (United States)

    Freitas, Saulo R.; Panetta, Jairo; Longo, Karla M.; Rodrigues, Luiz F.; Moreira, Demerval S.; Rosario, Nilton E.; Silva Dias, Pedro L.; Silva Dias, Maria A. F.; Souza, Enio P.; Freitas, Edmilson D.; hide

    2017-01-01

    We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers.

  9. Fuel biomass and combustion factors associated with fires in savanna ecosystems of South Africa and Zambia

    Science.gov (United States)

    Shea, Ronald W.; Shea, Barbara W.; Kauffman, J. Boone; Ward, Darold E.; Haskins, Craig I.; Scholes, Mary C.

    1996-10-01

    Fires are dominant factors in shaping the structure and composition of vegetation in African savanna ecosystems. Emissions such as CO2, NOx, CH4, and other compounds originating from these fires are suspected to contribute substantially to changes in global biogeochemical processes. Limited quantitative data exist detailing characteristics of biomass, burning conditions, and the postfire environment in African savannas. Fourteen test sites, differentiated by distinct burn frequency histories and land-use patterns, were established and burned during August and September 1992 in savanna parklands of South Africa and savanna woodlands of Zambia. Vegetation physiognomy, available fuel loads, the levels of biomass consumed by fire, environmental conditions, and fire behavior are described. In the South African sites, total aboveground fuel loads ranged from 2218 to 5492 kg ha-1 where fire return intervals were 1-4 years and exceeded 7000 kg ha-1 at a site subjected to 38 years of fire exclusion. However, fireline intensity was only 1419 kW m-1 at the fire exclusion site, while ranging from 480 to 6130 kW m-1 among the frequent fire sites. In Zambia, total aboveground fuel loads ranged from 3164 kg ha-1 in a hydromorphic grassland to 7343 kg ha-1 in a fallow shifting cultivation site. Dormant grass and litter constituted 70-98% of the total fuel load among all sites. Although downed woody debris was a relatively minor fuel component at most sites, it constituted 43-57% of the total fuel load in the fire exclusion and shifting cultivation sites. Fire line intensity ranged between 1734 and 4061 kW m-1 among all Zambian sites. Mean grass consumption generally exceeded 95%, while downed woody debris consumption ranged from 3 to 73% at all sites. In tropical savannas and savanna woodlands of southern Africa, differences in environmental conditions, land- use patterns, and fire regimes influence vegetation characteristics and thus influence fire behavior and biomass

  10. Changes in Carbon Emissions in Colombian Savannas Derived From Recent Land use and Land Cover Change

    Science.gov (United States)

    Etter, A.; Sarmiento, A.

    2007-12-01

    The global contribution of carbon emissions from land use dynamics and change to the global carbon (C) cycle is still uncertain, a major concern in global change modeling. Carbon emission from fires in the tropics is significant and represents 9% of the net primary production, and 50% of worldwide C emissions from fires are attributable to savanna fires. Such emissions may vary significantly due to differences in ecosystem types. Most savanna areas are devoted to grazing land uses making methane emissions also important in savanna ecosystems. Land use change driven by intensification of grazing and cropping has become a major factor affecting C emission dynamics from savanna regions. Colombia has some 17 MHa of mesic savannas which have been historically burned. Due to changes in market demands and improved accessibility during the last 20 years, important areas of savannas changed land use from predominantly extensive grazing to crops and intensive grazing systems. This research models and evaluates the impacts of such land use changes on the spatial and temporal burning patterns and C emissions in the Orinoco savannas of Colombia. We address the effects of land use change patterns using remote sensing data from MODIS and Landsat, ecosystem mapping products, and spatial GIS analysis. First we map the expansion of the agricultural frontier from the 1980s-2000s. We then model the changes in land use from the 1980s using a statistical modeling approach to analyze and quantify the impact of accessibility, ecosystem type and land tenure. We calculate the effects on C emissions from fire regimes and other sources of C based on patterns and extent of burned areas in the 2000s for different savanna ecosystem types and land uses. In the Llanos the fire regime exhibits a marked seasonal variability with most fire events occurring during the dry season between December-March. Our analysis shows that fire frequencies vary consistently between 0.6 and 2.8 fires.yr-1 per 2

  11. Tree-grass interactions in savannas

    CSIR Research Space (South Africa)

    Scholes, RJ

    1997-01-01

    Full Text Available Savannas occur where trees and grasses interact to create a biome that is neither grassland nor forest. Woody and gramineous plants interact by many mechanisms, some negative (competition) and some positive (facilitation). The strength and sign...

  12. Determinants of woody cover in African savannas

    Science.gov (United States)

    Sankaran, M.; Hanan, N.P.; Scholes, Robert J.; Ratnam, J.; Augustine, D.J.; Cade, B.S.; Gignoux, J.; Higgins, S.I.; Le, Roux X.; Ludwig, F.; Ardo, J.; Banyikwa, F.; Bronn, A.; Bucini, G.; Caylor, K.K.; Coughenour, M.B.; Diouf, A.; Ekaya, W.; Feral, C.J.; February, E.C.; Frost, P.G.H.; Hiernaux, P.; Hrabar, H.; Metzger, K.L.; Prins, H.H.T.; Ringrose, S.; Sea, W.; Tews, J.; Worden, J.; Zambatis, N.

    2005-01-01

    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties 1-3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1,2,4,5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ???650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered 'stable' systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ???650 mm, savannas are 'unstable' systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation 6 may considerably affect their distribution and dynamics. ?? 2005 Nature Publishing Group.

  13. Biochemical characterization of selected plant species from Brazilian Savannas

    Directory of Open Access Journals (Sweden)

    Samantha Salomão Caramori

    2004-06-01

    Full Text Available The aim of this work was to analyze and quantify the presence of antinutritional compounds such as lectins and trypsin-like inhibitors, polyphenols and tannins, and enzymatic activity of peroxidases and proteases in the seeds of Annona crassiflora Mart. (araticum, Hymenaea courbaril L. var. courbaril (jatobá, Plathymenia reticulata Benth. (vinhático, Zanthoxylum rhoifolium Lam. (maminha de porca, Apeiba tibourbou Aubl. (pau jangada, Salacia crassiflora Mart G. Don. (bacupari, and Sclerolobium paniculatum Vog. (carvoeiro. The results suggested that these plants could be used as new source of food.O Cerrado é constituído por inúmeras espécies vegetais com potencial econômico, as quais são utilizadas para os mais variados fins, como medicinal e nutricional. O objetivo deste trabalho foi analisar e quantificar a presença de atividade enzimática de peroxidases e proteases e fatores antinutricionais, como lectinas e inibidores de proteases, além de polifenóis e taninos em algumas espécies nativas do Cerrado. O material vegetal utilizado foram sementes de Annona crassiflora Mart. (araticum, Hymenaea courbaril L. var. courbaril (jatobá, Plathymenia reticulata Benth. (vinhático, Zanthoxylum rhoifolium Lam. (maminha de porca, Apeiba tibourbou Aubl. (pau jangada, Salacia crassiflora (Mart. G. Don. (bacupari e Sclerolobium paniculatum Vog. (carvoeiro, coletadas na cidade de Goiânia e municípios de Jataí e Caldas Novas, estado de Goiás. O uso potencial destas plantas e suas enzimas na indústria de alimentos, poderia resultar em aplicações ao aparecimento de novos produtos a partir das matérias-primas tradicionais, além do uso de novas fontes de alimentos.

  14. Seasonal variation of soluble carbohydrates and starch in Echinolaena inflexa, a native grass species from the Brazilian savanna, and in the invasive grass Melinis minutiflora Variações sazonais de carboidratos solúveis e amido em Echinolaena inflexa, uma espécie nativa do cerrado, e na gramínea invasora Melinis minutiflora

    Directory of Open Access Journals (Sweden)

    A. Souza

    2010-05-01

    Full Text Available Echinolaena inflexa (Poir. Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado; Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil. Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.Echinolaena inflexa (Poir. Chase é uma gramínea C3 muito abundante em áreas de cerrado e com alta produção de biomassa. Melinis minutiflora Beauv. é uma gramínea C4 de origem africana introduzida no Brasil para fins forrageiros, que se espalhou amplamente por áreas de cerrado, provavelmente deslocando espécies nativas. No presente trabalho, o conteúdo e a composição de carboidratos solúveis, o teor de amido e a biomassa aérea foram analisados sazonalmente em plantas de E. inflexa e M. minutiflora coletadas em dois transectos

  15. Implication of Forest-Savanna Dynamics on Biomass and Carbon Stock: Effectiveness of an Amazonian Ecological Station

    Science.gov (United States)

    Couto-Santos, F. R.; Luizao, F. J.

    2014-12-01

    The forests-savanna advancement/retraction process seems to play an important role in the global carbon cycle and in the climate-vegetation balance maintenance in the Amazon. To contribute with long term carbon dynamics and assess effectiveness of a protected area in reduce carbon emissions in Brazilian Amazon transitional areas, variations in forest-savanna mosaics biomass and carbon stock within Maraca Ecological Station (MES), Roraima/Brazil, and its outskirts non-protected areas were compared. Composite surface soil samples and indirect methods based on regression models were used to estimate aboveground tree biomass accumulation and assess vegetation and soil carbon stock along eleven 0.6 ha transects perpendicular to the forest-savanna limits. Aboveground biomass and carbon accumulation were influenced by vegetation structure, showing higher values within protected area, with great contribution of trees above 40 cm in diameter. In the savanna environments of protected areas, a higher tree density and carbon stock up to 30 m from the border confirmed a forest encroachment. This pointed that MES acts as carbon sink, even under variations in soil fertility gradient, with a potential increase of the total carbon stock from 9 to 150 Mg C ha-1. Under 20 years of fire and disturbance management, the results indicated the effectiveness of this protected area to reduce carbon emissions and mitigate greenhouse and climate change effects in a forest-savanna transitional area in Brazilian Northern Amazon. The contribution of this study in understanding rates and reasons for biomass and carbon variation, under different management strategies, should be considered the first approximation to assist policies of reducing emissions from deforestation and forest degradation (REDD) from underresearched Amazonian ecotone; despite further efforts in this direction are still needed. FINANCIAL SUPPORT: Boticário Group Foundation (Fundação Grupo Boticário); National Council for

  16. Biomass burning in West African savannas

    International Nuclear Information System (INIS)

    Menaut, J.C.; Abbadie, L.; Lavenu, F.; Loudjani, P.; Podaire, A.

    1991-01-01

    This chapter approaches the influence of West African savanna ecosystems on the regional climate by giving, as precisely as possible, the amount of volatilized elements (e.g., carbon, nitrogen, and sulfur) annually released by bush fires into the atmosphere. In spite of the relative functional similarity of West African savannas, fire behavior and effects vary with the different bioclimatic and phytogeographic zones of the region: Guinea or humid zone; Sudan or mesic zone; and, Sahel or arid zone. In order to reach an acceptable accuracy, results are given for each of the zones described and summarized for West Africa

  17. Determinants of woody cover in African savannas

    CSIR Research Space (South Africa)

    Sankaran, M

    2005-12-08

    Full Text Available workshop on savanna complexity funded by the NSF. We thank R. Boone, I. McHugh, R. Grant, H. Biggs, W. T. Starmer, P. M. Barbosa, D. Ruess, J. Rettenmayer, C. Williams, J. Klein, M. T. Anderson, W. J. Parton, J. C. Neff, N. Govender and the Kruger Park...

  18. Savanna browse production. 2: Prediction | Penderis | African ...

    African Journals Online (AJOL)

    Our study was initiated with the aim of modelling browse production rates of key savanna tree species in the northern Zululand region of KwaZulu-Natal, with the assumption that browse production equates to utilised browse biomass. Predictive models for the production of browse, at different game feeding levels, ...

  19. Restoration of midwestern oak woodlands and savannas

    Science.gov (United States)

    Dan C. Dey; John M. Kabrick

    2015-01-01

    There are various definitions for savanna and woodland in the ecological literature. Characteristic elements of each community are broadly defined and often overlap according to the authorities (Curtis 1959; Nuzzo 1986; Nelson 2010). Some confusion is inevitable when categorizing what is in reality a continuum of states from prairie to forest in which there can be much...

  20. Brazilian Consensus on Photoprotection

    Science.gov (United States)

    Schalka, Sérgio; Steiner, Denise; Ravelli, Flávia Naranjo; Steiner, Tatiana; Terena, Aripuanã Cobério; Marçon, Carolina Reato; Ayres, Eloisa Leis; Addor, Flávia Alvim Sant'anna; Miot, Helio Amante; Ponzio, Humberto; Duarte, Ida; Neffá, Jane; da Cunha, José Antônio Jabur; Boza, Juliana Catucci; Samorano, Luciana de Paula; Corrêa, Marcelo de Paula; Maia, Marcus; Nasser, Nilton; Leite, Olga Maria Rodrigues Ribeiro; Lopes, Otávio Sergio; Oliveira, Pedro Dantas; Meyer, Renata Leal Bregunci; Cestari, Tânia; dos Reis, Vitor Manoel Silva; Rego, Vitória Regina Pedreira de Almeida

    2014-01-01

    Brazil is a country of continental dimensions with a large heterogeneity of climates and massive mixing of the population. Almost the entire national territory is located between the Equator and the Tropic of Capricorn, and the Earth axial tilt to the south certainly makes Brazil one of the countries of the world with greater extent of land in proximity to the sun. The Brazilian coastline, where most of its population lives, is more than 8,500 km long. Due to geographic characteristics and cultural trends, Brazilians are among the peoples with the highest annual exposure to the sun. Epidemiological data show a continuing increase in the incidence of non-melanoma and melanoma skin cancers. Photoprotection can be understood as a set of measures aimed at reducing sun exposure and at preventing the development of acute and chronic actinic damage. Due to the peculiarities of Brazilian territory and culture, it would not be advisable to replicate the concepts of photoprotection from other developed countries, places with completely different climates and populations. Thus the Brazilian Society of Dermatology has developed the Brazilian Consensus on Photoprotection, the first official document on photoprotection developed in Brazil for Brazilians, with recommendations on matters involving photoprotection. PMID:25761256

  1. Changes in soil organic carbon after burning in a forest-savanna edge

    Directory of Open Access Journals (Sweden)

    Federico Sánchez Ojeda

    2017-10-01

    Full Text Available Soils are one of the largest terrestrial pools of carbon, yet there is still little understanding of spatial variability for ecosystems in the tropics. Fire plays an important role in neotropical savannas ecosystems and significantly contribute to global greenhouse gas (GHG fluxes. Nevertheless the impacts of burning on soil carbon is still uncertain in Latin America. We compared soil organic carbon (SOC in the first 20 cm depth in savannas in pre and post fire conditions along a forests-savanna edge typically present in these landscapes of the northern South America. We established 8 transects of 20 m longitude along the border with 1m2 plots sampled every 4 m. SOC pre-disturbance was on average 1.794 (±SE 0,043 and the minimum value found (1.08% was registered 6 months after the burning. Our results show that both the influence of the distance to the edge and the time of burning affect negatively the SOC and also there is a significant interaction between both variables. Our results provide improved estimates of the effect of fire on soil carbon stocks and its highly dynamic nature . We believe these finding will be a step to help better estimate GHG in this type of heterogeneous landscapes. Further it provides a tool for understanding C dynamics under a climate change context with predicted increased fire frequency, extent and severity.

  2. PHYTOSOCIOLOGY OF SOWN PASTURE WEEDS UNDER TWO LEVELS OF DEGRADATION IN BRAZILIAN SAVANNA AREAS, MATO GROSSO DO SUL STATE, BRAZIL FITOSSOCIOLOGIA DE PLANTAS DANINHAS DE PASTAGENS CULTIVADAS SOB DOIS NÍVEIS DE DEGRADAÇÃO EM CERRADO, NO MATO GROSSO DO SUL

    Directory of Open Access Journals (Sweden)

    Adriana Guglieri-Caporal

    2010-08-01

    Full Text Available

    Cultivated pastures, in general, go through a decline process, associated with the occurrence of weeds, whose successful management begins with the survey of species and their biology. This study aimed to carry out phytosociological surveys, during the rainy and dry seasons, in two pastures cultivated with Brachiaria (Urochloa spp., with cattle (AI and without cattle (AII, in Cerrado (Brazilian savanna areas of the Mato Grosso do Sul State, Brazil. The occurrence of 104 weedy herbaceous and subshrubby Phanerogams species was recorded. The families with the highest number of species were Fabaceae (23 species, Poaceae (16, and Asteraceae (15. Hemicryptophytes predominate with 41% of the species. The species with the highest importance value and relative coverage are B. decumbens and Sida rhombifolia, in AI, and B. brizantha and Desmodium incanum, in AII, plus Paspalum notatum, in both pastures. The Shannon diversity index was 4.19 and 4.43 nats, for AI and AII, respectively, indicating considerable weed species richness. The floristic dissimilarity index between AI and AII, obtained from the Euclidian

  3. Quantifying the relative importance of greenhouse gas emissions from current and future savanna land use change across northern Australia

    Directory of Open Access Journals (Sweden)

    M. Bristow

    2016-11-01

    Full Text Available The clearing and burning of tropical savanna leads to globally significant emissions of greenhouse gases (GHGs; however there is large uncertainty relating to the magnitude of this flux. Australia's tropical savannas occupy the northern quarter of the continent, a region of increasing interest for further exploitation of land and water resources. Land use decisions across this vast biome have the potential to influence the national greenhouse gas budget. To better quantify emissions from savanna deforestation and investigate the impact of deforestation on national GHG emissions, we undertook a paired site measurement campaign where emissions were quantified from two tropical savanna woodland sites; one that was deforested and prepared for agricultural land use and a second analogue site that remained uncleared for the duration of a 22-month campaign. At both sites, net ecosystem exchange of CO2 was measured using the eddy covariance method. Observations at the deforested site were continuous before, during and after the clearing event, providing high-resolution data that tracked CO2 emissions through nine phases of land use change. At the deforested site, post-clearing debris was allowed to cure for 6 months and was subsequently burnt, followed by extensive soil preparation for cropping. During the debris burning, fluxes of CO2 as measured by the eddy covariance tower were excluded. For this phase, emissions were estimated by quantifying on-site biomass prior to deforestation and applying savanna-specific emission factors to estimate a fire-derived GHG emission that included both CO2 and non-CO2 gases. The total fuel mass that was consumed during the debris burning was 40.9 Mg C ha−1 and included above- and below-ground woody biomass, course woody debris, twigs, leaf litter and C4 grass fuels. Emissions from the burning were added to the net CO2 fluxes as measured by the eddy covariance tower for other post-deforestation phases to

  4. Quantifying the relative importance of greenhouse gas emissions from current and future savanna land use change across northern Australia

    Science.gov (United States)

    Bristow, Mila; Hutley, Lindsay B.; Beringer, Jason; Livesley, Stephen J.; Edwards, Andrew C.; Arndt, Stefan K.

    2016-11-01

    The clearing and burning of tropical savanna leads to globally significant emissions of greenhouse gases (GHGs); however there is large uncertainty relating to the magnitude of this flux. Australia's tropical savannas occupy the northern quarter of the continent, a region of increasing interest for further exploitation of land and water resources. Land use decisions across this vast biome have the potential to influence the national greenhouse gas budget. To better quantify emissions from savanna deforestation and investigate the impact of deforestation on national GHG emissions, we undertook a paired site measurement campaign where emissions were quantified from two tropical savanna woodland sites; one that was deforested and prepared for agricultural land use and a second analogue site that remained uncleared for the duration of a 22-month campaign. At both sites, net ecosystem exchange of CO2 was measured using the eddy covariance method. Observations at the deforested site were continuous before, during and after the clearing event, providing high-resolution data that tracked CO2 emissions through nine phases of land use change. At the deforested site, post-clearing debris was allowed to cure for 6 months and was subsequently burnt, followed by extensive soil preparation for cropping. During the debris burning, fluxes of CO2 as measured by the eddy covariance tower were excluded. For this phase, emissions were estimated by quantifying on-site biomass prior to deforestation and applying savanna-specific emission factors to estimate a fire-derived GHG emission that included both CO2 and non-CO2 gases. The total fuel mass that was consumed during the debris burning was 40.9 Mg C ha-1 and included above- and below-ground woody biomass, course woody debris, twigs, leaf litter and C4 grass fuels. Emissions from the burning were added to the net CO2 fluxes as measured by the eddy covariance tower for other post-deforestation phases to provide a total GHG emission from

  5. Spatial Heterogeneity and Sources of Soil Carbon in Southern African Savannas

    Science.gov (United States)

    Macko, S.; Wang, L.; Okin, G.

    2007-12-01

    Soil organic carbon (SOC) is one of the largest and most dynamic reservoirs of C on Earth, with nearly twice as much C stored in SOC than in the biosphere and atmosphere combined. SOC storage in global tropical savannas constitutes approximately 56 Gt of C, which rises to 216 Gt of C (i.e., about 17% of the terrestrial non- agricultural SOC), when woodlands, shrublands, and desert scrub are included. Savannas cover about 20% of the global land surface, including about one-half of Africa, Australia and South America. The shared dominance of trees and grasses in savannas, the dominant physiognomy in southern Africa, add more complexity to soil C pool partitioning and dynamics than is found in landscapes with a single physiognomy. Here, the spatial variability of the soil C pool was investigated with particular emphasis on understanding the contribution to SOC from trees and grasses at two savanna sites of the Kalahari Transect, one wet and the other dry. Using a combination of stable isotope techniques and geostatistics, the results showed that spatial patterns of soil δ13 C exist and were related to the distributions of woody (C3) and herbaceous (C4) vegetation at both sites. Heterogeneity of the sources of SOC, as well as heterogeneity in the amount of SOC, was greater at the dry site relative to the wet site. At the dry site, the grasses were the major contributor to soil C whereas in the wet site, woody vegetation was the major contributor, regardless of the location with respect to woody canopies.

  6. Impacts of an extreme cyclone event on landscape-scale savanna fire, productivity and greenhouse gas emissions

    International Nuclear Information System (INIS)

    Hutley, L B; Maier, S W; Evans, B J; Beringer, J; Cook, G D; Razon, E

    2013-01-01

    North Australian tropical savanna accounts for 12% of the world’s total savanna land cover. Accordingly, understanding processes that govern carbon, water and energy exchange within this biome is critical to global carbon and water budgeting. Climate and disturbances drive ecosystem carbon dynamics. Savanna ecosystems of the coastal and sub-coastal of north Australia experience a unique combination of climatic extremes and are in a state of near constant disturbance from fire events (1 in 3 years), storms resulting in windthrow (1 in 5–10 years) and mega-cyclones (1 in 500–1000 years). Critically, these disturbances occur over large areas creating a spatial and temporal mosaic of carbon sources and sinks. We quantify the impact on gross primary productivity (GPP) and fire occurrence from a tropical mega-cyclone, tropical Cyclone Monica (TC Monica), which affected 10 400 km 2 of savanna across north Australia, resulting in the mortality and severe structural damage to ∼140 million trees. We estimate a net carbon equivalent emission of 43 Tg of CO 2 -e using the moderate resolution imaging spectroradiometer (MODIS) GPP (MOD17A2) to quantify spatial and temporal patterns pre- and post-TC Monica. GPP was suppressed for four years after the event, equivalent to a loss of GPP of 0.5 Tg C over this period. On-ground fuel loads were estimated to potentially release 51.2 Mt CO 2 -e, equivalent to ∼10% of Australia’s accountable greenhouse gas emissions. We present a simple carbon balance to examine the relative importance of frequency versus impact for a number of key disturbance processes such as fire, termite consumption and intense but infrequent mega-cyclones. Our estimates suggested that fire and termite consumption had a larger impact on Net Biome Productivity than infrequent mega-cyclones. We demonstrate the importance of understanding how climate variability and disturbance impacts savanna dynamics in the context of the increasing interest in

  7. Land Use Dynamics in the Brazilian Amazon

    Science.gov (United States)

    Robert Walker

    1996-01-01

    The articles presented in this special issue of Ecological Economics address the important theme of land use dynamics as it pertains to the Brazilian Amazon. Much environmental change is an ecological artifact of human agency, and such agency is often manifested in land use impacts, particularly in tropical areas. The critical problem of tropical deforestation is but...

  8. Structural, physiognomic and above-ground biomass variation in savanna–forest transition zones on three continents – how different are co-occurring savanna and forest formations?

    Directory of Open Access Journals (Sweden)

    E. M. Veenendaal

    2015-05-01

    continents coexistence was found to be confined to a well-defined edaphic–climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands. Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna data set. Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands.

  9. Unsustainable fuelwood extraction from South African savannas

    Science.gov (United States)

    Wessels, K. J.; Colgan, M. S.; Erasmus, B. F. N.; Asner, G. P.; Twine, W. C.; Mathieu, R.; van Aardt, J. A. N.; Fisher, J. T.; Smit, I. P. J.

    2013-03-01

    Wood and charcoal supply the majority of sub-Saharan Africa’s rural energy needs. The long-term supply of fuelwood is in jeopardy given high consumption rates. Using airborne light detection and ranging (LiDAR), we mapped and investigated savanna aboveground biomass across contrasting land uses, ranging from densely populated communal areas to highly protected areas in the Lowveld savannas of South Africa. We combined the LiDAR observations with socio-economic data, biomass production rates and fuelwood consumption rates in a supply-demand model to predict future fuelwood availability. LiDAR-based biomass maps revealed disturbance gradients around settlements up to 1.5 km, corresponding to the maximum distance walked to collect fuelwood. At current levels of fuelwood consumption (67% of households use fuelwood exclusively, with a 2% annual reduction), we calculate that biomass in the study area will be exhausted within thirteen years. We also show that it will require a 15% annual reduction in consumption for eight years to a level of 20% of households using fuelwood before the reduction in biomass appears to stabilize to sustainable levels. The severity of dwindling fuelwood reserves in African savannas underscores the importance of providing affordable energy for rural economic development.

  10. Unsustainable fuelwood extraction from South African savannas

    International Nuclear Information System (INIS)

    Wessels, K J; Colgan, M S; Asner, G P; Erasmus, B F N; Twine, W C; Fisher, J T; Mathieu, R; Van Aardt, J A N; Smit, I P J

    2013-01-01

    Wood and charcoal supply the majority of sub-Saharan Africa’s rural energy needs. The long-term supply of fuelwood is in jeopardy given high consumption rates. Using airborne light detection and ranging (LiDAR), we mapped and investigated savanna aboveground biomass across contrasting land uses, ranging from densely populated communal areas to highly protected areas in the Lowveld savannas of South Africa. We combined the LiDAR observations with socio-economic data, biomass production rates and fuelwood consumption rates in a supply–demand model to predict future fuelwood availability. LiDAR-based biomass maps revealed disturbance gradients around settlements up to 1.5 km, corresponding to the maximum distance walked to collect fuelwood. At current levels of fuelwood consumption (67% of households use fuelwood exclusively, with a 2% annual reduction), we calculate that biomass in the study area will be exhausted within thirteen years. We also show that it will require a 15% annual reduction in consumption for eight years to a level of 20% of households using fuelwood before the reduction in biomass appears to stabilize to sustainable levels. The severity of dwindling fuelwood reserves in African savannas underscores the importance of providing affordable energy for rural economic development. (letter)

  11. Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

    Science.gov (United States)

    Trugman, Anna T.; Medvigy, David; Hoffmann, William A.; Pellegrini, Adam F. A.

    2018-01-01

    Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2) with (i) a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests), and (ii) plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

  12. Morpho-anatomical features of underground systems in six Asteraceae species from the Brazilian Cerrado

    OpenAIRE

    Appezzato-da-Glória, Beatriz; Cury, Graziela

    2011-01-01

    In the Brazilian Cerrado (neotropical savanna), the development of bud-bearing underground systems as adaptive structures to fire and dry periods can comprise an important source of buds for this ecosystem, as already demonstrated in the Brazilian Campos grasslands and North American prairies. Asteraceae species from both woody and herbaceous strata have subterranean organs that accumulate carbohydrates, reinforcing the adaptive strategy of these plants to different environmental conditions. ...

  13. Changes in organic carbon stocks upon land use conversion in the Brazilian Cerrado: A review. Agriculture

    NARCIS (Netherlands)

    Batlle-Bayer, L.; Batjes, N.H.; Bindraban, P.S.

    2010-01-01

    This paper reviews current knowledge on changes in carbon stocks upon land use conversion in the Brazilian Cerrado. First, we briefly characterize the savanna ecosystem and summarize the main published data on C stocks under natural conditions. The effects of increased land use pressure in the

  14. Predictive Models of Primary Tropical Forest Structure from Geomorphometric Variables Based on SRTM in the Tapajós Region, Brazilian Amazon.

    Science.gov (United States)

    Bispo, Polyanna da Conceição; Dos Santos, João Roberto; Valeriano, Márcio de Morisson; Graça, Paulo Maurício Lima de Alencastro; Balzter, Heiko; França, Helena; Bispo, Pitágoras da Conceição

    2016-01-01

    Surveying primary tropical forest over large regions is challenging. Indirect methods of relating terrain information or other external spatial datasets to forest biophysical parameters can provide forest structural maps at large scales but the inherent uncertainties need to be evaluated fully. The goal of the present study was to evaluate relief characteristics, measured through geomorphometric variables, as predictors of forest structural characteristics such as average tree basal area (BA) and height (H) and average percentage canopy openness (CO). Our hypothesis is that geomorphometric variables are good predictors of the structure of primary tropical forest, even in areas, with low altitude variation. The study was performed at the Tapajós National Forest, located in the Western State of Pará, Brazil. Forty-three plots were sampled. Predictive models for BA, H and CO were parameterized based on geomorphometric variables using multiple linear regression. Validation of the models with nine independent sample plots revealed a Root Mean Square Error (RMSE) of 3.73 m2/ha (20%) for BA, 1.70 m (12%) for H, and 1.78% (21%) for CO. The coefficient of determination between observed and predicted values were r2 = 0.32 for CO, r2 = 0.26 for H and r2 = 0.52 for BA. The models obtained were able to adequately estimate BA and CO. In summary, it can be concluded that relief variables are good predictors of vegetation structure and enable the creation of forest structure maps in primary tropical rainforest with an acceptable uncertainty.

  15. Can savannas help balance the South African greenhouse gas budget?

    CSIR Research Space (South Africa)

    Scholes, RJ

    1996-02-01

    Full Text Available This article discusses the South African Greenhouse Experiment on Savannas (SAGES) study conducted by the CSIR' Division of Forest Science and Technology (Foretek) on the role of savannas in the balance of the greenhouse gas budget of South Africa...

  16. Fire in Australian savannas: from leaf to landscape

    Science.gov (United States)

    Beringer, Jason; Hutley, Lindsay B; Abramson, David; Arndt, Stefan K; Briggs, Peter; Bristow, Mila; Canadell, Josep G; Cernusak, Lucas A; Eamus, Derek; Edwards, Andrew C; Evans, Bradley J; Fest, Benedikt; Goergen, Klaus; Grover, Samantha P; Hacker, Jorg; Haverd, Vanessa; Kanniah, Kasturi; Livesley, Stephen J; Lynch, Amanda; Maier, Stefan; Moore, Caitlin; Raupach, Michael; Russell-Smith, Jeremy; Scheiter, Simon; Tapper, Nigel J; Uotila, Petteri

    2015-01-01

    Savanna ecosystems comprise 22% of the global terrestrial surface and 25% of Australia (almost 1.9 million km2) and provide significant ecosystem services through carbon and water cycles and the maintenance of biodiversity. The current structure, composition and distribution of Australian savannas have coevolved with fire, yet remain driven by the dynamic constraints of their bioclimatic niche. Fire in Australian savannas influences both the biophysical and biogeochemical processes at multiple scales from leaf to landscape. Here, we present the latest emission estimates from Australian savanna biomass burning and their contribution to global greenhouse gas budgets. We then review our understanding of the impacts of fire on ecosystem function and local surface water and heat balances, which in turn influence regional climate. We show how savanna fires are coupled to the global climate through the carbon cycle and fire regimes. We present new research that climate change is likely to alter the structure and function of savannas through shifts in moisture availability and increases in atmospheric carbon dioxide, in turn altering fire regimes with further feedbacks to climate. We explore opportunities to reduce net greenhouse gas emissions from savanna ecosystems through changes in savanna fire management. PMID:25044767

  17. Early Hg mobility in cultivated tropical soils one year after slash-and-burn of the primary forest, in the Brazilian Amazon.

    Science.gov (United States)

    Béliveau, Annie; Lucotte, Marc; Davidson, Robert; Lopes, Luis Otávio do Canto; Paquet, Serge

    2009-07-15

    In the Brazilian Amazon, forest conversion to agricultural lands (slash-and-burn cultivation) contributes to soil mercury (Hg) release and to aquatic ecosystem contamination. Recent studies have shown that soil Hg loss occurs rapidly after deforestation, suggesting that Hg mobility could be related to the massive cation input resulting from biomass burning. The objective of this research was to determine the effects of the first year of slash-and-burn agriculture on soil Hg levels at the regional scale of the Tapajós River, in the state of Pará, Brazilian Amazon. A total of 429 soil samples were collected in 26 farms of five riparian communities of the Tapajós basin. In September 2004, soil samples were collected from primary forest sites planned for slash-and-burn cultivation. In August 2005, one year after the initial burning, a second campaign was held and the exact same sites were re-sampled. Our results showed that total Hg levels in soils did not change significantly during the first year following slash-and-burn, suggesting no immediate release of soil Hg at that point in time. However, an early Hg mobility was detected near the surface (0-5 cm), reflected by a significant shift in Hg distribution in soil fractions. Indeed, a transfer of Hg from fine to coarser soil particles was observed, indicating that chemical bonds between Hg and fine particles could have been altered. A correspondence analysis (CA) showed that this process could be linked to a chemical competition caused by cation enrichment. The regional dimension of the study highlighted the prevailing importance of soil types in Hg dynamics, as shown by differentiated soil responses following deforestation according to soil texture. Confirming an early Hg mobility and indicating an eventual Hg release out of the soil, our results reinforce the call for the development of more sustainable agricultural practices in the Amazon.

  18. AFLP marker analysis revealing genetic structure of the tree Parapiptadenia rigida (Benth. Brenan (Leguminosae-Mimosoideae in the southern Brazilian Tropical Rainforest

    Directory of Open Access Journals (Sweden)

    Laís Bérgamo de Souza

    2013-01-01

    Full Text Available Parapiptadenia rigida is a tropical early secondary succession tree characteristic of the Tropical Atlantic Rainforest. This species is of great ecological importance in the recovery of degraded areas. In this study we investigated the variability and population genetic structure of eight populations of P. rigida. Five AFLP primer combinations were used in a sample of 159 individuals representing these eight populations, rendering a total of 126 polymorphic fragments. The averages of percentage of polymorphic loci, gene diversity, and Shannon index were 60.45%, 0.217, and 0.322, respectively. A significant correlation between the population genetic variability and the population sizes was observed. The genetic variability within populations (72.20% was higher than between these (22.80%. No perfect correlation was observed between geographic and genetic distances, which might be explained by differences in deforestation intensities that occurred in these areas. A dendrogram constructed by the UPGMA method revealed the formation of two clusters, these also confirmed by Bayesian analysis for the number of K cluster. These results show that it is necessary to develop urgent management strategies for the conservation of certain populations of P. rigida, while other populations still preserve reasonably high levels of genetic variability.

  19. Vulnerability of native savanna trees and exotic Khaya senegalensis to seasonal drought.

    Science.gov (United States)

    Arndt, Stefan K; Sanders, Gregor J; Bristow, Mila; Hutley, Lindsay B; Beringer, Jason; Livesley, Stephen J

    2015-07-01

    Seasonally dry ecosystems present a challenge to plants to maintain water relations. While native vegetation in seasonally dry ecosystems have evolved specific adaptations to the long dry season, there are risks to introduced exotic species. African mahogany, Khaya senegalensis Desr. (A. Juss.), is an exotic plantation species that has been introduced widely in Asia and northern Australia, but it is unknown if it has the physiological or phenotypic plasticity to cope with the strongly seasonal patterns of water availability in the tropical savanna climate of northern Australia. We investigated the gas exchange and water relations traits and adjustments to seasonal drought in K. senegalensis and native eucalypts (Eucalyptus tetrodonta F. Muell. and Corymbia latifolia F. Muell.) in a savanna ecosystem in northern Australia. The native eucalypts did not exhibit any signs of drought stress after 3 months of no rainfall and probably had access to deeper soil moisture late into the dry season. Leaf water potential, stomatal conductance, transpiration and photosynthesis all remained high in the dry season but osmotic adjustment was not observed. Overstorey leaf area index (LAI) was 0.6 in the native eucalypt savanna and did not change between wet and dry seasons. In contrast, the K. senegalensis plantation in the wet season was characterized by a high water potential, high stomatal conductance and transpiration and a high LAI of 2.4. In the dry season, K. senegalensis experienced mild drought stress with a predawn water potential -0.6 MPa. Overstorey LAI was halved, and stomatal conductance and transpiration drastically reduced, while minimum leaf water potentials did not change (-2 MPa) and no osmotic adjustment occurred. Khaya senegalensis exhibited an isohydric behaviour and also had a lower hydraulic vulnerability to cavitation in leaves, with a P50 of -2.3 MPa. The native eucalypts had twice the maximum leaf hydraulic conductance but a much higher P50 of -1.5 MPa

  20. A continental analysis of correlations between tree patterns in African savannas and human and environmental variables

    NARCIS (Netherlands)

    Groen, T.A.; Langevelde, van F.; Vijver, van de C.A.D.M.; Raad, de A.L.; Leeuw, de J.; Prins, H.H.T.

    2011-01-01

    This study analyses possible relationships between natural processes taking place in savannas and the tree patterns found in savannas. This can lead to new hypotheses about which processes are driving savanna physiognomy. To do so tree patterns were quantified for African savannas from historical

  1. Modeling soil moisture memory in savanna ecosystems

    Science.gov (United States)

    Gou, S.; Miller, G. R.

    2011-12-01

    Antecedent soil conditions create an ecosystem's "memory" of past rainfall events. Such soil moisture memory effects may be observed over a range of timescales, from daily to yearly, and lead to feedbacks between hydrological and ecosystem processes. In this study, we modeled the soil moisture memory effect on savanna ecosystems in California, Arizona, and Africa, using a system dynamics model created to simulate the ecohydrological processes at the plot-scale. The model was carefully calibrated using soil moisture and evapotranspiration data collected at three study sites. The model was then used to simulate scenarios with various initial soil moisture conditions and antecedent precipitation regimes, in order to study the soil moisture memory effects on the evapotranspiration of understory and overstory species. Based on the model results, soil texture and antecedent precipitation regime impact the redistribution of water within soil layers, potentially causing deeper soil layers to influence the ecosystem for a longer time. Of all the study areas modeled, soil moisture memory of California savanna ecosystem site is replenished and dries out most rapidly. Thus soil moisture memory could not maintain the high rate evapotranspiration for more than a few days without incoming rainfall event. On the contrary, soil moisture memory of Arizona savanna ecosystem site lasts the longest time. The plants with different root depths respond to different memory effects; shallow-rooted species mainly respond to the soil moisture memory in the shallow soil. The growing season of grass is largely depended on the soil moisture memory of the top 25cm soil layer. Grass transpiration is sensitive to the antecedent precipitation events within daily to weekly timescale. Deep-rooted plants have different responses since these species can access to the deeper soil moisture memory with longer time duration Soil moisture memory does not have obvious impacts on the phenology of woody plants

  2. Genotype-environment interaction of maternal influence characteristics in Nellore cattle bred in the Brazilian humid tropical regions by reaction norm

    Directory of Open Access Journals (Sweden)

    Jorge Luís Ferreira

    2015-08-01

    Full Text Available Reaction Norm (RN is the study of genotype-environment interaction (GxE that complies with alternative ways of genotypes within different environments. This study was carried out to verify GxE by a reaction norm model of weights at 120 (W120 and 210 (W210 days of age in Nellore cattle raised in the Humid Tropical Regions of Brazil. Environmental gradients were obtained by solutions of contemporary groups which were fitted as co-variables in the random regression model via reaction norms. Mean weight at 120 days of age was 127.97 kg, and environmental gradients ranged between -27 and +26 kg. Average was 185.60 kg at 210 days of age and gradients ranged from -54 to +55 kg. Scale changes in the breeding values and heritability estimates occurred along the gradients for the two weights; the genetic correlations between breeding value breeding values were also similar for both weights. These correlations were high between the close gradients, and low to even negative between extreme environments. Slopes representing the environmental sensitivity were high, with changes of scale and changes in classification of ten bulls with a great numbers of calves for the two traits. When regression slopes of the ten bulls with the highest breeding value breeding values were evaluated, these values were different in W120 from those in W210, perhaps due to the greater influence of maternal effect on W120. These results characterize the influence of GxE on the pre-weaning weights of animals in the humid tropical regions of Brazil. Due to this, it is possible to get greater precision on the predictions of the animals breeding values breeding value. A less biased selection and a greater genetic progress occurred.

  3. The effects of forest-savanna-grassland gradients on bird communities of Chiquitano Dry Forests domain, in western Brazil.

    Science.gov (United States)

    Godoi, Mauricio N; Souza, Edivaldo O DE

    2016-01-01

    Different vegetation types are distributed in mountains according to altitude, topography and soil. The composition and structure of bird communities in these areas can change in relation to the vegetation gradient, with particular communities occupying each habitat type. In this study we present the changes in composition, species richness and bird abundance over the gradient of forests, savannas and altitudinal grasslands of Maciço do Urucum, a mountainous region located in the Chiquitano Dry Forests domain in western Brazil. We recorded 165 bird species through qualitative and quantitative methods. Forested savannas, riparian forests and submontane forests presented the highest richness and abundance of birds, while arboreal savannas and altitudinal grasslands had intermediate and low values, respectively. The bird composition was similar between riparian and submontane forests, while other vegetation types present more dissimilar bird communities. Our results show differences in composition, richness and bird abundance among the vegetation types present at Maciço do Urucum, and highlight an important function of vegetation gradients for the conservation of bird communities in mountains. Additionally, this is the first study of the bird communities in the Brazilian Chiquitano Dry Forests, an important domain in the west of Brazil which has been poorly studied.

  4. Diversity and biomass of native macrophytes are negatively related to dominance of an invasive Poaceae in Brazilian sub-tropical streams

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Gonçalves Fernandes

    2013-06-01

    Full Text Available Besides exacerbated exploitation, pollution, flow alteration and habitats degradation, freshwater biodiversity is also threatened by biological invasions. This paper addresses how native aquatic macrophyte communities are affected by the non-native species Urochloa arrecta, a current successful invader in Brazilian freshwater systems. We compared the native macrophytes colonizing patches dominated and non-dominated by this invader species. We surveyed eight streams in Northwest Paraná State (Brazil. In each stream, we recorded native macrophytes' richness and biomass in sites where U. arrecta was dominant and in sites where it was not dominant or absent. No native species were found in seven, out of the eight investigated sites where U. arrecta was dominant. Thus, we found higher native species richness, Shannon index and native biomass values in sites without dominance of U. arrecta than in sites dominated by this invader. Although difficult to conclude about causes of such differences, we infer that the elevated biomass production by this grass might be the primary reason for alterations in invaded environments and for the consequent impacts on macrophytes' native communities. However, biotic resistance offered by native richer sites could be an alternative explanation for our results. To mitigate potential impacts and to prevent future environmental perturbations, we propose mechanical removal of the invasive species and maintenance or restoration of riparian vegetation, for freshwater ecosystems have vital importance for the maintenance of ecological services and biodiversity and should be preserved.

  5. Managing invasions at the cost of native habitat? An experimental test of the impact of fire on the invasion of Chromolaena odorata in a South African savanna

    OpenAIRE

    te Beest, Mariska; Cromsigt, Joris P. G. M.; Ngobese, Johan; Olff, Han

    2012-01-01

    Successfully managing invasive plants in natural systems is extremely difficult. Recently however, progress has been made with an approach focused on changing ecosystem processes through the disturbance regime. We performed a large-scale (3 ha) full-factorial field experiment in densely invaded woodland in Hluhluwe-iMfolozi Park, a savanna reserve in South Africa, to study the effect of fire on the control of the pan-tropical invasive exotic shrub Chromolaena odorata in combination with the c...

  6. Does the edge effect influence plant community structure in a tropical dry forest?

    Directory of Open Access Journals (Sweden)

    Diogo Gallo Oliveira

    2013-04-01

    Full Text Available Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.

  7. Indirect effects of mutualism: ant-treehopper associations deter pollinators and reduce reproduction in a tropical shrub.

    Science.gov (United States)

    Ibarra-Isassi, Javier; Oliveira, Paulo S

    2018-03-01

    Animal-pollinated plants can be susceptible to changes in pollinator availability. Honeydew-producing treehoppers frequently occur on inflorescences, potentially enhancing ant-mediated negative effects on pollination services. However, the effect of ant-attended, honeydew-producing insects on plant reproduction remains uncertain. We recorded the abundance of treehoppers and ants on Byrsonima intermedia (Malpighiaceae), and monitored floral visitors in a Brazilian cerrado savanna. We manipulated the presence of ants and ant-treehopper associations on inflorescences to assess their effect on pollination and fruit formation. We used dried ants pinned to inflorescences to evaluate the effect of ant presence and ant identity on potential pollinators. Results show that the presence of treehoppers increases ant abundance on flowers and disrupts pollination by oil-collecting bees, decreasing the frequency and duration of floral visits and reducing fruit and seed set. Treehopper herbivory has no direct effect on fruit or seed production, which are independent of treehopper density. Pinned ants promote avoidance by floral visitors, reducing the number of visits. Ant identity mediates visitation decisions, with Ectatomma brunneum causing greater avoidance by floral visitors than Camponotus rufipes. Field videos show that pollinating bees are harassed by ants near flowers, prompting avoidance behavior by the bees. This is the first demonstration of indirect effects by honeydew-gathering ants, via disrupted pollination, on plant reproduction in tropical cerrado savanna. Our results highlight the importance of studying other interactions near flowers, in addition to just observing pollinators, for a proper understanding of plant reproduction.

  8. Comparações entre as propriedades químicas de solos das regiões da floresta amazônica e do cerrado do Brasil Central Comparisons of chemical properties of forest (Amazon region and savanna soils (central region of Brazil

    Directory of Open Access Journals (Sweden)

    J.L.I. Demattê

    1993-09-01

    e para os solos argilosos a muito argilosos, o teor de carbono orgânico é sempre mais elevado na região de cerrado. Não houve diferenças significativas entre o teor de carbono orgânico dos solos com vegetação de cerrado e cerradão. Por outro lado, o teor de carbono orgânico dos latossolos da região Amazônica é mais elevado do que dos PVA.Chemical properties were studied in soil samples from two main fisiographic regions of Brazil: the Amazon region represented by the tropical rain forests and the Brazilian central region represented by the savanna (cerrado vegetation. For this study 17 profiles were selected from the Triângulo Mineiro area: 6 profiles from Goias state, and 5 profiles from the south eastern part of the Mato Grosso State. Most of the profiles are oxisols from medium to clayey texture. For the Amazon region 76 profiles were selected (38 oxisols and 38 ultisols located from Para to Acre States. The following depths were selected: 0-10 cm; 10-40 cm; 40-80 cm and 80-100 cm. The litter layer was not studied. The savanna region has soil in a more advanced weathered stage than the Amazon region. The Ki index of savanna soils varies from 6.0 to 1.5 and of Amazon soils the variation is from 1.3 to 2.5 that included Oxisols (Ki from 1.3 to 2.0 and Ultisols (Ki above 2.0. This indicates that the clay mineralogy of savanna soils is represented by an oxidic mineralogy that is more stable than in the Amazon region represented by a caulinitic mineralogy with 2:1 contribution. The Amazon soils are more acid and present exchangeable At in higher amounts than savanna soils with a direct effect on chemical management. Soils pH correction requires more lime in Amazon soils than in the savanna. The are great differences in both regions between base saturation and pH index. In Amazon soils the pH increase follows the base saturation while this does not occur in savanna soils. In sandy soils the organic carbon is higher in Amazon for all depths studied. In

  9. Identification of the wood-borer and the factors affecting its attack on Caryocar brasiliense trees in the Brazilian Savanna=Identificação do broqueador de tronco e os fatores que afetam o seu ataque em árvores de Caryocar brasiliense no cerrado brasileiro.

    Directory of Open Access Journals (Sweden)

    Germano Leão Demolin Leite

    2011-10-01

    Full Text Available The objectives of this work were to identify the wood-borer of the trunk of Caryocar brasiliense Camb. (Caryocaraceae and the effects of tree size, chemical and physical soil attributes, and floristic diversity in its attack. The wood-boring caterpillar of the trunck of C. brasiliense belongs to the family Cossidae (Lepidoptera. The number of pupae and the amount of sawdust produced by the wood-borer per tree was higher in the pasture 1 of Montes Claros and pasture in Ibiracatu than in the other four areas (pastures and savanna in Montes Claros and savanna in Ibiracatu. The number of pupae and the amount of sawdust was highest in the trunks of trees with diameters having a breast height (DBH more than 30 cm. This may explain the severity of attack in the areas mentioned above, which contain a higher percentage of plants with DBH> 30 cm. The soil properties also positively associate with higher attack of the wood-borer on trees when the soil is rich in potassium, calcium, magnesium, sum of bases, capacity of cationic exchange, and organic matter, while there was a negative correlation between attack and fine sand content. Systems with less floristic diversity, particularly trees of other species, may concentrate the attack of the wood-borer in the trunks of C. Brasiliense trees. Os objetivos deste trabalho foram identificar o broqueador do tronco de Caryocar brasiliense Camb. (Caryocaraceae e os efeitos de tamanho de árvore, atributos químico-físicos do solo e da diversidade florística em seu ataque. A lagarta broqueadora do tronco de C. brasiliense pertence à família Cossidae (Lepidoptera. O número de pupas e de serragem do broqueador por árvore foi maior na pastagem (1 em Montes Claros e pastagem em Ibiracatu do que nas outras quatro áreas (pastagens e cerrado em Montes Claros e cerrado em Ibiracatu. O número de pupas e da quantidade de serragem do broqueador foi maior em árvores cujo diâmetro de tronco na altura do peito (DAB foi

  10. Description of the savanna ecosystem project, Nylsvley, South Africa

    CSIR Research Space (South Africa)

    CSIR National Scientific Programmes Unit, CSIR

    1975-12-01

    Full Text Available practices. These savannas stretch in a broad belt across southern Africa and have been greatly affected by increasing exploitation during the past hundred years. Increases in useful productivity have been accompanied by such problems as bush encroachment...

  11. African savanna-forest boundary dynamics

    DEFF Research Database (Denmark)

    Cuni Sanchez, Aida; White, Lee J. T.; Calders, Kim

    2016-01-01

    -term inventory plots we quantify changes in vegetation structure, above-ground biomass (AGB) and biodiversity of trees ≥10 cm diameter over 20 years for five vegetation types: savanna; colonising forest (F1), monodominant Okoume forest (F2); young Marantaceae forest (F3); and mixed Marantaceae forest (F4...... substantially in structure, AGB or diversity. Critically, the stability of the F3 stage implies that this stage may be maintained for long periods. Soil carbon was low, and did not show a successional gradient as for AGB and diversity. TLS vertical plant profiles showed distinctive differences amongst...... the vegetation types, indicating that this technique can improve ecological understanding. We highlight two points: (i) as forest colonises, changes in biodiversity are much slower than changes in forest structure or AGB; and (ii) all forest types store substantial quantities of carbon. Multidecadal monitoring...

  12. Developing a savanna burning emissions abatement methodology for tussock grasslands in high rainfall regions of northern Australia

    Directory of Open Access Journals (Sweden)

    Jeremy Russell-Smith

    2014-06-01

    Full Text Available Fire-prone tropical savanna and grassland systems are a significant source of atmospheric emissions of greenhouse gases.  In recent years, substantial research has been directed towards developing accounting methodologies for savanna burning emissions to be applied in Australia’s National Greenhouse Gas Inventory, as well as for commercial carbon trading purposes.  That work has focused on woody savanna systems.  Here, we extend the methodological approach to include tussock grasslands and associated Melaleuca-dominated open woodlands (<10% foliage cover in higher rainfall (>1,000 mm/annum regions of northern Australia.  Field assessments under dry season conditions focused on deriving fuel accumulation, fire patchiness and combustion relationships for key fuel types: fine fuels − grass and litter; coarse woody fuels − twigs <6 mm diameter; heavy woody fuels − >6 mm diameter; and shrubs.  In contrast with previous savanna burning assessments, fire treatments undertaken under early dry season burning conditions resulted in negligible patchiness and very substantial consumption of fine fuels.  In effect, burning in the early dry season provides no benefits in greenhouse gas emissions and emissions reductions in tussock grasslands can be achieved only through reducing the extent of burning.  The practical implications of reduced burning in higher rainfall northern Australian grassland systems are discussed, indicating that there are significant constraints, including infrastructural, cultural and woody thickening issues.  Similar opportunities and constraints are observed in other international contexts, but especially project implementation challenges associated with legislative, political and governance issues.

  13. High frequency of trypanosomatids in gallery forest bats of a Neotropical savanna.

    Science.gov (United States)

    Lourenço, João Lucas M; Minuzzi-Souza, Thaís T C; Silva, Larissa R; Oliveira, Amanda C; Mendonça, Vagner J; Nitz, Nadjar; Aguiar, Ludmilla M S; Gurgel-Gonçalves, Rodrigo

    2018-01-01

    Bats are well-known hosts of trypanosomatids, though information about their role as reservoirs of these protozoans in the Brazilian savanna is poorly known. We aimed to analyze the occurrence of trypanosomatid species in bats occurring in remnants of gallery forests of Brasília, Federal District of Brazil. We sampled bats using mist nets in six sites, and we collected blood, wing fragments and oral swab samples from all captured individuals. Trypanosomatids were identified in the captured bats through sequencing of the SSUrRNA region and kDNA qPCR. We found no parasite in blood smears of 146 individuals of 14 species captured, but blood cultures were positive for nine bats. We detected trypanosomatids molecularly in 111 (76%) specimens of all bat species in the studied areas. Most of the infected bats had Leishmania-like DNA detected in blood and swab samples of the oral mucosa. We distinguished three species of Trypanosoma (Trypanosoma dionisii, T. rangeli and T. cruzi) in Carollia perspicillata. SSUrRNA PCR of oral samples is a non-invasive and practical method for identification of trypanosomatid species in bats. Our results support our belief that bats could be potential reservoirs for Trypanosoma and Leishmania-like species in the enzootic cycle of these parasites in gallery forests of the Brazilian Cerrado biome. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Quantifying responses of dung beetles to fire disturbance in tropical forests: the importance of trapping method and seasonality.

    Science.gov (United States)

    de Andrade, Rafael Barreto; Barlow, Jos; Louzada, Julio; Vaz-de-Mello, Fernando Zagury; Souza, Mateus; Silveira, Juliana M; Cochrane, Mark A

    2011-01-01

    Understanding how biodiversity responds to environmental changes is essential to provide the evidence-base that underpins conservation initiatives. The present study provides a standardized comparison between unbaited flight intercept traps (FIT) and baited pitfall traps (BPT) for sampling dung beetles. We examine the effectiveness of the two to assess fire disturbance effects and how trap performance is affected by seasonality. The study was carried out in a transitional forest between Cerrado (Brazilian Savanna) and Amazon Forest. Dung beetles were collected during one wet and one dry sampling season. The two methods sampled different portions of the local beetle assemblage. Both FIT and BPT were sensitive to fire disturbance during the wet season, but only BPT detected community differences during the dry season. Both traps showed similar correlation with environmental factors. Our results indicate that seasonality had a stronger effect than trap type, with BPT more effective and robust under low population numbers, and FIT more sensitive to fine scale heterogeneity patterns. This study shows the strengths and weaknesses of two commonly used methodologies for sampling dung beetles in tropical forests, as well as highlighting the importance of seasonality in shaping the results obtained by both sampling strategies.

  15. SWEET SORGHUM PERFORMANCE AFFECTED BY SOIL COMPACTION AND SOWING TIME AS A SECOND CROP IN THE BRAZILIAN CERRADO

    Directory of Open Access Journals (Sweden)

    Wellingthon da Silva Guimarães Júnnyor

    2015-12-01

    Full Text Available ABSTRACT Increasing attention has recently been given to sweet sorghum as a renewable raw material for ethanol production, mainly because its cultivation can be fully mechanized. However, the intensive use of agricultural machinery causes soil structural degradation, especially when performed under inadequate conditions of soil moisture. The aims of this study were to evaluate the physical quality of aLatossolo Vermelho Distroférrico (Oxisol under compaction and its components on sweet sorghum yield forsecond cropsowing in the Brazilian Cerrado (Brazilian tropical savanna. The experiment was conducted in a randomized block design, in a split plot arrangement, with four replications. Five levels of soil compaction were tested from the passing of a tractor at the following traffic intensities: 0 (absence of additional compaction, 1, 2, 7, and 15 passes over the same spot. The subplots consisted of three different sowing times of sweet sorghum during the off-season of 2013 (20/01, 17/02, and 16/03. Soil physical quality was measured through the least limiting water range (LLWR and soil water limitation; crop yield and technological parameters were also measured. Monitoring of soil water contents indicated a reduction in the frequency of water content in the soil within the limits of the LLWR (Fwithin as agricultural traffic increased (T0 = T1 = T2>T7>T15, and crop yield is directly associated with soil water content. The crop sown in January had higher industrial quality; however, there was stalk yield reduction when bulk density was greater than 1.26 Mg m-3, with a maximum yield of 50 Mg ha-1 in this sowing time. Cultivation of sweet sorghum as a second crop is a promising alternative, but care should be taken in cultivation under conditions of pronounced climatic risks, due to low stalk yield.

  16. The development of savanna afforestation in northern Nigeria

    Energy Technology Data Exchange (ETDEWEB)

    Kadeba, O. (Forestry Research Institute, Ibadan (Nigeria))

    1978-06-01

    The savanna woodland which covers over 80% of the land area of Nigeria is not capable of meeting the requirements of its population for wood and wood products. Since its inception in 1964, the Savanna Forestry Research Project has been concerned mainly with the problems of wood production in this region. The major constraints to tree planting, which include seasonal deficiencies of soil and atmospheric moisture, low levels of soil fertility, selection of suitable exotic tree species and competition in the early stages of tree growth with grasses, have been identified. References are made to some of the major problems that have been solved and those that are being tackled. Some species of exotic trees have proven adaptive to the savanna conditions and are known to be superior to the native savanna trees in terms of growth rates, yields and utility values. The exotic trees which can grown well in the different savanna climatic zones include several species of Eucalyptus and Pinus in addition to teak (Tectona grandis), Gmelina arborea, and neem (Azadirachta indica).

  17. Tropical Rainforests.

    Science.gov (United States)

    Nigh, Ronald B.; Nations, James D.

    1980-01-01

    Presented is a summary of scientific knowledge about the rainforest environment, a tropical ecosystem in danger of extermination. Topics include the current state of tropical rainforests, the causes of rainforest destruction, and alternatives of rainforest destruction. (BT)

  18. Seasonality of the activity pattern of Callithrix penicillata (Primates, Callitrichidae in the cerrado (scrub savanna vegetation

    Directory of Open Access Journals (Sweden)

    S. L. Vilela

    Full Text Available Two wild groups of Callithrix penicillata, the Black Pincelled Marmoset, were observed from January to September 1998, in two areas, one an area of dense scrub savanna vegetation (cerrado and the other, a semidecidual woodland (cerradão, both within the boundaries of the Ecological Reserve of IBGE (Brazilian Institute of Geography and Statistics, in an environmentally protected area, the APA (Portuguese abbreviation for "environmental protected area" Gama/Cabeça-de-Veado, Brasília, DF. The behavioral data collected during the rainy (January 15 to April 15 and dry season (June 1 to September 15 were compared. Because of the proximity to the Reserve facilities, the group from the dense scrub savanna vegetation (CD was submitted to antropic impacts different from the group in the semidecidual woodland (CE, which was using as territory an area that had been suffering from man-made fires every two years as part of a long-term experimental project on fire impacts. The behavioral data was quantified by instantaneous cross-section ("scan sampling" every ten minutes with records of locomotion, rest, foraging for insects, use of exudate, and feeding. During the whole year, the greatest percentage of time spent by CE and CD was in foraging for insects, with 44% and 39%, respectively. It was evident when comparing the data for the two seasons that, for both groups, foraging for insects was more intense during the dry season, possibly to complement the shortage of food, and locomotion increased during the rainy season. The greater the availability and distribution of fruit in the areas, the greater the locomotion of the groups to obtain these resources. None of the other behavioral patterns, including the use of exudates, presented significant differences between the two seasons. Both groups foraged more frequently during the dry season and locomoted more during the rainy one.

  19. Coupling carbon allocation with leaf and root phenology predicts tree-grass partitioning along a savanna rainfall gradient

    Science.gov (United States)

    Haverd, V.; Smith, B.; Raupach, M.; Briggs, P.; Nieradzik, L.; Beringer, J.; Hutley, L.; Trudinger, C. M.; Cleverly, J.

    2016-02-01

    The relative complexity of the mechanisms underlying savanna ecosystem dynamics, in comparison to other biomes such as temperate and tropical forests, challenges the representation of such dynamics in ecosystem and Earth system models. A realistic representation of processes governing carbon allocation and phenology for the two defining elements of savanna vegetation (namely trees and grasses) may be a key to understanding variations in tree-grass partitioning in time and space across the savanna biome worldwide. Here we present a new approach for modelling coupled phenology and carbon allocation, applied to competing tree and grass plant functional types. The approach accounts for a temporal shift between assimilation and growth, mediated by a labile carbohydrate store. This is combined with a method to maximize long-term net primary production (NPP) by optimally partitioning plant growth between fine roots and (leaves + stem). The computational efficiency of the analytic method used here allows it to be uniquely and readily applied at regional scale, as required, for example, within the framework of a global biogeochemical model.We demonstrate the approach by encoding it in a new simple carbon-water cycle model that we call HAVANA (Hydrology and Vegetation-dynamics Algorithm for Northern Australia), coupled to the existing POP (Population Orders Physiology) model for tree demography and disturbance-mediated heterogeneity. HAVANA-POP is calibrated using monthly remotely sensed fraction of absorbed photosynthetically active radiation (fPAR) and eddy-covariance-based estimates of carbon and water fluxes at five tower sites along the North Australian Tropical Transect (NATT), which is characterized by large gradients in rainfall and wildfire disturbance. The calibrated model replicates observed gradients of fPAR, tree leaf area index, basal area, and foliage projective cover along the NATT. The model behaviour emerges from complex feedbacks between the plant

  20. Biomass burning emissions of reactive gases estimated from satellite data analysis and ecosystem modeling for the Brazilian Amazon region

    Science.gov (United States)

    Potter, Christopher; Brooks-Genovese, Vanessa; Klooster, Steven; Torregrosa, Alicia

    2002-10-01

    To produce a new daily record of trace gas emissions from biomass burning events for the Brazilian Legal Amazon, we have combined satellite advanced very high resolution radiometer (AVHRR) data on fire counts together for the first time with vegetation greenness imagery as inputs to an ecosystem biomass model at 8 km spatial resolution. This analysis goes beyond previous estimates for reactive gas emissions from Amazon fires, owing to a more detailed geographic distribution estimate of vegetation biomass, coupled with daily fire activity for the region (original 1 km resolution), and inclusion of fire effects in extensive areas of the Legal Amazon (defined as the Brazilian states of Acre, Amapá, Amazonas, Maranhao, Mato Grosso, Pará, Rondônia, Roraima, and Tocantins) covered by open woodland, secondary forests, savanna, and pasture vegetation. Results from our emissions model indicate that annual emissions from Amazon deforestation and biomass burning in the early 1990s total to 102 Tg yr-1 carbon monoxide (CO) and 3.5 Tg yr-1 nitrogen oxides (NOx). Peak daily burning emissions, which occurred in early September 1992, were estimated at slightly more than 3 Tg d-1for CO and 0.1 Tg d-1for NOx flux to the atmosphere. Other burning source fluxes of gases with relatively high emission factors are reported, including methane (CH4), nonmethane hydrocarbons (NMHC), and sulfur dioxide (SO2), in addition to total particulate matter (TPM). We estimate the Brazilian Amazon region to be a source of between one fifth and one third for each of these global emission fluxes to the atmosphere. The regional distribution of burning emissions appears to be highest in the Brazilian states of Maranhao and Tocantins, mainly from burning outside of moist forest areas, and in Pará and Mato Grosso, where we identify important contributions from primary forest cutting and burning. These new daily emission estimates of reactive gases from biomass burning fluxes are designed to be used as

  1. Tropical Glaciers

    Science.gov (United States)

    Fountain, Andrew

    The term "tropical glacier" calls to mind balmy nights and palm trees on one hand and cold, blue ice on the other. Certainly author Gabriel Garcia Marqez exploited this contrast in One Hundred Years of Solitude. We know that tropical fish live in warm, Sun-kissed waters and tropical plants provide lush, dense foliage populated by colorful tropical birds. So how do tropical glaciers fit into this scene? Like glaciers everywhere, tropical glaciers form where mass accumulation—usually winter snow—exceeds mass loss, which is generally summer melt. Thus, tropical glaciers exist at high elevations where precipitation can occur as snowfall exceeds melt and sublimation losses, such as the Rwenzori Mountains in east Africa and the Maoke Range of Irian Jaya.

  2. Tropical radioecology

    CERN Document Server

    Baxter, M

    2012-01-01

    Tropical Radioecology is a guide to the wide range of scientific practices and principles of this multidisciplinary field. It brings together past and present studies in the tropical and sub-tropical areas of the planet, highlighting the unique aspects of tropical systems. Until recently, radioecological models for tropical environments have depended upon data derived from temperate environments, despite the differences of these regions in terms of biota and abiotic conditions. Since radioactivity can be used to trace environmental processes in humans and other biota, this book offers examples of studies in which radiotracers have been used to assess biokinetics in tropical biota. Features chapters, co-authored by world experts, that explain the origins, inputs, distribution, behaviour, and consequences of radioactivity in tropical and subtropical systems. Provides comprehensive lists of relevant data and identifies current knowledge gaps to allow for targeted radioecological research in the future. Integrate...

  3. Invasive Andropogon gayanus (gamba grass) is an ecosystem transformer of nitrogen relations in Australian savanna.

    Science.gov (United States)

    Rossiter-Rachor, N A; Setterfield, S A; Douglas, M M; Hutley, L B; Cook, G D; Schmidt, S

    2009-09-01

    Invasion by the African grass Andropogon gayanus is drastically altering the understory structure of oligotrophic savannas in tropical Australia. We compared nitrogen (N) relations and phenology of A. gayanus and native grasses to examine the impact of invasion on N cycling and to determine possible reasons for invasiveness of A. gayanus. Andropogon gayanus produced up to 10 and four times more shoot phytomass and root biomass, with up to seven and 2.5 times greater shoot and root N pools than native grass understory. These pronounced differences in phytomass and N pools between A. gayanus and native grasses were associated with an altered N cycle. Most growth occurs in the wet season when, compared with native grasses, dominance of A. gayanus was associated with significantly lower total soil N pools, lower nitrification rates, up to three times lower soil nitrate availability, and up to three times higher soil ammonium availability. Uptake kinetics for different N sources were studied with excised roots of three grass species ex situ. Excised roots of A. gayanus had an over six times higher-uptake rate of ammonium than roots of native grasses, while native grass Eriachne triseta had a three times higher uptake rate of nitrate than A. gayanus. We hypothesize that A. gayanus stimulates ammonification but inhibits nitrification, as was shown to occur in its native range in Africa, and that this modification of the soil N cycle is linked to the species' preference for ammonium as an N source. This mechanism could result in altered soil N relations and could enhance the competitive superiority and persistence of A. gayanus in Australian savannas.

  4. Mapping Large-Scale Mechanized Agriculture Across the Brazilian Cerrado Between 2001-2013

    Science.gov (United States)

    Spera, S. A.; Mustard, J. F.; VanWey, L.

    2014-12-01

    Brazil is a global commodities powerhouse. Over the last decade, dynamic changes in agricultural development and land transformations occurred within Brazil's tropical savanna region, the cerrado. This interdisciplinary study uses remote sensing tools to map land cover across more than 3.6 million km2 of cerrado and statistical methods to characterize drivers of this land-cover change. We use the MODIS Enhanced Vegetation Index 16-day data product and a decision-tree algorithm, proven highly accurate in Mato Grosso (Spera et al. 2014) and here modified for the broader cerrado region, to characterize crop type, cropping frequency, expansion, and abandonment of large-scale mechanized agriculture during the 2001-2013 period. The algorithm exploits phenological differences between forest, pasture and cerrado, and mechanized agriculture. It is parameterized to distinguish between crop rotations in Mato Grosso, Goias, and the new agricultural frontier spanning Maranhao, Tocantins, Piaui, and Bahia (MaToPiBa). Training and validation data were collected using Google's Earth Engine. We map single-cropped soy, corn, and cotton; double-cropped soy/corn and soy/cotton rotations; and irrigated agriculture across these six Brazilian cerrado states. We find that while double cropping dominates in Mato Grosso and Goias, single cropping is still the dominant form of mechanized agriculture in the burgeoning MaToPiBa region. In western Bahia alone, preliminary results show agriculture has expanded by almost 350,000 ha and double cropping has increased by almost 40,000 ha. With MaToPiBa touted as Brazil's latest and last agricultural frontier, we predict that the region will experience a transition similar to that of Mato Grosso during the 2000s—an expansion and intensification of agriculture—which may beget unprecedented ramifications on regional climate processes that can then affect ecosystem health and the economic feasibility of cultivating rain-fed export crops.

  5. Soil carbon storage in silvopasture and related land-use systems in the brazilian cerrado.

    Science.gov (United States)

    Tonucci, Rafael G; Nair, P K Ramachandran; Nair, Vimala D; Garcia, Rasmo; Bernardino, Fernando S

    2011-01-01

    Silvopastoral management of fast-growing tree plantations is becoming popular in the Brazilian Cerrado (savanna). To understand the influence of such systems on soil carbon (C) storage, we studied C content in three aggregate size classes in six land-use systems (LUS) on Oxisols in Minas Gerais, Brazil. The systems were a native forest, a treeless pasture, 24- and 4-yr-old eucalyptus ( sp.) plantations, and 15- and 4-yr-old silvopastures of fodder grass plus animals under eucalyptus. From each system, replicated soil samples were collected from four depths (0-10, 10-20, 20-50, and 50-100 cm), fractionated into 2000- to 250-, 250- to 53-, and <53-μm size classes representing macroaggregates, microaggregates, and silt + clay, respectively, and their C contents determined. Macroaggregate was the predominant size fraction under all LUS, especially in the surface soil layers of tree-based systems. In general, C concentrations (g kg soil) in the different aggregate size fractions did not vary within the same depth. The soil organic carbon (SOC) stock (Mg C ha) to 1-m depth was highest under pasture compared with other LUS owing to its higher soil bulk density. The soils under all LUS had higher C stock compared with other reported values for managed tropical ecosystems: down to 1 m, total SOC stock values ranged from 461 Mg ha under pasture to 393 Mg ha under old eucalyptus. Considering the possibility for formation and retention of microaggregates within macroggregates in low management-intensive systems such as silvopasture, the macroaggregate dynamics in the soil seem to be a good indicator of its C storage potential. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

  6. The Influence of Cattle Wastes on Degraded Savanna Soils of ...

    African Journals Online (AJOL)

    This paper examines the effects of cattle wastes on degraded savanna soils of Kwara State, Nigeria. A total of 40 soil samples were systematically collected from five quadrats of 12m x 12m. In 4 identified cattle sheds and 1 in adjacent fallow land (control field) on the same soil, climatic type and ecological zone. Standard ...

  7. Modelling annual evapotranspiration in a semi-arid, African savanna ...

    African Journals Online (AJOL)

    Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment-scale water balance.

  8. Transformation of a savanna grassland by drought and grazing | O ...

    African Journals Online (AJOL)

    The relative effects of drought and heavy grazing on the floristic composition, population size and and structure, and basal cover of an African savanna grassland were differentiated by comparing changes over eight years over eight years, which included a severe drought year, across a gradient of grazing history. Drought ...

  9. Restoring a disappearing ecosystem: the Longleaf Pine Savanna.

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Timothy B. [USFS; Miller, Karl V. [University of Georgia; Park, Noreen

    2013-05-01

    Longleaf pine (Pinus palustris) savannas of the southeastern United States contain some of the worlds most diverse plant communities, along with a unique complement of wildlife. Their traditionally open canopy structure and rich understory of grasses and herbs were critical to their vigor. However, a long history of land-use practices such as logging, farming, and fire exclusion have reduced this once-widespread ecosystem to only 3 percent of its original range. At six longleaf pine plantations in South Carolina, Tim Harrington with the Pacific Northwest Research Station and collaborators with the Southern Research Station used various treatments (including prescribed burns, tree thinning, and herbicide applications) to alter the forest structure and tracked how successful each one was in advancing savanna restoration over a 14-year period. They found that typical planting densities for wood production in plantations create dense understory shade that excludes many native herbaceous species important to savannas and associated wildlife. The scientists found that although tree thinning alone did not result in sustained gains, a combination of controlled burning, thinning, and herbicide treatments to reduce woody plants was an effective strategy for recovering the savanna ecosystem. The scientists also found that these efforts must be repeated periodically for enduring benefits.

  10. Nitrogen inputs by precipitation in the Nigerian Savanna | Adeniyi ...

    African Journals Online (AJOL)

    Inorganic nitrogen input via direct bulk precipitation was measured, and the relation between the different nitrogen species and rainfall characteristics determined over three rainy seasons at Shagunu, a remote, sparsely populated, non-industrialized site in the northern Guinea savanna of Nigeria. Nitrogen concentration per ...

  11. Savanna ecosystem project: phase I summary and phase II progress

    CSIR Research Space (South Africa)

    Huntely, BJ

    1978-07-01

    Full Text Available A summary of the results of the first phase (mid 1974 to mid 1976) of the South African Savanna Ecosystem Project being undertaken at Nylsvley in the northern Transvaal is presented. Phase I of this ten year study of the structure and functioning...

  12. Facilitation between bovids and equids on an African savanna

    NARCIS (Netherlands)

    Odadi, W.O.; Jain, M.; Wieren, van S.E.; Prins, H.H.T.; Rubenstein, D.I.

    2011-01-01

    Background: Equids, especially zebras and donkeys, and cattle (bovids) share habitats in many savanna ecosystems in Africa. The issue of competition for food between these ungulate guilds remains largely unresolved. Resolving it will provide insights into how wild zebra are likely to interact with

  13. Termites of the Savanna ecosystem project study area, Nylsvley

    CSIR Research Space (South Africa)

    Ferrar, P

    1982-09-01

    Full Text Available This report describes the termite fauna of the Savanna Ecosystem Project study area at the Nylsvley Nature Reserve, with an illustrated key for identification of species. Twenty-one species of fifteen genera and two families are recorded, and notes...

  14. Erratum: Vascular epiphyte vegetation in rocky savannas of southeastern Brazil

    Czech Academy of Sciences Publication Activity Database

    Alves, R. J. V.; Kolbek, Jiří; Becker, J.

    2009-01-01

    Roč. 27, č. 4 (2009), s. 351-352 ISSN 0107-055X Institutional research plan: CEZ:AV0Z60050516 Keywords : epiphytes * Brazil * rocky savannas Subject RIV: EF - Botanics Impact factor: 0.868, year: 2009

  15. Indigenous burning as conservation practice: neotropical savanna recovery amid agribusiness deforestation in Central Brazil.

    Science.gov (United States)

    Welch, James R; Brondízio, Eduardo S; Hetrick, Scott S; Coimbra, Carlos E A

    2013-01-01

    International efforts to address climate change by reducing tropical deforestation increasingly rely on indigenous reserves as conservation units and indigenous peoples as strategic partners. Considered win-win situations where global conservation measures also contribute to cultural preservation, such alliances also frame indigenous peoples in diverse ecological settings with the responsibility to offset global carbon budgets through fire suppression based on the presumed positive value of non-alteration of tropical landscapes. Anthropogenic fire associated with indigenous ceremonial and collective hunting practices in the Neotropical savannas (cerrado) of Central Brazil is routinely represented in public and scientific conservation discourse as a cause of deforestation and increased CO2 emissions despite a lack of supporting evidence. We evaluate this claim for the Xavante people of Pimentel Barbosa Indigenous Reserve, Brazil. Building upon 23 years of longitudinal interdisciplinary research in the area, we used multi-temporal spatial analyses to compare land cover change under indigenous and agribusiness management over the last four decades (1973-2010) and quantify the contemporary Xavante burning regime contributing to observed patterns based on a four year sample at the end of this sequence (2007-2010). The overall proportion of deforested land remained stable inside the reserve (0.6%) but increased sharply outside (1.5% to 26.0%). Vegetation recovery occurred where reserve boundary adjustments transferred lands previously deforested by agribusiness to indigenous management. Periodic traditional burning by the Xavante had a large spatial distribution but repeated burning in consecutive years was restricted. Our results suggest a need to reassess overreaching conservation narratives about the purported destructiveness of indigenous anthropogenic fire in the cerrado. The real challenge to conservation in the fire-adapted cerrado biome is the long

  16. Vegetation Structure and Carbon Stocks of Two Protected Areas within the South-Sudanian Savannas of Burkina Faso

    Directory of Open Access Journals (Sweden)

    Mohammad Qasim

    2016-09-01

    Full Text Available Savannas and adjacent vegetation types like gallery forests are highly valuable ecosystems contributing to several ecosystem services including carbon budgeting. Financial mechanisms such as REDD+ (Reduced Emissions from Deforestation and Forest Degradation can provide an opportunity for developing countries to alleviate poverty through conservation of its forestry resources. However, for availing such opportunities carbon stock assessments are essential. Therefore, a research study for this purpose was conducted at two protected areas (Nazinga Game Ranch and Bontioli Nature Reserve in Burkina Faso. Similarly, analysis of various vegetation parameters was also conducted to understand the overall vegetation structure of these two protected areas. For estimating above ground biomass, existing allometric equations for dry tropical woody vegetation types were used. Compositional structure was described by applying tree species and family importance indices. The results show that both sites collectively contain a mean carbon stock of 3.41 ± 4.98 Mg·C·ha−1. Among different savanna vegetation types, gallery forests recorded the highest mean carbon stock of 9.38 ± 6.90 Mg·C·ha−1. This study was an attempt at addressing the knowledge gap particularly on carbon stocks of protected savannas—it can serve as a baseline for carbon stocks for future initiatives such as REDD+ within these areas.

  17. Termite mounds as hot spots of nitrous oxide emissions in South-Sudanian savanna of Burkina Faso (West Africa)

    Science.gov (United States)

    Brümmer, Christian; Papen, Hans; Wassmann, Reiner; Brüggemann, Nicolas

    2009-05-01

    Despite a considerable knowledge of the significant role of termites in the global methane budget, very little is known about their contribution to the global nitrous oxide (N2O) budget. Release of N2O from termite (Cubitermes fungifaber) mounds was measured at a natural savanna site in the southwest of Burkina Faso from May to September 2006. Termite N2O emissions were around 20 μg N2O-N m-2 h-1 at the end of the dry season, and up to two orders of magnitude higher than N2O emissions from the surrounding termite-free soil after the onset of the rainy season. The average N2O emission rate from termite mounds during the observation period was 204 μg N2O-N m-2 h-1, and termite mounds contributed 3.0% to total N2O emissions from this savanna ecosystem. However, in other tropical terrestrial ecosystems with other termite species and/or higher termite density this share might be significantly higher.

  18. Brazilian energy

    International Nuclear Information System (INIS)

    O'Shaughnessy, H.

    1997-04-01

    Brazilian Energy provides all the information necessary for energy companies to invest and operate in Brazil, including: a review of Brazil's natural resources; an assessment of privatisation strategies at the federal, state and regional level; an analysis of the electricity industry and the future for Electrobras; an analysis of the oil industry and, in particular, Petrobras; a discussion of the fuel alcohol industry; the discovery of local natural gas, its prospects and the involvement of the auto industry; an assessment of the problems facing the coal industry and its future; a discussion of the regulatory framework for the newly privatised companies; the importance of intra-regional energy links and the booming membership of Mercosur; the difficulties experienced by foreign investors doing business in Brazil; brief profiles of the key energy companies; profiles of key people influencing the privatisation process in Brazil. Brazilian energy is essential reading for those wishing to advise and assist Brazil in this period of change and development, as well as those who wish to invest or become key players in the Brazilian energy sector. (author)

  19. Long-term energy balance and vegetation water stress monitoring of Mediterranean oak savanna using satellite thermal data

    Science.gov (United States)

    González-Dugo, Maria P.; Chen, Xuelong; Andreu, Ana; Carpintero, Elisabet; Gómez-Giraldez, Pedro; Su, Z.(Bob)

    2017-04-01

    Drought is one of the major hazards faced by natural and cropped vegetation in the Mediterranean Sea Basin. Water scarcity is likely to be worsened under the predicted conditions of climate change, which is expected to make this region both warmer and drier. A Holm oak savanna, known as dehesa in Spain and montado in Portugal, is an agro-silvo-pastoral system occupying more than 3 million hectares the Iberian Peninsula and Greece. It consists of widely-spaced oak trees (mostly Quercus ilex L.), combined with crops, pasture and Mediterranean shrubs. This ecosystem is considered an example of sustainable land use, supporting a large number of species and diversity of habitats and for its importance in rural economy. A similar ecosystem is worldwide distributed in areas with Mediterranean climate (as California or South Africa) and shares structural and functional properties with tropical savannas in Africa, Australia and South America. Remote sensing time series can assist the monitoring of the energy balance components, with special attention to the evapotranspiration and vegetation water stress over these areas. Long-term data analysis may improve our understanding of the functioning of the system, helping to assess drought impacts and leading to reduce the economic and environmental vulnerability of this ecosystem. This work analyzes the evolution the surface energy balance components, mapping the evapotranspiration and moisture stress of holm oak woodlands of Spain and Portugal during the last 15 years (2001-2015). The surface energy balance model (SEBS) has been applied over the Iberian Peninsula on a monthly time scale and 0.05° spatial resolution, using multi-satellite and meteorological forcing data. Modelled energy and water fluxes have been validated using ground measurements of two eddy covariance towers located in oak savanna sites during 3 years, resulting in moderate deviations from observations (10-25 W/m2). The departure of actual ET from the

  20. Nutrient Uptake and Metabolism Along a Large Scale Tropical Physical-Chemical Gradient

    Science.gov (United States)

    Tromboni, F.; Neres-Lima, V.; Saltarelli, W. A.; Miwa, A. C. P.; Cunha, D. G. F.

    2016-12-01

    Nutrient spiraling is a whole-system approach for estimating nutrient uptake that can be used to assess aquatic ecosystems' responses to environmental change and anthropogenic impacts. Historically research on nutrient dynamic uptake in streams has focused on single nutrient dynamics and only rarely the stoichiometric uptake has been considered and linked to carbon metabolism driven by autotrophic and heterotrophic production. We investigated the relationship between uptake of phosphate (PO43-), nitrate (NO3-) ammonium (NH4+) and total dissolve nitrogen (DIN)/ PO43-; and gross primary production (GPP), respiration (R), and net ecosystem productivity (NEP) in six relatively pristine streams with differences regarding canopy cover and physical characteristics, located in a large scale gradient from tropical Atlantic Forest to an Atlantic forest/Cerrado (Brazilian Savanna) transition. We carried out whole stream instantaneous additions of PO43-, NO3- and NH4+ added to each stream in combination, using the TASCC (Tracer Additions for Spiraling Curve Characterization) method. Metabolism measurements were performed in the same streams right after uptake was measured, using one-station open channel method and re-aeration estimations for those sites. We found different background concentrations in the streams located in the Atlantic forest compared with the transition area with Cerrado. In general PO43- and NO3- uptake increased with the decreasing of canopy cover, while a positive relation with background concentration better explained NH4+uptake. DIN/PO43- uptake increased with increasing R and NEP. Little work on functional characteristics of pristine streams has been conducted in this region and this work provides an initial characterization on nitrogen and phosphorus dynamics as well as their stoichiometric uptake in streams.

  1. Savanna ant species richness is maintained along a bioclimatic gradient of increasing latitude and decreasing rainfall in northern Australia

    DEFF Research Database (Denmark)

    Andersen, Alan N.; Del Toro, Israel; Parr, Catherine L.

    2015-01-01

    of 246 species from 37 genera. Mean observed species richness pooled across sampling periods was similar at sand (85.4) and loam (82.2) sites, but was less than half this at clay sites (40.0). Ant communities were also compositionally distinct on clay soils compared with sands and loams. Individual...... genera showed variable diversity patterns, ranging from a linear increase to a linear decrease in species richness along the NATT. However, total species richness was relatively uniform along the gradient. Patterns of ant species turnover were consistent with previously recognized biogeographical......Aim: Using a standardized sampling protocol along a 600-km transect in northern Australia, we tested whether ant diversity within a single biome, tropical savanna, decreases with increasing latitude (as a surrogate of temperature) and decreasing rainfall, as is expected for biodiversity in general...

  2. African Savanna-Forest Boundary Dynamics: A 20-Year Study

    Science.gov (United States)

    Cuni-Sanchez, Aida; White, Lee J. T.; Calders, Kim; Jeffery, Kathryn J.; Abernethy, Katharine; Burt, Andrew; Disney, Mathias; Gilpin, Martin; Gomez-Dans, Jose L.; Lewis, Simon L.

    2016-01-01

    Recent studies show widespread encroachment of forest into savannas with important consequences for the global carbon cycle and land-atmosphere interactions. However, little research has focused on in situ measurements of the successional sequence of savanna to forest in Africa. Using long-term inventory plots we quantify changes in vegetation structure, above-ground biomass (AGB) and biodiversity of trees ≥10 cm diameter over 20 years for five vegetation types: savanna; colonising forest (F1), monodominant Okoume forest (F2); young Marantaceae forest (F3); and mixed Marantaceae forest (F4) in Lopé National Park, central Gabon, plus novel 3D terrestrial laser scanning (TLS) measurements to assess forest structure differences. Over 20 years no plot changed to a new stage in the putative succession, but F1 forests strongly moved towards the structure, AGB and diversity of F2 forests. Overall, savanna plots showed no detectable change in structure, AGB or diversity using this method, with zero trees ≥10 cm diameter in 1993 and 2013. F1 and F2 forests increased in AGB, mainly as a result of adding recruited stems (F1) and increased Basal Area (F2), whereas F3 and F4 forests did not change substantially in structure, AGB or diversity. Critically, the stability of the F3 stage implies that this stage may be maintained for long periods. Soil carbon was low, and did not show a successional gradient as for AGB and diversity. TLS vertical plant profiles showed distinctive differences amongst the vegetation types, indicating that this technique can improve ecological understanding. We highlight two points: (i) as forest colonises, changes in biodiversity are much slower than changes in forest structure or AGB; and (ii) all forest types store substantial quantities of carbon. Multi-decadal monitoring is likely to be required to assess the speed of transition between vegetation types. PMID:27336632

  3. Ecological release in lizard assemblages of neotropical savannas.

    Science.gov (United States)

    Mesquita, Daniel Oliveira; Colli, Guarino Rinaldi; Vitt, Laurie J

    2007-08-01

    We compare lizard assemblages of Cerrado and Amazonian savannas to test the ecological release hypothesis, which predicts that niche dimensions and abundance should be greater in species inhabiting isolated habitat patches with low species richness (Amazonian savannas and isolated Cerrado patches) when compared with nonisolated areas in central Cerrado with greater species richness. We calculated microhabitat and diet niche breadths with data from 14 isolated Cerrado patches and Amazon savanna areas and six central Cerrado populations. Morphological data were compared using average Euclidean distances, and lizard abundance was estimated using the number of lizards captured in pitfall traps over an extended time period. We found no evidence of ecological release with respect to microhabitat use, suggesting that historical factors are better microhabitat predictors than ecological factors. However, data from individual stomachs indicate that ecological release occurs in these areas for one species (Tropidurus) but not others (Ameiva ameiva, Anolis, Cnemidophorus, and Micrablepharus), suggesting that evolutionary lineages respond differently to environmental pressures, with tropidurids being more affected by ecological factors than polychrotids, teiids, and gymnophthalmids. We found no evidence that ecological release occurs in these areas using morphological data. Based on abundance data, our results indicate that the ecological release (density compensation) hypothesis is not supported: lizard species are not more abundant in isolated areas than in nonisolated areas. The ecology of species is highly conservative, varying little from assemblage to assemblage. Nevertheless, increases in niche breadth for some species indicate that ecological release occurs as well.

  4. Weak leaf photosynthesis and nutrient content relationships from tropical vegetation

    Science.gov (United States)

    Domingues, T. F.; Ishida, F. Y.; Feldpaush, T.; Saiz, G.; Grace, J.; Meir, P.; Lloyd, J.

    2015-12-01

    Evergreen rain forests and savannas are the two major vegetations of tropical land ecosystems, in terms of land area, biomass, biodiversity, biogeochemical cycles and rates of land use change. Mechanistically understanding ecosystem functioning on such ecosystems is still far from complete, but important for generation of future vegetation scenarios in response to global changes. Leaf photosynthetic rates is a key processes usually represented on land surface-atmosphere models, although data from tropical ecosystems is scarce, considering the high biodiversity they contain. As a shortcut, models usually recur to relationships between leaf nutrient concentration and photosynthetic rates. Such strategy is convenient, given the possibility of global datasets on leave nutrients derived from hyperspectral remote sensing data. Given the importance of Nitrogen on enzyme composition, this nutrient is usually used to infer photosynthetic capacity of leaves. Our experience, based on individual measurements on 1809 individual leaves from 428 species of trees and shrubs naturally occurring on tropical forests and savannas from South America, Africa and Australia, indicates that the relationship between leaf nitrogen and its assimilation capacity is weak. Therefore, leaf Nitrogen alone is a poor predictor of photosynthetic rates of tropical vegetation. Phosphorus concentrations from tropical soils are usually low and is often implied that this nutrient limits primary productivity of tropical vegetation. Still, phosphorus (or other nutrients) did not exerted large influence over photosynthetic capacity, although potassium influenced vegetation structure and function. Such results draw attention to the risks of applying universal nitrogen-photosynthesis relationships on biogeochemical models. Moreover, our data suggests that affiliation of plant species within phylogenetic hierarchy is an important aspect in understanding leaf trait variation. The lack of a strong single

  5. Pollination syndromes ignored: importance of non-ornithophilous flowers to Neotropical savanna hummingbirds

    Science.gov (United States)

    Maruyama, Pietro K.; Oliveira, Genilda M.; Ferreira, Carolina; Dalsgaard, Bo; Oliveira, Paulo E.

    2013-11-01

    Generalization prevails in flower-animal interactions, and although animal visitors are not equally effective pollinators, most interactions likely represent an important energy intake for the animal visitor. Hummingbirds are nectar-feeding specialists, and many tropical plants are specialized toward hummingbird-pollination. In spite of this, especially in dry and seasonal tropical habitats, hummingbirds may often rely on non-ornithophilous plants to meet their energy requirements. However, quantitative studies evaluating the relative importance of ornithophilous vs. non-ornithophilous plants for hummingbirds in these areas are scarce. We here studied the availability and use of floral resources by hummingbirds in two different areas of the Cerrado, the seasonal savannas in Central Brazil. Roughly half the hummingbird visited plant species were non-ornithophilous, and these contributed greatly to increase the overall nectar availability. We showed that mean nectar offer, at the transect scale, was the only parameter related to hummingbird visitation frequency, more so than nectar offer at single flowers and at the plant scale, or pollination syndrome. Centrality indices, calculated using hummingbird-plant networks, showed that ornithophilous and non-ornithophilous plants have similar importance for network cohesion. How this foraging behaviour affects reproduction of non-ornithophilous plants remains largely unexplored and is probably case specific, however, we suggest that the additional energy provided by non-ornithophilous plants may facilitate reproduction of truly ornithophilous flowers by attracting and maintaining hummingbirds in the area. This may promote asymmetric hummingbird-plant associations, i.e., pollination depends on floral traits adapted to hummingbird morphology, but hummingbird visitation is determined more by the energetic "reward" than by pollination syndromes.

  6. Does the edge effect influence plant community structure in a tropical dry forest? O efeito de borda influencia a estrutura da comunidade vegetal em uma floresta tropical seca?

    Directory of Open Access Journals (Sweden)

    Diogo Gallo Oliveira

    2013-04-01

    Full Text Available Edge effects are considered a key factor in regulating the structure of plant communities in different ecosystems. However, regardless to few studies, edge influence does not seem to be decisive in semiarid regions such as the Brazilian tropical dry forest known as Caatinga but this issue remains inconclusive. The present study tests the null hypothesis that the plant community of shrubs and trees does not change in its structure due to edge effects. Twenty-four plots (20 x 20 m were set up in a fragment of Caatinga, in which 12 plots were in the forest edges and 12 plots were inside the fragment. Tree richness, abundance and species composition did not differ between edge and interior plots. The results of this study are in agreement with the pattern previously found for semiarid environments and contrasts with previous results obtained in different environments such as Rainforests, Savanna and Forest of Araucaria, which indicate abrupt differences between the border and interior of the plant communities in these ecosystems, and suggest that the community of woody plants of the Caatinga is not ecologically affected by the presence of edges.Efeitos de borda são considerados fator-chave na regulação da estrutura de comunidades vegetais em diferentes ecossistemas. Entretanto, apesar dos poucos estudos relacionados, o efeito de borda parece não ser determinante em regiões semiáridas, como a floresta tropical seca brasileira, conhecida como Caatinga. Este estudo testou a hipótese nula de que a comunidade vegetal arbustivo-arbórea não sofre alterações em sua estrutura, riqueza e composição devido ao efeito de borda. Foram instaladas 24 parcelas (20 x 20 m em um fragmento de Caatinga arbórea, sendo 12 parcelas na borda do fragmento e 12 parcelas no seu interior. A riqueza, abundância e composição das espécies não diferiram estatisticamente entre as parcelas de borda e interior. Os resultados deste estudo corroboram um possível padr

  7. Genetic divergence between populations of the stingless bee uruçu amarela (Melipona rufiventris group, Hymenoptera, Meliponini: is there a new Melipona species in the Brazilian state of Minas Gerais?

    Directory of Open Access Journals (Sweden)

    Mara Garcia Tavares

    2007-01-01

    Full Text Available Allozyme, microsatellite and random amplified polymorphic DNA (RAPD molecular markers were used to investigate the within and between population genetic variability and between population genetic differentiation of the Brazilian stingless bee uruçu amarela (nominally Melipona rufiventris Lepeletier, 1836 present in savanna and Atlantic forest habitats of the Brazilian state of Minas Gerais (MG. We found low levels of within population variability, although there were a large number of private alleles that specifically characterized these populations. The F ST values indicated a high level of genetic diversity between populations. Analysis of molecular variance (AMOVA showed a high degree of population differentiation between the savanna and Atlantic forest habitats, confirmed by population pairwise F ST data. Principal coordinates analysis and unweighted pair-group method using an arithmetic average (UPGMA dendrograms also confirmed that in Minas Gerais the savanna populations (M. rufiventris were genetically distinct from those present in the Atlantic forest (M. mondury. In addition, populations from locations near the towns of Dom Bosco and Brasilândia de Minas were genetically different from those collected in other localities in the savanna. Our data indicate that populations of uruçu amarela found in the savanna and Atlantic forest habitats of Minas Gerais state should be treated separately for conservation purposes and that special attention should be given to the populations found in the region of Dom Bosco and Brasilândia de Minas until their taxonomic status is clarified.

  8. Seasonal Effects in a Lake Sediment Archaeal Community of the Brazilian Savanna

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    Thiago Rodrigues

    2014-01-01

    Full Text Available The Cerrado is a biome that corresponds to 24% of Brazil’s territory. Only recently microbial communities of this biome have been investigated. Here we describe for the first time the diversity of archaeal communities from freshwater lake sediments of the Cerrado in the dry season and in the transition period between the dry and rainy seasons, when the first rains occur. Gene libraries were constructed, using Archaea-specific primers for the 16S rRNA and amoA genes. Analysis revealed marked differences between the archaeal communities found in the two seasons. I.1a and I.1c Thaumarchaeota were found in greater numbers in the transition period, while MCG Archaea was dominant on the dry season. Methanogens were only found in the dry season. Analysis of 16S rRNA sequences revealed lower diversity on the transition period. We detected archaeal amoA sequences in both seasons, but there were more OTUs during the dry season. These sequences were within the same cluster as Nitrosotalea devanaterra’s amoA gene. The principal coordinate analysis (PCoA test revealed significant differences between samples from different seasons. These results provide information on archaeal diversity in freshwater lake sediments of the Cerrado and indicates that rain is likely a factor that impacts these communities.

  9. Seasonal effects in a lake sediment archaeal community of the Brazilian Savanna.

    Science.gov (United States)

    Rodrigues, Thiago; Catão, Elisa; Bustamante, Mercedes M C; Quirino, Betania F; Kruger, Ricardo H; Kyaw, Cynthia M

    2014-01-01

    The Cerrado is a biome that corresponds to 24% of Brazil's territory. Only recently microbial communities of this biome have been investigated. Here we describe for the first time the diversity of archaeal communities from freshwater lake sediments of the Cerrado in the dry season and in the transition period between the dry and rainy seasons, when the first rains occur. Gene libraries were constructed, using Archaea-specific primers for the 16S rRNA and amoA genes. Analysis revealed marked differences between the archaeal communities found in the two seasons. I.1a and I.1c Thaumarchaeota were found in greater numbers in the transition period, while MCG Archaea was dominant on the dry season. Methanogens were only found in the dry season. Analysis of 16S rRNA sequences revealed lower diversity on the transition period. We detected archaeal amoA sequences in both seasons, but there were more OTUs during the dry season. These sequences were within the same cluster as Nitrosotalea devanaterra's amoA gene. The principal coordinate analysis (PCoA) test revealed significant differences between samples from different seasons. These results provide information on archaeal diversity in freshwater lake sediments of the Cerrado and indicates that rain is likely a factor that impacts these communities.

  10. Response of fish communities to intense drought in Brazilian savanna streams

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    Dianne Michelle Alves da Silva

    2017-08-01

    Full Text Available The physical structures of streams are subjected to intense changes throughout the seasons. Intense drought in dry periods has been frequent and potentially harmful to aquatic species. In this study, we tested whether the changes in the habitat structure of the streams during the dry period determine the organization of fish communities. Five streams in the Upper Tocantins River were studied in the dry and rainy seasons. The species were characterized by 13 functional traits based on morphological measurements. The descriptors of functional diversity were: mean pairwise functional distance of species in the community (MPD and mean functionally nearest species distance (MNTD. We also calculated the standardized effect size for MPD and MNTD, an indicator of functional redundancy, and compared the observed patterns with those expected by chance. Streams differed between seasons with respect to environmental variables. Functional diversity in the rainy season did not differ from the pattern expected by chance for both metrics. While functional diversity in the dry season has not differed from the pattern expected by chance for SESMPD, a greater functional redundancy for SESMNTD was found in this season. These results indicate that environmental changes in the streams during the dry season are important constraints for fish occurrence, preventing the occurrence of functionally original species. Therefore, a prospective scenario of dry-period intensification could result in functionally redundant communities, with functional homogenization of the regional species pool.

  11. The assessment of multi-sensor image fusion using wavelet transforms for mapping the Brazilian Savanna

    NARCIS (Netherlands)

    Weimar Acerbi, F.; Clevers, J.G.P.W.; Schaepman, M.E.

    2006-01-01

    Multi-sensor image fusion using the wavelet approach provides a conceptual framework for the improvement of the spatial resolution with minimal distortion of the spectral content of the source image. This paper assesses whether images with a large ratio of spatial resolution can be fused, and

  12. Deep drainage modeling for a fertigated coffee plantation in the brazilian savanna

    NARCIS (Netherlands)

    Pinto, Victor Meriguetti; Reichardt, Klaus; Dam, van Jos; Lier, Quirijn D.J.V.; Bruno, Isabeli Pereira; Durigon, Angelica; Dourado-Neto, Durval; Bortolotto, Rafael Pivotto

    2015-01-01

    Modeling in agriculture represents an important tool to understand processes as water and nutrient losses by drainage, or to test different conditions and scenarios of soil and crop management. Among the existing computational models to describe hydrological processes, SWAP (Soil, Water,

  13. Fire effects on the population structure of Zanthoxylum rhoifolium Lam (Rutaceae in a Brazilian savanna

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    IA. Silva

    Full Text Available Since cerrado fires may impede the growth of seedlings into trees, they may shape the population of woody species. In this study, we assessed the effects of a severe fire on the population structure and spatial distribution of Zanthoxylum rhoifolium, a widespread cerrado tree. We were interested to know the importance of the resprouting and sexual reproduction in regenerating the population. The study area had been for about six years protected from fire, before a severe fire at the end of the dry season in 2006. We sampled and measured all individuals of Z. rhoifolium found in 80 plots of 25 m². We found 149 individuals before the fire and 112 after the fire, of which 77 were resprouts from burned seedlings and saplings. We did not find significant differences between the population structure before and after the fire. The spatial distribution of the population remained clumped after the fire. Thus, the Z. rhoifolium population was very resilient to a severe fire. We did not find any new seedlings. As a consequence, resprouting seems to be more important than sexual reproduction in promptly regenerating the Z. rhoifolium populations.

  14. Divergent Hydraulic Safety Strategies in Three Co-occurring Anacardiaceae Tree Species in a Chinese Savanna.

    Science.gov (United States)

    Zhang, Shu-Bin; Zhang, Jiao-Lin; Cao, Kun-Fang

    2016-01-01

    Vulnerability segmentation, the condition under which plant leaves are more vulnerable to drought-induced cavitation than stems, may act as a "safety valve" to protect stems from hydraulic failure. Evergreen, winter-deciduous, and drought-deciduous tree species co-occur in tropical savannas, but there have been no direct studies on the role of vulnerability segmentation and stomatal regulation in maintaining hydraulic safety in trees with these three leaf phenologies. To this end, we selected three Anacardiaceae tree species co-occurring in a Chinese savanna, evergreen Pistacia weinmanniifolia , drought-deciduous Terminthia paniculata , and winter-deciduous Lannea coromandelica , to study inter-species differentiation in leaf and stem hydraulic safety. We found that the two deciduous species had significantly higher sapwood-specific hydraulic conductivity and leaf-specific hydraulic conductance than the evergreen species. Moreover, two deciduous species were more vulnerable to stem cavitation than the evergreen species, although both drought-deciduous species and evergreen species had drought-resistance leaves. The evergreen species maintained a wide hydraulic safety margin (HSM) in stems and leaves; which was achieved by embolism resistance of both stems and leaves and isohydric stomatal control. Both deciduous species had limited HSMs in stems and leaves, being isohydric in the winter-deciduous species and anisohydric in drought-deciduous species. The difference in water potential at 50% loss of hydraulic conductivity between the leaves and the terminal stems (P50 leaf-stem ) was positive in P. weinmanniifolia and L. coromandelica , whereas, T. paniculata exhibited a lack of vulnerability segmentation. In addition, differences in hydraulic architecture were found to be closely related to other structural traits, i.e., leaf mass per area, wood density, and sapwood anatomy. Overall, the winter-deciduous species exhibits a drought-avoidance strategy that maintains

  15. Plant composition in oak savanna and woodland restoration at Prairie Fork Conservation Area in Missouri

    Science.gov (United States)

    Nadia E. Navarrete-Tindall; J.W. Van Sambeek; Jamie Coe; Warren Taylor

    2007-01-01

    The wooded areas of the Prairie Fork Conservation Area in central Missouri are typical of the oak/hickory forest/prairie transition zone that will require active management to restore pre-settlement, grass dominated savannas and open woodlands to improve habitat for wildlife. We initiated a management program to restore savannas and woodlands by reducing the midstory (...

  16. Frequent burning promotes invasions of alien plants into a mesic African savanna

    NARCIS (Netherlands)

    Masocha, M.; Skidmore, A.K.; Poshiwa, X.; Prins, H.H.T.

    2011-01-01

    Fire is both inevitable and necessary for maintaining the structure and functioning of mesic savannas. Without disturbances such as fire and herbivory, tree cover can increase at the expense of grass cover and over time dominate mesic savannas. Consequently, repeated burning is widely used to

  17. Tree invasion in a semi-arid savanna in Zimbabwe : seedling recruitment of Acacia karroo

    NARCIS (Netherlands)

    Chirara, C. (Chipangura)

    2001-01-01

    In this thesis Chirara reports on his study on the competitive interaction between savanna grasses and young tree seedlings of Acacia karroo, from hereon indicated as ' Acacia seedlings' . Acacia is one of the tree species that dominates savanna grassland in situations of overgrazing (bush

  18. Pattern of invasion by Adhatoda vasica in savannas of Sariska Tiger Reserve, Rajasthan, Western India

    NARCIS (Netherlands)

    Bhatt, Priyanka; Rawat, G.S.; Sankar, K.; Tomlinson, K.W.; Langevelde, van F.

    2015-01-01

    As part of global experiments on Savanna vegetation, we examined the ecological characteristics of an important
    semiarid savanna in the Indian sub-continent i.e Sariska Tiger Reserve, Rajasthan, Western India during April 2009 to
    May 2011. 149 plots across five line transects were sampled

  19. Heaths and forests of the western hills of Chia, Bogota savanna, Colombia

    International Nuclear Information System (INIS)

    Cortes S, Sandra P.; Van der Hammen, Thomas; Rangel Ch, J Orlando

    2000-01-01

    The authors make a study of the heaths and forests of the western hills of the population of Chia, located in the savanna of Bogota and the presence or absences of these in the same Bogota savanna; the authors treat topics like their physiognomy and composition, distribution and ecology among other topics

  20. Chromosome studies on Brazilian cerrado plants

    Directory of Open Access Journals (Sweden)

    Eliana Regina Forni-Martins

    2000-12-01

    Full Text Available Cerrado is the Brazilian name for the neotropical savanna, which occurs mainly in Brazilian Central Plateau, composed of herbaceous-subshrubby and shrubby-arboreal floras, both of which are heliophilous, highly diverse and regionally differentiated. Considering species distribution and chromosome numbers, some authors have proposed that the herbaceous-subshrubby flora of the neotropical savanna is quite old, while the shrubby-arboreal flora is derived from forests, a hypothesis that implies higher chromosome numbers in the savanna than in the forest. If, however, chromosome numbers are similar in the cerrado and in forests, both could be similarly old, indicating that bi-directional flow of flora occurred in the past. This paper presents data on chromosome numbers and microsporogenesis for 20 species in 13 families collected in the States of São Paulo, Goiás and Minas Gerais, providing previously unpublished data for Myrcia (Myrtaceae, Luxemburgia (Ochnaceae and Hortia (Rutaceae. Meiosis proved to be normal, indicating regularity in the sexual reproductive process. Chromosome numbers varied from 2n = 18 (Allamanda angustifolia: Apocynaceae to 2n = ca. 104 (Ouratea spectabilis: Ochnaceae, being low (20 Cerrado é a palavra que, no Brasil, designa a savana neotropical, com área nuclear no Planalto Central, constituída de uma flora herbáceo-subarbustiva e outra arbustivo-arbórea, ambas heliófilas, altamente diversificadas e regionalmente diferenciadas. Considerando a distribuição de espécies e de números cromossômicos, alguns autores propuseram que a flora herbáceo-subarbustiva da savanna neotropical seria bastante antiga, enquanto a flora arbustivo-arbórea seria derivada das florestas Atlântica e Amazônica, uma hipótese que implica na ocorrência de números cromossômicos mais altos no cerrado que nas florestas. Porém, se os números cromossômicos forem similares no cerrado e nas florestas, ambos os tipos de formação poderiam

  1. Impacts of Human Activities on Tree Species Composition Along the Forest Savanna Boundary in Nigeria

    Directory of Open Access Journals (Sweden)

    Christiana Ndidi Egbinola

    2016-02-01

    Full Text Available The study investigated the tree species composition along the forest-savanna boundary in Oyo state of Nigeria with the aim of assessing the impact of human activities on the floristic composition. A transect was placed along the study area and species data was collected from quadrats placed in study plots within different study sites. Detrended Correspondence Analysis (DCA was used to determine vegetation assemblages, while both correlation and the analysis of variance (ANOVA were used to show the relationship between species in the different study sites. Results of the DCA revealed three species assemblages, an area with only forest species, another with only savanna species and a third with both forest/savanna species. ANOVA results further revealed that within the forest and savanna assemblages, species in mature and successional sites were alike. The study therefore revealed that human activities’ within the region is leading to the establishment of savanna species and an elimination of forest species.

  2. AVHRR for monitoring global tropical deforestation

    Science.gov (United States)

    Malingreau, J. P.; Laporte, N.; Tucker, C. J.

    1989-01-01

    Advanced Very High Resolution Radiometer (AVHRR) data have been used to assess the dynamics of forest trnsformations in three parts of the tropical belt. A large portion of the Amazon Basin has been systematically covered by Local Area Coverage (LAC) data in the 1985-1987 period. The analysis of the vegetation index and thermal data led to the identification and measurement of large areas of active deforestation. The Kalimantan/Borneo forest fires were monitored and their impact was evaluated using the Global Area Coverage (GAC) 4 km resolution data. Finally, High Resolution Picture Transmission (HRPT) data have provided preliminary information on current activities taking place at the boundary between the savanna and the forest in the Southern part of West Africa. The AVHRR approach is found to be a highly valuable means for carrying out deforestation assessments in regional and global perspectives.

  3. Horizontal and vertical variability of soil moisture in savanna ecosystems

    Science.gov (United States)

    Caylor, K.; D'Odorico, P.; Rodriguez-Iturbe, I.

    2004-12-01

    Soil moisture is a key hydrological variable that mediates the interactions between climate, soil, and vegetation dynamics in water-limited ecosystems. Because of the importance of water limitation in savannas, a number of theoretical models of tree-grass coexistence have been developed which differ in their underlying assumptions about the ways in which trees and grasses access and use soil moisture. However, clarification of the mechanisms that allow savanna vegetation to persist as a mixture of grasses and trees remains a vexing problem in both hydrological and vegetation science. A particular challenge is the fact that the spatial pattern of vegetation is both a cause and effect of variation in water availability in semiarid ecosystems. At landscape to regional scales, climatic and geologic constraints on soil moisture availability are primary determinants of vegetation structural pattern. However, at local to landscape scales the patchy vegetation structural mosaic serves to redistribute the availability of soil moisture in ways that have important consequences for structural dynamics and community composition. In this regard, the emerging field of ecohydrology is well suited to investigate questions concerning couplings between the patchy structural mosaic of savanna vegetation and the kinds self-organizing dynamics known to exist in other light and nutrient-limited vegetation systems. Here we address the role of patchy vegetation structure through the use of a lumped model of soil moisture dynamics that accounts for the effect of tree canopy on the lateral and vertical distribution of soil moisture. The model includes mechanisms for the drying of the ground surface due to soil evaporation in the sites with no tree cover, and for the lateral water uptake due to root invading areas with no canopy cover located in the proximity of trees. The model, when applied to a series of sites along a rainfall gradient in southern Africa, is able to explain the cover

  4. Deforestation in the Brazilian Amazon: A Classroom Project.

    Science.gov (United States)

    Nijman, Jan; Hill, A. David

    1991-01-01

    Presents a classroom project dealing with tropical deforestation in the Brazilian Amazon. Addresses environmental consequences and economic, social, and political causes. Involves both lectures and individual research and reports by student groups on deforestation causes. Includes a note-playing activity in which students make recommendations for…

  5. Patterns in woody vegetation structure across African savannas

    Science.gov (United States)

    Axelsson, Christoffer R.; Hanan, Niall P.

    2017-07-01

    Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP) modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs), which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality), soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr-1) to the wettest (1200-1400 mm yr-1) end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand content suggesting that maximal

  6. Patterns in woody vegetation structure across African savannas

    Directory of Open Access Journals (Sweden)

    C. R. Axelsson

    2017-07-01

    Full Text Available Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs, which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality, soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr−1 to the wettest (1200–1400 mm yr−1 end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand

  7. Taxonomy Icon Data: African savanna elephant [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available African savanna elephant Loxodonta africana Chordata/Vertebrata/Mammalia/Theria/Eutheria/etc. Loxodonta_afri...cana_L.png Loxodonta_africana_NL.png Loxodonta_africana_S.png Loxodonta_africana_NS....png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+africana&t=L http://biosciencedbc.jp/taxonom...y_icon/icon.cgi?i=Loxodonta+africana&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+afric...ana&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+africana&t=NS ...

  8. Tropical Deforestation.

    Science.gov (United States)

    Raven, Peter H.

    1988-01-01

    Outlines the deforestation problem and some efforts for solving the problem. Considers the impact of population growth, poverty, and ignorance. Includes a discussion of the current rapid decline in tropical forests, the consequences of destruction, and an outlook for the future. (YP)

  9. Seasonality, diaspore traits and the structure of plant-frugivore networks in Neotropical savanna forest

    Science.gov (United States)

    Darosci, Adriano Antonio Brito; Bruna, Emilio M.; Motta-Junior, José Carlos; Ferreira, Cristiane da Silva; Blake, John Gilman; Munhoz, Cássia Beatriz Rodrigues

    2017-10-01

    Complex frugivory networks are common in heterogeneous environments, but how the structure of those networks varies due to seasonality and other environmental factors remains unclear. For example, seasonal variation in rainfall can influence fruit production and diaspore characteristics, which could alter the quantity and quality of resources available to different animals in the network and, hence, network structure. We investigated how a frugivory network varied seasonally in Brazilian savanna (Cerrado), where there are well-defined dry and wet seasons and fructification mainly during the rainy season for most tree species. We recorded fruit consumption by animals during the dry and wet seasons in two different gallery forests and used these data to test the hypotheses that connectance, links per species and nestedness would be higher in the dry season than rainy season due to low available food in the former that would be consumed by various species of frugivores. Concomitantly, we also measured seed width and lipid content from diaspores of the fruiting trees to determine if these characteristics influenced interaction properties between fruiting trees and frugivores. Among the measured network parameters, connectance, links per species and specialization varied between seasons in one site but not in the other, indicating that seasonal variation in networks is not necessarily consistent over time or space. The number of tree species with small diaspores with high lipid content differed between seasons, and those characteristics were key factors increasing the interaction parameter of fruiting trees. We suggest that network stability between seasons may be related to local frugivore diversity, resource availability, and fruit quality.

  10. Streptomyces odonnellii sp. nov., a proteolytic streptomycete isolated from soil under cerrado (savanna) vegetation cover.

    Science.gov (United States)

    Pereira, Pedro Henrique Freitas; Macrae, Andrew; Reinert, Fernanda; de Souza, Rodrigo Fonseca; Coelho, Rosalie Reed Rodrigues; Pötter, Gabrielle; Klenk, Hans-Peter; Labeda, David P

    2017-12-01

    A novel streptomycete, strain 594 T , isolated from Brazilian soil collected under cerrado (savanna) vegetation cover is described. Strain 594 T produced thermophilic chitinolytic proteases in assays containing feather meal and corn steep liquor as sole sources of carbon and nitrogen. The strain produced white to grey aerial mycelium and spiral chains of spiny-surfaced spores on the aerial mycelium and did not produce diffusible pigments. The ll-isomer of diaminopimelic acid was present in the cell wall and menaquinones were predominantly MK-9(H6) (52 %) and MK-9(H8) (30 %) with 6 % MK-9(H4) and slightly less than 1 % MK-9(H2). Polar lipids present were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unknown phospholipid. The major fatty acids were anteiso-C15 : 0, anteiso-C16 : 0, anteiso-C14 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 70.4 mol%. Phylogenetic analysis of the nearly complete 16S rRNA gene sequence indicated that it differed from described Streptomyces species. Multilocus sequence analysis (MLSA) using five housekeeping genes (atpD, gyrB, rpoB, recA and trpB) comparing Streptomyces type strains showed that the MLSA distance of strain 594 T to the most closely related species was greater than the 0.007 threshold. The in silico DNA-DNA relatedness between the genome sequence of strain 594 T and that of the phylogenetically nearest species was well below the species level recommendation. There was thus multiple evidence justifying the description of this strain as representing a novel species, for which the name Streptomyces odonnellii sp. nov. is proposed. The type strain is 594 T (=IMPPG 594 T =DSM 41949 T =NRRL B-24891 T ).

  11. Metapopulation dynamics of the mistletoe and its host in savanna areas with different fire occurrence.

    Directory of Open Access Journals (Sweden)

    Grazielle Sales Teodoro

    Full Text Available Mistletoes are aerial hemiparasitic plants which occupy patches of favorable habitat (host trees surrounded by unfavorable habitat and may be possibly modeled as a metapopulation. A metapopulation is defined as a subdivided population that persists due to the balance between colonization and extinction in discrete habitat patches. Our aim was to evaluate the dynamics of the mistletoe Psittacanthus robustus and its host Vochysia thyrsoidea in three Brazilian savanna areas using a metapopulation approach. We also evaluated how the differences in terms of fire occurrence affected the dynamic of those populations (two areas burned during the study and one was fire protected. We monitored the populations at six-month intervals. P. robustus population structure and dynamics met the expected criteria for a metapopulation: i the suitable habitats for the mistletoe occur in discrete patches; (ii local populations went extinct during the study and (iii colonization of previously non-occupied patches occurred. The ratio of occupied patches decreased in all areas with time. Local mistletoe populations went extinct due to two different causes: patch extinction in area with no fire and fire killing in the burned areas. In a burned area, the largest decrease of occupied patch ratios occurred due to a fire event that killed the parasites without, however, killing the host trees. The greatest mortality of V. thyrsoidea occurred in the area without fire. In this area, all the dead trees supported mistletoe individuals and no mortality was observed for parasite-free trees. Because P. robustus is a fire sensitive species and V. thyrsoidea is fire tolerant, P. robustus seems to increase host mortality, but its effect is lessened by periodic burning that reduces the parasite loads.

  12. e-phenology: monitoring leaf phenology and tracking climate changes in the tropics

    Science.gov (United States)

    Morellato, Patrícia; Alberton, Bruna; Almeida, Jurandy; Alex, Jefersson; Mariano, Greice; Torres, Ricardo

    2014-05-01

    The e-phenology is a multidisciplinary project combining research in Computer Science and Phenology. Its goal is to attack theoretical and practical problems involving the use of new technologies for remote phenological observation aiming to detect local environmental changes. It is geared towards three objectives: (a) the use of new technologies of environmental monitoring based on remote phenology monitoring systems; (b) creation of a protocol for a Brazilian long term phenology monitoring program and for the integration across disciplines, advancing our knowledge of seasonal responses within tropics to climate change; and (c) provide models, methods and algorithms to support management, integration and analysis of data of remote phenology systems. The research team is composed by computer scientists and biology researchers in Phenology. Our first results include: Phenology towers - We set up the first phenology tower in our core cerrado-savanna 1 study site at Itirapina, São Paulo, Brazil. The tower received a complete climatic station and a digital camera. The digital camera is set up to take daily sequence of images (five images per hour, from 6:00 to 18:00 h). We set up similar phenology towers with climatic station and cameras in five more sites: cerrado-savanna 2 (Pé de Gigante, SP), cerrado grassland 3 (Itirapina, SP), rupestrian fields 4 ( Serra do Cipo, MG), seasonal forest 5 (Angatuba, SP) and Atlantic raiforest 6 (Santa Virginia, SP). Phenology database - We finished modeling and validation of a phenology database that stores ground phenology and near-remote phenology, and we are carrying out the implementation with data ingestion. Remote phenology and image processing - We performed the first analyses of the cerrado sites 1 to 4 phenology derived from digital images. Analysis were conducted by extracting color information (RGB Red, Green and Blue color channels) from selected parts of the image named regions of interest (ROI). using the green color

  13. Stratifying Tropical Fires by Land Cover: Insights into Amazonian Fires, Aerosol Loading, and Regional Deforestation

    Science.gov (United States)

    TenHoeve, J. E.; Remer, L. A.; Jacobson, M. Z.

    2010-01-01

    This study analyzes changes in the number of fires detected on forest, grass, and transition lands during the 2002-2009 biomass burning seasons using fire detection data and co-located land cover classifications from the Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the total number of detected fires correlates well with MODIS mean aerosol optical depth (AOD) from year to year, in accord with other studies. However, we also show that the ratio of forest to savanna fires varies substantially from year to year. Forest fires have trended downward, on average, since the beginning of 2006 despite a modest increase in 2007. Our study suggests that high particulate matter loading detected in 2007 was likely due to a large number of savanna/agricultural fires that year. Finally, we illustrate that the correlation between annual Brazilian deforestation estimates and MODIS fires is considerably higher when fires are stratified by MODIS-derived land cover classifications.

  14. Using Paleoecology to Inform Land Management as Climates Change: An Example from an Oak Savanna Ecosystem

    Science.gov (United States)

    Spencer, Jessica D.; Brunelle, Andrea; Hepola, Tim

    2017-12-01

    Oak savanna, a transitional ecosystem between open prairie and dense oak forest, was once widespread in Minnesota. Upon European settlement much of the oak savanna was destroyed. Recently, efforts to restore this ecosystem have increased and often include the reintroduction of fire. Though fire is known to serve an important role within oak savannas, there are currently few studies which address fire regimes on timescales longer than the last century. This research presents a paleoecological history of Sherburne National Wildlife Refuge (SNWR) in MN, USA, spanning the last 8000 years. The objectives of this study were to use charcoal, pollen, and magnetic susceptibility of lake sediments collected from Johnson Slough (JS) within the refuge to evaluate the natural range of variability and disturbance history of the oak savanna within the refuge, assess the success of current restoration strategies, and add to the regional paleoecological history. The mid/late Holocene period of the JS record shows a period of high fire activity from ca. 6500 to 2600 cal year BP, with a shift from prairie to oak savanna occurring over this same period. A (possibly agricultural) disturbance to JS sediments affected the period from ca. 2600 cal year BP to 1963 AD, which includes the time of Euro-American settlement. However, the destruction and subsequent restoration of the oak savanna is evident in a pollen ratio of Quercus:Poaceae, indicating that current restoration efforts have been successful at restoring the oak savanna to within the natural range of variability seen just prior to destruction.

  15. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

    Science.gov (United States)

    Beckley, Carl S; Shaban, Salisu; Palmer, Guy H; Hudak, Andrew T; Noh, Susan M; Futse, James E

    2016-01-01

    Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc) were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B. bigemina prevalence

  16. Disaggregating Tropical Disease Prevalence by Climatic and Vegetative Zones within Tropical West Africa.

    Directory of Open Access Journals (Sweden)

    Carl S Beckley

    Full Text Available Tropical infectious disease prevalence is dependent on many socio-cultural determinants. However, rainfall and temperature frequently underlie overall prevalence, particularly for vector-borne diseases. As a result these diseases have increased prevalence in tropical as compared to temperate regions. Specific to tropical Africa, the tendency to incorrectly infer that tropical diseases are uniformly prevalent has been partially overcome with solid epidemiologic data. This finer resolution data is important in multiple contexts, including understanding risk, predictive value in disease diagnosis, and population immunity. We hypothesized that within the context of a tropical climate, vector-borne pathogen prevalence would significantly differ according to zonal differences in rainfall, temperature, relative humidity and vegetation condition. We then determined if these environmental data were predictive of pathogen prevalence. First we determined the prevalence of three major pathogens of cattle, Anaplasma marginale, Babesia bigemina and Theileria spp, in the three vegetation zones where cattle are predominantly raised in Ghana: Guinea savannah, semi-deciduous forest, and coastal savannah. The prevalence of A. marginale was 63%, 26% for Theileria spp and 2% for B. bigemina. A. marginale and Theileria spp. were significantly more prevalent in the coastal savannah as compared to either the Guinea savanna or the semi-deciduous forest, supporting acceptance of the first hypothesis. To test the predictive power of environmental variables, the data over a three year period were considered in best subsets multiple linear regression models predicting prevalence of each pathogen. Corrected Akaike Information Criteria (AICc were assigned to the alternative models to compare their utility. Competitive models for each response were averaged using AICc weights. Rainfall was most predictive of pathogen prevalence, and EVI also contributed to A. marginale and B

  17. Interactions between atmospheric circulation, nutrient deposition, and tropical forest primary production (Invited)

    Science.gov (United States)

    Randerson, J. T.; Chen, Y.; Rogers, B. M.; Morton, D. C.; van der Werf, G.; Mahowald, N. M.

    2010-12-01

    Tropical forests influence regional and global climate by means of several pathways, including by modifying surface energy exchange and by forming clouds. High levels of precipitation, leaching, and soil weathering limit nutrient availability in these ecosystems. Phosphorus (P) is a key element limiting net primary production, and in some areas, including forests recovering from prior disturbance, nitrogen (N) also may limit some components of production. Here we quantified atmospheric P and N inputs to these forests from fires using satellite-derived estimates of emissions and atmospheric models. In Africa and South America, cross-biome transport of fire-emitted aerosols and reactive N gases from savannas and areas near the deforestation frontier increased deposition of P and N in interior forests. Equatorward atmospheric transport during the dry (fire) season in one hemisphere was linked with surface winds moving toward the inter-tropical convergence zone (ITCZ) in the other hemisphere. Deposition levels were higher in tropical forests in Africa than in South America because of large savanna areas with high levels of fire emissions in both southern and northern Africa. We conclude by describing a potential feedback loop by which equatorward transport of fire emissions, dust, and spores sustains the productivity of tropical forests. We specifically assessed evidence that savanna-to-forest atmospheric transport of nutrients increases forest productivity, height, and rates of evapotranspiration (ET). In parallel, we examined the degree to which increases in ET and surface roughness in tropical forests have the potential to strengthen several components of the Hadley circulation, including deep convection, equatorward return flow (near the surface), and the intensity of seasonal drought in the subtropics (thereby increasing fires). These interactions are important for understanding biogeochemical - climate interactions on millennial timescales and for quantifying how

  18. Influence of Fire Mosaics, Habitat Characteristics and Cattle Disturbance on Mammals in Fire-Prone Savanna Landscapes of the Northern Kimberley.

    Science.gov (United States)

    Radford, Ian J; Gibson, Lesley A; Corey, Ben; Carnes, Karin; Fairman, Richard

    2015-01-01

    Patch mosaic burning, in which fire is used to produce a mosaic of habitat patches representative of a range of fire histories ('pyrodiversity'), has been widely advocated to promote greater biodiversity. However, the details of desired fire mosaics for prescribed burning programs are often unspecified. Threatened small to medium-sized mammals (35 g to 5.5 kg) in the fire-prone tropical savannas of Australia appear to be particularly fire-sensitive. Consequently, a clear understanding of which properties of fire mosaics are most instrumental in influencing savanna mammal populations is critical. Here we use mammal capture data, remotely sensed fire information (i.e. time since last fire, fire frequency, frequency of late dry season fires, diversity of post-fire ages in 3 km radius, and spatial extent of recently burnt, intermediate and long unburnt habitat) and structural habitat attributes (including an index of cattle disturbance) to examine which characteristics of fire mosaics most influence mammals in the north-west Kimberley. We used general linear models to examine the relationship between fire mosaic and habitat attributes on total mammal abundance and richness, and the abundance of the most commonly detected species. Strong negative associations of mammal abundance and richness with frequency of late dry season fires, the spatial extent of recently burnt habitat (post-fire age fire age classes in the models. Our results indicate that both a high frequency of intense late dry season fires and extensive, recently burnt vegetation are likely to be detrimental to mammals in the north Kimberley. A managed fire mosaic that reduces large scale and intense fires, including the retention of ≥4 years unburnt patches, will clearly benefit savanna mammals. We also highlighted the importance of fire mosaics that retain sufficient shelter for mammals. Along with fire, it is clear that grazing by introduced herbivores also needs to be reduced so that habitat quality is

  19. Assessment of UAV and Ground-Based Structure from Motion with Multi-View Stereo Photogrammetry in a Gullied Savanna Catchment

    Directory of Open Access Journals (Sweden)

    Jack Koci

    2017-10-01

    Full Text Available Structure from Motion with Multi-View Stereo photogrammetry (SfM-MVS is increasingly used in geoscience investigations, but has not been thoroughly tested in gullied savanna systems. The aim of this study was to test the accuracy of topographic models derived from aerial (via Unmanned Aerial Vehicle, ‘UAV’ and ground-based (via handheld digital camera, ‘ground’ SfM-MVS in modelling hillslope gully systems in a dry-tropical savanna, and to assess the strengths and limitations of the approach at a hillslope scale and an individual gully scale. UAV surveys covered three separate hillslope gully systems (with areas of 0.412–0.715 km2, while ground surveys assessed individual gullies within the broader systems (with areas of 350–750 m2. SfM-MVS topographic models, including Digital Surface Models (DSM and dense point clouds, were compared against RTK-GPS point data and a pre-existing airborne LiDAR Digital Elevation Model (DEM. Results indicate that UAV SfM-MVS can deliver topographic models with a resolution and accuracy suitable to define gully systems at a hillslope scale (e.g., approximately 0.1 m resolution with 0.4–1.2 m elevation error, while ground-based SfM-MVS is more capable of quantifying gully morphology (e.g., approximately 0.01 m resolution with 0.04–0.1 m elevation error. Despite difficulties in reconstructing vegetated surfaces, uncertainty as to optimal survey and processing designs, and high computational demands, this study has demonstrated great potential for SfM-MVS to be used as a cost-effective tool to aid in the mapping, modelling and management of hillslope gully systems at different scales, in savanna landscapes and elsewhere.

  20. Increased tree densities in South African savannas: >50 years of data suggests CO2 as driver

    CSIR Research Space (South Africa)

    Buitenwerf, R

    2012-02-01

    Full Text Available EC et al. (2007) Effects of four decades of fire manipulation on woody vegetation structure in savanna. Ecology, 88, 1119-1125. Hoffman MT, O'Connor TG (1999) Vegetation change over 40 years in the Weenen/Muden area, KwaZulu-Natal: evidence from... response of savanna woody plant species following harvesting: the value of persistence. Forest Ecology and Management, 232, 114-123. O'Connor TG (1985) A synthesis of field experiments concerning the grass layer in the savanna regions of southern...

  1. Projections of 21st Century African Climate: Implications for African Savanna Fire Dynamics, Human Health and Food Security

    Science.gov (United States)

    Adegoke, J. O.

    2015-12-01

    Fire is a key agent of change in the African savannas, which are shaped through the complex interactions between trees, C4 grasses, rainfall, temperature, CO2 and fire. These fires and their emitted smoke can have numerous direct and indirect effects on the environment, water resources, air quality, and climate. For instance, veld fires in southern Africa cause large financial losses to agriculture, livestock production and forestry on an annual basis. This study contributes to our understanding of the implications of projected surface temperature evolution in Africa for fire risk, human health and agriculture over the coming decades. We use an ensemble of high-resolution regional climate model simulations of African climate for the 21st century. Regional dowscalings and recent global circulation model projections obtained for Africa indicate that African temperatures are likely to rise at 1.5 times the global rate of temperature increase in the tropics, and at almost twice the global rate of increase in the subtropics. Warming is projected to occur during the 21st century, with increases of 4-6 °C over the subtropics and 3-5 °C over the tropics plausible by the end of the century relative to present-day climate under the A2 (low mitigation) scenario. We explore the significance of the projected warming by documenting increases in projected high fire danger days and heat-wave days. General drying is projected across the continent, even for areas (e.g. tropical Africa) where an increase in rainfall is plausible. This is due to the drastic increases in temperature that are projected, which leads to drier soils (through enhanced evaporation) despite the rainfall increases. This will likely impact negatively on crop yield, particularly on the maize crop that is of crucial importance in terms of African food security.

  2. Inferences of Present and Past Changes at Isolated Enclaves and Matrix of Savannas by Carbon Isotopes in a Transitional Forest-Savanna Area in Northern Amazonia

    Science.gov (United States)

    Couto-Santos, F. R.; Luizao, F. J.; Camargo, P. B.

    2013-12-01

    The evolutionary history of savannas influenced by short term climate cycles, during the Quaternary Period, could prompt variations in forest cover often related to movements of the forest-savanna boundary. In this study we investigated current and past changes in the structure of vegetation and the origins of savannas of different natures in a biogeographically and climatic transitional forest-savanna area in northern Amazonia. Variations in the isotopic composition of soil organic matter (δ13C) from surface soils (0-10 cm) along forest-savanna boundaries, detected by a sigmoidal non-linear function, were used to identify current changes in vegetation, while past changes were inferred by discontinuities in the evolution of δ13C with soil depth using piecewise regression associated with radiocarbon dating (14C). By comparing small isolated savanna enclaves inside a strictly protected nature reserve (ESEC Maracá) with its outskirts unprotected continuous savanna matrix, we found that origins and the patterns of dynamics were distinct between these areas and did not respond in the same way to climate change and fire events, either in the last decades or during the Holocene. The stability of the present boundaries of the surrounding savanna matrix reflects the resilience of the transitional forests under a recent intensified fire regime and favorable climate, while the deep forest soil isotopic signal indicated a forest shrinkage of at least 70 m occurring since its origin in early Holocene until 780 years BP associated with a climate drier than the current one. Contrarily, the protected enclaves inside ESEC Maracá, remained stable since the middle Holocene, suggesting a non-anthropogenic origin related to soil edaphic conditions, but with recent dynamics of advancing forest by 8 m century-1 favored by current climate and lacking fire events. A detailed understanding of the origins of savannas of distinct natures and the way they are affected by climate and fire

  3. Diversity of the ground-dwelling ant fauna (Hymenoptera: Formicidae) of a moist, Montane forest of the semi-arid Brazilian "Nordeste".

    Science.gov (United States)

    Hites, N L; Mourão, M A N; Araújo, F O; Melo, M V C; de Biseau, J C; Quinet, Y

    2005-01-01

    Although the so called "green islands" of the semi-arid Brazilian "Nordeste" are economically, socially, and ecologically important. relatively little is known about their biodiversity. We present the results of the first survey of the ground-dwelling ant fauna of a secondary forest in the Serra de Baturité (4 degrees 05'-4 degrees 40' S / 38 degrees 30'-39 degrees 10' W), among the biggest of the moist, montane forests of the state of Ceará, Brazil. From February to March 2001, samples were taken every 50 m along twelve 200 m transects, each separated from the others by at least 50 m and cut on either side of a recreational trail. Where possible, two transects were cut from the same starting point on the trail, one on either side. At each sample site two methods were used, as recommended in the ALL. protocol: a pitfall trap and the treatment of 1 m2 of leaf litter with the Winkler extractor. The myrmecofauna of the Serra de Baturité is quite diverse: individuals from 72 species, 23 genera, and six subfamilies were collected. The observed patterns of specific richness show the same tendencies noted in other tropical regions, particularly the frequency of capture distribution with many rare and few abundant species. Differences with the Atlantic and Amazonian forests were also observed, especially the relative importance of the Ponerinac and Formicinae subfamilies, indicating a possible influence of the surrounding "caatinga" (savanna-like ecosystem) on the myrmecofauna of the moist, montane forest.

  4. Management of Herbaceous Seeps and Wet Savannas for Threatened and Endangered Species

    National Research Council Canada - National Science Library

    Harper, Mary

    1998-01-01

    Wetland communities such as herbaceous seeps and wet savannas occur on military installations throughout the southeastern United States, usually as pockets of wet habitat within a matrix of drier longleaf pine woodlands...

  5. Hyper-temporal c-band SAR for baseline woody structural assessments in deciduous savannas

    CSIR Research Space (South Africa)

    Mathieu, Renaud SA

    2016-08-01

    Full Text Available deciduous savanna environment. Results showed that: the temporal filter reduced image variance; the random forest model out-performed the linear model; while the TCV metric consistently showed marginally higher accuracies than the TCC metric. Combinations...

  6. Nylsvley - South African Savanna ecosystem project: objectives, organisation and research programme

    CSIR Research Space (South Africa)

    Huntley, BJ

    1978-03-01

    Full Text Available A description of the objectives, organization and research programme of the Savanna Ecosystem Project being undertaken at Nylsvley in the northern Transvaal is presented. The project is a cooperative multi-disciplinary study of the structure...

  7. Mapping big tree presence in open savanna, using tree shadow and high resolution multispectral imagery

    CSIR Research Space (South Africa)

    Mathieu, Renaud SA

    2012-10-01

    Full Text Available Large scattered trees play an important role in the functioning of savanna landscapes. They act as focal points for various organism activities, which influence the distribution of nutrients and water within the landscape, which in turn influences...

  8. Global extent and determinants of savanna and forest as alternative biome states

    CSIR Research Space (South Africa)

    Staver, C

    2011-10-01

    Full Text Available Theoretically, fire–tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire- driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. The authors...

  9. Variáveis relacionadas à estabilidade de complexos organo-minerais em solos tropicais e subtropicais brasileiros Selected soil-variables related to the stability of organo-minerals complexes in tropical and subtropical brazilian soils

    Directory of Open Access Journals (Sweden)

    Alberto Vasconcellos Inda Junior

    2007-10-01

    Full Text Available A estabilidade de complexos organo-minerais é uma característica importante quanto à química e física de solos tropicais e subtropicais. O objetivo deste estudo foi identificar variáveis relacionadas à estabilidade de complexos organo-minerais, avaliada pela energia de ultra-som necessária para a dispersão total do solo em partículas primárias, em seis solos das regiões Sul e Centro-Oeste do Brasil com textura e mineralogia distintas. A energia de ultra-som necessária para dispersão total dos solos variou de 239 a 2.389J mL-1, sendo diretamente relacionada aos teores de carbono orgânico (R²=0,799, PThe stability of organo-mineral complexes is an important characteristic related to the soil chemistry and physics of tropical and subtropical soils. This study was aimed at identifing the variables related to the stability of organo-mineral complexes, evaluated by ultrasonic energy necessary to complete soil dispersion, of six soils from South and West-Center regions of Brazil with distint texture and mineralogy. The ultrasonic energy to complete soil dispersion varied from 239 a 2389J mL-1, and was positively related to the soil organic carbon concentrations (R²=0.799, P<0.05. The clay mineralogy had an important role to the stability of organo-mineral complexes, which were related to the content of low cristalinity iron oxides (R²=0.586, P<0.10, but did not had relationship with the total pedogenic iron oxides. The qualitative analysis of the clay mineralogy, by X-ray diffraction, evidenced that gibbsite and goethite are the main clay minerals related to the stability of organo-mineral complexes, reinforcing the importance of these minerals on the physical protection and coloidal stability of the soil organic matter in the tropical and subtropical soils.

  10. Soil C dynamics under intensive oil palm plantations in poor tropical soils

    Science.gov (United States)

    Guillaume, Thomas; Ruegg, Johanna; Quezada, Juan Carlos; Buttler, Alexandre

    2017-04-01

    Oil palm cultivation mainly takes place on heavily-weathered tropical soils where nutrients are limiting factors for plant growth and microbial activity. Intensive fertilization and changes of C input by oil palms strongly affects soil C and nutrient dynamics, challenging long-term soil fertility. Oil palm plantations management offers unique opportunities to study soil C and nutrients interactions in field conditions because 1) they can be considered as long-term litter manipulation experiments since all aboveground C inputs are concentrated in frond pile areas and 2) mineral fertilizers are only applied in specific areas, i.e. weeded circle around the tree and interrows, but not in harvest paths. Here, we determined impacts of mineral fertilizer and organic matter input on soil organic carbon dynamics and microbial activity in mature oil palm plantation established on savanna grasslands. Rates of savanna-derived soil organic carbon (SOC) decomposition and oil palm-derived SOC net stabilization were determined using changes in isotopic signature of in C input following a shift from C4 (savanna) to C3 (oil palm) vegetation. Application of mineral fertilizer alone did not affect savanna-derived SOC decomposition or oil palm-derived SOC stabilization rates, but fertilization associated with higher C input lead to an increase of oil palm-derived SOC stabilization rates, with about 50% of topsoil SOC derived from oil palm after 9 years. High carbon and nutrients inputs did not increase microbial biomass but microorganisms were more active per unit of biomass and SOC. In conclusion, soil organic matter decomposition was limited by C rather than nutrients in the studied heavily-weathered soils. Fresh C and nutrient inputs did not lead to priming of old savanna-derived SOC but increased turnover and stabilization of new oil palm-derived SOC.

  11. Consequences to precipitation regimes of replacing native Brazilian Cerrado by managed Eucalyptus

    Science.gov (United States)

    Siqueira, M. B.; Mota, F. C. M.

    2016-12-01

    Before the large people influx and development of the central part of Brazil in the sixties, due to new capital Brasília, Cerrado, a typical Brazilian savanna-type vegetation, used to occupy about 2 million km2, going from the Amazon tropical forest, in the north, to the edges of what used to be the Atlantic forest in the southeast. Today, somewhat 50% of this area has given place to agriculture, pasture and managed forests. Understanding how Cerrado interacts with the atmosphere and how this interaction will be modified with this land-use change is a crucial step towards improving predictions of future climate-change scenarios. Cerrado is a vegetation adapted to a climate characterized by two distinct seasons, a wet season (Nov-Mar) and dry season (May-Ago), with April and October being transitions between seasons. Typically, 75% of precipitation happens in the wet-season months and only 5% during dry-season. In this study, it is investigated the potential impacts of the substitution of Cerrado to the eco-hydrological characteristics of the region. The focus here is Eucalyptus plantation, which has increased substantially in the last decade due to government incentives. Two eddy-covariance (EC) systems were installed, one in an undisturbed Cerrado Stricto area and other in a recently-established Eucalyptus plantation. The two areas are 1,400m apart and are subjected to the same meteorology and similar edaphic conditions. Besides instrumentation typical of EC towers, a soil-moisture profiling system was installed in each site. Surface flux data from the eddy-covariance towers, along with daily upper air sounding profiles collected at the Brasília International Airport (located 10Km from the towers), were used to drive a simplified Atmospheric Boundary Layer (ABL) slab model in order to investigate possible consequences of a large-scale shift from Cerrado to Eucalyptus to precipitation regimes in the region. Preliminary results show that replacing Cerrado for

  12. Impacts of landuse and climate change on the dynamics and biodiversity in the Thornbush Savanna Biome

    CSIR Research Space (South Africa)

    Jeltsch, F

    2010-01-01

    Full Text Available pressure on dryland ecosystem services takes place in regions of intermediate aridity and not, as might be expected, in dry subhumid ar- eas where population density is highest, or in hyperarid areas, where population is lowest. The high... of households (Ericson & Watson 2009). They can function as a model-region for a broad range of dry- lands, especially non-humid savannas, worldwide?in particular as projected climatic changes for most subhumid and semiarid savanna regions indicate major...

  13. Brazilian minerals annual report

    International Nuclear Information System (INIS)

    1977-01-01

    Statistics of Brazilian mineral resources and production in 1977 are presented. Data included refer also to economic aspects, market, taxes, government incentives, manpower, exportation, importation, etc [pt

  14. The individual and interactive effects of tree-tree establishment competition and fire on savanna structure and dynamics

    OpenAIRE

    Calabrese, Justin; Vázquez, Federico; López, Cristóbal; San Miguel, Maxi; Grimm, Volker

    2010-01-01

    The mechanisms regulating savanna tree populations are still not well understood. Recent empirical work suggests that both tree-tree competition and fire are key factors in semi-arid to mesic savannas. However, the potential for competition to structure savannas, particularly in interaction with fire, has received little theoretical attention. We develop a minimalistic and analytically tractable stochastic cellular automaton to study the individual and combined effects of competition and fire...

  15. Óxidos de ferro em latossolos tropicais e subtropicais brasileiros em plantio direto Iron oxides in tropical and subtropical Brazilian oxisols under long-term no-tillage

    Directory of Open Access Journals (Sweden)

    Luís de França da Silva Neto

    2008-10-01

    Full Text Available O sistema plantio direto (SPD altera a taxa dos processos que ocorrem no solo, porém pouco se conhece sobre sua influência na mineralogia de solos tropicais e subtropicais. Este estudo teve por objetivo avaliar o efeito do SPD na mineralogia dos óxidos de Fe pedogênicos e sua relação com a matéria orgânica do solo (MOS. Amostras de solos foram coletadas em 14 profundidades da camada superficial (0 a 0,20 m de dois Latossolos sob SPD e sistema de preparo convencional (SPC, em áreas experimentais de longa duração, no sul do Brasil (Santo Ângelo, RS e na região do Cerrado (Dourados, MS. A identificação mineralógica foi realizada por difração de raios X (DRX, sendo determinados os teores de Fe extraídos por DCB (Fed e por oxalato de amônio (Feo e os teores de carbono orgânico total (COT. Nos dois solos predominaram os minerais caulinita e hematita, e o SPD não afetou os teores médios de Fed, Feo, COT e a razão Feo/Fed na camada de 0-0,20 m, em comparação ao solo em SPC. Entretanto, no Latossolo subtropical (LVdf-1, com boa distribuição de chuvas durante o ano e temperaturas mais amenas, houve aumento dos teores de COT e da fração humina na camada superficial do solo (0-0,03 m sob SPD. Ademais, essas variáveis apresentaram relação positiva com os teores de Feo e razão Feo/Fed. Contrariamente, no Latossolo tropical (LVdf-2, com concentração das chuvas no verão (outubro a março, não houve efeito do SPD na distribuição do COT e das frações húmicas no solo. Neste solo, os teores de Feo e da razão Feo/Fed apresentaram relação positiva com a profundidade do solo e negativa com os teores de COT e da fração humina. Provavelmente esses resultados são conseqüência do reordenamento dos óxidos de Fe, possivelmente a partir da dissolução redutiva da hematita e da maghemita nas camadas mais superficiais e da neoformação de óxidos de Fe de baixa cristalinidade nas camadas mais profundas.The no-tillage system

  16. Leaf green-up in a semi-arid African savanna - separating tree and grass responses to environmental cues

    CSIR Research Space (South Africa)

    Archibald, S

    2007-01-01

    Full Text Available -arid African savanna - 583 Journal of Vegetation Science 18: 583-594, 2007 © IAVS; Opulus Press Uppsala. Leaf green-up in a semi-arid African savanna – separating tree and grass responses to environmental cues Archibald, S.1* & Scholes, R.J.1,2 1Natural... to identify tree and grass green-up dates in a semi-arid savanna system, and are there predictable environmental cues for green-up for each life form? Location: Acacia nigrescens/Combretum apiculatum savanna, Kruger National Park, South Africa (25° S, 31...

  17. Chemical variability of the essential oils from fruits of Pterodon emarginatus in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    Suzana F. Alves

    2013-02-01

    Full Text Available Pterodon emarginatus Vogel, Fabaceae, is a tree species commonly known as "sucupira-branca". It is a popular medicinal plant in the Brazilian cerrado (Savanna. This study investigates the chemical variability of the essential oils from fruits of P. emarginatus. The fruits were collected from five sites in the Brazilian Cerrado and their essential oils were analyzed by GC/MS. The results obtained by Principal Component and Cluster Analysis identified two groups: cluster I containing β-caryophyllene and δ-elemene and cluster II containing α-copaene, β-cubebene, allo-aromadendrene, α-cubebene and γ-muurulene. The Canonical Discriminant Analysis was used to differentiate between clusters on the basis of essential oil composition. The results showed high variability in the composition of the essential oils from fruits of P. emarginatus, contributing to studies of domestication of this species.

  18. Estratégias para o desenvolvimento de novas cultivares de mangueira para o semiárido brasileiro Mango strategies to develop new varieties to the Brazilian tropical semi-arid region

    Directory of Open Access Journals (Sweden)

    Carlos Antonio Fernandes Santos

    2010-06-01

    Full Text Available A mangueira é uma das principais fruteiras comerciais no Semiárido brasileiro, sendo que a cultivar Tommy Atkins ocupa 85% da área total cultivada com a cultura. O objetivo deste trabalho foi avaliar o emprego de estratégias para reduzir o período juvenil e as trabalhosas polinizações manuais em mangueira, de forma a acelerar o desenvolvimento de novas cultivares da espécie para o Semiárido brasileiro. Foram identificadas plantas isoladas das cultivares Haden e Espada dentro de plantios comerciais da cultivar Tommy Atkins, numa fazenda exportadora de manga, em Petrolina-PE. Mudas das progênies foram transplantadas com seis meses de idade para o campo. O manejo para a indução floral foi realizado com poda, controle da irrigação e aplicação de Paclobutrazol e nitrato de potássio. O DNA extraído das progênies e parentais foi submetido a análises com marcadores microssatélites publicados para Mangifera indica L. O manejo combinado foi eficiente para induzir a floração e a frutificação em, aproximadamente, 70% das progênies após dois anos e meio de transplantio. Dos 94 indivíduos analisados com três microssatélites, 83% foram identificados como híbridos entre 'Haden' x 'T. Atkins'. Dos 401 indivíduos analisados com um microssatélite, 10% foram identificados como híbridos entre 'Espada' x 'T. Atkins'. A estratégia adotada foi eficiente para reduzir o período juvenil e evitar os trabalhosos cruzamentos manuais em mangueira, sendo que o desenvolvimento de novas cultivares da espécie para a região pode ser concluído com oito a dez anos, incluindo as rigorosas avaliações agronômicas.Mango is one of the most important fruit crop in the Brazilian Semi-Arid region. The cultivar Tommy Atkins has been grown in 85% of total area dedicated to this crop. The goal of this research was to evaluate strategies to reduce the juvenile period and to replace the laborious hand pollinization in order to accelerate the development

  19. Anthropogenic edges, isolation and the flowering time and fruit set of Anadenanthera peregrina, a cerrado savanna tree.

    Science.gov (United States)

    Athayde, Eduardo Anversa; Morellato, Leonor Patrícia Cerdeira

    2014-05-01

    Fragmentation exposes plants to extreme environmental conditions with implications for species phenology and reproduction.We investigated whether isolation and edge effects influence size, flowering time, fruit set, and seedling establishment of Anadenanthera peregrina var. falcata. We compared trees in the interior (n =85), and on the edge (n =74) of a cerrado savanna fragment as well as in a pasture (n =26) with respect to size, flowering phenology, flower and fruit production, fruit and seed set, predispersal seed predation, and seedling establishment. Trees in the pasture were larger and produced a higher number of flowers and fruits than trees on the edge and interior, yet seed set did not differ across environments. The plant size structure explained the flower and fruit production, and the self-compatibility breeding system caused a similar seed set regardless of the environment. First flowering was later and fruit set higher in the interior. We argue that time of first flower influenced the fruit set of Anadenathera. Edge and isolated trees started to flower earlier as a response to microclimatic conditions--mainly temperature--reducing the fruit set. Predispersal seed predation was lower among pasture trees. Conversely, we found seedlings only on the edge and in the interior of cerrado, suggesting that the pasture was of poor quality habitat for Anadenanthera recruitment. Isolation affected the plant size structure and reproduction of Anadenanthera trees. Studies comparing plant phenology under contrasting environmental conditions may offer clues on how global change may affect plant reproduction in the tropics.

  20. Evaluating fire danger in Brazilian biomes: present and future patterns

    Science.gov (United States)

    Silva, Patrícia; Bastos, Ana; DaCamara, Carlos; Libonati, Renata

    2017-04-01

    Climate change is expected to have a significant impact on fire occurrence and activity, particularly in Brazil, a region known to be fire-prone [1]. The Brazilian savanna, commonly referred to as cerrado, is a fire-adapted biome covering more than 20% of the country's total area. It presents the highest numbers of fire events, making it particularly susceptible to changes in climate. It is thus essential to understand the present fire regimes in Brazilian biomes, in order to better evaluate future patterns. The CPTEC/INPE, the Brazilian Center for Weather Forecasting and Climate Research at the Brazilian National Institute of Space Research developed a fire danger index based on the occurrence of hundreds of thousands of fire events in the main Brazilian biomes [2]: the Meteorological Fire Danger Index (MFDI). This index indicates the predisposition of vegetation to be burned on a given day, for given climate conditions preceding that day. It relies on daily values of air temperature, relative humidity, accumulated precipitation and vegetation cover. In this study we aim to access the capability of the MFDI to accurately replicate present fire conditions for different biomes, with a special focus on cerrado. To this end, we assess the link between the MFDI as calculated by three different reanalysis (ERA-Interim, NCEP/DOE Reanalysis 2 and MERRA-2) and the observed burned area. We further calculate the validated MFDI using a regional climate model, the RCA4 as forced by EC-Earth from CORDEX, to understand the ability of the model to characterize present fire danger. Finally, the need to calibrate the model to better characterize future fire danger was also evaluated. This work was developed within the framework of the Brazilian Fire-Land-Atmosphere System (BrFLAS) Project financed by the Portuguese and Brazilian science foundations, FCT and FAPESP (project references FAPESP/1389/2014 and 2014/20042-2). [1] KRAWCHUK, M.A.; MORITZ, M.A.; PARISIEN, M.A.; VAN DORN, J

  1. Sexo tropical em um país europeu: migração de brasileiras para a Itália no marco do "turismo sexual" internacional Tropical sex in a European country: Brazilian women's migration to Italy in the frame of international sex tourism

    Directory of Open Access Journals (Sweden)

    Adriana Piscitelli

    2007-12-01

    Full Text Available Em Fortaleza, uma das cidades vinculadas ao turismo sexual no Nordeste do Brasil, jovens mulheres das camadas baixas deixam o país com ou convidadas por turistas sexuais. Algumas se inserem na indústria do sexo na Europa. Outras, porém, a deixam, casando-se com europeus. Centrando-me em um universo de casais integrados por mulheres do Nordeste do Brasil e italianos, discuto as categorias de diferenciação que adquirem centralidade quando esses relacionamentos, iniciados em um terreno ambíguo da sexualidade, interesse econômico e romance no qual se misturam, são contextualizados na Itália. Analiso as implicações culturais, políticas e econômicas desse tipo de migração, refletindo sobre os significados adquiridos pela sexualidade tropical na migração para esse país do Norte.In Fortaleza, which is one of the main cities linked to sex tourism in the Northeast of Brazil, young low income women leave the country with or invited by sex tourists. While some indeed engage themselves in the sex industry in Europe, others leave it when marrying European men. Focusing on the universe of integrants of couples integrated women from the Northeast from Brazil and Italian men, this paper addresses the differentiations that acquire centrality when these relationships, formed in an ambiguous terrain where sexuality, economic interest and romance intermingle, are contextualized in Italy. I analyze the cultural, political and economic implications of that migration. The study discusses the relationship between gender and economic negotiations in those couples, reflecting on the meanings acquired by "tropical sexuality" in the migration to that Northern country.

  2. References from Brazilian medical journals in national publications.

    Science.gov (United States)

    Teixeira, Renan Kleber Costa; Botelho, Nara Macedo; Petroianu, Andy

    2013-01-01

    To assess whether there is a preference for international journal citation to the detriment of national ones in ten Brazilian medical journals, in two different periods. All references in the articles published in Arquivos Brasileiros de Oftalmologia, Revista Brasileira de Cirurgia Cardiovascular, Revista da Associação Médica Brasileira, São Paulo Medical Journal, Arquivos Brasileiros de Endocrinologia e Metabologia, Clinics, Jornal Brasileiro de Pneumologia, Revista da Sociedade Brasileira de Medicina Tropical, Revista Brasileira de Psiquiatria e Acta Ortopédica Brasileira in the years 2011 and 2007 were analyzed, assessing the number of articles published in national and international journals. A total of 36,125 references from 1,462 articles published in the 10 aforementioned journals were analyzed. Of the total number, 4.242 (11.74%) were from Brazilian journals. There was no significant difference between the two analyzed periods. A total of 453 (30,98%) of the articles studied non-cited brazilian papers,and 81 (5.54%) articles had more Brazilian than international references. Of total references analyzed, 11.74% were related to articles published in Brazilian journals. This number, when compared to the percentage of Brazilian articles published in the medical area, demonstrates a good number of citations of national articles. Copyright © 2012 Elsevier Editora Ltda. All rights reserved.

  3. Produção de blends a partir de frutos tropicais e nativos da Amazônia Production of blends based on tropical and native fruits from brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Leandro Camargo Neves

    2011-03-01

    Full Text Available Neste trabalho, objetivou-se o enriquecimento nutricional de néctares de frutos, pelo processamento de blends, usando-se fruteiras tropicais e Amazônicas produzidas em Roraima. Foram utilizados néctares de abacaxi, buriti, caju, camu-camu, carambola, maracujá, murici, lima-ácida Tahiti e taperebá. Foi realizado um ensaio preliminar onde se constatou que os néctares de abacaxi e maracujá seriam utilizados como matrizes e, dos quais, saíram os tratamentos: 2 controles - 100% de abacaxi e 100% de maracujá; 1 blend entre as matrizes - 50% de abacaxi + 50% de maracujá; 7 blends de cada matriz com cada fruto escolhido, na proporção de 1:1. Foram adicionados benzoato de sódio e dióxido de enxofre, nas concentrações de 500 e 200 ppm, respectivamente, em todos os néctares e blends trabalhados. Os resultados referentes à composição nutricional dos blends refletiram aumento significativo nos valores nutricionais quando em comparação com as matrizes, bem como com os néctares individuais de cada fruto. O mesmo comportamento foi observado mesmo após 10 dias de armazenamento não refrigerado. Com relação à estabilidade microbiológica, apenas os blends que utilizaram o buriti como componente apresentaram comprometimento. As análises químicas dos blends demonstraram padrões distintos das matrizes; entretanto, quando submetidos à análise sensorial, mostraram-se satisfatórias por parte dos julgadores. As composições que mais agradaram os julgadores foram os blends de ambas as matrizes associadas ao camu-camu e murici.The aim of this work was to obtain the nutritional enrichment of nectars of fruits, by means of blends processament, using tropical and Amazonian fruit produced in Roraima. Nectars of pineapple, buriti, cashew, camu-camu, star fruit, passion fruit, murici, Tahiti lime and taperebá were used. A preliminary assay was carried out where it was observed that the nectars of pineapple and passion fruit would be used as

  4. Ability of crassulacean acid metabolism plants to overcome interacting stresses in tropical environments.

    Science.gov (United States)

    Lüttge, Ulrich

    2010-01-01

    Single stressors such as scarcity of water and extreme temperatures dominate the struggle for life in severely dry desert ecosystems or cold polar regions and at high elevations. In contrast, stress in the tropics typically arises from a dynamic network of interacting stressors, such as availability of water, CO(2), light and nutrients, temperature and salinity. This requires more plastic spatio-temporal responsiveness and versatility in the acquisition and defence of ecological niches. The mode of photosynthesis of crassulacean acid metabolism (CAM) is described and its flexible expression endows plants with powerful strategies for both acclimation and adaptation. Thus, CAM plants are able to inhabit many diverse habitats in the tropics and are not, as commonly thought, successful predominantly in dry, high-insolation habitats. Typical tropical CAM habitats or ecosystems include exposed lava fields, rock outcrops of inselbergs, salinas, savannas, restingas, high-altitude páramos, dry forests and moist forests. Morphotypical and physiotypical plasticity of CAM phenotypes allow a wide ecophysiological amplitude of niche occupation in the tropics. Physiological and biochemical plasticity appear more responsive by having more readily reversible variations in performance than do morphological adaptations. This makes CAM plants particularly fit for the multi-factor stressor networks of tropical forests. Thus, while the physiognomy of semi-deserts outside the tropics is often determined by tall succulent CAM plants, tropical forests house many more CAM plants in terms of quantity (biomass) and quality (species diversity).

  5. Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

    Directory of Open Access Journals (Sweden)

    A. Ngomanda

    2009-10-01

    Full Text Available Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, Elaeis guineensis, and the shrub, Alchornea cordifolia (Euphorbiaceae. A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact.

  6. Implications of the spatial dynamics of fire spread for the bistability of savanna and forest.

    Science.gov (United States)

    Schertzer, E; Staver, A C; Levin, S A

    2015-01-01

    The role of fire in expanding the global distribution of savanna is well recognized. Empirical observations and modeling suggest that fire spread has a threshold response to fuel-layer continuity, which sets up a positive feedback that maintains savanna-forest bistability. However, modeling has so far failed to examine fire spread as a spatial process that interacts with vegetation. Here, we use simple, well-supported assumptions about fire spread as an infection process and its effects on trees to ask whether spatial dynamics qualitatively change the potential for savanna-forest bistability. We show that the spatial effects of fire spread are the fundamental reason that bistability is possible: because fire spread is an infection process, it exhibits a threshold response to fuel continuity followed by a rapid increase in fire size. Other ecological processes affecting fire spread may also contribute including temporal variability in demography or fire spread. Finally, including the potential for spatial aggregation increases the potential both for savanna-forest bistability and for savanna and forest to coexist in a landscape mosaic.

  7. IDESSA: An Integrative Decision Support System for Sustainable Rangeland Management in Southern African Savannas

    Science.gov (United States)

    Meyer, Hanna; Authmann, Christian; Dreber, Niels; Hess, Bastian; Kellner, Klaus; Morgenthal, Theunis; Nauss, Thomas; Seeger, Bernhard; Tsvuura, Zivanai; Wiegand, Kerstin

    2017-04-01

    Bush encroachment is a syndrome of land degradation that occurs in many savannas including those of southern Africa. The increase in density, cover or biomass of woody vegetation often has negative effects on a range of ecosystem functions and services, which are hardly reversible. However, despite its importance, neither the causes of bush encroachment, nor the consequences of different resource management strategies to combat or mitigate related shifts in savanna states are fully understood. The project "IDESSA" (An Integrative Decision Support System for Sustainable Rangeland Management in Southern African Savannas) aims to improve the understanding of the complex interplays between land use, climate patterns and vegetation dynamics and to implement an integrative monitoring and decision-support system for the sustainable management of different savanna types. For this purpose, IDESSA follows an innovative approach that integrates local knowledge, botanical surveys, remote-sensing and machine-learning based time-series of atmospheric and land-cover dynamics, spatially explicit simulation modeling and analytical database management. The integration of the heterogeneous data will be implemented in a user oriented database infrastructure and scientific workflow system. Accessible via web-based interfaces, this database and analysis system will allow scientists to manage and analyze monitoring data and scenario computations, as well as allow stakeholders (e. g. land users, policy makers) to retrieve current ecosystem information and seasonal outlooks. We present the concept of the project and show preliminary results of the realization steps towards the integrative savanna management and decision-support system.

  8. Spatial pattern enhances ecosystem functioning in an African savanna.

    Science.gov (United States)

    Pringle, Robert M; Doak, Daniel F; Brody, Alison K; Jocqué, Rudy; Palmer, Todd M

    2010-05-25

    The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termite mounds are often hotspots of plant growth (primary productivity). Using detailed observations and manipulative experiments in an African savanna, we show that these mounds are also local hotspots of animal abundance (secondary and tertiary productivity): insect abundance and biomass decreased with distance from the nearest termite mound, as did the abundance, biomass, and reproductive output of insect-eating predators. Null-model analyses indicated that at the landscape scale, the evenly spaced distribution of termite mounds produced dramatically greater abundance, biomass, and reproductive output of consumers across trophic levels than would be obtained in landscapes with randomly distributed mounds. These emergent properties of spatial pattern arose because the average distance from an arbitrarily chosen point to the nearest feature in a landscape is minimized in landscapes where the features are hyper-dispersed (i.e., uniformly spaced). This suggests that the linkage between patterning and ecosystem functioning will be common to systems spanning the range of human management intensities. The centrality of spatial pattern to system-wide biomass accumulation underscores the need to conserve pattern-generating organisms and mechanisms, and to incorporate landscape patterning in efforts to restore degraded habitats and maximize the delivery of ecosystem services.

  9. Neglected tropical diseases in Brazil.

    Science.gov (United States)

    Lindoso, José Angelo L; Lindoso, Ana Angélica B P

    2009-01-01

    Poverty is intrinsically related to the incidence of Neglected Tropical Diseases (NTDs). The main countries that have the lowest human development indices (HDI) and the highest burdens of NTDs are located in tropical and subtropical regions of the world. Among these countries is Brazil, which is ranked 70th in HDI. Nine out of the ten NTDs established by the World Health Organization (WHO) are present in Brazil. Leishmaniasis, tuberculosis, dengue fever and leprosy are present over almost the entire Brazilian territory. More than 90% of malaria cases occur in the Northern region of the country, and lymphatic filariasis and onchocerciasis occur in outbreaks in a particular region. The North and Northeast regions of Brazil have the lowest HDIs and the highest rates of NTDs. These diseases are considered neglected because there is not important investment in projects for the development of new drugs and vaccines and existing programs to control these diseases are not sufficient. Another problem related to NTDs is co-infection with HIV, which favors the occurrence of severe clinical manifestations and therapeutic failure. In this article, we describe the status of the main NTDs currently occurring in Brazil and relate them to the HDI and poverty.

  10. Surviving and growing amidst others : the effect of environmental factors on germination and establishment of savanna trees

    NARCIS (Netherlands)

    Moribe Barbosa, E.R.

    2013-01-01

    Savanna ecosystems are characterized by a continuous grass layer intermixed with a discontinuous layer of trees and shrubs. A complex set of environmental drivers, such as water, soil nutrients, solar radiance, fire and herbivory, determines vegetation structure and composition in savannas.Such

  11. Microbial properties and litter and soil nutrients after two prescribed fires in developing savannas in an upland Missouri Ozark Forest

    Science.gov (United States)

    Felix, Jr. Ponder; Mahasin Tadros; Edward F. Loewenstein

    2009-01-01

    On some landscapes periodic fire may be necessary to develop and maintain oak-dominated savannas. We studied the effects of two annual prescribed burns to determine their effect on microbial activity and soil and litter nutrients 1 year after the last burn. Surface litter and soil from the upper 0?5 cm soil layer in three developing savannas (oak-hickory, ...

  12. Overlap in nitrogen sources and redistribution of nitrogen between trees and grasses in a semi-arid savanna

    NARCIS (Netherlands)

    Priyadarshini, K.V.R.; Prins, H.H.T.; Bie, de S.; Heitkonig, I.M.A.; Woodborne, S.; Gort, G.; Kirkman, K.; Fry, B.; Kroon, de H.

    2014-01-01

    A key question in savanna ecology is how trees and grasses coexist under N limitation. We used N stable isotopes and N content to study N source partitioning across seasons from trees and associated grasses in a semi-arid savanna. We also used 15N tracer additions to investigate possible

  13. Bird species and numbers of birds in oak savannas of the Southwestern Borderlands region including effects of burning

    Science.gov (United States)

    Peter F. Ffolliott; Hui Chen; Gerald J. Gottfried

    2011-01-01

    Oak savannas of the Southwestern Borderlands region provide food, cover, and sites for nesting, roosting, and perching for a diversity of bird species. The results of a five-year (2003-2007) study of bird species, numbers of birds, and their diversities in the naturally occurring (unburned) oak savannas of the region are reported in this paper. Effects of cool-season...

  14. Eastern wood-pewee (Contopus virens) breeding demography across a gradient of savanna, woodland, and forest in the Missouri Ozarks

    Science.gov (United States)

    Sarah W. Kendrick; Frank R. Thompson; Jennifer L. Reidy

    2013-01-01

    Better knowledge of bird response to savanna and woodland restoration is needed to inform management of these communities. We related temporal and habitat variables to breeding demography and densities of the Eastern Wood-Pewee (Contopus virens) across a gradient of savanna, woodland, and forest. We determined nest success, clutch size, young fledged...

  15. A probabilistic analysis of fire-induced tree-grass coexistence in savannas.

    Science.gov (United States)

    D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

    2006-03-01

    Fires play an important role in determining the composition and structure of vegetation in semiarid ecosystems. The study of the interactions between fire and vegetation requires a stochastic approach because of the random and unpredictable nature of fire occurrences. To this end, this article develops a minimalist probabilistic framework to investigate the impact of intermittent fire occurrences on the temporal dynamics of vegetation. This framework is used to analyze the emergence of statistically stable conditions favorable to tree-grass coexistence in savannas. It is found that these conditions can be induced and stabilized by the stochastic fire regime. A decrease in fire frequency leads to bush encroachment, while more frequent and intense fires favor savanna-to-grassland conversions. The positive feedback between fires and vegetation can convert states of tree-grass coexistence in semiarid savannas into bistable conditions, with both woodland and grassland as possible, though mutually exclusive, stable states of the system.

  16. The global extent and determinants of savanna and forest as alternative biome states.

    Science.gov (United States)

    Staver, A Carla; Archibald, Sally; Levin, Simon A

    2011-10-14

    Theoretically, fire-tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire-driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. We use tree cover, climate, fire, and soils data sets to show that tree cover is globally discontinuous. Climate influences tree cover globally but, at intermediate rainfall (1000 to 2500 millimeters) with mild seasonality (less than 7 months), tree cover is bimodal, and only fire differentiates between savanna and forest. These may be alternative states over large areas, including parts of Amazonia and the Congo. Changes in biome distributions, whether at the cost of savanna (due to fragmentation) or forest (due to climate), will be neither smooth nor easily reversible.

  17. Biodiversity, threats and conservation challenges in the Cerrado of Amapá, an Amazonian savanna

    Directory of Open Access Journals (Sweden)

    Karen Mustin

    2017-10-01

    Full Text Available An Amazonian savanna in northern Brazil known as the Cerrado of Amapá is under imminent threat from poor land-use planning, the expansion of large-scale agriculture and other anthropogenic pressures. These savannas house a rich and unique flora and fauna, including endemic plants and animals. However, the area remains under-sampled for most taxa, and better sampling may uncover new species. We estimate that only ~9.16% of these habitats have any kind of protection, and legislative changes threaten to further weaken or remove this protection. Here we present the status of knowledge concerning the biodiversity of the Cerrado of Amapá, its conservation status, and the main threats to the conservation of this Amazonian savanna. To secure the future of these unique and imperilled habitats, we suggest urgent expansion of protected areas, as well as measures that would promote less-damaging land uses to support the local population.

  18. Brazilian uranium exploration program

    International Nuclear Information System (INIS)

    Marques, J.P.M.

    1981-01-01

    General information on Brazilian Uranium Exploration Program, are presented. The mineralization processes of uranium depoits are described and the economic power of Brazil uranium reserves is evaluated. (M.C.K.) [pt

  19. Competition between trees and grasses for both soil water and mineral nitrogen in dry savannas.

    Science.gov (United States)

    Donzelli, D; De Michele, C; Scholes, R J

    2013-09-07

    The co-existence of trees and grasses in savannas in general can be the result of processes involving competition for resources (e.g. water and nutrients) or differential response to disturbances such as fire, animals and human activities; or a combination of both broad mechanisms. In moist savannas, the tree-grass coexistence is mainly attributed to of disturbances, while in dry savannas, limiting resources are considered the principal mechanism of co-existence. Virtually all theoretical explorations of tree-grass dynamics in dry savannas consider only competition for soil water. Here we investigate whether coexistence could result from a balanced competition for two resources, namely soil water and mineral nitrogen. We introduce a simple dynamical resource-competition model for trees and grasses. We consider two alternative hypotheses: (1) trees are the superior competitors for nitrogen while grasses are superior competitors for water, and (2) vice-versa. We study the model properties under the two hypotheses and test each hypothesis against data from 132 dry savannas in Africa using Kendall's test of independence. We find that Hypothesis 1 gets much more support than Hypothesis 2, and more support than the null hypothesis that neither is operative. We further consider gradients of rainfall and nitrogen availability and find that the Hypothesis 1 model reproduces the observed patterns in nature. We do not consider our results to definitively show that tree-grass coexistence in dry savannas is due to balanced competition for water and nitrogen, but show that this mechanism is a possibility, which cannot be a priori excluded and should thus be considered along with the more traditional explanations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Brazilian Cerrado soil Actinobacteria ecology.

    Science.gov (United States)

    Suela Silva, Monique; Naves Sales, Alenir; Teixeira Magalhães-Guedes, Karina; Ribeiro Dias, Disney; Schwan, Rosane Freitas

    2013-01-01

    A total of 2152 Actinobacteria strains were isolated from native Cerrado (Brazilian Savannah) soils located in Passos, Luminárias, and Arcos municipalities (Minas Gerais State, Brazil). The soils were characterised for chemical and microbiological analysis. The microbial analysis led to the identification of nine genera (Streptomyces, Arthrobacter, Rhodococcus, Amycolatopsis, Microbacterium, Frankia, Leifsonia, Nakamurella, and Kitasatospora) and 92 distinct species in both seasons studied (rainy and dry). The rainy season produced a high microbial population of all the aforementioned genera. The pH values of the soil samples from the Passos, Luminárias, and Arcos regions varied from 4.1 to 5.5. There were no significant differences in the concentrations of phosphorus, magnesium, and organic matter in the soils among the studied areas. Samples from the Arcos area contained large amounts of aluminium in the rainy season and both hydrogen and aluminium in the rainy and dry seasons. The Actinobacteria population seemed to be unaffected by the high levels of aluminium in the soil. Studies are being conducted to produce bioactive compounds from Actinobacteria fermentations on different substrates. The present data suggest that the number and diversity of Actinobacteria spp. in tropical soils represent a vast unexplored resource for the biotechnology of bioactives production.

  1. Brazilian Cerrado Soil Actinobacteria Ecology

    Directory of Open Access Journals (Sweden)

    Monique Suela Silva

    2013-01-01

    Full Text Available A total of 2152 Actinobacteria strains were isolated from native Cerrado (Brazilian Savannah soils located in Passos, Luminárias, and Arcos municipalities (Minas Gerais State, Brazil. The soils were characterised for chemical and microbiological analysis. The microbial analysis led to the identification of nine genera (Streptomyces, Arthrobacter, Rhodococcus, Amycolatopsis, Microbacterium, Frankia, Leifsonia, Nakamurella, and Kitasatospora and 92 distinct species in both seasons studied (rainy and dry. The rainy season produced a high microbial population of all the aforementioned genera. The pH values of the soil samples from the Passos, Luminárias, and Arcos regions varied from 4.1 to 5.5. There were no significant differences in the concentrations of phosphorus, magnesium, and organic matter in the soils among the studied areas. Samples from the Arcos area contained large amounts of aluminium in the rainy season and both hydrogen and aluminium in the rainy and dry seasons. The Actinobacteria population seemed to be unaffected by the high levels of aluminium in the soil. Studies are being conducted to produce bioactive compounds from Actinobacteria fermentations on different substrates. The present data suggest that the number and diversity of Actinobacteria spp. in tropical soils represent a vast unexplored resource for the biotechnology of bioactives production.

  2. Spatial pattern enhances ecosystem functioning in an African savanna.

    Directory of Open Access Journals (Sweden)

    Robert M Pringle

    2010-05-01

    Full Text Available The finding that regular spatial patterns can emerge in nature from local interactions between organisms has prompted a search for the ecological importance of these patterns. Theoretical models have predicted that patterning may have positive emergent effects on fundamental ecosystem functions, such as productivity. We provide empirical support for this prediction. In dryland ecosystems, termite mounds are often hotspots of plant growth (primary productivity. Using detailed observations and manipulative experiments in an African savanna, we show that these mounds are also local hotspots of animal abundance (secondary and tertiary productivity: insect abundance and biomass decreased with distance from the nearest termite mound, as did the abundance, biomass, and reproductive output of insect-eating predators. Null-model analyses indicated that at the landscape scale, the evenly spaced distribution of termite mounds produced dramatically greater abundance, biomass, and reproductive output of consumers across trophic levels than would be obtained in landscapes with randomly distributed mounds. These emergent properties of spatial pattern arose because the average distance from an arbitrarily chosen point to the nearest feature in a landscape is minimized in landscapes where the features are hyper-dispersed (i.e., uniformly spaced. This suggests that the linkage between patterning and ecosystem functioning will be common to systems spanning the range of human management intensities. The centrality of spatial pattern to system-wide biomass accumulation underscores the need to conserve pattern-generating organisms and mechanisms, and to incorporate landscape patterning in efforts to restore degraded habitats and maximize the delivery of ecosystem services.

  3. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Science.gov (United States)

    E. Sousa Neto; J.B. Carmo; Michael Keller; S.C. Martins; L.F. Alves; S.A. Vieira; M.C. Piccolo; P. Camargo; H.T.Z. Couto; C.A. Joly; L.A. Martinelli

    2011-01-01

    Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes along an altitudinal transect and the...

  4. Tropical Soil Chemistry

    DEFF Research Database (Denmark)

    Borggaard, Ole K.

    and environmental protection. Tropical Soil Chemistry by Ole K. Borggaard provides an overview of the composition, occurrence, properties, processes, formation, and environmental vulnerability of various tropical soil types (using American Soil Taxonomy for classification). The processes and the external factors...... soil chemical issues are also presented to assess when, why, and how tropical soils differ from soils in other regions. This knowledge can help agricultural specialists in the tropics establish sustainable crop production. Readers are assumed to be familiar with basic chemistry, physics...

  5. Neglected tropical diseases

    Directory of Open Access Journals (Sweden)

    David Molyneux

    2013-08-01

    Full Text Available Seventeen neglected tropical diseases (NTDs have been identified by the World Health Organization (WHO. It is estimated that over 1 billion people are infected with NTDs, with a further 1 billion at risk. The majority of NTDs occur in the tropics and sub-tropics and have particular characteristics in common.

  6. Tropical Freshwater Biology

    African Journals Online (AJOL)

    Tropical Freshwater Biology promotes the publication of scientific contributions in the field of freshwater biology in the tropical and subtropical regions of the world. One issue is published annually but this number may be increased. Original research papers and short communications on any aspect of tropical freshwater ...

  7. Quality maintenance Tropical Plants

    Directory of Open Access Journals (Sweden)

    Gláucia Moraes Dias

    2016-11-01

    Full Text Available The climatic characteristics of the country favor the cultivation of tropical flowers. The continued expansion of this market is due the beauty, exoticit nature and postharvest longevity of flower. However, little is known about the postharvest of tropical plants. Therefore, this paper provides information on harvest, handling and storage of cut tropical plantspostharvest, storage temperature, conditioning solution.

  8. Water, land, fire, and forest: Multi-scale determinants of rainforests in the Australian monsoon tropics.

    Science.gov (United States)

    Ondei, Stefania; Prior, Lynda D; Williamson, Grant J; Vigilante, Tom; Bowman, David M J S

    2017-03-01

    The small rainforest fragments found in savanna landscapes are powerful, yet often overlooked, model systems to understand the controls of these contrasting ecosystems. We analyzed the relative effect of climatic variables on rainforest density at a subcontinental level, and employed high-resolution, regional-level analyses to assess the importance of landscape settings and fire activity in determining rainforest density in a frequently burnt Australian savanna landscape. Estimates of rainforest density (ha/km 2 ) across the Northern Territory and Western Australia, derived from preexisting maps, were used to calculate the correlations between rainforest density and climatic variables. A detailed map of the northern Kimberley (Western Australia) rainforests was generated and analyzed to determine the importance of geology and topography in controlling rainforests, and to contrast rainforest density on frequently burnt mainland and nearby islands. In the northwestern Australian, tropics rainforest density was positively correlated with rainfall and moisture index, and negatively correlated with potential evapotranspiration. At a regional scale, rainforests showed preference for complex topographic positions and more fertile geology. Compared with mainland areas, islands had significantly lower fire activity, with no differences between terrain types. They also displayed substantially higher rainforest density, even on level terrain where geomorphological processes do not concentrate nutrients or water. Our multi-scale approach corroborates previous studies that suggest moist climate, infrequent fires, and geology are important stabilizing factors that allow rainforest fragments to persist in savanna landscapes. These factors need to be incorporated in models to predict the future extent of savannas and rainforests under climate change.

  9. Influence of Fire Mosaics, Habitat Characteristics and Cattle Disturbance on Mammals in Fire-Prone Savanna Landscapes of the Northern Kimberley.

    Directory of Open Access Journals (Sweden)

    Ian J Radford

    Full Text Available Patch mosaic burning, in which fire is used to produce a mosaic of habitat patches representative of a range of fire histories ('pyrodiversity', has been widely advocated to promote greater biodiversity. However, the details of desired fire mosaics for prescribed burning programs are often unspecified. Threatened small to medium-sized mammals (35 g to 5.5 kg in the fire-prone tropical savannas of Australia appear to be particularly fire-sensitive. Consequently, a clear understanding of which properties of fire mosaics are most instrumental in influencing savanna mammal populations is critical. Here we use mammal capture data, remotely sensed fire information (i.e. time since last fire, fire frequency, frequency of late dry season fires, diversity of post-fire ages in 3 km radius, and spatial extent of recently burnt, intermediate and long unburnt habitat and structural habitat attributes (including an index of cattle disturbance to examine which characteristics of fire mosaics most influence mammals in the north-west Kimberley. We used general linear models to examine the relationship between fire mosaic and habitat attributes on total mammal abundance and richness, and the abundance of the most commonly detected species. Strong negative associations of mammal abundance and richness with frequency of late dry season fires, the spatial extent of recently burnt habitat (post-fire age <1 year within 3 km radius and level of cattle disturbance were observed. Shrub cover was positively related to both mammal abundance and richness, and availability of rock crevices, ground vegetation cover and spatial extent of ≥4 years unburnt habitat were all positively associated with at least some of the mammal species modelled. We found little support for diversity of post-fire age classes in the models. Our results indicate that both a high frequency of intense late dry season fires and extensive, recently burnt vegetation are likely to be detrimental to

  10. Spatio-temporal dynamics of the tropical rain forest

    Energy Technology Data Exchange (ETDEWEB)

    Chave, J. [CEN Saclay, Gif-sur-Yvette (France). Service de Physique de l' Etat Condense

    2000-07-01

    Mechanisms which drive the dynamics of forest ecosystems are complex, from seedling establishment to pollination, and seed dispersal by animals, running water or wind. These processes are more complex when the ecosystem shelters a large number of species and of vegetative forms, as it is the case in the tropical rainforest. To take them into account, we must develop and use models. I present a review of the fundamental mechanisms for the of a natural forest dynamics - photosynthesis, tree growth, recruitment and mortality - as well as a description of the past and of the present of tropical rainforests. This information is used to develop a spatially-explicit and individual-based forest model. Simplified models are deduced from it, and they serve to address more specific issues, such as the resilience of the forest to climate disturbances, or savanna-forest dynamics. The last topic is related to the spatio-temporal description of tropical plant biodiversity. A detailed introduction to the problem is provided, and models accounting for the maintenance of diversity are compared. These models include non spatial as well a spatial approaches (branching anihilating random walks and voter model with mutation). (orig.)

  11. Narratives of Brazilian Modernism. Tarsila do Amaral and the Anthropophagic Movement as Aesthetic Decolonization

    Directory of Open Access Journals (Sweden)

    María Elena Lucero

    2015-01-01

    this image the igures blend into their own environment, imbued in a visual gigantism that can seem threatening. The surrounding jungle recreated a version of tropicalism as a space of power or synergy set in a local atmosphere, which distanced itself from preconcieved ways of symbolizing the Brazilian landscape, and reconstructed a vigorous visuality that confronted the stereotyped invention of the American landscape.

  12. Multiple endmember spectral-angle-mapper (SAM) analysis improves discrimination of Savanna tree species

    CSIR Research Space (South Africa)

    Cho, Moses A

    2009-08-01

    Full Text Available of this paper was to evaluate the classification performance of a multiple-endmember spectral angle mapper (SAM) classification approach in discriminating seven common African savanna tree species and to compare the results with the traditional SAM classifier...

  13. Soil erosion and deposition before and after fire in oak savannas

    Science.gov (United States)

    Peter F. Ffolliott; Gerald J. Gottfried; Hui Chen; Aaron T. Kauffman; Cody L. Stropki; Daniel G. Neary

    2013-01-01

    Effects of low severity prescribed burning treatments and a wildfire on soil erosion and deposition in the oak savannas in the Southwestern Borderlands are reported. Measurements in the spring and fall, respectively, characterize soil movements following winter rains and high-intensity summer rainstorms. Annual values are also presented. Relationships between soil...

  14. Biomass partitioning and root morphology of savanna trees across a water gradient

    NARCIS (Netherlands)

    Tomlinson, K.W.; Sterck, F.J.; Bongers, F.; Silva, da D.A.; Barbosa, E.R.; Ward, D.; Bakker, F.T.; Kaauwen, van M.P.W.; Prins, H.H.T.; Bie, de S.; Langevelde, van F.

    2012-01-01

    1. Plant organ biomass partitioning has been hypothesized to be driven by resources, such that species from drier environments allocate more biomass to roots than species from wetter environments to access water at greater soil depths. In savanna systems, fire may select for greater allocation to

  15. Changing forest-woodland-savanna mosaics in Uganda: with implications for conservation

    NARCIS (Netherlands)

    Nangendo, G.

    2005-01-01

    Forest-Woodland-Savanna (FWS) mosaics are complex, highly varied and dynamic landscapes.Until recently, they were considered poor in terms of biodiversity. Consequently, only few scientific studies have been done on them and little attention has been paid to their

  16. Interacting effects of grass height and herbivores on the establishment of an encroaching savanna shrub

    NARCIS (Netherlands)

    Hagenah, N.; Munkert, H.; Gerhardt, K.; Olff, H.

    2009-01-01

    Shrub encroachment is a widely observed problem in Southern African savannas. Although the effects of herbivory and grass height on woody species recruitment have been studied individually, little information exists about how these factors interact. In this study seeds and seedlings of the

  17. Synthesis of field experiments concerning the grass layer in the savanna regions of southern Africa

    CSIR Research Space (South Africa)

    O'Connor, TG

    1985-10-01

    Full Text Available The purpose of this synthesis of long term experiments was to develop an account of how the principal determinants (rainfall, soil type, woody/grass ratio, herbivory, fire) influence the dynamics of the grass layer of southern African savannas...

  18. Improved quality of beneath-canopy grass in South African savannas: Local and seasonal variation

    NARCIS (Netherlands)

    Treydte, A.C.; Looringh van Beeck, F.A.; Ludwig, F.; Heitkonig, I.M.A.

    2008-01-01

    Questions: Do large trees improve the nutrient content and the structure of the grass layer in savannas? Does the magnitude of this improvement differ with locality ( soil nutrients) and season ( water availability)? Are grass structure and species composition beneath tree canopies influenced by

  19. Composition and species diversity of pine-wiregrass savannas of the Green Swamp, North Carolina

    Science.gov (United States)

    Joan Walker; Robert K. Peet

    1983-01-01

    Fire-maintained, species-rich pines wiregrass savannas in the Green Swamp, North Carolina were sampled over their natural range of environmental conditions and fire frequencies. Species composition, species richness, diversity (Exp H', I/ C), and aboveground production were documented and fertilization experiments conducted to assess possible mechanisms for the...

  20. Trophic ecology of Lepidoptera larvae associated with woody vegetation in a savanna ecosystem

    CSIR Research Space (South Africa)

    Scholtz, CH

    1982-06-01

    Full Text Available This study represents a quantitative survey of a Lepidoptera community and deals with the trophic ecology of the 27 species of foliage-feeding Lepidoptera on the eight dominant woody plants in the Burkea africana-Eragrostis pallens savanna...

  1. Ethno-management of plinthic and ironpan soils in the savanna ...

    African Journals Online (AJOL)

    Ethno-management of plinthic and ironpan soils in the savanna regions of West Africa. ... Ghana Journal of Agricultural Science ... tracts of land, the Zaï method of chiselling into the pan and growing crops in the pits is adopted These indigenous farmers' practices need scientific improvement to make them more effective.

  2. Dry season mapping of savanna forage quality, using the hyperspectral Carnegie

    NARCIS (Netherlands)

    Knox, N.; Skidmore, A.K.; Prins, H.H.T.; Asner, P.; Werff, van der H.M.A.; Boer, de W.F.; Waal, van der C.; Knegt, de H.J.; Kohi, E.; Slotow, R.; Grant, R.C.

    2011-01-01

    Forage quality within an African savanna depends upon limiting nutrients (nitrogen and phosphorus) and nutrients that constrain the intake rates (non-digestible fibre) of herbivores. These forage quality nutrients are particularly crucial in the dry season when concentrations of limiting nutrients

  3. Impact of goat browsing on Aloe ferox in a South African savanna ...

    African Journals Online (AJOL)

    The extent and impact of the utilisation of Aloe ferox by Boer goats during winter in a South African savanna was determined using a plant-based approach. All Aloe plants rooted within the transects were eaten by goats, with small plants utilised more frequently than tall plants. The density of dying and dead Aloe plants was ...

  4. Unlocking resources in savannas: how goats and other mixed feeders overcome the negative effects of tannins

    NARCIS (Netherlands)

    Mkhize, N.R.

    2015-01-01

    Abstract

    This thesis contributes insights on how condensed tannins might mediate the interactions between woody plants and large herbivores in the African savannas. Current understanding in this regard is still based on data from short-term laboratory experiments, mostly

  5. Estimating and mapping grass phosphorus concentration in an African savanna using hyperspectral image data

    NARCIS (Netherlands)

    Mutanga, O.; Kumar, L.

    2007-01-01

    We tested the utility of imaging spectroscopy and neural networks to map phosphorus concentration in savanna grass using airborne HyMAP image data. We also sought to ascertain the key wavelengths for phosphorus prediction using hyperspectral remote sensing. The remote sensing of foliar phosphorus

  6. Ecology and management of oak woodlands and savannas in the southwestern Borderlands Region

    Science.gov (United States)

    Gerald J. Gottfried; Peter F. Ffolliott

    2013-01-01

    Management of the Madrean oak woodlands and the less dense and ecologically different oak savannas must be based on sound ecological information. However, relatively little is known about the Madrean oak ecosystems in spite of the fact that they cover about 80,000 km2 in the southwestern United States and northern Mexico. Emory oak (Quercus emoryi), the dominant tree...

  7. Recent shift from forest to savanna burning in the Amazon Basin observed by satellite

    International Nuclear Information System (INIS)

    Ten Hoeve, J E; Jacobson, M Z; Remer, L A; Correia, A L

    2012-01-01

    The numbers of fires detected on forest, savanna and transition lands during the 2002–10 biomass burning seasons in Amazonia are shown using fire count data and co-located land cover classifications from the Moderate Resolution Imaging Spectroradiometer (MODIS). The ratio of forest fires to savanna fires has varied substantially over the study period, with a maximum ratio of 0.65:1 in 2005 and a minimum ratio of 0.27:1 in 2009, with the four lowest years occurring in 2007–10. The burning during the droughts of 2007 and 2010 is attributed to a higher number of savanna fires relative to the drought of 2005. A decrease in the regional mean single scattering albedo of biomass burning aerosols, consistent with the shift from forest to savanna burning, is also shown. During the severe drought of 2010, forest fire detections were lower in many areas compared with 2005, even though the drought was more severe in 2010. This result suggests that improved fire management practices, including stricter burning regulations as well as lower deforestation burning, may have reduced forest fires in 2010 relative to 2005 in some areas of the Amazon Basin. (letter)

  8. Impacts of communal fuelwood extraction on lidar-estimated biomass patterns of savanna woodlands

    CSIR Research Space (South Africa)

    Wessels, Konrad J

    2012-07-01

    Full Text Available Approximately 54% of rural households in South Africa continue to use wood as their main source of energy, mainly for cooking and heating. The provision of biomass by savanna woodlands is thus of considerable value to rural households and therefore...

  9. Characterization of habitat preferences for selected wildlife species in encinal savannas of the Southwest [Poster

    Science.gov (United States)

    Wendy D. Jones; Carlton M. Jones; Peter F. Ffolliott; Gerald J. Gottfried

    2005-01-01

    The encinal savannas of the sub-mogollon southwestern United States are important for livestock grazing and wildlife habitat. Little data have been collected on the ecology of these Sierra Madrean types of woodland land areas, which makes management difficult. Obtaining information such as habitat preferences for selected wildlife species and livestock can be an...

  10. Abundance of birds in the oak savannas of the southwestern United States

    Science.gov (United States)

    Wendy D. Jones; Carlton M. Jones; Peter F. Ffolliott; Gerald J. Gottfried

    2005-01-01

    Oak ecosystems of the Southwestern United States are important habitats for a variety of wildlife species. Information is available on the abundance and habitat preferences of some species inhabiting the more densely structured oak woodlands, but little information is available on these topics for the comparatively open oak savannas. Studies are underway to alleviate...

  11. The importance of herbivore interactions for the dynamics of African savanna woodlands : an hypothesis

    NARCIS (Netherlands)

    Van de Koppel, J; Prins, HHT

    Current hypotheses to explain dynamic transitions between savanna grasslands and woodlands in Africa focus on grazing by elephant or the influence of fire. Using a simple mathematical model, this paper argues that interactions between small herbivores such as impala or buffalo and large herbivores

  12. Assessing effect of rainfall on rate of alien shrub expansion in a southern African savanna

    NARCIS (Netherlands)

    Masocha, Mhosisi; Dube, Timothy; Skidmore, A.K.; Holmgren, Milena; Prins, Herbert

    2017-01-01

    Understanding the environmental factors governing the spread of alien shrubs is crucial for conserving biodiversity. In the semi-arid savannas of Africa, alien shrub invasion often occurs simultaneously with native shrub encroachment but climate-dependent differences in encroachments of native and

  13. Soil properties in fire-consumed log burnout openings in a Missouri oak savanna

    Science.gov (United States)

    Charles C. Rhoades; A. J. Meier; A. J. Rebertus

    2004-01-01

    Downed logs are known to increase species diversity in many forest ecosystems by increasing resource and structural complexity and by altering fire behavior in fire-prone ecosystems. In a frequently burned oak savanna in central Missouri, combustion of downed logs formed patches that have remained free of herbaceous vegetation for more than 3 years. To assess the...

  14. From savanna to campus woodlot: the historical ecology of farm woodlots in southern Illinois

    Science.gov (United States)

    C. M. Ruffner; A. Trieu; S. Chandy; M. D. Davis; D. Fishel; G. Gipson; J. Lhotka; K. Lynch; P. Perkins; S. van de Gevel; W. Watson; E. White

    2003-01-01

    The historical ecology of Thompson Woods, a 4.1 ha forest remnant on the campus of Southern Illinois University-Carbondale, was investigated through stand structure analysis, dendroecology, and historical records. Historical records indicate the area was a savanna ecosystem prior to European settlement dominated by large, open grown mixed oak-hickory trees. No trees in...

  15. The influence of savanna trees on nutrient, water and light availability and the understorey vegetation

    NARCIS (Netherlands)

    Ludwig, F.; Kroon, de H.; Berendse, F.; Prins, H.H.T.

    2004-01-01

    In an East African savanna herbaceous layer productivity and species composition were studied around Acacia tortilis trees of three different age classes, as well as around dead trees and in open grassland patches. The effects of trees on nutrient, light and water availability were measured to

  16. Application of Object Based Classification and High Resolution Satellite Imagery for Savanna Ecosystem Analysis

    Directory of Open Access Journals (Sweden)

    Jane Southworth

    2010-12-01

    Full Text Available Savanna ecosystems are an important component of dryland regions and yet are exceedingly difficult to study using satellite imagery. Savannas are composed are varying amounts of trees, shrubs and grasses and typically traditional classification schemes or vegetation indices cannot differentiate across class type. This research utilizes object based classification (OBC for a region in Namibia, using IKONOS imagery, to help differentiate tree canopies and therefore woodland savanna, from shrub or grasslands. The methodology involved the identification and isolation of tree canopies within the imagery and the creation of tree polygon layers had an overall accuracy of 84%. In addition, the results were scaled up to a corresponding Landsat image of the same region, and the OBC results compared to corresponding pixel values of NDVI. The results were not compelling, indicating once more the problems of these traditional image analysis techniques for savanna ecosystems. Overall, the use of the OBC holds great promise for this ecosystem and could be utilized more frequently in studies of vegetation structure.

  17. Mapping Cropland in Smallholder-Dominated Savannas: Integrating Remote Sensing Techniques and Probabilistic Modeling

    Directory of Open Access Journals (Sweden)

    Sean Sweeney

    2015-11-01

    Full Text Available Traditional smallholder farming systems dominate the savanna range countries of sub-Saharan Africa and provide the foundation for the region’s food security. Despite continued expansion of smallholder farming into the surrounding savanna landscapes, food insecurity in the region persists. Central to the monitoring of food security in these countries, and to understanding the processes behind it, are reliable, high-quality datasets of cultivated land. Remote sensing has been frequently used for this purpose but distinguishing crops under certain stages of growth from savanna woodlands has remained a major challenge. Yet, crop production in dryland ecosystems is most vulnerable to seasonal climate variability, amplifying the need for high quality products showing the distribution and extent of cropland. The key objective in this analysis is the development of a classification protocol for African savanna landscapes, emphasizing the delineation of cropland. We integrate remote sensing techniques with probabilistic modeling into an innovative workflow. We present summary results for this methodology applied to a land cover classification of Zambia’s Southern Province. Five primary land cover categories are classified for the study area, producing an overall map accuracy of 88.18%. Omission error within the cropland class is 12.11% and commission error 9.76%.

  18. Structure, root systems and periodicity of savanna plants and vegetations in Northern Surinam

    NARCIS (Netherlands)

    Donselaar-ten Bokkel Huinink, van W.A.E.

    1966-01-01

    From July 1958 to May 1959 an investigation was carried out of the relation between physiognomic characteristics of the vegetation and the habitat on some savannas in the vicinity of Zanderij, Surinam. Root systems, structure, periodicity and characteristics of the leaves were considered, both of

  19. Dynamics of woody vegetation in a semi-arid savanna, with a focus ...

    African Journals Online (AJOL)

    Increases in the tree:grass ratio with accompanying changes in herbaceous composition, called bush or shrub encroachment, is a worldwide phenomenon in ... Acacia mellifera-dominated savannas in the Northern Cape, South Africa, were investigated by means of vegetation classification and analyses of sequential aerial ...

  20. Long-term trends and interannual variability of forest, savanna and agricultural fires in South America

    NARCIS (Netherlands)

    Chen, Y.; Morton, D. C.; Yin, Y. F.; Collatz, G. J.; Kasibhatla, P. S.; van der Werf, G.R.; DeFries, R. S.; Randerson, J. T.

    2013-01-01

    Background: Landscape fires in South America have considerable impacts on ecosystems, air quality and the climate system. We examined long-term trends and interannual variability of forest, savanna and agricultural fires for the continent during 2001-2012 using multiple satellite-derived fire

  1. Elephant distribution around a volcanic shield dominated by a mosaic of forest and savanna (Marsabit, Kenya)

    NARCIS (Netherlands)

    Ngene, S.M.; Skidmore, A.K.; Gils, H.; Douglas-Hamilton, I.; Omondi, P.

    2009-01-01

    We investigated the factors that influenced the distribution of the African elephant around a volcanic shield dominated by a mosaic of forest and savanna in northern Kenya. Data on elephant distribution were acquired from four female and five bull elephants, collared with satellite-linked

  2. Gastrointestinal Parasites of Savanna Chimpanzees (Pan troglodytes schweinfurthii) in Ugalla, Tanzania

    Czech Academy of Sciences Publication Activity Database

    Kalousová, B.; Piel, A. K.; Pomajbíková, Kateřina; Modrý, David; Stewart, F.A.; Petrželková, Klára Judita

    2014-01-01

    Roč. 35, č. 2 (2014), s. 463-475 ISSN 0164-0291 Institutional support: RVO:60077344 Keywords : hominoid * Pan troglodytes schweinfurthii * gastrointestinal parasites * savanna * Spirurids * transmission * Ugalla * Tanzania Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.993, year: 2014

  3. Gastrointestinal parasites of savanna chimpanzees (Pan troglodytes schweinfurthii) in Ugalla, Tanzania

    Czech Academy of Sciences Publication Activity Database

    Kalousová, B.; Piel, A. K.; Pomajbíková, K.; Modrý, D.; Stewart, F. A.; Petrželková, Klára Judita

    2014-01-01

    Roč. 35, č. 2 (2014), s. 436-475 ISSN 0164-0291 R&D Projects: GA ČR GA206/09/0927 Institutional support: RVO:68081766 Keywords : Hominoid * Pan troglodytes schweinfurthii * Gastrointestinal parasites * Savanna * Spirurids * Transmission * Ugalla * Tanzania Subject RIV: EG - Zoology Impact factor: 1.993, year: 2014

  4. Water-removed spectra increase the retrieval accuracy when estimating savanna grass nitrogen and phosphorus concentrations

    CSIR Research Space (South Africa)

    Ramoelo, Abel

    2011-01-01

    Full Text Available . Ritchie and H. H. T. Prins (2002). Global enviromental controls of diversity of large hervivores. Nature 415: 901-904. 26 Owen-Smith, N. and S. M. Cooper (1987). Palatabilty of woody plants to browsing ruminants in a South African savanna. In...

  5. Spatial vegetation patterns and neighborhood competition among woody plants in an East African savanna.

    Science.gov (United States)

    Dohn, Justin; Augustine, David J; Hanan, Niall P; Ratnam, Jayashree; Sankaran, Mahesh

    2017-02-01

    The majority of research on savanna vegetation dynamics has focused on the coexistence of woody and herbaceous vegetation. Interactions among woody plants in savannas are relatively poorly understood. We present data from a 10-yr longitudinal study of spatially explicit growth patterns of woody vegetation in an East African savanna following exclusion of large herbivores and in the absence of fire. We examined plant spatial patterns and quantified the degree of competition among woody individuals. Woody plants in this semiarid savanna exhibit strongly clumped spatial distributions at scales of 1-5 m. However, analysis of woody plant growth rates relative to their conspecific and heterospecific neighbors revealed evidence for strong competitive interactions at neighborhood scales of up to 5 m for most woody plant species. Thus, woody plants were aggregated in clumps despite significantly decreased growth rates in close proximity to neighbors, indicating that the spatial distribution of woody plants in this region depends on dispersal and establishment processes rather than on competitive, density-dependent mortality. However, our documentation of suppressive effects of woody plants on neighbors also suggests a potentially important role for tree-tree competition in controlling vegetation structure and indicates that the balanced-competition hypothesis may contribute to well-known patterns in maximum tree cover across rainfall gradients in Africa. © 2016 by the Ecological Society of America.

  6. Fire and life in Tarangire : effects of burning and herbivory on an East African Savanna system

    NARCIS (Netherlands)

    Vijver, van de C.A.D.M.

    1999-01-01

    This thesis investigates the effects of fire on quality and quantity of forage for grazers in the savannas of East Africa where fire has been used as a tool in pasture management for centuries. Hereby the mechanisms that cause the effects, as well as the manner in which the effects are

  7. Dynamics of allochthonous organic matter in a tropical Brazilian headstream

    Directory of Open Access Journals (Sweden)

    José Francisco Gonçalves Júnior

    2006-11-01

    Full Text Available The species composition of the riparian vegetation and the seasonal contribution of input and storage of fine and coarse particulate organic matter were assessed in a 3rd order stretch. Fourteen tree species in the riparian zone were identified, with 3 species contributing with 68% of total litter input: Miconia chartacea Triana (43%, Miconia cyathanthera Triana (16% and Erythroxylum pelletarianum St. Hil (9%. The allochthonous input of coarse particulate organic matter (CPOM was composed mainly by leaves (over 50%. Species composition and the contribution of each plant species biomass for vertical, lateral and soil inputs and benthic stocks varied along the study period. The maximum values found in September, November and December coincided with the beginning of the rainy season. There were no differences between the allochthonous vertical and lateral inputs of CPOM to the stream. Differently to other studies, this result was probably due to the peculiar composition of stream’s riparian vegetation at Serra do Cipó.Foram determinadas as espécies que compõem a vegetação ripária e avaliada a variação sazonal da entrada e o estoque de matéria orgânica particulada grossa (MOPG em um trecho de 3ª ordem. Três espécies dentre 14 identificadas foram as mais abundantes na região ripária: Miconia chartacea Triana (43%, Miconia cyathanthera Triana (16% and Erythroxylum pelletarianum St. Hil (9%. A matéria orgânica particulada alóctone foi composta principalmente por folhas (acima de 50% Foi observado que MOPG e MOPF no estoque bêntico aumentou de julho a dezembro de 2001, sendo mais elevado em setembro, novembro e dezembro com o início da estação chuvosa. A composição de espécies e a biomassa de cada espécie no aporte de matéria orgânica vertical, lateral, no solo e estoque bêntico variaram ao longo do período estudado. Não foram encontradas diferenças significativas entre os aportes de matéria orgânica vertical, lateral e no solo. Este resultado contraria os encontrados em outros estudos, o que provavelmente expressa um caráter peculiar da vegetação ripária dos riachos de altitude na Serra do Cipó.

  8. The Brazilian Nuclear Energy Program

    International Nuclear Information System (INIS)

    Carvalho, H.G. de

    1980-01-01

    A survey is initially of the international-and national situation regarding energetic resources. The Brazilian Nuclear Energy Policy and the Brazilian Nuclear Program are dealt with, as well as the Nuclear Cooperation agreement signed with the Federal Republic of Germany. The situation of Brazil regarding Uranium and the main activities of the Brazilian Nuclear Energy Commission are also discussed [pt

  9. Efficiency of Individual Tree Detection Approaches Based on Light-Weight and Low-Cost UAS Imagery in Australian Savannas

    Directory of Open Access Journals (Sweden)

    Grigorijs Goldbergs

    2018-01-01

    Full Text Available The reliability of airborne light detection and ranging (LiDAR for delineating individual trees and estimating aboveground biomass (AGB has been proven in a diverse range of ecosystems, but can be difficult and costly to commission. Point clouds derived from structure from motion (SfM matching techniques obtained from unmanned aerial systems (UAS could be a feasible low-cost alternative to airborne LiDAR scanning for canopy parameter retrieval. This study assesses the extent to which SfM three-dimensional (3D point clouds—obtained from a light-weight mini-UAS quadcopter with an inexpensive consumer action GoPro camera—can efficiently and effectively detect individual trees, measure tree heights, and provide AGB estimates in Australian tropical savannas. Two well-established canopy maxima and watershed segmentation tree detection algorithms were tested on canopy height models (CHM derived from SfM imagery. The influence of CHM spatial resolution on tree detection accuracy was analysed, and the results were validated against existing high-resolution airborne LiDAR data. We found that the canopy maxima and watershed segmentation routines produced similar tree detection rates (~70% for dominant and co-dominant trees, but yielded low detection rates (<35% for suppressed and small trees due to poor representativeness in point clouds and overstory occlusion. Although airborne LiDAR provides higher tree detection rates and more accurate estimates of tree heights, we found SfM image matching to be an adequate low-cost alternative for the detection of dominant and co-dominant tree stands.

  10. Resource-use efficiency explains grassy weed invasion in a low-resource savanna in north Australia

    Directory of Open Access Journals (Sweden)

    Emilie eEns

    2015-08-01

    Full Text Available Comparative studies of plant resource use and ecophysiological traits of invasive and native resident plant species can elucidate mechanisms of invasion success and ecosystem impacts. In the seasonal tropics of north Australia, the alien C4 perennial grass Andropogon gayanus (gamba grass has transformed diverse, mixed tree-grass savanna ecosystems into dense monocultures. To better understand the mechanisms of invasion, we compared resource acquisition and usage efficiency using leaf-scale ecophysiological and stand-scale growth traits of A. gayanus with a co-habiting native C4 perennial grass Alloteropsis semialata. Under wet season conditions, A. gayanus had higher rates of stomatal conductance, assimilation and water use, plus a longer daily assimilation period than the native species A. semialata. Growing season length was also ~2 months longer for the invader. Wet season measures of leaf scale water use efficiency (WUE and light use efficiency (LUE did not differ between the two species, although photosynthetic nitrogen use efficiency (PNUE was significantly higher in A. gayanus. By May (dry season the drought avoiding native species A. semialata had senesced. In contrast, rates of A. gayanus gas exchange was maintained into the dry season, albeit at lower rates that the wet season, but at higher WUE and PNUE, evidence of significant physiological plasticity. High PNUE and leaf 15N isotope values suggested that A. gayanus was also capable of preferential uptake of soil ammonium, with utilisation occurring into the dry season. High PNUE and fire tolerance in an N-limited and highly flammable ecosystem confers a significant competitive advantage over native grass species and a broader niche width. As a result A. gayanus is rapidly spreading across north Australia with significant consequences for biodiversity and carbon and retention.

  11. HETROSIS AND COMBINING ABILITY OF SUB TROPICAL MAIZE ...

    African Journals Online (AJOL)

    ACSS

    were significant differences among GCA and SCA effects for grain yield; both GCA ..... drought conditions in northern Guinea and ... Sudan Savannas of Borno State, Nigeria. Peak. Journal of ... characters in a typical southern guinea savanna ...

  12. Monitoring Effect of Fire on Ant Assemblages in Brazilian Rupestrian Grasslands: Contrasting Effects on Ground and Arboreal Fauna

    Directory of Open Access Journals (Sweden)

    Diego Anjos

    2017-06-01

    Full Text Available Fire is one of the most relevant ecological disturbances in nature. Little is known about the effects of fire on biodiversity in ecosystems like rupestrian grasslands, which share characteristics with savanna and forest biomes. Brazilian rupestrian grasslands are part of an endangered ecosystem that has been modified by anthropogenic fire events that have become more intense in recent decades. In this study, we evaluated the effects of fire on ground and arboreal ant assemblages through a two-year monitoring program (24 monthly samplings. We found that fire does not change cumulative species richness after 24 months, and that fire does not affect mean ant richness, abundance, and species composition in arboreal ants. On the other hand, fire increased mean ground ant species richness and abundance, and caused a significant change in species composition. Our results indicate a weak and beneficial effect of fire only for ground ant communities, which generally agrees with results from other studies in Brazilian savannas. Taken together, results from these studies may be useful for improvement of fire suppression policy in fire-prone habitats in Brazil.

  13. Diversity of shrub tree layer, leaf litter decomposition and N release in a Brazilian Cerrado under N, P and N plus P additions

    International Nuclear Information System (INIS)

    Khan Baiocchi Jacobson, Tamiel; Cunha Bustamante, Mercedes Maria da; Rodrigues Kozovits, Alessandra

    2011-01-01

    This study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensu stricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified. - Highlights: → Simultaneous addition of N and P affected richness and diversity of the shrub-tree layer of a Brazilian savanna more significantly than addition of N or P separately. → Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. → The results indicated that if increases in N deposition in Cerrado ecosystems are not accompanied by P additions, higher N losses through leaching and gas emissions can occur with other ecosystem impacts. - Shrub-tree diversity and functioning of Brazilian savanna are affected by increasing nutrient availability.

  14. Diversity of shrub tree layer, leaf litter decomposition and N release in a Brazilian Cerrado under N, P and N plus P additions

    Energy Technology Data Exchange (ETDEWEB)

    Khan Baiocchi Jacobson, Tamiel, E-mail: tamiel@unb.br [Departamento de Ecologia, Universidade de Brasilia, Brasilia-DF 70919-970 (Brazil); Cunha Bustamante, Mercedes Maria da, E-mail: mercedes@unb.br [Departamento de Ecologia, Universidade de Brasilia, Brasilia-DF 70919-970 (Brazil); Rodrigues Kozovits, Alessandra, E-mail: kozovits@icep.ufop.br [Departamento de Ecologia, Universidade de Brasilia, Brasilia-DF 70919-970 (Brazil)

    2011-10-15

    This study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensu stricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified. - Highlights: > Simultaneous addition of N and P affected richness and diversity of the shrub-tree layer of a Brazilian savanna more significantly than addition of N or P separately. > Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. > The results indicated that if increases in N deposition in Cerrado ecosystems are not accompanied by P additions, higher N losses through leaching and gas emissions can occur with other ecosystem impacts. - Shrub-tree diversity and functioning of Brazilian savanna are affected by increasing nutrient availability.

  15. Tree cover in sub-Saharan Africa: rainfall and fire constrain forest and savanna as alternative stable states

    CSIR Research Space (South Africa)

    Staver, AC

    2011-01-01

    Full Text Available Savannas are known as ecosystems with tree cover below climate-defined equilibrium values. However, a predictive framework for understanding constraints on tree cover is lacking. The authors present a) a spatially extensive analysis of tree cover...

  16. The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Tâmara Dias Oliveira Machado

    Full Text Available BACKGROUND Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. OBJECTIVE To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs in the city of Palmas and to determine the rate of natural infection by trypanosomatids. METHODS Gallery forests and adjacent household areas were sampled on July (dry season and November (rainy season in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing. FINDINGS A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp. and 578 (22 spp. were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri. MAIN CONCLUSIONS These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins, Brazil.

  17. Analysis of evapotranspiration and biomass in pastures with degradation indicatives in the Upper Tocantins River Basin, in Brazilian Savanna

    Directory of Open Access Journals (Sweden)

    Ricardo Guimarães Andrade

    Full Text Available ABSTRACT The objective of this study was to apply the Simple Algorithm For Evapotranspiration Retrieving (SAFER with MODIS images together with meteorological data to analyze evapotranspiration (ET and biomass production (BIO according to indicative classes of pasture degradation in Upper Tocantins River Basin. Indicative classes of degraded pastures were obtained from the NDVI time-series (2002-2012. To estimate ET and BIO in each class, MODIS images and data from meteorological stations of the year 2012 were used. The results show that compared to not-degraded pastures, ET and BIO were different in pastures with moderate to strong degradation, mainly during water stress period. Therefore, changes in energy balance partition may occur according to the degradation levels, considering that those indicatives of degradation processes were identified in 24% of the planted pasture areas. In this context, ET and BIO estimates using remote sensing techniques can be a reliable indicator of forage availability, and large-scale aspects related to the degradation of pastures. It is expected that this knowledge may contribute to initiatives of public policies aimed at controlling the loss of production potential of pasture areas in the Upper Tocantins River Basin in the state of Goiás, Brazil.

  18. The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna.

    Science.gov (United States)

    Machado, Tâmara Dias Oliveira; Minuzzi-Souza, Thaís Tâmara Castro; Ferreira, Tauana de Sousa; Freire, Luciana Pereira; Timbó, Renata Velôzo; Vital, Tamires Emanuele; Nitz, Nadjar; Silva, Mariana Neiva; Santos, Alcinei de Souza; Sales, Nathyla Morgana Cunha; Obara, Marcos Takashi; Andrade, Andrey José de; Gurgel-Gonçalves, Rodrigo

    2017-10-01

    Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs) in the city of Palmas and to determine the rate of natural infection by trypanosomatids. Gallery forests and adjacent household areas were sampled on July (dry season) and November (rainy season) in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing. A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp.) and 578 (22 spp.) were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens) identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri. These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins, Brazil.

  19. Brazilian savanna fruits contain higher bioactive compounds content and higher antioxidant activity relative to the conventional red delicious apple.

    Directory of Open Access Journals (Sweden)

    Egle Machado de Almeida Siqueira

    Full Text Available The bioactive compounds content and the antioxidant activity (AA of twelve fruits native to the Cerrado were compared with the Red Delicious apple by means of the antiradical efficiency (using the 2,2-diphenyl-1-picrylhydrazil assay/DPPH, ferric reducing antioxidant power (FRAP and the β-carotene/linoleic system. The antiradical efficiency (AE and the kinetic parameters (Efficient concentration/EC50 and time needed to reach the steady state to EC50 concentration/TEC50 of the DPPH curve were also evaluated for comparison with the Trolox equivalent (TE values. A strong, significant and positive correlation was observed between the TE and AE values, whereas a weak and negative correlation was observed between TE and EC50, suggesting that the values of AE and TE are more useful for the determination of antiradical activity in fruits than the widely used EC50. The total phenolic content found in the fruits corresponded positively to their antioxidant activity. The high content of bioactive compounds (flavanols, anthocyanins or vitamin C relative to the apple values found in araticum, cagaita, cajuzinho, jurubeba, lobeira, magaba and tucum corresponded to the high antioxidant activity of these fruits. Flavanols and anthocyanins may be the main bioactive components in these Cerrado fruits. The daily consumption of at least seven of the twelve Cerrado fruits studied, particularly, araticum, cagaita, lobeira and tucum, may confer protection against oxidative stress, and thus, they may prevent chronic diseases and premature aging. The findings of this study should stimulate demand, consumption and cultivation of Cerrado fruits and result in sustainable development of the region where this biome dominates.

  20. Leafcutter Ant Nests Inhibit Low-Intensity Fire Spread in the Understory of Transitional Forests at the Amazon's Forest-Savanna Boundary

    Directory of Open Access Journals (Sweden)

    Karine S. Carvalho

    2012-01-01

    Full Text Available Leaf-cutter ants (Atta spp. remove leaf litter and woody debris—potential fuels—in and around their nests and foraging trails. We conducted single and three annual experimental fires to determine the effects of this leaf-cutter ant activity on the behavior of low-intensity, slow-moving fires. In a transitional forest, where the southern Amazon forest meets the Brazilian savanna, we tested whether leaf-cutter ant nests and trails (i inhibit fire spread due to a lack of fuels, and (ii, thereby, reduce the total burned area during these experimental low-intensity fires, particularly at forest edges where leaf-cutter ant abundance was higher. Fine-medium fuel mass increased with an increase in distance from ant nest, and the mean area of bare soil was greater on nests than on the forest floor. Between 60 to 90 percent of the unburned area was within 30 m of ant nests, and burned area significantly increased with increasing distance to ant nests. In addition, the number of ant nests declined with increasing distance from the forest edge, and, with exception of the first experimental fire, burned area also increased with increasing distance from the edge. The present study provides new insight to fire ecology in Amazon environments.

  1. Mediterranean savanna system: understanding and modeling of olive orchard.

    Science.gov (United States)

    Brilli, Lorenzo; Moriondo, Marco; Bindi, Marco

    2013-04-01

    Nowadays most of the studies on C and N exchange were focused on forest ecosystems and crop systems, while only few studies have been focused on so called "savanna systems". They are long-term agro-ecosystems (fruit trees, grapevines and olive trees, etc.) usually characterized by two different layers (ground vegetation and trees). Generally, there is a lack of knowledge about these systems due to their intrinsic structural complexity (different eco-physiological characteristics so as agricultural practices). However, given their long-term carbon storage capacity, these systems can play a fundamental role in terms of global C cycle. Among all of them, the role that olive trees can play in C sequestration should not be neglected, especially in Mediterranean areas where they typify the rural landscape and are widely cultivated (Loumou and Giourga, 2003). It is therefore fundamental modelling the C-fluxes exchanges coming from these systems through a tool able to well reproduce these dynamics in one of the most exposed areas to the risk of climate change (IPCC, 2007). In this work, 2 years of Net CO2 Ecosystem Exchange (NEE) measures from eddy covariance were used to test the biogeochemistry model DayCent. The study was conducted in a rain-fed olive orchard situated in Follonica, South Tuscany, Italy (42 ° 55'N, 10 ° 45'E), in an agricultural area near the coast. The instrumentation for flux measurement was placed 1.9 m above the canopy top (6.5 m from the ground) so that the footprint area, expressed as the area containing 90% of the observed flux, was almost entirely contained within the olive orchard limits (Brilli et al., in press). Ancillary slow sensors have included soil temperature profiles, global radiation, air temperature and humidity, rain gauge. Fluxes of sensible heat, latent heat, momentum and CO2 as well as ancillary data were derived at half-hourly time resolution. Specific soil (texture, current and historical land use and vegetation cover) and

  2. Brazilian women in politics.

    Science.gov (United States)

    Sanders, T G

    1987-01-01

    Women are gradually gaining influence in Brazilian politics, especially since recent advances in the women's movement, but they still play a limited role. There have been journals devoted to feminism and some notable feminists since 1850. In 1932 suffragettes in Brazil gained women the right to vote. Women's associations burgeoned in the 1940s and 1950s, culminating in a peak in number of women in national elected positions in 1965. A repressive military regime reversed the process, which resumed in 1975. 1975 was also significant for the Brazilian women's movement because of the U.N. Women's Year. Several large, influential feminist political action groups were formed, typically by upper class women with leftist views, although some church and union groups from lower classes also appeared. In 1979-1981, the coherence of these groups fell into schism and fragmentation, because of disagreements over the feminist political doctrines and roles, views on legality of abortion, and special interest groups such as lesbians. Another bitter dispute is opposition by leftist women to BEMFAM, the Brazilian Society of Family Welfare, which provides family planning for the poor: leftists oppose BEMFAM because it is supported by funds from "imperialist" countries such as the U.S. There are several types of feminists groups: those that emphasize health, sexuality and violence; those composed of lesbians; those originating from lower classes and unions; publicly instituted organizations. Brazilian law forbids discrimination against women holding public office, but in reality very few women actually do hold office, except for mayors of small towns and a few administrators of the Education and Social Security ministries. Political office in Brazil is gained by clientism, and since women rarely hold powerful positions in business, they are outsiders of the system. Brazilian women have achieved much, considering the low female literacy rate and traditional power system, but their

  3. Methane fluxes from the mound-building termite species of North Australian savannas

    Science.gov (United States)

    Jamali, H.; Livesely, S. J.; Arndt, S. K.; Dawes-Gromadzki, T.; Cook, G. D.; Hutley, L.

    2009-04-01

    Termites are estimated to contribute 3-19% to the global methane emissions. These estimates have large uncertainties because of the limited number of field-based studies and species studied, as well as issues of diel and seasonal variation. We measured methane fluxes from four common mound-building termite species (Microcerotermes nervosus, n=26; M. serratus, n=4; Tumulitermes pastinator, n=5; and Amitermes darwini, n=4) in tropical savannas near Darwin in the Northern Territory, Australia. Methane fluxes from replicated termite mounds were measured in the field using manual chambers with fluxes reported on a mound volume basis. Methane flux was measured in both wet and dry seasons and diel variation was investigated by measuring methane flux every 4 hours over a 24 hour period. Mound temperature was measured concurrently with flux to examine this relationship. In addition, five M. nervosus mounds removed from the field and incubated under controlled temperature conditions over a 24 hour period to remove the effect of varying temperature. During the observation campaigns, mean monthly minimum and maximum temperatures for February (wet season) were 24.7 and 30.8°C, respectively, and were 20.1 to 31.4 °C in June (dry season). Annual rainfall in 2008 for Darwin was 1970.1 mm, with a maximum of 670 mm falling in February and no rain in May and June. Methane fluxes were greatest in the wet season for all species, ranging from 265.1±101.1 (T. pastinator) to 2256.6±757.1 (M. serratus) µg CH4-C/m3/h. In the dry season, methane fluxes were at their lowest, ranging from 10.0±5.5 (T. pastinator) to 338.0±165.9 (M. serratus) µg CH4-C/m3/h. On a diel basis, methane fluxes were smallest at the coolest time of the day (~0700 hrs) and greatest at the warmest (~1400 hrs) for all species, and for both wet and dry seasons. Typical diel variation in flux from M. serratus dominated mounds ranged from 902.6±261.9 to 1392.1±408.1 µg CH4-C/m3/h in wet season and 99.6±57.4 to

  4. Morpho-anatomical features of underground systems in six Asteraceae species from the Brazilian Cerrado.

    Science.gov (United States)

    Appezzato-da-Glória, Beatriz; Cury, Graziela

    2011-09-01

    In the Brazilian Cerrado (neotropical savanna), the development of bud-bearing underground systems as adaptive structures to fire and dry periods can comprise an important source of buds for this ecosystem, as already demonstrated in the Brazilian Campos grasslands and North American prairies. Asteraceae species from both woody and herbaceous strata have subterranean organs that accumulate carbohydrates, reinforcing the adaptive strategy of these plants to different environmental conditions. This study aims to analyse the morpho-anatomy of underground systems of six species of Asteraceae (Mikania cordifolia L.f. Willd., Mikania sessilifolia DC, Trixis nobilis (Vell.) Katinas, Pterocaulon alopecuroides (Lam.) DC., Vernonia elegans Gardner and Vernonia megapotamica Spreng.), to describe these structures and to verify the occurrence and origin of shoot buds, and to analyse the presence of reserve substances. Individuals sampled in Cerrado areas in São Paulo State showed thick underground bud-bearing organs, with adventitious or lateral roots and presence of fructans. Xylopodium was found in all studied species, except for Trixis nobilis, which had stem tuber. The presence of fructans as reserve, and the capacity of structures in the formation of buds indicate the potential of herbaceous species of Asteraceae in forming a viable bud bank for vegetation regeneration in the Brazilian Cerrado.

  5. Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. IV. Alopoglossidae, Gymnophthalmidae.

    Science.gov (United States)

    Ribeiro-Júnior, Marco A; Amaral, Silvana

    2017-05-22

    We present distribution data of all Alopoglossidae and Gymnophthalmidae lizards known from the Brazilian Amazonia, totaling 54 species-level taxa, belonging to 17 genera and two families. This represents 22 more species-level taxa than previously reported. Data were based on 17,431 specimens deposited in three North American and eight Brazilian museums, including the main collections harboring Amazonian material. Most species (~80%) are endemic to Amazonia; non-endemic species are mainly associated with open vegetation (savanna) enclaves or open dry (semideciduous) forest in Amazonia, with a few exceptions. As a whole, seven taxa (including one species complex) are widespread in Amazonia, six are restricted to eastern Amazonia, seven to western Amazonia, two to southwestern Amazonia, 11 to southern Amazonia, 11 to northern Amazonia (either in part of it or widespread in the Guiana region), and six to the southern peripheral portion of Amazonia. Besides, four species present unique distributions. Considering this study and the other three catalogues of distribution of lizards already published, the total number of lizard species from Brazilian Amazonia increased from 97 to 142 species-level tava. It represents an increase of 45 species from the region since the last revision.

  6. Brazilian research on extremophiles in the context of astrobiology

    Science.gov (United States)

    Duarte, Rubens T. D.; Nóbrega, Felipe; Nakayama, Cristina R.; Pellizari, Vivian H.

    2012-10-01

    Extremophiles are organisms adapted to grow at extreme ranges of environmental variables, such as high or low temperatures, acid or alkaline medium, high salt concentration, high pressures and so forth. Most extremophiles are micro-organisms that belong to the Archaea and Bacteria domains, and are widely spread across the world, which include the polar regions, volcanoes, deserts, deep oceanic sediments, hydrothermal vents, hypersaline lakes, acid and alkaline water bodies, and other extreme environments considered hostile to human life. Despite the tropical climate, Brazil has a wide range of ecosystems which include some permanent or seasonally extreme environments. For example, the Cerrado is a biome with very low soil pH with high Al+3 concentration, the mangroves in the Brazilian coast are anaerobic and saline, Pantanal has thousands of alkaline-saline lakes, the Caatinga arid and hot soils and the deep sea sediments in the Brazilian ocean shelf. These environments harbour extremophilic organisms that, coupled with the high natural biodiversity in Brazil, could be explored for different purposes. However, only a few projects in Brazil intended to study the extremophiles. In the frame of astrobiology, for example, these organisms could provide important models for defining the limits of life and hypothesize about life outside Earth. Brazilian microbiologists have, however, studied the extremophilic micro-organisms inhabiting non-Brazilian environments, such as the Antarctic continent. The experience and previous results obtained from the Brazilian Antarctic Program (PROANTAR) provide important results that are directly related to astrobiology. This article is a brief synopsis of the Brazilian experience in researching extremophiles, indicating the most important results related to astrobiology and some future perspectives in this area.

  7. The effects of gap size and disturbance type on invasion of wet pine savanna by cogongrass, Imperata cylindrica (Poaceae)

    Science.gov (United States)

    King, S.E.; Grace, J.B.

    2000-01-01

    Cogongrass is a nonindigenous species perceived to threaten native communities of the southeastern United States through modification of species composition and alteration of community processes. To examine how gap size and disturbance type influence the invasion of wet pine savannas by cogongrass, we performed three field experiments to evaluate the response of cogongrass seeds and transplanted seedlings to four different gap sizes, four types of site disturbance, and recent burning of savanna vegetation. Cogongrass germinated, survived, and grew in all gap sizes, from 0 to 100 cm in diameter. Similarly, disturbance type had no effect on germination or seedling and transplant survival. Tilling, however, significantly enhanced transplanted seedling growth, resulting in a tenfold increase in biomass over the other disturbance types. Seedling survival to 1 and 2 mo was greater in burned savanna than unburned savanna, although transplant survival and growth were not affected by burning. Results of this study suggest that cogongrass can germinate, survive, and grow in wet pine savanna communities regardless of gap size or type of disturbance, including burning. Burning of savanna vegetation may enhance establishment by improving early seedling survival, and soil disturbance can facilitate invasion of cogongrass by enhancing plant growth.

  8. Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil

    Directory of Open Access Journals (Sweden)

    K. G. Massi

    2017-05-01

    Full Text Available Abstract In Cerrado, studies of post-fire vegetation recovery show that some herbaceous species are able to flower shortly after fires. However, these were mainly short-term studies that focused on grasslands and savannas. Little is known about the effects of fire on ground layer of forests that border the savannas in Central Brazil. Thus, an accidental burning gave us the opportunity to describe the reproductive activity of the ground layer vegetation after a fire event along a savanna-forest boundary at the IBGE Ecological Reserve, Brasília, Brazil. During the 16-month of the inventory, we registered 170 herbaceous species flowering or fruiting, of which 52 species (31% may have been influenced by fire that changed their times of reproduction. In the savanna plots reproduction peaked at the end of the rainy season. Of the total number of reproducing species, 90 species occurred only in the savanna and four in the forest. Five herbs were recorded in the forest, savanna and border environments. Late dry season fire probably lead the majority of herbaceous species to have their reproduction spread throughout the study time.

  9. Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil.

    Science.gov (United States)

    Massi, K G; Eugênio, C U O; Franco, A C

    2017-11-01

    In Cerrado, studies of post-fire vegetation recovery show that some herbaceous species are able to flower shortly after fires. However, these were mainly short-term studies that focused on grasslands and savannas. Little is known about the effects of fire on ground layer of forests that border the savannas in Central Brazil. Thus, an accidental burning gave us the opportunity to describe the reproductive activity of the ground layer vegetation after a fire event along a savanna-forest boundary at the IBGE Ecological Reserve, Brasília, Brazil. During the 16-month of the inventory, we registered 170 herbaceous species flowering or fruiting, of which 52 species (31%) may have been influenced by fire that changed their times of reproduction. In the savanna plots reproduction peaked at the end of the rainy season. Of the total number of reproducing species, 90 species occurred only in the savanna and four in the forest. Five herbs were recorded in the forest, savanna and border environments. Late dry season fire probably lead the majority of herbaceous species to have their reproduction spread throughout the study time.

  10. Development of anthers and pollen in Brazilian heterostylic species of Erythroxylum (Erythroxylaceae): an ecological approach

    International Nuclear Information System (INIS)

    Silva, L.D.; Fernandes, C. L.

    2016-01-01

    This study describes the development of anthers and pollen in heterostylic flowers of two species of Erythroxylum. The features of anthers and their developmental pattern, which is of the dicotyledonous type, do not vary according to morphs or species. The pollen grains of both morphs show differences in their morphology, development, and content stored as a reserve source. In both species, thrum (short-styled) flowers presented bicellular pollen grains, while pin (long-styled) ones yielded bi- and tricellular pollen grains. The presence of inviable pollen grains in the two flower morphs of both species and the malformation of one of the four microsporanges in the thrum flowers of E. campestre are noteworthy. We verified that features found both in the anther wall and in the pollen grains could be related to the reproductive success and adaptation of the species to the Brazilian savanna biome. (author)

  11. Greenhouse Gas Emissions from Brazilian Sugarcane Soils

    Science.gov (United States)

    Carmo, J.; Pitombo, L.; Cantarella, H.; Rosseto, R.; Andrade, C.; Martinelli, L.; Gava, G.; Vargas, V.; Sousa-Neto, E.; Zotelli, L.; Filoso, S.; Neto, A. E.

    2012-04-01

    Bioethanol from sugarcane is increasingly seen as a sustainable alternative energy source. Besides having high photosynthetic efficiency, sugarcane is a perennial tropical grass crop that can re-grow up to five or more years after being planted. Brazil is the largest producer of sugarcane in the world and management practices commonly used in the country lead to lower rates of inorganic N fertilizer application than sugarcane grown elsewhere, or in comparison to other feedstocks such as corn. Therefore, Brazilian sugarcane ethanol potentially promotes greenhouse gas savings. For that reason, several recent studies have attempted to assess emissions of greenhouse gases (GHG) during sugarcane production in the tropics. However, estimates have been mainly based on models due to a general lack of field data. In this study, we present data from in situ experiments on emission of three GHG (CO2, N2O, and CH4) in sugarcane fields in Brazil. Emissions are provided for sugarcane in different phases of the crop life cycle and under different management practices. Our results show that the use of nitrogen fertilizer in sugarcane crops resulted in an emission factor for N2O similar to those predicted by IPCC (1%), ranging from 0.59% in ratoon cane to 1.11% in plant cane. However, when vinasse was applied in addition to mineralN fertilizer, emissions of GHG increased in comparison to those from the use of mineral N fertilizer alone. Emissions increased significantly when experiments mimicked the accumulation of cane trash on the soil surface with 14 tons ha-1and 21 tons ha-1, which emission factor were 1.89% and 3.03%, respectively. This study is representative of Brazilian sugarcane systems under specific conditions for key factors affecting GHG emissions from soils. Nevertheless, the data provided will improve estimates of GHG from Brazilian sugarcane, and efforts to assess sugarcane ethanol sustainability and energy balance. Funding provided by the São Paulo Research

  12. Old tropical botanical collections

    DEFF Research Database (Denmark)

    Friis, Ib

    2017-01-01

    The early history of botanical collections is reviewed, with particular emphasis on old collections from the tropics. The information available about older and newer botanical collections from the tropics was much improved after World War Two, including better lists of validly published names, more...

  13. Tropical Veterinarian: Submissions

    African Journals Online (AJOL)

    Author Guidelines. 2012 Author Guidelines: Instructions to Authors: TROPICAL VETERINARIAN welcomes original work on all aspects of veterinary science as practiced in the Tropics, including livestock production and management, animal disease (domestic and wild), various aspects of preventive medicine and public ...

  14. Tropical Cyclone Propagation

    National Research Council Canada - National Science Library

    Gray, William

    1994-01-01

    This paper discusses the question of tropical cyclone propagation or why the average tropical cyclone moves 1-2 m/s faster and usually 10-20 deg to the left of its surrounding (or 5-7 deg radius) deep layer (850-300 mb) steering current...

  15. Computing Tropical Varieties

    DEFF Research Database (Denmark)

    Speyer, D.; Jensen, Anders Nedergaard; Bogart, T.

    2005-01-01

    The tropical variety of a d-dimensional prime ideal in a polynomial ring with complex coefficients is a pure d-dimensional polyhedral fan. This fan is shown to be connected in codimension one. We present algorithmic tools for computing the tropical variety, and we discuss our implementation...

  16. Trace gas emissions to the atmosphere by biomass burning in the west African savannas

    Science.gov (United States)

    Frouin, Robert J.; Iacobellis, Samuel F.; Razafimpanilo, Herisoa; Somerville, Richard C. J.

    1994-01-01

    Savanna fires and atmospheric carbon dioxide (CO2) detection and estimating burned area using Advanced Very High Resolution Radiometer_(AVHRR) reflectance data are investigated in this two part research project. The first part involves carbon dioxide flux estimates and a three-dimensional transport model to quantify the effect of north African savanna fires on atmospheric CO2 concentration, including CO2 spatial and temporal variability patterns and their significance to global emissions. The second article describes two methods used to determine burned area from AVHRR data. The article discusses the relationship between the percentage of burned area and AVHRR channel 2 reflectance (the linear method) and Normalized Difference Vegetation Index (NDVI) (the nonlinear method). A comparative performance analysis of each method is described.

  17. Dynamics in carbon exchange fluxes for a grazed semi-arid savanna ecosystem in West Africa

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Cropley, Ford

    2015-01-01

    variable in scaling carbon fluxes from ground observations using earth observation data. The net ecosystem exchange of carbon dioxide (NEE) 2010-2013 was measured using the eddy covariance technique at a grazed semi-arid savanna site in Senegal, West Africa. Night-time NEE was not related to temperature......-arid savanna sites; half-hourly GPP and Reco peaked at -43μmol CO2m-2s-1 and 20μmol CO2m-2s-1, and daily GPP and Reco peaked at -15gCm-2 and 12gCm-2, respectively. Possible explanations for the high CO2 fluxes are a high fraction of C4 species, alleviated water stress conditions, and a strong grazing pressure...

  18. Introduction to tropical geometry

    CERN Document Server

    Maclagan, Diane

    2015-01-01

    Tropical geometry is a combinatorial shadow of algebraic geometry, offering new polyhedral tools to compute invariants of algebraic varieties. It is based on tropical algebra, where the sum of two numbers is their minimum and the product is their sum. This turns polynomials into piecewise-linear functions, and their zero sets into polyhedral complexes. These tropical varieties retain a surprising amount of information about their classical counterparts. Tropical geometry is a young subject that has undergone a rapid development since the beginning of the 21st century. While establishing itself as an area in its own right, deep connections have been made to many branches of pure and applied mathematics. This book offers a self-contained introduction to tropical geometry, suitable as a course text for beginning graduate students. Proofs are provided for the main results, such as the Fundamental Theorem and the Structure Theorem. Numerous examples and explicit computations illustrate the main concepts. Each of t...

  19. Radiation absorption and use by humid savanna grassland: assessment using remote sensing and modelling

    International Nuclear Information System (INIS)

    Roux, X. le; Gauthier, H.; Begue, A.; Sinoquet, H.

    1997-01-01

    The components of the canopy radiation balance in photosynthetically active radiation (PAR), phytomass and leaf area index (LAI) were measured during a complete annual cycle in an annually burned African humid savanna. Directional reflectances measured by a hand-held radiometer were used to compute the canopy normalized difference vegetation index (NDVI). The fraction f APAR of PAR absorbed by the canopy (APAR) and canopy reflectances were simulated by the scattering from arbitrarily inclined leaves (SAIL) and the radiation interception in row intercropping (RIRI) models. The daily PAR to solar radiation ratio was linearly related to the daily fraction of diffuse solar radiation with an annual value around 0.47. The observed f APAR was non-linearly related to NDVI. The SAIL model simulated reasonably well directional reflectances but noticeably overestimated f APAR during most of the growing season. Comparison of simulations performed with the 1D and 3D versions of the RIRI model highlighted the weak influence of the heterogeneous structure of the canopy after fire and of the vertical distribution of dead and green leaves on total f APAR . Daily f APAR values simulated by the 3D-RIRI model were linearly related to and 9.8% higher than observed values. For sufficient soil water availability, the net production efficiency ϵ n of the savanna grass canopy was 1.92 and 1.28 g DM MJ −1 APAR (where DM stands for dry matter) during early regrowth and mature stage, respectively. In conclusion, the linear relationship between NDVI and f APAR used in most primary production models operating at large scales may slightly overestimate f APAR by green leaves for the humid savanna biome. Moreover, the net production efficiency of humid savannas is close to or higher than values reported for the other major natural biomes. (author)

  20. The influence of canopy strata on remotely sensed observations of savanna-woodlands

    International Nuclear Information System (INIS)

    Fuller, D.O.; Prince, S.D.; Astle, W.L.

    1997-01-01

    Upwelling radiance from savanna woodlands may originate from two separate layers: (1) the field layer, which is a mixture of soil, litter and herbs, and (2) the tree layer composed of woody parts and leaves. Unless detailed field data are available for a particular savanna location, it is unknown how the individual layers may influence the red and near-infrared signals and whether radiative interactions between layers are important. We employed an existing radiative transfer model (SAIL) in conjunction with a simple, single-scattering model to analyse the variation in Advanced Very High Resolution Radiometer (AVHRR) channel 1 and 2 response as well as NDVI for savanna-woodland vegetation in eastern Zambia. Linear fits between predicted and observed values of reflectance and NDVI were significant ( p 0.05) in the red and in NDVI, however, the model failed to explain a high proportion of the variation in near-infrared. Red and NDVI in sites where tree cover was high were also poorly modelled, which suggests that multiple interactions between canopy layers make a single-scattering model unreliable, particularly in the near-infrared. Modelled results were also compared to aircraft radiometer measurements provided by the integrated camera and radiometer instrument (ICAR). Simulations parameterized with field data suggest that the model may be used to infer tree and field layer influences at different points during the seasonal cycle. Results also suggest that the field layer dominated the signal in our savanna woodland sites throughout most points of the seasonal cycle, which is consistent with other canopy radiative-transfer studies. Simulations indicated that the tree layer was a relatively more important component of NDVI during the dry season when the field layer was largely senescent, accounting for 20-40 per cent of the satellite signal. (author)

  1. Seasonality and Interannual Variability of Carbon Uptake and Respiration in a California Oak Savanna

    Science.gov (United States)

    Ma, S.; Baldocchi, D.; Xu, L.

    2005-12-01

    Estimating terrestrial carbon sink with large-scale modeling research requires understanding the physiological and ecological processes associated with the carbon uptake and respiration of ecosystems and their variability in seasons and years. This study was conducted in an oak/grass savanna ecosystem in California, USA. The savanna ecosystem consists of blue oak trees ( Quercus douglasii) in the overstory and annual C3 grasses in the understory. Fluxes of CO2 were measured above the canopy (overstory) and the grasses (understory) from 2001 to 2005 with two eddy covariance systems. Under typical Mediterranean Climate, net ecosystem exchange of CO2 (NEE), ecosystem respiration (Reco), and gross primary production (GPP) in this savanna ecosystem had a distinctive dry-wet seasonal pattern. Leaf area index, leaf nitrogen concentration, and leaf carbon stable isotope discrimination reflected the responses of leaf to the seasonality and interannual variability. Light- use efficiency, the ratio of GPP to absorbed photosynthetically active radiation (aPAR), was not consistent within a year or from year to year, indicating that photosynthesis process was constrained with low temperature during the beginning of the wet season and limited by precipitation during the summer drought. Annual NEE, Reco, and GPP above the canopy varied significantly between years, varying from -108 - 133 gC m-2, 780 - 988 gC m-2, and 646 - 963 gC m-2, respectively. The difference of interannual Reco was 1.2 times of that of interannual GPP. There was a tight relationship between annual NEE and the precipitation during the period with daily mean temperature varying between 10 - 20°C, equivalent to precipitation during March and April. The longer the period lasted, the higher carbon uptake occurred. Estimated annual NEE from 1949 - 2005 in the savanna ecosystem varied between ~-400 - 200 gC m-2.

  2. Topo-edaphic controls over woody plant biomass in South African savannas

    Directory of Open Access Journals (Sweden)

    M. S. Colgan

    2012-05-01

    Full Text Available The distribution of woody biomass in savannas reflects spatial patterns fundamental to ecosystem processes, such as water flow, competition, and herbivory, and is a key contributor to savanna ecosystem services, such as fuelwood supply. While total precipitation sets an upper bound on savanna woody biomass, the extent to which substrate and terrain constrain trees and shrubs below this maximum remains poorly understood, often occluded by local-scale disturbances such as fire and trampling. Here we investigate the role of hillslope topography and soil properties in controlling woody plant aboveground biomass (AGB in Kruger National Park, South Africa. Large-area sampling with airborne Light Detection and Ranging (LiDAR provided a means to average across local-scale disturbances, revealing an unexpectedly linear relationship between AGB and hillslope-position on basalts, where biomass levels were lowest on crests, and linearly increased toward streams (R2 = 0.91. The observed pattern was different on granite substrates, where AGB exhibited a strongly non-linear relationship with hillslope position: AGB was high on crests, decreased midslope, and then increased near stream channels (R2 = 0.87. Overall, we observed 5-to-8-fold lower AGB on clayey, basalt-derived soil than on granites, and we suggest this is due to herbivore-fire interactions rather than lower hydraulic conductivity or clay shrinkage/swelling, as previously hypothesized. By mapping AGB within and outside fire and herbivore exclosures, we found that basalt-derived soils support tenfold higher AGB in the absence of fire and herbivory, suggesting high clay content alone is not a proximal limitation on AGB. Understanding how fire and herbivory contribute to AGB heterogeneity is critical to predicting future savanna carbon storage under a changing climate.

  3. Implication of climate change for the persistence of raptors in arid savanna

    Energy Technology Data Exchange (ETDEWEB)

    Wichmann, M.C.; Wissel, C. [UFZ-Center for Environmental Research, Dept. of Ecological Modelling, Leipzig (Germany); Jeltsch, F. [Univ. of Potsdam, Inst. for Biochemistry and Biology, Potsdam (Germany); Dean, W.R.J. [Univ. of Cape Town, Percy FitzPatrick Inst. of African Ornithology, Rondebosch (South Africa); Moloney, K.A. [Iowa State Univ., Dept. of Botany, Ames, IA (United States)

    2003-07-01

    Arid savannas are regarded as one of the ecosystems most likely to be affected by climate change. In these dry conditions, even top predators like raptors are affected by water availability and precipitation. However, few research initiatives have a adressed the question of how climate change will affect population dynamics and extinction risk of particular species in and ecosystems. Here, we use an individual-oriented modeling approach to conduct experiments on the population dynamics of long lived raptors. We investigate the potential impact of precipitation variation caused by climate change on raptors in and savanna using the tawny eagle (Aquila rapax) in the southern Kalahari as a case study. We simulated various modifications of precipitation scenarios predicted for climate change, such as lowered annual precipitation mean, increased inter-annual variation and increased auto-correlation in precipitation. We found a high impact of these modifications on extinction risk of tawny eagles, with reduced population persistence in most cases. Decreased mean annual precipitation and increased inter-annual variation both caused dramatic decreases in population persistence. Increased autocorrelation in precipitation led only to slightly accelerated extinction of simulated populations. Finally. for various patterns of periodically fluctuating precipitation, we found both increased and decreased population persistence. In summary, our results suggest that the impacts on raptor population dynamics and survival caused by climate change in and savannas will be great. We emphasize that even if under climate change the mean annual precipitation remains constant but the inter-annual variation increases the persistence of raptor populations in and savannas will decrease considerably. This suggests a new dimension, of climate change driven impacts on population persistence and consequently on biodiversity. However, more investigations on particular species and/or species groups

  4. Accuracy assessment of vegetation community maps generated by aerial photography interpretation: perspective from the tropical savanna, Australia

    Science.gov (United States)

    Lewis, Donna L.; Phinn, Stuart

    2011-01-01

    Aerial photography interpretation is the most common mapping technique in the world. However, unlike an algorithm-based classification of satellite imagery, accuracy of aerial photography interpretation generated maps is rarely assessed. Vegetation communities covering an area of 530 km2 on Bullo River Station, Northern Territory, Australia, were mapped using an interpretation of 1:50,000 color aerial photography. Manual stereoscopic line-work was delineated at 1:10,000 and thematic maps generated at 1:25,000 and 1:100,000. Multivariate and intuitive analysis techniques were employed to identify 22 vegetation communities within the study area. The accuracy assessment was based on 50% of a field dataset collected over a 4 year period (2006 to 2009) and the remaining 50% of sites were used for map attribution. The overall accuracy and Kappa coefficient for both thematic maps was 66.67% and 0.63, respectively, calculated from standard error matrices. Our findings highlight the need for appropriate scales of mapping and accuracy assessment of aerial photography interpretation generated vegetation community maps.

  5. Rooting strategies in a subtropical savanna: a landscape-scale three-dimensional assessment.

    Science.gov (United States)

    Zhou, Yong; Boutton, Thomas W; Wu, X Ben; Wright, Cynthia L; Dion, Anais L

    2018-04-01

    In resource-limited savannas, the distribution and abundance of fine roots play an important role in acquiring essential resources and structuring vegetation patterns and dynamics. However, little is known regarding the three-dimensional distribution of fine roots in savanna ecosystems at the landscape scale. We quantified spatial patterns of fine root density to a depth of 1.2 m in a subtropical savanna landscape using spatially specific sampling. Kriged maps revealed that fine root density was highest at the centers of woody patches, decreased towards the canopy edges, and reached lowest values within the grassland matrix throughout the entire soil profile. Lacunarity analyses indicated that spatial heterogeneities of fine root density decreased continuously to a depth of 50 cm and then increased in deeper portions of the soil profile across this landscape. This vertical pattern might be related to inherent differences in root distribution between trees/shrubs and herbaceous species, and the presence/absence of an argillic horizon across this landscape. The greater density of fine roots beneath woody patches in both upper and lower portions of the soil profile suggests an ability to acquire disproportionately more resources than herbaceous species, which may facilitate the development and persistence of woody patches across this landscape.

  6. Estimating vegetation dryness to optimize fire risk assessment with spot vegetation satellite data in savanna ecosystems

    Science.gov (United States)

    Verbesselt, J.; Somers, B.; Lhermitte, S.; van Aardt, J.; Jonckheere, I.; Coppin, P.

    2005-10-01

    The lack of information on vegetation dryness prior to the use of fire as a management tool often leads to a significant deterioration of the savanna ecosystem. This paper therefore evaluated the capacity of SPOT VEGETATION time-series to monitor the vegetation dryness (i.e., vegetation moisture content per vegetation amount) in order to optimize fire risk assessment in the savanna ecosystem of Kruger National Park in South Africa. The integrated Relative Vegetation Index approach (iRVI) to quantify the amount of herbaceous biomass at the end of the rain season and the Accumulated Relative Normalized Difference vegetation index decrement (ARND) related to vegetation moisture content were selected. The iRVI and ARND related to vegetation amount and moisture content, respectively, were combined in order to monitor vegetation dryness and optimize fire risk assessment in the savanna ecosystems. In situ fire activity data was used to evaluate the significance of the iRVI and ARND to monitor vegetation dryness for fire risk assessment. Results from the binary logistic regression analysis confirmed that the assessment of fire risk was optimized by integration of both the vegetation quantity (iRVI) and vegetation moisture content (ARND) as statistically significant explanatory variables. Consequently, the integrated use of both iRVI and ARND to monitor vegetation dryness provides a more suitable tool for fire management and suppression compared to other traditional satellite-based fire risk assessment methods, only related to vegetation moisture content.

  7. Savanna fire and the origins of the 'underground forests' of Africa.

    Science.gov (United States)

    Maurin, Olivier; Davies, T Jonathan; Burrows, John E; Daru, Barnabas H; Yessoufou, Kowiyou; Muasya, A Muthama; van der Bank, Michelle; Bond, William J

    2014-10-01

    The origin of fire-adapted lineages is a long-standing question in ecology. Although phylogeny can provide a significant contribution to the ongoing debate, its use has been precluded by the lack of comprehensive DNA data. Here, we focus on the 'underground trees' (=geoxyles) of southern Africa, one of the most distinctive growth forms characteristic of fire-prone savannas. We placed geoxyles within the most comprehensive dated phylogeny for the regional flora comprising over 1400 woody species. Using this phylogeny, we tested whether African geoxyles evolved concomitantly with those of the South American cerrado and used their phylogenetic position to date the appearance of humid savannas. We found multiple independent origins of the geoxyle life-form mostly from the Pliocene, a period consistent with the origin of cerrado, with the majority of divergences occurring within the last 2 million yr. When contrasted with their tree relatives, geoxyles occur in regions characterized by higher rainfall and greater fire frequency. Our results indicate that the geoxylic growth form may have evolved in response to the interactive effects of frequent fires and high precipitation. As such, geoxyles may be regarded as markers of fire-maintained savannas occurring in climates suitable for forests. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.

  8. The Brazilian Twin Registry.

    Science.gov (United States)

    Ferreira, Paulo H; Oliveira, Vinicius C; Junqueira, Daniela R; Cisneros, Lígia C; Ferreira, Lucas C; Murphy, Kate; Ordoñana, Juan R; Hopper, John L; Teixeira-Salmela, Luci F

    2016-12-01

    The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.

  9. BRAZILIAN NEWS PORTALS CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Heloiza G. Herckovitz

    2011-02-01

    Full Text Available A content analysis of four Brazilian news media portals found that economic news dominated the top headlines with little attention paid to education, the environment and welfare. Other trends included a focus on local events and national news sources, reliance on few sources, mostly official ones, and a low percentage of news that fitted the concept of newsworthiness (a combination of both social significance and deviance concepts. Other findings of a study of 432 top news stories published by UOL, Estadão, iG and Terra during a 15-day period between February and March 2008 indicate that the top portions of the portals’ front pages carry news that lacks story depth, editorial branding, and multimedia applications. The results suggest that online news portals are in their infancy although Brazil has the largest online population of Latin America. This study hopes to shed light on the gatekeeping process in Brazilian news portals. Brazilian media portals have yet to become a significant editorial force able to provide knowledge about social issues and public affairs in a socially responsible fashione.

  10. The invasive white ginger lily ( Hedichium coronarium simplifies the trait composition of an insect assemblage in the littoral zone of a Savanna reservoir

    Directory of Open Access Journals (Sweden)

    Hugo Henrique Lanzi Saulino

    Full Text Available ABSTRACT The invasive white ginger lily (Hedichium coronarium - J. Köenig, 1783 simplifies the trait composition of an insect assemblage in the littoral zone of a Savanna reservoir. Invasive plants are believed to shift the trait composition of aquatic insects dwelling in banks of lentic ecosystems. In this study, we analyzed the relationship between the presence of the invasive white ginger lily (H. coronarium and the functional trait indices of the aquatic insect assemblage in the littoral zone of a tropical reservoir. We sampled aquatic insects on the invaded and non-invaded banks of the reservoir and then analyzed the insect trait indices by estimating the Functional Dispersion (FDis, Functional Evenness (FEve and the Functional Divergence (FDiv, as well as the Community level Weight-Mean traits (CWM. Finally, we compared these indices between invaded and non-invaded banks as well as their relationship with the abiotic variables, such as dissolved oxygen, pH, depth and water temperature. The result confirmed that the invaded banks had lower values of functional indices as well as dissolved oxygen. However, this abiotic variable was found to have no effect on the functional indices. In addition, the white ginger lily bank presented higher contribution of collector-gathering to predator-piercer groups. We suggest that the invasion of white ginger lily promotes low heterogeneity habitat resulting in simplification on functional traits of aquatic insect assemblage.

  11. The invasive white ginger lily (Hedichium coronarium simplifies the trait composition of an insect assemblage in the littoral zone of a Savanna reservoir

    Directory of Open Access Journals (Sweden)

    Hugo Henrique Lanzi Saulino

    2017-01-01

    Full Text Available The invasive white ginger lily (Hedichium coronarium – J. Köenig, 1783 simplifies the trait composition of an insect assemblage in the littoral zone of a Savanna reservoir. Invasive plants are believed to shift the trait composition of aquatic insects dwelling in banks of lentic ecosystems. In this study, we analyzed the relationship between the presence of the invasive white ginger lily (H. coronarium and the functional trait indices of the aquatic insect assemblage in the littoral zone of a tropical reservoir. We sampled aquatic insects on the invaded and non-invaded banks of the reservoir and then analyzed the insect trait indices by estimating the Functional Dispersion (FDis, Functional Evenness (FEve and the Functional Divergence (FDiv, as well as the Community level Weight-Mean traits (CWM. Finally, we compared these indices between invaded and non-invaded banks as well as their relationship with the abiotic variables, such as dissolved oxygen, pH, depth and water temperature. The result confirmed that the invaded banks had lower values of functional indices as well as dissolved oxygen. However, this abiotic variable was found to have no effect on the functional indices. In addition, the white ginger lily bank presented higher contribution of collector-gathering to predator-piercer groups. We suggest that the invasion of white ginger lily promotes low heterogeneity habitat resulting in simplification on functional traits of aquatic insect assemblage. Keywords: Biodiversity, Biological invasions, Functional diversity, Lentic system

  12. Landscape changes in a neotropical forest-savanna ecotone zone in central Brazil: The role of protected areas in the maintenance of native vegetation.

    Science.gov (United States)

    Garcia, Andrea S; Sawakuchi, Henrique O; Ferreira, Manuel Eduardo; Ballester, Maria Victoria R

    2017-02-01

    In the Amazon-savanna ecotone in northwest Brazil, the understudied Araguaia River Basin contains high biodiversity and seasonal wetlands. The region is representative of tropical humid-dry ecotone zones, which have experienced intense land use and land cover (LULC) conversions. Here we assessed the LULC changes for the last four decades in the central portion of the Araguaia River Basin to understand the temporal changes in the landscape composition and configuration outside and inside protected areas. We conducted these analyzes by LULC mapping and landscape metrics based on patch classes. During this period, native vegetation was reduced by 26%. Forests were the most threatened physiognomy, with significant areal reduction and fragmentation. Native vegetation cover was mainly replaced by croplands and pastures. Such replacement followed spatial and temporal trends related to the implementation of protected areas and increases in population cattle herds. The creation of most protected areas took place between 1996 and 2007, the same period during which the conversion of the landscape matrix from natural vegetation to agriculture occurred. We observed that protected areas mitigate fragmentation, but their roles differ according to their location and level of protection. Still, we argue that landscape characteristics, such as suitability for agriculture, also influence landscape conversions and should be considered when establishing protected areas. The information provided in this study can guide new research on species conservation and landscape planning, as well as improve the understanding of the impacts of landscape composition and configuration changes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Feedbacks between land cover and climate changes in the Brazilian Amazon and Cerrado biomes

    Science.gov (United States)

    Coe, M. T.; Silverio, D. V.; Bustamante, M.; Macedo, M.; Shimbo, J.; Brando, P. M.

    2016-12-01

    An estimated 20% of Amazon forests and 45% of Cerrado savannas have been cleared to make way for the expansion of croplands and pasturelands in Brazil. Although deforestation rates have decreased or remained steady over the last decade, the cumulative area deforested continues to grow in both biomes. These land-use transitions are expected to influence regional climate by reducing evapotranspiration (ET), increasing land surface temperatures (LST), and ultimately reducing regional precipitation. Here we present results from spatial analyses to quantify the impact of land-use transitions on the regional climate of the Amazon-Cerrado agricultural frontier. The analyses combine satellite observations and model outputs from the MODIS dataset. Results from the southeastern Amazon indicate that transitions from forest to pasture or cropland decreased mean annual ET (by 24% and 32%, respectively) and increased LST (by 4.2°C and 6.4°C). Preliminary results from the Cerrado indicate that transitions from woody savannas to pasture or cropland also result in substantial reductions in mean annual ET (23% and 20%, respectively) and increases in LST (by 1.6°C in both cases). These results reinforce the need to better understand how land-use change at regional scales may alter climate by changing ecosystem properties (beyond carbon stocks and fluxes). It is important to evaluate these responses across different biomes, particularly in tropical regions under increasing deforestation pressure.

  14. Morphological and functional diversity of primary producers group in savannas; Diversidad morfologica y funcional del grupo de productores primarios en sabanas

    Energy Technology Data Exchange (ETDEWEB)

    Medina, E [Instituto Venezolano de Investigaciones Cientificas (IVIC). Centro de Ecologia. Laboratorio de Ecofisiologia Vegetal, Altos de Pipe (Venezuela)

    1996-07-01

    (mutual symbiosis) affect the availability of nutritious, and in consequence the productive capacity of savannas. Although there is a theoretical mark to explain the mechanisms that allow the coexistence of similar species in tropical savannas, the specific echo-physiologic properties are still ignored, even for the most dominant species. The advance in the diversity-function study of tropical savannas requires ambitious programs in order to characterize the way how the different primary producer species make use of the available environmental resources. [Spanish] El significado de la diversidad biologica para el funcionamiento y estabilidad de los ecosistemas naturales es materia de gran interes teorico y practico. La aparicion y permanencia de una especie en un ambiente dado indica su capacidad de competir con otras especies de habito y requerimientos similares y acumular los recursos que le permiten reproducirse. Por otra parte, la coexistencia de especies similares en un mismo ecosistema permite preguntarse si existe 'redundancia biologica', es decir, si coexisten varias especies con una misma funcion dentro del ecosistema, de manera que la desaparicion de una de ellas no tendria consecuencias biologicas significativas. Una estrategia para simplificar el analisis de las relaciones entre biodiversidad y funcionamiento de ecosistemas es la agrupacion de especies de funcion similar, los llamados grupos funcionales. En este trabajo se analiza el grupo funcional de los productores primarios, esencialmente plantas superiores, en ecosistemas de sabanas. El analisis establece que el grupo de los productores primarios es heterogeneo y complejo, tanto morfologica como funcionalmente: 1) La complejidad estructural y diversidad de formas de vida en un ecosistema de sabanas estan asociadas con la explotacion estratificada de recursos por encima (luz) debajo del suelo (nutrientes y agua). Cambios de diversidad que afecten la estructura del sistema muy probablemente afectaran su

  15. Bezerromycetales and Wiesneriomycetales ord. nov. (class Dothideomycetes), with two novel genera to accommodate endophytic fungi from Brazilian cactus

    NARCIS (Netherlands)

    Bezerra, Jadson D. P.; Oliveira, Rafael J. V.; Paiva, Laura M.; Silva, Gladstone A.; Groenewald, Johannes Z.; Crous, Pedro W.; Souza-Motta, Cristina M.

    During a survey of endophytic fungi from the cactus Tacinga inamoena in a Brazilian tropical dry forest (Caatinga) some undescribed ascomycetous fungi were isolated. These fungi are characterized by superficial and immersed, globose to subglobose, smooth or hairy ascomata, bitunicate asci, and

  16. The impact of wood biochar as a soil amendment in aerobic rice systems of the Brazilian Savannah

    NARCIS (Netherlands)

    Carvalho, M.T.M.

    2015-01-01

    Abstract

    Keywords: tropical Savannah, biochar, soil fertility, aerobic rice, grain yield, N2O emission

    Márcia Thaís de Melo Carvalho (2015). The impact of wood biochar as a soil amendment in aerobic rice systems of the Brazilian Savannah. PhD thesis,

  17. Isotopes in tropical agriculture

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1962-04-15

    Ways in which the use of radioisotopes and radiation can help to improve the agriculture of tropical Africa were discussed by a panel of experts. The panel included scientists from Africa, Europe, and the United States, most of whom had had actual experience dealing with agricultural problems in various parts of tropical Africa. The experts agreed that radioisotopes and radiation might now be employed to particular advantage in tropical Africa to improve crop nutrition and combat insect pests. Other applications discussed were in the fields of hydrology, plant breeding and food preservation

  18. Isotopes in tropical agriculture

    International Nuclear Information System (INIS)

    1962-01-01

    Ways in which the use of radioisotopes and radiation can help to improve the agriculture of tropical Africa were discussed by a panel of experts. The panel included scientists from Africa, Europe, and the United States, most of whom had had actual experience dealing with agricultural problems in various parts of tropical Africa. The experts agreed that radioisotopes and radiation might now be employed to particular advantage in tropical Africa to improve crop nutrition and combat insect pests. Other applications discussed were in the fields of hydrology, plant breeding and food preservation

  19. Study of the mobilization of pollutants in soils of the Bogota Savanna - phase 1, Heavy Metals

    International Nuclear Information System (INIS)

    Gonzalez, Luz Myrian; Vargas Zarate, Orlando

    1997-01-01

    In this study the soils contamination of the Bogota Savanna was evaluated by heavy metals, that they have importance to be this the area of population's of the country bigger density, where the use of the soils has suffered changes in the last years that have affected its properties, as consequence of the not controlled growth of the urban area, of the industrialization and of the agricultural use not planned. As a first stage toward the risk evaluation for the presence of metals weighed in the soils of the Bogota Savanna, the concentrations of cadmium, cobalt, chromium, copper, manganese, nickel, lead, zinc, molybdenum, arsenic and mercury were measured. It was also measured the movilizable fraction and the mobile fraction, that is to say, the quantity of metals that can be taken by the roots of the plants or that it can be leached toward the water bodies. Equally, the soils of the Savanna were characterized in an area of the plane part that covers 800 km 2 , as for the physical and chemical properties that can affect the retention and mobilization of heavy metals. The results obtained shows elements, that will allow in a future to develop mobilization and transport models, adapted for our specific conditions and to make an risks evaluation for the population's health, foods consumption on these soils or for the possibility of contamination of the underground waters. The obtained data of levels of heavy metals and other properties of the soils will serve as base for future studies of the conditions of the Savanna soils and for the establishment of standard of quality in our country. During 1997 it plans to enlarge the study area to 1200 km 2 and to begin the sampling and analysis of the soils. In the first phase of the study were found levels of heavy metals that overcome the world averages especially cadmium, cobalt, nickel, lead and zinc and in some cases chromium and mercury, levels that put in evidence the existence an ecological risk and for the population

  20. Precipitation chemistry and wet deposition in a remote wet savanna site in West Africa: Djougou (Benin)

    Science.gov (United States)

    Akpo, A. B.; Galy-Lacaux, C.; Laouali, D.; Delon, C.; Liousse, C.; Adon, M.; Gardrat, E.; Mariscal, A.; Darakpa, C.

    2015-08-01

    In the framework of the IDAF (IGAC/DEBITS/AFrica) international program, this study aims to study the chemical composition of precipitation and associated wet deposition at the rural site of Djougou in Benin, representative of a West and Central African wet savanna. Five hundred and thirty rainfall samples were collected at Djougou, Benin, from July 2005 to December 2009 to provide a unique database. The chemical composition of precipitation was analyzed for inorganic (Ca2+, Mg2+, Na+, NH4+, K+, NO3-, Cl-, SO42-) and organic (HCOO-, CH3COO-, C2H5COO-, C2O42-) ions, using ion chromatography. The 530 collected rain events represent a total of 5706.1 mm of rainfall compared to the measured pluviometry 6138.9 mm, indicating that the collection efficiency is about 93%. The order of total annual loading rates for soluble cations is NH4+ > Ca2+ > Mg2+ > K+. For soluble anions the order of loading is carbonates > HCOO- > NO3- > CH3COO- > SO42- > Cl- > C2O42- > C2H5COO-. In the wet savanna of Djougou, 86% of the measured pH values range between 4.7 and 5.7 with a median pH of 5.19, corresponding to a VWM (Volume Weighed Mean) H+ concentration of 6.46 μeq·L-1. This acidity results from a mixture of mineral and organic acids. The annual sea salt contribution was computed for K+, Mg2+, Ca2+ and SO42- and represents 4.2% of K+, 41% of Mg2+, 1.3% of Ca2+, and 7.4% of SO42-. These results show that K+, Ca2+, SO42-, and Mg2+ were mainly of non-marine origin. The marine contribution is estimated at 9%. The results of the chemical composition of rainwater of Djougou indicates that, except for the carbonates, ammonium has the highest VWM concentration (14.3 μeq·L-1) and nitrate concentration is 8.2 μeq·L-1. The distribution of monthly VWM concentration for all ions is computed and shows the highest values during the dry season, comparing to the wet season. Identified nitrogenous compound sources (NOx and NH3) are domestic animals, natural emissions from savanna soils, biomass

  1. Project 11. Cowpea - Cereals Systems Improvement in the Dry Savannas

    International Nuclear Information System (INIS)

    1998-01-01

    The research agenda of the IITA is subdivided into a portfolio of 16 projects (Annex 1), around which these annual reports are prepared. These projects address different aspects of attaining sustainable increases in productivity of dominant farming systems and utilization practices in the various agroecologies of Sub-Saharan Africa (SSA). Research and training activities carried out in the 16 projects are being implemented together with national program partners in order to increase the well-being of poor people in SSA through higher levels of food production, better income and nutritional status, and reduced drudgery - particularly for women. Additionally IITA serves as the convening centre for the Ecoregional Program for the Humid and Sub Humid Tropics of Sub-Saharan Africa (EPHTA) and the Systemwide Project on Integrated Pest Management (SP-IPM). The institute-wide log frame (Annex 2) shows the expected contribution of each project to the overall institute goal, with the specific project log frame presented in Annex 3. Highlights from all these projects can be found in Annex 4, which thus provides an illustrative overview of IITA's research activities and achievements of the year. Annex 5 shows all the agroecological zones of sub-saharan Africa in which IITA conducts research. The project management arrangement for implementing IITA's research agenda is relatively new, and continues to evolve from a divisional/program structure. In earlier years, detailed research outputs and achievements were reported in divisional reports; this is the third year that implementation of IITA's research agenda is being presented in individual project reports. To satisfy the continuing needs of disciplinary groups in partner and other interested institutions, portions from the individual project reports will be collated into subject matter reports corresponding to current research divisions -Crop improvement, Plant Health Management, and Resource and Crop Management

  2. Hydrological studies in Brazilian Northeast

    International Nuclear Information System (INIS)

    1981-01-01

    Studies carried on as a result of collaboration between the Federal University of Ceara, Brazil (research team) and the Brazilian Northeastern Bank (financing agency), aiming at a better knowledge of the hydrological problems of Brazilian Northeastern region, are described. (I.C.R.) [pt

  3. Brazilian Portuguese Ethnonymy and Europeanisms.

    Science.gov (United States)

    Stephens, Thomas M.

    1994-01-01

    Delineates the incorporation and analyzes the impact of European borrowings in Brazilian racio-ethnic terminology. This overview covers French, Italian, Spanish, and English influences. Borrowings from European languages have had a small impact on the calculus of Brazilian racio-ethnic terms. (43 references) (Author/CK)

  4. Managing migration: the Brazilian case

    OpenAIRE

    Eduardo L. G. Rios-Neto

    2005-01-01

    The objective of this paper is to present the Brazilian migration experience and its relationship with migration management. The article is divided into three parts. First, it reviews some basic facts regarding Brazilian immigration and emigration processes. Second, it focuses on some policy and legal issues related to migration. Finally, it addresses five issues regarding migration management in Brazil.

  5. Tropical Diabetic Hand Syndrome

    African Journals Online (AJOL)

    2015 Annals of Medical and Health Sciences Research | Published by Wolters Kluwer - Medknow. 473. Introduction ... diabetes.[2,3] Tropical diabetic hand syndrome is a terminology .... the importance of seeking medical attention immediately.

  6. Malaria and Tropical Travel

    Centers for Disease Control (CDC) Podcasts

    Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection.

  7. GARP Atlantic Tropical Experiment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The GARP Atlantic Tropical Experiment (GATE) was the first major international experiment of the Global Atmospheric Research Program (GARP). It was conducted over...

  8. Nesting success of grassland and savanna birds on reclaimed surface coal mines of the midwestern United States

    Energy Technology Data Exchange (ETDEWEB)

    Galligan, E.W.; DeVault, T.L.; Lima, S.L. [Indiana State University, Terre Haute, IN (United States)

    2006-12-15

    Reclaimed surface coal mines in southwestern Indiana support many grassland and shrub/savanna bird species of conservation concern. We examined the nesting success of birds on these reclaimed mines to assess whether such 'unnatural' places represent productive breeding habitats for such species. We established eight study sites on two large, grassland-dominated mines in southwestern Indiana and classified them into three categories (open grassland, shrub/savanna, and a mixture of grassland and shrub/savanna) based on broad vegetation and landscape characteristics. During the 1999 and 2000 breeding seasons, we found and monitored 911 nests of 31 species. Daily nest survival for the most commonly monitored grassland species ranged from 0.903 (Dickcissel, Spiza americana) to 0.961 (Grasshopper Sparrow, Ammodramus savannarum). Daily survival estimates for the dominant shrub/savanna nesting species ranged from 0.932 (Brown Thrasher, Toxostoma rufum) to 0.982 (Willow Flycatcher, Empidonax traillii). Vegetation and landscape effects on nesting success were minimal, and only Eastern Meadowlarks (Sturnella magna) showed a clear time-of-season effect, with greater nesting success in the first half of the breeding season. Rates of Brown-headed Cowbird (Molothrus ater) parasitism were only 2.1% for grassland species and 12.0% for shrub/savanna species. The nesting success of birds on reclaimed mine sites was comparable to that in other habitats, indicating that reclaimed habitats on surface mines do not necessarily represent reproductive traps for birds.

  9. IASI-derived NH3 enhancement ratios relative to CO for the tropical biomass burning regions

    Science.gov (United States)

    Whitburn, Simon; Van Damme, Martin; Clarisse, Lieven; Hurtmans, Daniel; Clerbaux, Cathy; Coheur, Pierre-François

    2017-10-01

    Vegetation fires are a major source of ammonia (NH3) in the atmosphere. Their emissions are mainly estimated using bottom-up approaches that rely on uncertain emission factors. In this study, we derive new biome-specific NH3 enhancement ratios relative to carbon monoxide (CO), ERNH3 / CO (directly related to the emission factors), from the measurements of the IASI sounder onboard the Metop-A satellite. This is achieved for large tropical regions and for an 8-year period (2008-2015). We find substantial differences in the ERNH3 / CO ratios between the biomes studied, with calculated values ranging from 7 × 10-3 to 23 × 10-3. For evergreen broadleaf forest these are typically 50-75 % higher than for woody savanna and savanna biomes. This variability is attributed to differences in fuel types and size and is in line with previous studies. The analysis of the spatial and temporal distribution of the ERNH3 / CO ratio also reveals a (sometimes large) within-biome variability. On a regional level, woody savanna shows, for example, a mean ERNH3 / CO ratio for the region of Africa south of the Equator that is 40-75 % lower than in the other five regions studied, probably reflecting regional differences in fuel type and burning conditions. The same variability is also observed on a yearly basis, with a peak in the ERNH3 / CO ratio observed for the year 2010 for all biomes. These results highlight the need for the development of dynamic emission factors that take into better account local variations in fuel type and fire conditions. We also compare the IASI-derived ERNH3 / CO ratio with values reported in the literature, usually calculated from ground-based or airborne measurements. We find general good agreement in the referenced ERNH3 / CO ratio except for cropland, for which the ERNH3 / CO ratio shows an underestimation of about 2-2.5 times.

  10. Radioprotection in Brazilian universities

    International Nuclear Information System (INIS)

    Caballero, K.C.; Borges, J.C.

    1992-01-01

    The purpose of this work was to obtain a broad knowledge of the circumstances under which activities involving ionizing radiations are held at brazilian academic institutions. Around 90 institutions (universities and isolated schools of both public and private sectors) were invited, by mail, to answer an inquiry with questions from technical to legal aspects of their activities with radiations. Information received from 2/3 of institutions contacted, permitted conclusions as: there is a wide ignorance about radioprotection procedures and legislation, although few universities maintain some efficient radioprotection staff; there is a need for the establishment of a standard radioprotection text dedicated to those specific activities of the sector. (author)

  11. Brazilian energy overview

    International Nuclear Information System (INIS)

    Souza, J.A.M. de.

    1975-01-01

    The Brazilian energy overview compared with the rest of the world is presented, as well as the current situation and prospects for the future. In a first part, the evalution from the past through the present time is considered, and in a second part, attention is given on the future prospects for Brazil and the different countries in connection with the energy field. It is expected that the current per capita energy consumption in Brazil, in all of its various forms, now totalling 6 million kcal/inh, will reach at least 22 million kcal/inh toward the end of this century

  12. Pneumonia in the tropics.

    Science.gov (United States)

    Lim, Tow Keang; Siow, Wen Ting

    2018-01-01

    Pneumonia in the tropics poses a heavy disease burden. The complex interplay of climate change, human migration influences and socio-economic factors lead to changing patterns of respiratory infections in tropical climate but also increasingly in temperate countries. Tropical and poorer countries, especially South East Asia, also bear the brunt of the global tuberculosis (TB) pandemic, accounting for almost one-third of the burden. But, as human migration patterns evolve, we expect to see more TB cases in higher income as well as temperate countries, and rise in infections like scrub typhus from ecotourism activities. Fuelled by the ease of air travel, novel zoonotic infections originating from the tropics have led to global respiratory pandemics. As such, clinicians worldwide should be aware of these new conditions as well as classical tropical bacterial pneumonias such as melioidosis. Rarer entities such as co-infections of leptospirosis and chikungunya or dengue will need careful consideration as well. In this review, we highlight aetiologies of pneumonia seen more commonly in the tropics compared with temperate regions, their disease burden, variable clinical presentations as well as impact on healthcare delivery. © 2017 Asian Pacific Society of Respirology.

  13. Long-term effects of fire frequency and season on herbaceous vegetation in savannas of the Kruger National Park, South Africa

    CSIR Research Space (South Africa)

    Smith, MD

    2012-05-01

    Full Text Available in savannas, the experimental burn plots (EBPs), which is located in the Kruger National Park (South Africa) and encompasses four major savanna vegetation types that span broad spatial gradients of rainfall (450–700mm) and soil fertility....

  14. Biodiversity effects on ecosystem function due to land use: The case of buffel savannas in the Sky Islands Seas in the central region of Sonora

    Science.gov (United States)

    A. E. Castellanos; H. Celaya; C. Hinojo; A. Ibarra; J. R. Romo

    2013-01-01

    Buffel savannas have been an important landscape on cattle grazing ranches in Sonora over the past 50 years or more. Changes in land use result in biodiversity changes that may produce ecosystem functional changes; however, these are less well documented. Although fire driven processes have been proposed for Buffel savannas, this is not generally the case, and other...

  15. On the suitability of MODIS time series metrics to map vegetation types in dry savanna ecosystems: A case study in the Kalahari of NE Namibia

    NARCIS (Netherlands)

    Hüttich, C.; Gessner, U.; Herold, M.; Strohbach, B.; Schmidt, M.; Keil, M.; Dech, S.

    2009-01-01

    The characterization and evaluation of the recent status of biodiversity in Southern Africa’s Savannas is a major prerequisite for suitable and sustainable land management and conservation purposes. This paper presents an integrated concept for vegetation type mapping in a dry savanna ecosystem

  16. Variation in wood anatomy of species with a distribution covering both rain forest and savanna areas of the Ivory Coast, West-Africa

    NARCIS (Netherlands)

    Outer, den R.W.; Veenendaal, van W.L.H.

    1976-01-01

    The variation in wood anatomy within 30 hardwood species, each with a distribution covering both rain forest and savanna areas of the Ivory Coast, Africa, has been studied. Compared to specimens from the rain forest, material from the savanna tends to have more wood ray tissue (rays are higher,

  17. Neglected tropical diseases outside the tropics.

    Directory of Open Access Journals (Sweden)

    Francesca F Norman

    Full Text Available BACKGROUND: The neglected tropical diseases (NTDs cause significant morbidity and mortality worldwide. Due to the growth in international travel and immigration, NTDs may be diagnosed in countries of the western world, but there has been no specific focus in the literature on imported NTDs. METHODS: Retrospective study of a cohort of immigrants and travelers diagnosed with one of the 13 core NTDs at a Tropical Medicine Referral Unit in Spain during the period April 1989-December 2007. Area of origin or travel was recorded and analyzed. RESULTS: There were 6168 patients (2634 immigrants, 3277 travelers and 257 VFR travelers in the cohort. NTDs occurred more frequently in immigrants, followed by VFR travelers and then by other travelers (p<0.001 for trend. The main NTDs diagnosed in immigrants were onchocerciasis (n = 240, 9.1% acquired mainly in sub-Saharan Africa, Chagas disease (n = 95, 3.6% in immigrants from South America, and ascariasis (n = 86, 3.3% found mainly in immigrants from sub-Saharan Africa. Most frequent NTDs in travelers were: schistosomiasis (n = 43, 1.3%, onchocerciasis (n = 17, 0.5% and ascariasis (n = 16, 0.5%, and all were mainly acquired in sub-Saharan Africa. The main NTDs diagnosed in VFR travelers were onchocerciasis (n = 14, 5.4%, and schistosomiasis (n = 2, 0.8%. CONCLUSIONS: The concept of imported NTDs is emerging as these infections acquire a more public profile. Specific issues such as the possibility of non-vectorial transmission outside endemic areas and how some eradication programmes in endemic countries may have an impact even in non-tropical western countries are addressed. Recognising NTDs even outside tropical settings would allow specific prevention and control measures to be implemented and may create unique opportunities for research in future.

  18. Linking spatial patterns of land-use to agents of deforestation in the Brazilian Amazon

    OpenAIRE

    Borrego Lorena, Rodrigo

    2008-01-01

    Changes in land use and land cover are associated with many environmental issues observed on the earth’s surface. In the last decades, these changes were unprece-dented, mainly in tropical forest areas. The Brazilian Amazon, the world’s largest tropical forest, lost around 200.000 km² of primary forest in the last ten years (INPE, 2005). Considering this, and the consequences caused by this deforestation, it is important to know and define correctly the responsible agents, aiming at better pu...

  19. Community owned solutions for fire management in tropical ecosystems: case studies from Indigenous communities of South America.

    Science.gov (United States)

    Mistry, Jayalaxshmi; Bilbao, Bibiana A; Berardi, Andrea

    2016-06-05

    Fire plays an increasingly significant role in tropical forest and savanna ecosystems, contributing to greenhouse gas emissions and impacting on biodiversity. Emerging research shows the potential role of Indigenous land-use practices for controlling deforestation and reducing CO2 emissions. Analysis of satellite imagery suggests that Indigenous lands have the lowest incidence of wildfires, significantly contributing to maintaining carbon stocks and enhancing biodiversity. Yet acknowledgement of Indigenous peoples' role in fire management and control is limited, and in many cases dismissed, especially in policy-making circles. In this paper, we review existing data on Indigenous fire management and impact, focusing on examples from tropical forest and savanna ecosystems in Venezuela, Brazil and Guyana. We highlight how the complexities of community owned solutions for fire management are being lost as well as undermined by continued efforts on fire suppression and firefighting, and emerging approaches to incorporate Indigenous fire management into market- and incentive-based mechanisms for climate change mitigation. Our aim is to build a case for supporting Indigenous fire practices within all scales of decision-making by strengthening Indigenous knowledge systems to ensure more effective and sustainable fire management.This article is part of the themed issue 'The interaction of fire and mankind'. © 2016 The Author(s).

  20. Studying the Effects of Amazonian Land Cover Change on Glacier Mass Balance in the Tropical Andes

    Science.gov (United States)

    Mark, B. G.; Fernandez, A.; Gabrielli, P.; Montenegro, A.; Postigo, J.; Hellstrom, R. A.

    2017-12-01

    Recent research has highlighted several ongoing environmental changes occurring across Tropical South America, including Andean glacier retreat, drought, as well as changes in land-use and land-cover. As the regional climate of the area is mostly characterized by land-ocean interactions, the atmospheric convection in the Amazon, and the effect of the Andes on circulation patterns, it follows that changes in one of those regions may affect the other. Most scholars who have studied the causes of tropical glaciers' fluctuations have not analyzed the linkages with changes in the Amazon with the same attention paid to the influence of Pacific sea surface temperature. Here we study the response of glacier surface mass balance in the Cordillera Blanca, Peru (10°S), to a scenario where the Amazonian rainforest is replaced by savannas. We ran climatic simulations at 2-km spatial resolution utilizing the Weather Research and Forecasting (WRF) model considering two scenarios: (a) control (CRTL), with today's rainforest extent; and (b) land cover change (LCC), where all the rainforest was replaced by savanna. WRF output was in turn ingested into a glacier energy and mass balance (GEMB) model that we validate by reconstructing both the accumulated mass balance from available observations, and the altitudinal distribution of mass balance in the region. Seasonal comparison between CRTL and LCC scenarios indicates that forest replacement by savanna results in more positive glacier mass balance. This shift to more positive mass balance contrasts with a (WRF) modeled rise in the elevation of the freezing line (0°C) between 30 to 120 m for the LCC scenario. Our results are surprising because most previous studies have shown that reducing Amazon forest cover diminishes rainfall and increases temperature, suggesting that glaciers should lose mass. We hypothesize and discuss implications of possible land-atmospheric processes that might drive this tropical glacier response to

  1. Whole-island carbon stocks in the tropical Pacific: implications for mangrove conservation and upland restoration.

    Science.gov (United States)

    Donato, D C; Kauffman, J B; Mackenzie, R A; Ainsworth, A; Pfleeger, A Z

    2012-04-30

    Management of forest carbon (C) stocks is an increasingly prominent land-use issue. Knowledge of carbon storage in tropical forests is improving, but regional variations are still poorly understood, and this constrains forest management and conservation efforts associated with carbon valuation mechanisms (e.g., carbon markets). This deficiency is especially pronounced in tropical islands and low-lying coastal areas where climate change impacts are expected to be among the most severe. This study presents the first field estimate of island-wide carbon storage in ecosystems of Oceania, with special attention to the regional role of coastal mangroves, which occur on islands and coastal zones throughout the tropics. On two island groups of Micronesia (Yap and Palau), we sampled all above- and belowground C pools, including soil and vegetation, in 24 sites distributed evenly among the three major vegetation structural types: mangroves, upland forests, and open savannas (generally on degraded lands formerly forested). Total C stocks were estimated to be 3.9 and 15.2 Tg C on Yap and Palau, respectively. Mangroves contained by far the largest per-hectare C pools (830-1218 Mg C ha(-1)), with deep organic-rich soils alone storing more C (631-754 Mg C ha(-1)) than all pools combined in upland systems. Despite covering just 12-13% of land area, mangroves accounted for 24-34% of total island C stocks. Savannas (156-203 Mg C ha(-1)) contained significantly lower C stocks than upland forests (375-437 Mg C ha(-1)), suggesting that reforesting savannas where appropriate has high potential for carbon-based funding to aid restoration objectives. For mangroves, these results demonstrate the key role of these systems within the broader context of C storage in island and coastal landscapes. Sustainable management of mangrove forests and their large C stocks is of high importance at the regional scale, and climate change mitigation programs such as REDD+ could play a large role in

  2. The Brazilian Bolsa Escola

    Directory of Open Access Journals (Sweden)

    Rachel Cassidy

    2008-12-01

    Full Text Available The Bolsa Escola (‘school stipend’ and its successor the Bolsa Familia (‘family stipend’ schemes have formed a crucial and successful part of Brazil’s welfare program. Bolsa Escola provided aid to Brazil’s poorest families on the condition that their children attended school, and Bolsa Familia has extended this idea, giving aid on the condition that children both attend school and receive vaccinations. Bolsa Familia is currently the largest Conditional Cash Transfer Program (CCTP in the world, costing roughly 0.5% of Brazilian GDP and helping around 11.2 million families (around 44 million Brazilians, constituting roughly one fifth of the population. Multilateral institutions have praised the schemes, and they are setting a leading example to other developing nations. In 2005, Paul Wolfowitz (former president of the World Bank said, ‘Bolsa Familia has already become a highly praised model of effective social policy. Countries around the world are drawing lessons from Brazil’s experience and are trying to produce the same results for their own people’.

  3. Phosphorus migration analysis using synchrotron radiation in soil treated with Brazilian granular fertilizers

    International Nuclear Information System (INIS)

    Castro, Robson C. de; Melo Benites, Vinícius de; César Teixeira, Paulo; Anjos, Marcelino José dos; Oliveira, Luis Fernando de

    2015-01-01

    The aim of this study was to evaluate the phosphorus (P) mobility in a tropical Brazilian soil type red Oxisol treated with three different forms of granular fertilizer. Total Reflection X-Ray Fluorescence (TXRF) was applied to determine the concentration of P at different distances from granular fertilizer application point. The results showed that most of the P from fertilizers tends to concentrate in a region of up to 10 mm around the place of the fertilizer deposition. - Highlights: • Phosphorus (P) mobility in a tropical Brazilian soil. • Total Reflection X-Ray Fluorescence was applied to determine the concentration of P. • Fertilizers used monoammonium phosphate and polymer coated monoammonium phosphate.

  4. Origin and dynamics of the northern South American coastal savanna belt during the Holocene - the role of climate, sea-level, fire and humans

    Science.gov (United States)

    Alizadeh, Kamaleddin; Cohen, Marcelo; Behling, Hermann

    2015-08-01

    Presence of a coastal savanna belt expanding from British Guiana to northeastern Brazil cannot be explained by present-day climate. Using pollen and charcoal analyses on an 11.6 k old sediment core from a coastal depression in the savanna belt near the mouth of the Amazon River we investigated the paleoenvironmental history to shed light on this question. Results indicate that small areas of savanna accompanied by a forest type composed primarily by the genus Micropholis (Sapotaceae) that has no modern analog existed at the beginning of the Holocene. After 11,200 cal yr BP, savanna accompanied by few trees replaced the forest. In depressions swamp forest developed and by ca 10,000 cal yr BP replaced by Mauritia swamps. Between 8500 and 5600 cal yr BP gallery forest (composed mainly of Euphorbiaceae) and swamp forest succeeded the treeless savanna. The modern vegetation with alternating gallery forest and savanna developed after 5600 cal yr BP. We suggest that the early Holocene no-analog forest is a relict of previously more extensive forest under cooler and moister Lateglacial conditions. The early Holocene savanna expansion indicates a drier phase probably related to the shift of the Intertropical Convergence Zone (ITCZ) towards its northernmost position. The mid-Holocene forest expansion is probably a result of the combined influence of equatorwards shift of ITCZ joining the South Atlantic Convergence Zone (SACZ). The ecosystem variability during the last 5600 cal yr BP, formed perhaps under influence of intensified ENSO condition. High charcoal concentrations, especially during the early Holocene, indicate that natural and/or anthropogenic fires may have maintained the savanna. However, our results propose that climate change is the main driving factor for the formation of the coastal savanna in this region. Our results also show that the early Holocene sea level rise established mangroves near the study site until 7500 cal yr BP and promoted swamp formation in

  5. Preferential Production and Transport of Grass-Derived Pyrogenic Carbon in NE-Australian Savanna Ecosystems

    Directory of Open Access Journals (Sweden)

    Gustavo Saiz

    2018-01-01

    Full Text Available Understanding the main factors driving fire regimes in grasslands and savannas is critical to better manage their biodiversity and functions. Moreover, improving our knowledge on pyrogenic carbon (PyC dynamics, including formation, transport and deposition, is fundamental to better understand a significant slow-cycling component of the global carbon cycle, particularly as these ecosystems account for a substantial proportion of the area globally burnt. However, a thorough assessment of past fire regimes in grass-dominated ecosystems is problematic due to challenges in interpreting the charcoal record of sediments. It is therefore critical to adopt appropriate sampling and analytical methods to allow the acquisition of reliable data and information on savanna fire dynamics. This study uses hydrogen pyrolysis (HyPy to quantify PyC abundance and stable isotope composition (δ13C in recent sediments across 38 micro-catchments covering a wide range of mixed C3/C4 vegetation in north Queensland, Australia. We exploited the contrasting δ13C values of grasses (i.e., C4; δ13C > −15‰ and woody vegetation (i.e., C3; δ13C < −24‰ to assess the preferential production and transport of grass-derived PyC in savanna ecosystems. Analyses were conducted on bulk and size-fractionated samples to determine the fractions into which PyC preferentially accumulates. Our data show that the δ13C value of PyC in the sediments is decoupled from the δ13C value of total organic carbon, which suggests that a significant component of PyC may be derived from incomplete grass combustion, even when the proportion of C4 grass biomass in the catchment was relatively small. Furthermore, we conducted 16 experimental burns that indicate that there is a comminution of PyC produced in-situ to smaller particles, which facilitates the transport of this material, potentially affecting its preservation potential. Savanna fires preferentially burn the grass understory rather than

  6. Life Expectancy of Brazilian Neurosurgeons.

    Science.gov (United States)

    Botelho, Ricardo Vieira; Jardim Miranda, Bárbara Cristina; Nishikuni, Koshiro; Waisberg, Jaques

    2018-06-01

    Life expectancy (LE) refers to the number of years that an individual is expected to survive. Emphasis is frequently placed on the relationship between LE and the conditions under which a population lives, but fewer studies have investigated the relationship between stress factors associated with specific professions and their effects on LE. The aim of this study is to evaluate Brazilian neurosurgeons' life expectancies (BNLEs) and compare them with those of physicians (both Brazilian and foreign) from other fields, as well as with Brazilian nondoctors. The Brazilian Society of Neurosurgery death registry was used to obtain data that compared LEs from non-neurosurgeon physicians, as described in the national and international literature. BNLEs were also compared with the LEs of Brazilian citizens. Fifty-one neurosurgeons died between 2009 and 2016. All were males. The mean age at death was 68.31 ± 17.71 years. Among all-cause mortality, the breakdown was 20% cardiovascular diseases, 39% malignancies, 10% external factors, 6% gastrointestinal disorders, 12% neurologic illnesses, and 14% unknown causes. BNLE was shorter than LE of male Brazilian citizens. LE was similar among neurosurgeons and other doctors but shorter compared with Brazilian citizens. Further research is needed to provide data that can add to and confirm these results. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. The costs of living at the edge: Seasonal stress in wild savanna-dwelling chimpanzees.

    Science.gov (United States)

    Wessling, Erin G; Kühl, Hjalmar S; Mundry, Roger; Deschner, Tobias; Pruetz, Jill D

    2018-04-20

    Adaptations associated with shifting from a predominately forested habitat to a more open environment are considered a crucial step in hominin evolution. Understanding how chimpanzees, one of our closest-living relatives, are exposed to the selection pressures associated with living in a relatively sparse, hot, and dry environment can inform us about the relative importance of potential environmental stressors involved in adaptations to drier environments. We investigated the extent to which chimpanzees living in an extreme savanna habitat experience seasonal variability in either energy balance or thermoregulation (dehydration and heat exposure), as well as whether these potential environmental constraints are taxing to chimpanzee individuals. Specifically, we tested the hypothesis that savanna environments impose seasonally-relevant costs to chimpanzees. To this end, we collected 368 urine samples from one community of chimpanzees at Fongoli, Senegal, and measured c-peptide, creatinine, and cortisol as measures of physiological responses to environmental food, water, and heat constraints, respectively. We then evaluated the influence of climatic and phenological factors on these indicators. Results illustrated significant seasonal variation in all biomarkers, which corresponded to relevant ecological correlates. Furthermore, creatinine but not c-peptide correlated with cortisol levels, suggesting that chimpanzees in this environment endure periods of heat and dehydration stress, but are able to avoid stressful levels of negative energy balance. Using savanna chimpanzees as a referential model, our research lends support to the notion that thermoregulatory challenges were a significant factor in hominin evolution, and suggests these challenges may have overshadowed the challenges of maintaining adequate energetic balance during the expansion of the hominin range from wetter to drier environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Carbon mapping of Argentine savannas: Using fractional tree cover to scale from field to region

    Science.gov (United States)

    González-Roglich, M.; Swenson, J. J.

    2015-12-01

    Programs which intend to maintain or enhance carbon (C) stocks in natural ecosystems are promising, but require detailed and spatially explicit C distribution models to monitor the effectiveness of management interventions. Savanna ecosystems are significant components of the global C cycle, covering about one fifth of the global land mass, but they have received less attention in C monitoring protocols. Our goal was to estimate C storage across a broad savanna ecosystem using field surveys and freely available satellite images. We first mapped tree canopies at 2.5 m resolution with a spatial subset of high resolution panchromatic images to then predict regional wall-to-wall tree percent cover using 30-m Landsat imagery and the Random Forests algorithms. We found that a model with summer and winter spectral indices from Landsat, climate and topography performed best. Using a linear relationship between C and % tree cover, we then predicted tree C stocks across the gradient of tree cover, explaining 87 % of the variability. The spatially explicit validation of the tree C model with field-measured C-stocks revealed an RMSE of 8.2 tC/ha which represented ~30% of the mean C stock for areas with tree cover, comparable to studies based on more advanced remote sensing methods, such as LiDAR and RADAR. Sample spatial distribution highly affected the performance of the RF models in predicting tree cover, raising concerns regarding the predictive capabilities of the model in areas for which training data is not present. The 50,000 km2 has ~41 Tg C, which could be released to the atmosphere if agricultural pressure intensifies in this semiarid savanna.

  9. Evaporation from cultivated and semi-wild Sudanian Savanna in west Africa

    Science.gov (United States)

    Ceperley, Natalie C.; Mande, Theophile; van de Giesen, Nick; Tyler, Scott; Yacouba, Hamma; Parlange, Marc B.

    2017-08-01

    Rain-fed farming is the primary livelihood of semi-arid west Africa. Changes in land cover have the potential to affect precipitation, the critical resource for production. Turbulent flux measurements from two eddy-covariance towers and additional observations from a dense network of small, wireless meteorological stations combine to relate land cover (savanna forest and agriculture) to evaporation in a small (3.5 km2) catchment in Burkina Faso, west Africa. We observe larger sensible and latent heat fluxes over the savanna forest in the headwater area relative to the agricultural section of the watershed all year. Higher fluxes above the savanna forest are attributed to the greater number of exposed rocks and trees and the higher productivity of the forest compared to rain-fed, hand-farmed agricultural fields. Vegetation cover and soil moisture are found to be primary controls of the evaporative fraction. Satellite-derived vegetation index (NDVI) and soil moisture are determined to be good predictors of evaporative fraction, as indicators of the physical basis of evaporation. Our measurements provide an estimator that can be used to derive evaporative fraction when only NDVI is available. Such large-scale estimates of evaporative fraction from remotely sensed data are valuable where ground-based measurements are lacking, which is the case across the African continent and many other semi-arid areas. Evaporative fraction estimates can be combined, for example, with sensible heat from measurements of temperature variance, to provide an estimate of evaporation when only minimal meteorological measurements are available in remote regions of the world. These findings reinforce local cultural beliefs of the importance of forest fragments for climate regulation and may provide support to local decision makers and rural farmers in the maintenance of the forest areas.

  10. Termites and large herbivores influence seed removal rates in an African savanna.

    Science.gov (United States)

    Acanakwo, Erik Francis; Sheil, Douglas; Moe, Stein R

    2017-12-01

    Seed removal can influence plant community dynamics, composition, and resulting vegetation characteristics. In the African savanna, termites and large herbivores influence vegetation in various ways, likely including indirect effects on seed predators and secondary dispersers. However, the intensity and variation of seed removal rates in African savannas has seldom been studied. We experimentally investigated whether termites and large herbivores were important factors in the mechanisms contributing to observed patterns in tree species composition on and off mounds, in Lake Mburo National Park, Uganda. Within fenced (excluding large herbivores) and unfenced termite mound and adjacent savanna plots, we placed seeds of nine native tree species within small open "cages," accessed by all animals, roofed cages that only allowed access to small vertebrates and invertebrates, and closed cages that permitted access by smaller invertebrates only (5 mm wire mesh). We found that mean seed removal rate was high (up to 87.3% per 3 d). Mound habitats experienced significantly higher removal rates than off-mound habitats. The mean removal rate of native seeds from closed cages was 11.1% per 3 d compared with 19.4% and 23.3% removed per 3 d in the roofed and open cages, respectively. Smaller seeds experienced higher removal rates than larger seeds. Large herbivore exclusion on mounds reduced native seed removal rates by a mean of 8.8% in the open cages, but increased removal rates by 1.7% in the open cages when off-mound habitats were fenced. While removal rates from open cages were higher on active mounds (30.9%) than on inactive mounds (26.7%), the removal rates from closed cages were lower on active vs. inactive mounds (6.1% vs. 11.6%, respectively). Thus, we conclude that large herbivores and Macrotermes mounds influence seed removal rates, though these effects appear indirect. © 2017 by the Ecological Society of America.

  11. Carbon dioxide fluxes from contrasting ecosystems in the Sudanian Savanna in West Africa.

    Science.gov (United States)

    Quansah, Emmanuel; Mauder, Matthias; Balogun, Ahmed A; Amekudzi, Leonard K; Hingerl, Luitpold; Bliefernicht, Jan; Kunstmann, Harald

    2015-12-01

    The terrestrial land surface in West Africa is made up of several types of savanna ecosystems differing in land use changes which modulate gas exchanges between their vegetation and the overlying atmosphere. This study compares diurnal and seasonal estimates of CO 2 fluxes from three contrasting ecosystems, a grassland, a mixture of fallow and cropland, and nature reserve in the Sudanian Savanna and relate them to water availability and land use characteristics. Over the study period, and for the three study sites, low soil moisture availability, high vapour pressure deficit and low ecosystem respiration were prevalent during the dry season (November to March), but the contrary occurred during the rainy season (May to October). Carbon uptake predominantly took place in the rainy season, while net carbon efflux occurred in the dry season as well as the dry to wet and wet to dry transition periods (AM and ND) respectively. Carbon uptake decreased in the order of the nature reserve, a mixture of fallow and cropland, and grassland. Only the nature reserve ecosystem at the Nazinga Park served as a net sink of CO 2 , mostly by virtue of a several times larger carbon uptake and ecosystem water use efficiency during the rainy season than at the other sites. These differences were influenced by albedo, LAI, EWUE, PPFD and climatology during the period of study. These results suggest that land use characteristics affect plant physiological processes that lead to flux exchanges over the Sudanian Savanna ecosystems. It affects the diurnal, seasonal and annual changes in NEE and its composite signals, GPP and RE. GPP and NEE were generally related as NEE scaled with photosynthesis with higher CO 2 assimilation leading to higher GPP. However, CO 2 effluxes over the study period suggest that besides biomass regrowth, other processes, most likely from the soil might have also contributed to the enhancement of ecosystem respiration.

  12. The ghosts of trees past: savanna trees create enduring legacies in plant species composition.

    Science.gov (United States)

    Stahlheber, Karen A; Crispin, Kimberly L; Anton, Cassidy; D'Antonio, Carla M

    2015-09-01

    Isolated trees in savannas worldwide are known to modify their local environment and interact directly with neighboring plants. Less is known about how related tree species differ in their impacts on surrounding communities, how the effects of trees vary between years, and how composition might change following loss of the tree. To address these knowledge gaps, we explored the following questions: How do savanna trees influence the surrounding composition of herbaceous plants? Is the influence of trees consistent across different species and years? How does this change following the death of the tree? We surveyed herbaceous species composition and environmental attributes surrounding living and dead evergreen and deciduous Quercus trees in California (USA) savannas across several years that differed in their total precipitation. Oak trees of all species created distinct, homogenous understory communities dominated by exotic grasses across several sites. The composition of the low-diversity understory communities showed less interannual variation than open grassland, despite a two-fold difference in precipitation between the driest and wettest year. Vegetation composition was correlated with variation in soil properties, which were strongly affected by trees. Oaks also influenced the communities beyond the edge of the crown, but this depended on site and oak species. Low-diversity understory communities persisted up to 43 years following the death of the tree. A gradual decline in the effect of trees on the physical, environment following death did not result in vegetation becoming more similar to open grassland over time. The presence of long-lasting legacies of past tree crowns highlights the difficulty of assigning control of the current distribution of herbaceous species in grassland to their contemporary environment.

  13. Beyond Precipitation: Physiographic Gradients Dictate the Relative Importance of Environmental Drivers on Savanna Vegetation

    Science.gov (United States)

    Campo-Bescós, Miguel A.; Muñoz-Carpena, Rafael; Kaplan, David A.; Southworth, Jane; Zhu, Likai; Waylen, Peter R.

    2013-01-01

    Background Understanding the drivers of large-scale vegetation change is critical to managing landscapes and key to predicting how projected climate and land use changes will affect regional vegetation patterns. This study aimed to improve our understanding of the role, magnitude and spatial distribution of the key environmental factors driving vegetation change in southern African savanna, and how they vary across physiographic gradients. Methodology/Principal Findings We applied Dynamic Factor Analysis (DFA), a multivariate times series dimension reduction technique to ten years of monthly remote sensing data (MODIS-derived normalized difference vegetation index, NDVI) and a suite of environmental covariates: precipitation, mean and maximum temperature, soil moisture, relative humidity, fire and potential evapotranspiration. Monthly NDVI was described by cyclic seasonal variation with distinct spatiotemporal patterns in different physiographic regions. Results support existing work emphasizing the importance of precipitation, soil moisture and fire on NDVI, but also reveal overlooked effects of temperature and evapotranspiration, particularly in regions with higher mean annual precipitation. Critically, spatial distributions of the weights of environmental covariates point to a transition in the importance of precipitation and soil moisture (strongest in grass-dominated regions with precipitation950 mm). Conclusions/Significance We quantified the combined spatiotemporal effects of an available suite of environmental drivers on NDVI across a large and diverse savanna region. The analysis supports known drivers of savanna vegetation but also uncovers important roles of temperature and evapotranspiration. Results highlight the utility of applying the DFA approach to remote sensing products for regional analyses of landscape change in the context of global environmental change. With the dramatic increase in global change research, this methodology augurs well for

  14. Pharmacogenetics in the Brazilian population

    Directory of Open Access Journals (Sweden)

    Guilherme eSuarez-Kurtz

    2010-10-01

    Full Text Available Brazil is the 5th largest country in the world and its present population, in excess of 190 million, is highly heterogeneous, as a result of centuries of admixture between Amerindians, Europeans and Sub-Saharan Africans. The estimated individual proportions of biogeographical ancestry vary widely and continuously among Brazilians, most individuals - irrespective of self-identification as White, Brown or Black, the major categories of the Brazilian Census race/color system - having significant degrees of European and African ancestry, while a sizeable number display also Amerindian ancestry. These features have important pharmacogenetic (PGx implications: first, extrapolation of PGx data from relatively well-defined ethnic groups is clearly not applicable to the majority of Brazilians; second, the frequency distribution of polymorphisms in pharmacogenes (e.g. CYP3A5, CYP2C9, GSTM1, ABCB1, GSTM3, VKORC, etc varies continuously among Brazilians and is not captured by race/color self-identification; third, the intrinsic heterogeneity of the Brazilian population must be acknowledged in the design and interpretation of PGx studies in order to avoid spurious conclusions based on improper matching of study cohorts. The peculiarities of PGx in Brazilians are illustrated with data for different therapeutic groups, such as anticoagulants, HIV-protease inhibitors and nonsteroidal antinflammatory drugs, and the challenges and advantages created by population admixture for the study and implementation of PGx are discussed. PGx data for Amerindian groups and Brazilian-born, first generation Japanese are presented to illustrate the rich diversity of the Brazilian population. Finally, I introduce the reader to the Brazilian Pharmacogenetic Network or Refargen (www.refargen.org.br, a nationwide consortium of research groups, with the mission to provide leadership in PGx research and education in Brazil, with a population health impact.

  15. AGROECOLOGY AND CLIMATE CHANGE IN THE SEMIARID TROPICS

    Directory of Open Access Journals (Sweden)

    Guillermo Gamarra-Rojas

    2017-04-01

    Full Text Available This article makes a theoretical and, to a certain extent, propositional reflection on the conceptions, assumptions and evidences of climate change in the tropics, with emphasis on the Brazilian semiarid region. The contributions of agriculture to climate change are presented and the impacts of climate change on family agriculture in the semiarid region are analyzed. Evidence of mitigation and adaptation in agroecological systems of the semiarid region is presented and an outline of an agenda of the sector based on the commitments assumed by the country and the needs of mitigation and adaptation is provided.

  16. Preferential production and transport of grass-derived pyrogenic carbon in NE-Australian savanna ecosystems

    Science.gov (United States)

    Saiz, Gustavo; Goodrick, Iain; Wurster, Christopher; Nelson, Paul N.; Wynn, Jonathan; Bird, Michael

    2017-12-01

    Understanding the main factors driving fire regimes in grasslands and savannas is critical to better manage their biodiversity and functions. Moreover, improving our knowledge on pyrogenic carbon (PyC) dynamics, including formation, transport and deposition, is fundamental to better understand a significant slow-cycling component of the global carbon cycle, particularly as these ecosystems account for a substantial proportion of the area globally burnt. However, a thorough assessment of past fire regimes in grass-dominated ecosystems is problematic due to challenges in interpreting the charcoal record of sediments. It is therefore critical to adopt appropriate sampling and analytical methods to allow the acquisition of reliable data and information on savanna fire dynamics. This study uses hydrogen pyrolysis (HyPy) to quantify PyC abundance and stable isotope composition (δ13C) in recent sediments across 38 micro-catchments covering a wide range of mixed C3/C4 vegetation in north Queensland, Australia. We exploited the contrasting δ13C values of grasses (i.e. C4; δ13C >-15‰) and woody vegetation (i.e. C3; δ13C <-24‰) to assess the preferential production and transport of grass-derived PyC in savanna ecosystems. Analyses were conducted on bulk and size-fractionated samples to determine the fractions into which PyC preferentially accumulates. Our data show that the δ13C value of PyC in the sediments is decoupled from the δ13C value of total organic carbon, which suggests that a significant component of PyC may be derived from incomplete grass combustion, even when the proportion of C4 grass biomass in the catchment was relatively small. Furthermore, we conducted 16 experimental burns that indicate that there is a comminution of PyC produced in-situ to smaller particles, which facilitates the transport of this material, potentially affecting its preservation potential. Savanna fires preferentially burn the grass understory rather than large trees, leading to

  17. Rainfall and topo-edaphic influences on woody community phenology in South African savannas

    CSIR Research Space (South Africa)

    Shackleton, CM

    1999-03-01

    Full Text Available the limiting periods, i.e. at Stockholm. the start and cessation of the rainy season. This was Fatubarin, A. (1985) Observations on the phenology of not reflected in the data presented here with respect to the woody plants and grasses in a savanna ecosystem... of temperature on evaporative demand (Bate, Furniss & Pendle, 1982).∗ Current address: Environmentek, CSIR, P.O. Box At a gross scale, annual rainfall is a coarse index of395, Pretoria 0001, South Africa. e-mail: csh- ackle@csir.co.za. seasonal plant available...

  18. Assessment of bird populations in a high quality savanna/woodland: a banding approach

    Science.gov (United States)

    Wilmore, Sandra L.; Glowacki, Gary A.; Grundel, Ralph

    2005-01-01

    Between 1999 and 2004, Save the Dunes Conservation Fund's Miller Woods Bird Banding Program monitored migrating and breeding bird populations within a high quality black oak, dry-mesic sand savanna/woodland with ridge and swale topography. The objectives of this program were to collect consistent and reliable demographic and abundance data on the bird populations, to investigate long-term population trends, and to contribute to improved land management decisions at regional and national scales. The technique employed involved capturing birds in mist nets that were deployed for set periods of time at 17 net sites in two banding areas in Miller Woods.

  19. World climate patterns in grassland and savanna and their relation to growing seasons

    Directory of Open Access Journals (Sweden)

    R. Kirk Steinhorst

    1977-11-01

    Full Text Available The climate at eleven IBP savanna or grassland study sites from five continents are described and principal components analysis is used to compare them. A multivariate linear discriminant function based on mean monthly precipitation, mean monthly temperature, latitude and altitude, is used to predict the length of the growing season at each site. At most sites, the actual and predicted start and end of the growing season agreed closely. It is concluded that growing season on a world-wide basis may be predicted fairly reliably from a small number of abiotic variables by means of a multivariate discriminant function.

  20. The rise of Brazilian agriculture

    DEFF Research Database (Denmark)

    Jensen, Hans Grinsted; Vink, Nick; Sandrey, Ron

    2014-01-01

    of Brazilian agricultural policies, namely farmer support, the research and technology transfer system and land issues. The implications for South African agriculture can be summarized as the recognition that history, geography, the development path and agricultural policies all matter. The article......The purpose of this article is to explore some of the possible lessons for South African agriculture from the Brazilian experience. To this end, the article discusses the performance of Brazilian agriculture in terms of land and labour use, production, and exports. This is followed by aspects...... then identifies five important lessons for agricultural development in South Africa....

  1. Epidemiology and treatment of psoriasis: a Brazilian perspective

    Directory of Open Access Journals (Sweden)

    Duarte GV

    2015-04-01

    Full Text Available Gleison V Duarte,1 Larissa Porto-Silva,2 Maria de Fátima Paim de Oliveira1 1Dermatology Department, Federal University of Bahia, Salvador, 2Escola Bahiana de Medicina e Saúde Pública, Salvador, BA, Brazil Abstract: Psoriasis is a chronic immune-mediated systemic disease that is influenced by genetic and environmental factors, is associated with comorbidities, and has a negative impact on the quality of life of affected individuals. The prevalence of psoriasis varies among different ethnic groups, but this topic has not been studied in Brazil to date. In this review, we evaluate the epidemiology and treatment of psoriasis from a Brazilian perspective. We focused on studies that involved Brazilian subjects. The prevalence of psoriasis in Brazil is estimated to be 2.5%, but no population study has been performed previously. Environmental factors, such as tropical climate, in association with genetic factors, such as miscegenation, may exert a beneficial impact on the course and frequency of psoriasis in Brazil. A number of studies have advanced our understanding of the cardiovascular, ophthalmic, and oral comorbidities that are associated with psoriasis. Concerns about biological therapy, such as endemic leprosy, human T-cell lymphotropic virus (HTLV, and tuberculosis infections, are discussed. The nonavailability of treatment options for psoriasis in the public health system contradicts the Brazilian Society of Dermatology guidelines, stimulating the judicialization of access to medicines in psoriasis care. Keywords: psoriasis, epidemiology, comorbidities, health services accessibility, health care disparities, insurance, health care costs

  2. Epidemiology and treatment of psoriasis: a Brazilian perspective.

    Science.gov (United States)

    Duarte, Gleison V; Porto-Silva, Larissa; de Oliveira, Maria de Fátima Paim

    2015-01-01

    Psoriasis is a chronic immune-mediated systemic disease that is influenced by genetic and environmental factors, is associated with comorbidities, and has a negative impact on the quality of life of affected individuals. The prevalence of psoriasis varies among different ethnic groups, but this topic has not been studied in Brazil to date. In this review, we evaluate the epidemiology and treatment of psoriasis from a Brazilian perspective. We focused on studies that involved Brazilian subjects. The prevalence of psoriasis in Brazil is estimated to be 2.5%, but no population study has been performed previously. Environmental factors, such as tropical climate, in association with genetic factors, such as miscegenation, may exert a beneficial impact on the course and frequency of psoriasis in Brazil. A number of studies have advanced our understanding of the cardiovascular, ophthalmic, and oral comorbidities that are associated with psoriasis. Concerns about biological therapy, such as endemic leprosy, human T-cell lymphotropic virus (HTLV), and tuberculosis infections, are discussed. The nonavailability of treatment options for psoriasis in the public health system contradicts the Brazilian Society of Dermatology guidelines, stimulating the judicialization of access to medicines in psoriasis care.

  3. Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. III. Anguidae, Scincidae, Teiidae.

    Science.gov (United States)

    Ribeiro-Júnior, Marco A; Amaral, Silvana

    2016-12-09

    We present distribution data of all Anguidae, Scincidae, and Teiidae lizards known from the Brazilian Amazonia, totaling 29 species-level taxa, belonging to 14 genera. This represents 11 more species-level taxa than previously reported for these families in this area. Data were based on literature and 46,806 specimens deposited in three North American and eight Brazilian museums, including the main collections harboring Amazonian material. Most species (~55%) are endemic to Amazonia. Except for Ameiva ameiva, that is present in several environments and domains, non-endemic species are either associated with open dry (semideciduous) forest or open vegetation (savanna) enclaves in Amazonia, occupying similar environments outside Amazonia, gallery forests within the Cerrado, or present disjunct populations in the Atlantic Forest. As a whole, six taxa are widespread in Amazonia, four are restricted to eastern Amazonia, four to western Amazonia, three to southwestern Amazonia, one to northern Amazonia, and seven to the southern peripheral portion of Amazonia. Besides, two species present apparently more restricted, unique distributions. Only three species have a distribution that is congruent with one of the areas of endemism (AE) recognized for other organisms (birds and primates), of which two occur in AE Guiana and one in AE Inambari.

  4. Brazilian readers and contextual reference Brazilian readers and contextual reference

    Directory of Open Access Journals (Sweden)

    Lilia M. O. Carioni

    2008-04-01

    Full Text Available This article describes an experiment carried out using Brazilian university students at UFSC, the purpose being to check comprehension relationships between two types of contextual reference and two languages, Portuguese and English. A major stimulus for the research was the question: are Brazilian students' difficulties in reading English related more to English language difficulties or to difficulties in processing text in general?

  5. Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. I. Dactyloidae, Hoplocercidae, Iguanidae, Leiosauridae, Polychrotidae, Tropiduridae.

    Science.gov (United States)

    Ribeiro-Júnior, Marco A

    2015-07-08

    I present distribution data of all Dactyloidae, Hoplocercidae, Iguanidae, Leiosauridae, Polychrotidae and Tropiduridae lizards known from the Brazilian Amazonia, totaling 40 species-level taxa, belonging to 11 genera. This represents four more species-level taxa than previously reported for these families. Data were based on the direct examination of 41,243 specimens deposited in three North American and eight Brazilian musea, including the main collections harboring Amazonian material. Most species (62.5%) are endemic to the Amazonia; non-endemic species are mainly associated with open dry (semideciduous) forest or open vegetation (savanna) enclaves in Amazonia, with a few exceptions. As a whole, seven taxa are widespread in Amazonia, one is restricted to eastern Amazonia, three to western Amazonia, five to northern Amazonia (either in part of it or widespread in the Guiana region), two to northwestern Amazonia, one to southern Amazonia, nine to southwestern Amazonia, and seven to the southern peripheral portion of Amazonia. Five species have unique distributions and five species have a distribution that is congruent with one of the areas of endemism (AE) recognized for other organisms (birds and primates). The first herpetological gazetteer for the Brazilian Amazonia with about 3,600 georeferenced localities was also produced.

  6. Orbital Forcing driving climate variability on Tropical South Atlantic

    Science.gov (United States)

    Oliveira, A. S.; Baker, P. A.; Silva, C. G.; Dwyer, G. S.; Chiessi, C. M.; Rigsby, C. A.; Ferreira, F.

    2017-12-01

    Past research on climate response to orbital forcing in tropical South America has emphasized on high precession cycles influencing low latitude hydrologic cycles, and driving the meridional migration of Intertropical Convergence Zone (ITCZ).However, marine proxy records from the tropical Pacific Ocean showed a strong 41-ka periodicities in Pleistocene seawater temperature and productivity related to fluctuations in Earth's obliquity. It Indicates that the western Pacific ITCZ migration was influenced by combined precession and obliquity changes. To reconstruct different climate regimes over the continent and understand the orbital cycle forcing over Tropical South America climate, hydrological reconstruction have been undertaken on sediment cores located on the Brazilian continental slope, representing the past 1.6 million years. Core CDH 79 site is located on a 2345 m deep seamount on the northern Brazilian continental slope (00° 39.6853' N, 44° 20.7723' W), 320 km from modern coastline of the Maranhão Gulf. High-resolution XRF analyses of Fe, Ti, K and Ca are used to define the changes in precipitation and sedimentary input history of Tropical South America. The response of the hydrology cycle to orbital forcing was studied using spectral analysis.The 1600 ka records of dry/wet conditions presented here indicates that orbital time-scale climate change has been a dominant feature of tropical climate. We conclude that the observed oscillation reflects variability in the ITCZ activity associated with the Earth's tilt. The prevalence of the eccentricity and obliquity signals in continental hydrology proxies (Ti/Ca and Fe/K) as implicated in our precipitation records, highlights that these orbital forcings play an important role in tropics hydrologic cycles. Throughout the Quaternary abrupt shifts of tropical variability are temporally correlated with abrupt climate changes and atmospheric reorganization during Mid-Pleistocene Transition and Mid-Brunhes Events

  7. Regeneration after fire in campo rupestre : Short- and long-term vegetation dynamics

    OpenAIRE

    Le Stradic , Soizig; Hernandez , Pauline; Fernandes , Geraldo Wilson; Buisson , Elise

    2018-01-01

    International audience; The Cerrado (Brazilian savanna) is the second largest biome in Brazil, covering 22% of the country, and campo rupestre is one of the most biodiverse ecosystem. Campo rupestre are extremely old mountaintop tropical ecosystems, composed of a mosaic of herbaceous, shrubland and savanna vegetation, generally located above 900 m above sea level characterized by shallow, acidic and nutrient-poor soils. In the context of increased land-use changes, effective conservation and ...

  8. Tropical Agro-Sciences

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The Tropical Agro-Sciences Division has two functions: conduct research on the impact of air pollution on tropical agricultural and to provide training to UPR graduate students and visiting scientists. Since the reorientation of the Center's interests under ERDA, the Division has directed its research activities, with particular emphasis on the effects of atmospheric pollution on tropical agriculture in the Guayanilla-Penuelas region, which has a fossil-fuel power plant, petroleum refineries, and associated industries. This new area of research is important to ERDA because the knowledge gained regarding the effects of air pollution related to energy technology on the agricultural environment and productivity will be useful in planning future energy developments. Information about the potential harm of air pollutants to man through the food chain and about ways of alleviating their impact on agriculture are of practical importance. Studies of the mechanisms involved in pollution injury, protection, and tolerance are of basic significance

  9. Desiring the city: the urban imaginary in rural collective settlements in a Brazilian submontane Atlantic forest reserve

    Directory of Open Access Journals (Sweden)

    Bruno César Cavalcanti

    Full Text Available This article discusses data obtained in a study on populations who live near an important Brazilian submontane Atlantic forest, a geographical zone of north-eastern states located between the beach zone and the savanna-scrub zone. The populations in question live in a so-called Ecological Station from Murici (Esec-Murici, in the Murici Forest Complex (CFM, in the forest zone of Alagoas, distributed between two Incra rural collective settlements and on farms. Cultural forms used by such populations have been discussed by using social indexes taken from this survey and associating them with economical and environmental sustainability notions in their interfaces with these groups' social development and with regards to the actions of other agents in the CFM, suggesting that the maintenance of an urban imaginary which produces new subjectivities can be easily linked with environmental conservation policies.

  10. The effect of size and density on nut removal in Syagrus loefgrenii Glassman (Arecaceae in the Brazilian Cerrado

    Directory of Open Access Journals (Sweden)

    J. Ragusa-Netto

    2017-07-01

    Full Text Available Abstract In this study I tested the effect of Syagrus loefgrenii nut size and number on the intensity of removal by rodents across seasons. Trials were performed in which piles of either small or large endocarps (1, 3, 6, 12, and 25 were subjected to removal by rodents in the Cerrado (Brazilian savanna. Despite of variations in the intensity of removal, always this process decrease conform endocarp number. Also, mean proportion of endocarp removal was unrelated to year period, initial number, and size of endocarps. Hence, endocarp removal was consistently negative density-dependent. As, in principle, the observed patterns of nut removal point out similar survival chances for both nut sizes, the pervasive negative density-dependent response emerges as a strategy in S. loefgrenii to swamp rodents all year round irrespective of seed size.

  11. 1997 Annual Tropical Cyclone Report

    National Research Council Canada - National Science Library

    Dillon, C

    1997-01-01

    .... Separate bulletins are issued for the Western Pacific and the Indian Ocean. TROPICAL CYCLONE FORMATION ALERT - Defines a specific area when synoptic, satellite, or other germane data indicate development of a significant tropical cyclone (TC...

  12. Shallow-water Aplysina Nardo (Aplysinidae, Verongida, Demospongiae from the São Sebastião Channel and its environs (Tropical southwestern Atlantic, with the description of a new species and a literature review of other brazilian records of the genus

    Directory of Open Access Journals (Sweden)

    Ulisses dos Santos Pinheiro

    2001-07-01

    Full Text Available Two species of Aplysina Nardo, 1834 are described in this article, Aplysina caissara sp. n. and A. fulva (Pallas, 1766. Additionally, a possible third species was identified as A. aff. cauliformis. Collections were done in the São Sebastião Channel area as an ongoing effort to assess the poriferan biodiversity of the northern sector of the São Paulo State coastline. Specimens were collected by scuba diving, and descriptions of external morphology are based on the observation of populations alive, and on extensive underwater photography. A literature review of other brazilian records of Aplysina was undertaken, and an ammended species list is offered.

  13. Genomic DNA sequences from mastodon and woolly mammoth reveal deep speciation of forest and savanna elephants.

    Directory of Open Access Journals (Sweden)

    Nadin Rohland

    2010-12-01

    Full Text Available To elucidate the history of living and extinct elephantids, we generated 39,763 bp of aligned nuclear DNA sequence across 375 loci for African savanna elephant, African forest elephant, Asian elephant, the extinct American mastodon, and the woolly mammoth. Our data establish that the Asian elephant is the closest living relative of the extinct mammoth in the nuclear genome, extending previous findings from mitochondrial DNA analyses. We also find that savanna and forest elephants, which some have argued are the same species, are as or more divergent in the nuclear genome as mammoths and Asian elephants, which are considered to be distinct genera, thus resolving a long-standing debate about the appropriate taxonomic classification of the African elephants. Finally, we document a much larger effective population size in forest elephants compared with the other elephantid taxa, likely reflecting species differences in ancient geographic structure and range and differences in life history traits such as variance in male reproductive success.

  14. Temperature fluctuations inside savanna termite mounds: Do size and plant shade matter?

    Science.gov (United States)

    Ndlovu, M; Pérez-Rodríguez, A

    2018-05-01

    Mound building termites are key ecosystem engineers of subtropical savanna regions. Mounds allow termites to maintain suitable conditions for termite reproduction and food cultivation ('fungus gardens'). We studied how the internal mound temperature of Macrotermes natalensis, a dominant mound-building termite of the subtropical savanna of southern Africa, responds to a number of environmental variables. We used general additive mixed models (GAMM) to determine how external temperature, mound size (volume) and the amount of vegetation shade affects mound internal temperature over a 24-h period. Internal mound temperature varied daily following changes of the external temperature, although the range of variation was much smaller. Active termite mounds maintained a higher internal temperature than inactive ones, and mound activity reinforced the positive effect of mound size and moderated the negative effect of vegetation shade on internal temperatures. In turn, external temperature fluctuations equally affected active and inactive mounds. Large mounds maintained near optimal internal temperatures compared to smaller sized mounds. We therefore conclude that termite mound size is a stronger determinant of internal mound temperature stability compared to plant shade cover. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Burned area detection based on Landsat time series in savannas of southern Burkina Faso

    Science.gov (United States)

    Liu, Jinxiu; Heiskanen, Janne; Maeda, Eduardo Eiji; Pellikka, Petri K. E.

    2018-02-01

    West African savannas are subject to regular fires, which have impacts on vegetation structure, biodiversity and carbon balance. An efficient and accurate mapping of burned area associated with seasonal fires can greatly benefit decision making in land management. Since coarse resolution burned area products cannot meet the accuracy needed for fire management and climate modelling at local scales, the medium resolution Landsat data is a promising alternative for local scale studies. In this study, we developed an algorithm for continuous monitoring of annual burned areas using Landsat time series. The algorithm is based on burned pixel detection using harmonic model fitting with Landsat time series and breakpoint identification in the time series data. This approach was tested in a savanna area in southern Burkina Faso using 281 images acquired between October 2000 and April 2016. An overall accuracy of 79.2% was obtained with balanced omission and commission errors. This represents a significant improvement in comparison with MODIS burned area product (67.6%), which had more omission errors than commission errors, indicating underestimation of the total burned area. By observing the spatial distribution of burned areas, we found that the Landsat based method misclassified cropland and cloud shadows as burned areas due to the similar spectral response, and MODIS burned area product omitted small and fragmented burned areas. The proposed algorithm is flexible and robust against decreased data availability caused by clouds and Landsat 7 missing lines, therefore having a high potential for being applied in other landscapes in future studies.

  16. Age-related tooth wear differs between forest and savanna primates.

    Directory of Open Access Journals (Sweden)

    Jordi Galbany

    Full Text Available Tooth wear in primates is caused by aging and ecological factors. However, comparative data that would allow us to delineate the contribution of each of these factors are lacking. Here, we contrast age-dependent molar tooth wear by scoring percent of dentine exposure (PDE in two wild African primate populations from Gabonese forest and Kenyan savanna habitats. We found that forest-dwelling mandrills exhibited significantly higher PDE with age than savanna yellow baboons. Mandrills mainly feed on large tough food items, such as hard-shell fruits, and inhabit an ecosystem with a high presence of mineral quartz. By contrast, baboons consume large amounts of exogenous grit that adheres to underground storage organs but the proportion of quartz in the soils where baboons live is low. Our results support the hypothesis that not only age but also physical food properties and soil composition, particularly quartz richness, are factors that significantly impact tooth wear. We further propose that the accelerated dental wear in mandrills resulting in flatter molars with old age may represent an adaptation to process hard food items present in their environment.

  17. Tropical varieties, maps and gossip

    NARCIS (Netherlands)

    Frenk, B.J.

    2013-01-01

    Tropical geometry is a relatively new field of mathematics that studies the tropicalization map: a map that assigns a certain type of polyhedral complex, called a tropical variety, to an embedded algebraic variety. In a sense, it translates algebraic geometric statements into combinatorial ones. An

  18. Stranding Events of Kogia Whales along the Brazilian Coast.

    Directory of Open Access Journals (Sweden)

    Jailson F Moura

    Full Text Available The genus Kogia, which comprises only two extant species, Kogia sima and Kogia breviceps, represents one of the least known groups of cetaceans in the global ocean. In some coastal regions, however, stranding events of these species have been relatively common over the last decades. Stranding provides the opportunity to investigate the biology of these cetaceans and to explore the epidemiological aspects associated with the mortality of the organisms found on the beach. A number of disturbances (including pelagic fisheries, chemical pollution, boat strikes, and noise pollution have been confirmed to pose a particular threat to the Kogia species. However, no study has yet investigated potential relationships between environmental conditions and stranding events. Here we analyse how a collection of environmental, physical, and biological variables, such as wind, sea surface temperature (SST, water depth, and chlorophyll-a, correlate to Kogia stranding events along the Brazilian coast. The results of our statistical analyses suggest that K. sima is more likely found in warm tropical waters, which provide an explanation for the high frequency of stranding in northeastern Brazilian coast. In contrast, K. breviceps appears to have a preference for temperate and productive waters. Wind speed results to be also an important factor for predicting Kogia strandings in Brazilian coast. Additionally, literature information in combination with our own data and analyses of stomach contents confirms that oceanic cephalopods constitute the primary nutritional source of both Kogia species. By using the available information as a qualitative proxy for habitat preference and feeding ecology, our study provides a novel and comprehensive assessment of Kogia stranding data in relation to environmental conditions along the Brazilian coast.

  19. Tropical Cyclone Report, 1988

    Science.gov (United States)

    1988-01-01

    Cmdr. David Gray; National Weather Service 5. Cooperation with the Naval Environmental Pacific Region for the startup of 24-hour operatiois at Ponape...0.1 27.7 TOTAL CASES 3 1 1 4 12 27 54 56 30 25 7 1 221 * (GRAY, 1979) TABLE 4-3 ANNUAL VARIATION C SOTR MUSHER TROPICAL CYCLOUZ BY O(EN BASIN SOUTH

  20. Utilization of tropical rabbits

    African Journals Online (AJOL)

    5,0' a,b"differ (P<0,05) for reproducing rabbits, and may aid the prevention of enteric diseases. In Trial 3, ADG of several tropical legumes was the same as that obtained with alfalfa (Table 3). Gains with guinea grass, cassava, stylosanthes and the winged bean were lower than with alfalfa. Digestibilityof the protein and fibre ...

  1. [Tropical sprue (author's transl)].

    Science.gov (United States)

    Gras, C; Chapoy, P; Aubry, P

    1981-01-01

    Tropical sprue is a disease of the small intestine characterized by a malabsorption syndrome with a subtotal or partial mucosal atrophy. It is observed in Asia and Central America. It appears to be rare in Africa but its real frequency is unknown as small bowel biopsys are not routinely done. Bacterial overgrowth as well as giardiasis may be trigger factors of the disease the pathogenesis of which is still incompletely understood. The disease beginning as chronic diarrhea is later on characterized by an aphtoïd stomatitis and a macrocytic anemia. Treatment with antibiotics and folic acid is efficient and has a diagnostic value. If treatment is started lately, vitamin B 12 is then also necessary. In any intestinal syndrome observed in tropical areas without an ascertained etiologic diagnosis, peroral biopsie of the small intestine is requested. However, with the use of pediatric endoscope it will be possible to appreciate the respective incidence of tropical sprue and asymptomatic tropical sprue in Africa South of the Sahara.

  2. Securing tropical forest carbon

    DEFF Research Database (Denmark)

    Scharlemann, Jörn P. W.; Kapos, Valerie; Campbell, Alison

    2010-01-01

    Forest loss and degradation in the tropics contribute 6-17% of all greenhouse gas emissions. Protected areas cover 217.2 million ha (19.6%) of the world's humid tropical forests and contain c. 70.3 petagrams of carbon (Pg C) in biomass and soil to 1 m depth. Between 2000 and 2005, we estimate...... that 1.75 million ha of forest were lost from protected areas in humid tropical forests, causing the emission of 0.25-0.33 Pg C. Protected areas lost about half as much carbon as the same area of unprotected forest. We estimate that the reduction of these carbon emissions from ongoing deforestation...... in protected sites in humid tropical forests could be valued at USD 6,200-7,400 million depending on the land use after clearance. This is >1.5 times the estimated spending on protected area management in these regions. Improving management of protected areas to retain forest cover better may be an important...

  3. Tropic Testing of Vehicles

    Science.gov (United States)

    2014-08-27

    kilometer track running through tropical forest. The track is a combination of a bauxite /dirt base with grades on the road up to 20 percent and log...bridges crossing 11 creeks. The track site is located in a private concession used mainly for gold mining ; however, logging operations are active in the

  4. Effects of repeated burning on woody vegetation structure and composition in a semi-arid southern African savanna

    NARCIS (Netherlands)

    Gandiwa, E.

    2011-01-01

    The objective of this study was to investigate the effects of repeated dry season annual hot fires on woody plants in a semiarid southern African savanna in Zimbabwe. Parts of the National University of Science and Technology (NUST) research fields in Bulawayo, Zimbabwe have been burnt annually in

  5. Rapid Assessment of Key Structural Elements of Different Vegetation Types of West African Savannas in Burkina Faso

    Directory of Open Access Journals (Sweden)

    Qasim Mohammad

    2016-01-01

    Full Text Available Estimations of Leaf Area Index (LAI have recently gained attention due to the sensitivity to the effects of climate change and its impact on forest ecosystems. Hence, a study was conducted on the LAI estimation of four vegetation types: (i gallery forests, (ii woodland savannas, (iii tree savannas, and (iv shrub savannas, at two protected areas of Nazinga Game Ranch and Bontioli Nature Reserve, Burkina Faso. A relationship between LAI and Crown Diameter was also investigated at these two sites. Digital hemispherical photography was used for the LAI estimation. Crown diameters (CD were determined perpendicular to each other and averaged for each tree and shrub. Overall results revealed that LAI ranged from 0-1.33 and the CD was recorded in the range of 0.46-11.01 m. The gallery forests recorded the highest mean LAI 1.33 ± 0.32 as well as the highest mean CD 7.69 ± 1.90 m. The LAI for the vegetation types were at their lower ends as the study was conducted in summer season, higher values are therefore expected in the wet season, as a significant correlation between LAI and precipitation has been emphasized by various studies. Continuous LAI monitoring and studies on various growth parameters of different vegetation types at the study sites are recommended towards enhanced monitoring and an ecologically feasible forest- and savanna-use and management to maintain essential ecosystem functions and services.

  6. Functional traits of trees on and off termite mounds : Understanding the origin of biotically-driven heterogeneity in savannas

    NARCIS (Netherlands)

    van der Plas, F.; Howison, R.; Reinders, J.; Fokkema, W.; Olff, H.

    Questions In African savannas, Macrotermes termites contribute to small-scale heterogeneity by constructing large mounds. Operating as islands of high nutrient and water availability and low fire frequency, these mounds support distinct, diverse communities of trees that have been shown to be highly

  7. Habitat differences in dung beetle assemblages in an African savanna-forest ecotone: implications for secondary seed dispersal.

    Science.gov (United States)

    Kunz, Britta K; Krell, Frank-Thorsten

    2011-06-01

    The probability and pattern of secondary seed dispersal by dung beetles (Scarabaeinae) depend on their community structure and composition at the site of primary deposition, which, in turn, seem to be strongly determined by vegetation. Consequently, we expected pronounced differences in secondary seed dispersal between forest and savanna in the northern Ivory Coast, West Africa. We found 99 dung beetle species at experimentally exposed dung piles of the olive baboon (Papio anubis (Lesson, 1827)), an important primary seed disperser in West Africa. Seventy-six species belonged to the roller and tunneler guilds, which are relevant for secondary seed dispersal. Most species showed a clear habitat preference. Contrary to the Neotropics, species number and abundance were much higher in the savanna than in the forest. Rollers and tunnelers each accounted for approximately 50% of the individuals in the savanna, but in the forest rollers made up only 4%. Seeds deposited into the savanna by an omnivorous primary disperser generally have a higher overall probability of being more rapidly dispersed secondarily by dung beetles than seeds in the forest. Also, rollers disperse seeds over larger distances. In contrast to other studies, small rollers were active in dispersal of large seeds, which were seemingly mistaken for dung balls. Our results suggest that rollers can remove seeds from any plant dispersed in primate dung in this ecosystem. © 2011 ISZS, Blackwell Publishing and IOZ/CAS.

  8. Relationships between bat occupancy and habitat and landscape structure along a savanna, woodland, forest gradient in the Missouri Ozarks

    Science.gov (United States)

    Clarissa A. Starbuck; Sybill K. Amelon; Frank R. III. Thompson

    2015-01-01

    Many land-management agencies are restoring savannas and woodlands using prescribed fire and forest thinning, and information is needed on how wildlife species respond to these management activities. Our objectives were to evaluate support for relationships of bat site occupancy with vegetation structure and management and landscape composition and structure across a...

  9. History of fire and Douglas-fir establishment in a savanna and sagebrush-grassland mosaic, southwestern Montana, USA

    Science.gov (United States)

    Emily K. Heyerdahl; Richard F. Miller; Russell A. Parsons

    2006-01-01

    Over the past century, trees have encroached into grass- and shrublands across western North America. These include Douglas-fir trees (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco) encroaching into mountain big sagebrush Nutt. ssp. vaseyana (Rydb.) Beetle) from stable islands of savanna in...

  10. Biomass and leaf-level gas exchange characteristics of three African savanna C4 grass species under optimum growth conditions

    NARCIS (Netherlands)

    Mantlana, K.B.; Veenendaal, E.M.; Arneth, A.; Grispen, V.; Bonyongo, C.M.; Heitkönig, I.M.A.; Lloyd, J.

    2009-01-01

    C4 savanna grass species, Digitaria eriantha, Eragrostis lehmanniana and Panicum repens, were grown under optimum growth conditions with the aim of characterizing their above- and below-ground biomass allocation and the response of their gas exchange to changes in light intensity, CO2 concentration

  11. Opposing resonses to ecological gradients structure amphibian and reptile communities across a temperate grassland-savanna-forest landscape

    Science.gov (United States)

    Grundel, Ralph; Beamer, David; Glowacki, Gary A.; Frohnapple, Krystal; Pavlovic, Noel B.

    2014-01-01

    Temperate savannas are threatened across the globe. If we prioritize savanna restoration, we should ask how savanna animal communities differ from communities in related open habitats and forests. We documented distribution of amphibian and reptile species across an open-savanna–forest gradient in the Midwest U.S. to determine how fire history and habitat structure affected herpetofaunal community composition. The transition from open habitats to forests was a transition from higher reptile abundance to higher amphibian abundance and the intermediate savanna landscape supported the most species overall. These differences warn against assuming that amphibian and reptile communities will have similar ecological responses to habitat structure. Richness and abundance also often responded in opposite directions to some habitat characteristics, such as cover of bare ground or litter. Herpetofaunal community species composition changed along a fire gradient from infrequent and recent fires to frequent but less recent fires. Nearby (200-m) wetland cover was relatively unimportant in predicting overall herpetofaunal community composition while fire history and fire-related canopy and ground cover were more important predictors of composition, diversity, and abundance. Increased developed cover was negatively related to richness and abundance. This indicates the importance of fire history and fire related landscape characteristics, and the negative effects of development, in shaping the upland herpetofaunal community along the native grassland–forest continuum.

  12. An idealized model for tree-grass coexistence in savannas : The role of life stage structure and fire disturbances

    NARCIS (Netherlands)

    Baudena, Mara|info:eu-repo/dai/nl/340303867; D'Andrea, Fabio; Provenzale, A.

    2010-01-01

    1. We discuss a simple implicit-space model for the competition of trees and grasses in an idealized savanna environment. The model represents patch occupancy dynamics within the habitat and introduces life stage structure in the tree population, namely adults and seedlings. A tree can be

  13. Tree-grass interactions on an East African savanna : the effects of facilitation, competition, and hydraulic lift

    NARCIS (Netherlands)

    Ludwig, F.

    2001-01-01

    Keywords: Rangelands, Semi-arid areas, stable isotopes, Acacia, C 4- grasses, plant nutrients, soil nutrients, soil water, plant water relations

    Savanna trees can either increase or decrease the productivity of understorey grasses. Trees reduce grass

  14. Analysis of the herbaceous undergrowth of the woody savanna in the Fathala reserve, Delta du Saloum National park (Senegal)

    Czech Academy of Sciences Publication Activity Database

    Hejcmanová, P.; Hejcman, M.; Camara, A. A.; Antonínová, M.; Pavlů, V.; Černý, Tomáš; Ba, A. T.

    2006-01-01

    Roč. 138, č. 2 (2006), s. 119-228 ISSN 0778-4031 R&D Projects: GA AV ČR IAA6093404 Institutional research plan: CEZ:AV0Z60050516 Keywords : vegetation analysis * herb layer * woody savanna Subject RIV: EF - Botanics Impact factor: 0.208, year: 2006

  15. Eddy covariance and biometric measurements show that a savanna ecosystem in Southwest China is a carbon sink

    Science.gov (United States)

    Fei, Xuehai; Jin, Yanqiang; Zhang, Yiping; Sha, Liqing; Liu, Yuntong; Song, Qinghai; Zhou, Wenjun; Liang, Naishen; Yu, Guirui; Zhang, Leiming; Zhou, Ruiwu; Li, Jing; Zhang, Shubin; Li, Peiguang

    2017-02-01

    Savanna ecosystems play a crucial role in the global carbon cycle. However, there is a gap in our understanding of carbon fluxes in the savanna ecosystems of Southeast Asia. In this study, the eddy covariance technique (EC) and the biometric-based method (BM) were used to determine carbon exchange in a savanna ecosystem in Southwest China. The BM-based net ecosystem production (NEP) was 0.96 tC ha-1 yr-1. The EC-based estimates of the average annual gross primary productivity (GPP), ecosystem respiration (Reco), and net ecosystem carbon exchange (NEE) were 6.84, 5.54, and -1.30 tC ha-1 yr-1, respectively, from May 2013 to December 2015, indicating that this savanna ecosystem acted as an appreciable carbon sink. The ecosystem was more efficient during the wet season than the dry season, so that it represented a small carbon sink of 0.16 tC ha-1 yr-1 in the dry season and a considerable carbon sink of 1.14 tC ha-1 yr-1 in the wet season. However, it is noteworthy that the carbon sink capacity may decline in the future under rising temperatures and decreasing rainfall. Consequently, further studies should assess how environmental factors and climate change will influence carbon-water fluxes.

  16. Eddy covariance and biometric measurements show that a savanna ecosystem in Southwest China is a carbon sink

    Science.gov (United States)

    Fei, Xuehai; Jin, Yanqiang; Zhang, Yiping; Sha, Liqing; Liu, Yuntong; Song, Qinghai; Zhou, Wenjun; Liang, Naishen; Yu, Guirui; Zhang, Leiming; Zhou, Ruiwu; Li, Jing; Zhang, Shubin; Li, Peiguang

    2017-01-01

    Savanna ecosystems play a crucial role in the global carbon cycle. However, there is a gap in our understanding of carbon fluxes in the savanna ecosystems of Southeast Asia. In this study, the eddy covariance technique (EC) and the biometric-based method (BM) were used to determine carbon exchange in a savanna ecosystem in Southwest China. The BM-based net ecosystem production (NEP) was 0.96 tC ha−1 yr−1. The EC-based estimates of the average annual gross primary productivity (GPP), ecosystem respiration (Reco), and net ecosystem carbon exchange (NEE) were 6.84, 5.54, and −1.30 tC ha−1 yr−1, respectively, from May 2013 to December 2015, indicating that this savanna ecosystem acted as an appreciable carbon sink. The ecosystem was more efficient during the wet season than the dry season, so that it represented a small carbon sink of 0.16 tC ha−1 yr−1 in the dry season and a considerable carbon sink of 1.14 tC ha−1 yr−1 in the wet season. However, it is noteworthy that the carbon sink capacity may decline in the future under rising temperatures and decreasing rainfall. Consequently, further studies should assess how environmental factors and climate change will influence carbon-water fluxes. PMID:28145459

  17. Symbiotic Performance of Herbaceous Legumes in Tropical Cover Cropping Systems

    Directory of Open Access Journals (Sweden)

    Basil Ibewiro

    2001-01-01

    Full Text Available Increasing use of herbaceous legumes such as mucuna (Mucuna pruriens var. utilis [Wright] Bruck and lablab (Lablab purpureus [L.] Sweet in the derived savannas of West Africa can be attributed to their potential to fix atmospheric nitrogen (N2. The effects of management practices on N2 fixation in mucuna and lablab were examined using 15N isotope dilution technique. Dry matter yield of both legumes at 12 weeks was two to five times more in in situ mulch (IM than live mulch (LM systems. Land Equivalent Ratios, however, showed 8 to 30% more efficient utilization of resources required for biomass production under LM than IM systems. Live mulching reduced nodule numbers in the legumes by one third compared to values in the IM systems. Similarly, nodule mass was reduced by 34 to 58% under LM compared to the IM systems. The proportion of fixed N2 in the legumes was 18% higher in LM than IM systems. Except for inoculated mucuna, the amounts of N fixed by both legumes were greater in IM than LM systems. Rhizobia inoculation of the legumes did not significantly increase N2 fixation compared to uninoculated plots. Application of N fertilizer reduced N2 fixed in the legumes by 36 to 51% compared to inoculated or uninoculated systems. The implications of cover cropping, N fertilization, and rhizobia inoculation on N contributions of legumes into tropical low-input systems were discussed.

  18. Brazilian multipurpose reactor

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2014-07-01

    The Brazilian Multipurpose Reactor (RMB) Project is an action of the Federal Government, through the Ministry of Science Technology and Innovation (MCTI) and has its execution under the responsibility of the Brazilian National Nuclear Energy Commission (CNEN). Within the CNEN, the project is coordinated by the Research and Development Directorate (DPD) and developed through research units of this board: Institute of Nuclear Energy Research (IPEN); Nuclear Engineering Institute (IEN); Centre for Development of Nuclear Technology (CDTN); Regional Center of Nuclear Sciences (CRCN-NE); and Institute of Radiation Protection and Dosimetry (IRD). The Navy Technological Center in Sao Paulo (CTMSP) and also the participation of other research centers, universities, laboratories and companies in the nuclear sector are important and strategic partnerships. The conceptual design and the safety analysis of the reactor and main facilities, related to nuclear and environmental licensing, are performed by technicians of the research units of DPD / CNEN. The basic design was contracted to engineering companies as INTERTHECNE from Brazil and INVAP from Argentine. The research units from DPD/CNEN are also responsible for the design verification on all engineering documents developed by the contracted companies. The construction and installation should be performed by specific national companies and international partnerships. The Nuclear Reactor RMB will be a open pool type reactor with maximum power of 30 MW and have the OPAL nuclear reactor of 20 MW, built in Australia and designed by INVAP, as reference. The RMB reactor core will have a 5x5 configuration, consisting of 23 elements fuels (EC) of U{sub 3}Si{sub 2} dispersion-type Al having a density of up to 3.5 gU/cm{sup 3} and enrichment of 19.75% by weight of {sup 23{sup 5}}U. Two positions will be available in the core for materials irradiation devices. The main objectives of the RMB Reactor and the other nuclear and radioactive

  19. Assessing Brazilian educational inequalities

    Directory of Open Access Journals (Sweden)

    Benoit Lorel

    2008-03-01

    Full Text Available This paper provides an evaluation of schooling inequality in Brazil using different indicators such as the Education Gini coefficient, the Education Standard Deviation and the Average number of Years of Schooling. We draw up a statistical description of Brazilian human capital dispersion in time over the last half century, across regions and states. Our analysis suggests several conclusions: 1 Strong reduction of educational inequalities measured by Education Gini index. 2 A three parts picture of Brazil seems to emerge, reflecting initial conditions. 3 High increase of the Average number of Years of Schooling. 4 A significant link between Education Gini and the average education length. 5 Education Standard Deviation leads to inverted results compared to Education Gini. 6 Brazilian data are consistent with an Education Kuznets curve if we consider Education Standard Deviation.Esse trababalho busca avaliar o grau de desigualdade educacional no Brasil baseado-se em diferentes indicatores tais como: o índice de Gini educacional, os anos médios de escolaridade e no desvio padrão educacional. Tenta-se colocar uma descrição estatistica da distribuição do capital humano no Brasil, incluindo as diferenças estaduais e regionais observadas durante a ultima metade do século. As conclusões da nossa análise são as seguintes: 1 Forte reduç ão das desigualdades educativas calculadas com o Gini educacional. 2 Um retrato tripartido do Brasil parece se formar refletindo as condições iniciais. 3 Um forte aumento dos níveis de escolarização. 4 Uma relação significativa entre o Gini educacional e os anos médios de estudos. 5 O desvio padrão educacional leva aos resultados inversos do Gini educacional. 6 Os dados brasileiros admitem uma curva de Kuznets educacional se considerarmos o desvio padrão educacional.

  20. Brazilian multipurpose reactor

    International Nuclear Information System (INIS)

    2014-01-01

    The Brazilian Multipurpose Reactor (RMB) Project is an action of the Federal Government, through the Ministry of Science Technology and Innovation (MCTI) and has its execution under the responsibility of the Brazilian National Nuclear Energy Commission (CNEN). Within the CNEN, the project is coordinated by the Research and Development Directorate (DPD) and developed through research units of this board: Institute of Nuclear Energy Research (IPEN); Nuclear Engineering Institute (IEN); Centre for Development of Nuclear Technology (CDTN); Regional Center of Nuclear Sciences (CRCN-NE); and Institute of Radiation Protection and Dosimetry (IRD). The Navy Technological Center in Sao Paulo (CTMSP) and also the participation of other research centers, universities, laboratories and companies in the nuclear sector are important and strategic partnerships. The conceptual design and the safety analysis of the reactor and main facilities, related to nuclear and environmental licensing, are performed by technicians of the research units of DPD / CNEN. The basic design was contracted to engineering companies as INTERTHECNE from Brazil and INVAP from Argentine. The research units from DPD/CNEN are also responsible for the design verification on all engineering documents developed by the contracted companies. The construction and installation should be performed by specific national companies and international partnerships. The Nuclear Reactor RMB will be a open pool type reactor with maximum power of 30 MW and have the OPAL nuclear reactor of 20 MW, built in Australia and designed by INVAP, as reference. The RMB reactor core will have a 5x5 configuration, consisting of 23 elements fuels (EC) of U 3 Si 2 dispersion-type Al having a density of up to 3.5 gU/cm 3 and enrichment of 19.75% by weight of 23 5 U. Two positions will be available in the core for materials irradiation devices. The main objectives of the RMB Reactor and the other nuclear and radioactive facilities are

  1. Tropical myeloneuropathies: the hidden endemias.

    Science.gov (United States)

    Román, G C; Spencer, P S; Schoenberg, B S

    1985-08-01

    Tropical myeloneuropathies include tropical ataxic neuropathy and tropical spastic paraparesis. These disorders occur in geographic isolates in several developing countries and are associated with malnutrition, cyanide intoxication from cassava consumption, tropical malabsorption (TM), vegetarian diets, and lathyrism. TM-malnutrition was a probable cause of myeloneuropathies among Far East prisoners of war in World War II. Clusters of unknown etiology occur in India, Africa, the Seychelles, several Caribbean islands, Jamaica, and Colombia. Treponemal infection (yaws) could be an etiologic factor in the last two. Tropical myeloneuropathies, a serious health problem, are multifactorial conditions that provide unsurpassed opportunities for international cooperation and neurologic research.

  2. Estimating the Above-Ground Biomass in Miombo Savanna Woodlands (Mozambique, East Africa Using L-Band Synthetic Aperture Radar Data

    Directory of Open Access Journals (Sweden)

    Maria J. Vasconcelos

    2013-03-01

    Full Text Available The quantification of forest above-ground biomass (AGB is important for such broader applications as decision making, forest management, carbon (C stock change assessment and scientific applications, such as C cycle modeling. However, there is a great uncertainty related to the estimation of forest AGB, especially in the tropics. The main goal of this study was to test a combination of field data and Advanced Land Observing Satellite (ALOS Phased Array L-band Synthetic Aperture Radar (PALSAR backscatter intensity data to reduce the uncertainty in the estimation of forest AGB in the Miombo savanna woodlands of Mozambique (East Africa. A machine learning algorithm, based on bagging stochastic gradient boosting (BagSGB, was used to model forest AGB as a function of ALOS PALSAR Fine Beam Dual (FBD backscatter intensity metrics. The application of this method resulted in a coefficient of correlation (R between observed and predicted (10-fold cross-validation forest AGB values of 0.95 and a root mean square error of 5.03 Mg·ha−1. However, as a consequence of using bootstrap samples in combination with a cross validation procedure, some bias may have been introduced, and the reported cross validation statistics could be overoptimistic. Therefore and as a consequence of the BagSGB model, a measure of prediction variability (coefficient of variation on a pixel-by-pixel basis was also produced, with values ranging from 10 to 119% (mean = 25% across the study area. It provides additional and complementary information regarding the spatial distribution of the error resulting from the application of the fitted model to new observations.

  3. Dynamic vegetation modeling of tropical biomes during Heinrich events

    Science.gov (United States)

    Handiani, Dian Noor; Paul, André; Dupont, Lydie M.

    2010-05-01

    changed from warm temperate forest during the last glacial maximum to the grassland and dry shrubland, suggesting a drier climate during Heinrich event 1. In south-western Africa savanna and dry woodland changed into boreal forest and boreal-temperate forest suggesting wetter conditions. The biomes diagnosed from the control-run, were compared to the modern vegetation reconstruction of BIOME 4 (http://www.bridge.bris.ac.uk/resources/Databases/BIOMES_data). Consistent biome patterns were simulated for the tropical forests of western and south-western Africa and the grasslands of northern Africa. On the other hand, in southern Europe, where the BIOME 4 vegetation reconstruction is dominated by warm temperate and temperate forest, our model shows a strong bias towards the grassland.

  4. Fire Frequency and Vegetation Composition Influence Soil Nitrogen Cycling and Base Cations in an Oak Savanna Ecosystem

    Science.gov (United States)

    McLauchlan, K. K.; Nelson, D. M.; Perakis, S.; Marcotte, A. L.

    2017-12-01

    Fire frequency is crucial for maintaining savannas in the transition between forests and grasslands. In general, increasing fire frequency has two effects: it increases herbaceous plant cover more than woody plant cover, and it lowers soil organic matter stocks. These effects have been demonstrated at a long-term prescribed fire experiment in an oak savanna ecosystem at Cedar Creek Ecosystem Science Reserve, Minnesota, U.S.A. The fire experiment began in 1964 and oak savannas are burned at various frequencies ranging from every year to not at all. This has led to changes in vegetation ranging from almost 100% grassland to 100% oak forest. Additionally, nitrogen stocks almost doubled in the sites that were not burned, as it accumulated in the trees, leaf litter, and soil. We addressed additional soil changes taking place at this experiment by asking the question: How have fire and oak-grass balance affected soil nutrients, specifically nitrogen and base cations? Surface soils were collected from 12 plots on the oak savanna burn experiment. Soils were collected in increments to 100 cm depth, from under grass-dominated vegetation and from under tree-dominated vegetation. We non-destructively estimated soil base cations by measuring elemental concentrations of dried soil subsamples with a handheld x-ray fluorescence analyzer. We also measured carbon and nitrogen concentrations and isotopic composition of the soil samples. Soils in plots with high fire frequency had higher concentrations of calcium than soils in unburned plots (low fire frequency). Similar trends were seen for soil potassium, magnesium, and phosphorus concentrations. In contrast, soils in plots with high fire frequency had dramatically lowered nitrogen cycling rates and stocks across the oak savanna. The contrast between the responses of different nutrients to changing fire frequency has important implications for the consequences of fire and tree-grass composition on nutrient cycling dynamics.

  5. Estimating forest biomass and identifying low-intensity logging areas using airborne scanning lidar in Antimary State Forest, Acre State, Western Brazilian Amazon

    Science.gov (United States)

    Marcus V.N. d' Oliveira; Stephen E. Reutebuch; Robert J. McGaughey; Hans-Erik. Andersen

    2012-01-01

    The objectives of this study were to estimate above ground forest biomass and identify areas disturbed by selective logging in a 1000 ha Brazilian tropical forest in the Antimary State Forest using airborne lidar data. The study area consisted of three management units, two of which were unlogged, while the third unit was selectively logged at a low intensity. A...

  6. Tropical Fruit Pulps: Processing, Product Standardization and Main Control Parameters for Quality Assurance

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo de Farias Silva

    2017-05-01

    Full Text Available ABSTRACT Fruit pulp is the most basic food product obtained from fresh fruit processing. Fruit pulps can be cold stored for long periods of time, but they also can be used to fabricate juices, ice creams, sweets, jellies and yogurts. The exploitation of tropical fruits has leveraged the entire Brazilian fruit pulp sector due mainly to the high acceptance of their organoleptic properties and remarkable nutritional facts. However, several works published in the last decades have pointed out unfavorable conditions regarding the consumption of tropical fruit pulps. This negative scenario has been associated with unsatisfactory physico-chemical and microbiological parameters of fruits pulps as outcomes of little knowledge and improper management within the fruit pulp industry. There are protocols for delineating specific identity and quality standards (IQSs and standardized good manufacturing practices (GMP for fruit pulps, which also embrace standard operating procedures (SOPs and hazard analysis and critical control points (HACCP, although this latter is not considered mandatory by the Brazilian legislation. Unfortunately, the lack of skilled labor, along with failures in complying established protocols have impaired quality of fruit pulps. It has been necessary to collect all information available with the aim to identify the most important hazards within fruit pulp processing lines. Standardizing methods and practices within the Brazilian fruit pulp industry would assurance high quality status to tropical fruit pulps and the commercial growth of this vegetal product towards international markets.

  7. Plant litter dynamics in the forest-stream interface: precipitation is a major control across tropical biomes.

    Science.gov (United States)

    Tonin, Alan M; Gonçalves, José F; Bambi, Paulino; Couceiro, Sheyla R M; Feitoza, Lorrane A M; Fontana, Lucas E; Hamada, Neusa; Hepp, Luiz U; Lezan-Kowalczuk, Vânia G; Leite, Gustavo F M; Lemes-Silva, Aurea L; Lisboa, Leonardo K; Loureiro, Rafael C; Martins, Renato T; Medeiros, Adriana O; Morais, Paula B; Moretto, Yara; Oliveria, Patrícia C A; Pereira, Evelyn B; Ferreira, Lidiane P; Pérez, Javier; Petrucio, Mauricio M; Reis, Deusiano F; S Rezende, Renan; Roque, Nadia; Santos, Luiz E P; Siegloch, Ana E; Tonello, Gabriela; Boyero, Luz

    2017-09-07

    Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth's land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m -2 y -1 , storage: 55, 113 and 38 g m -2 , on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas.

  8. Drought sensitivity changes over the last century at the North American savanna-forest boundary

    Science.gov (United States)

    Heilman, K.; McLachlan, J. S.

    2017-12-01

    Future environmental changes can affect the sensitivity of tree growth to climate. Theses changes are of particular concern at biome boundaries where tree distribution could shift as a result of changes in both drought and drought sensitivity. One such region is the North American savanna-forest boundary, where increased CO2 and droughts could alter savanna and forest ecosystem distributions in two contrasting ways: 1). More severe droughts may increase drought sensitivity, favoring open savanna ecosystems or, 2). Increases in water use efficiency resulting from higher atmospheric CO2 may decrease drought sensitivity, promoting forest expansion. This study sought to understand whether the past 100 years of climate and CO2 changes have impacted regional tree growth-climate sensitivity. To test for these climate sensitivity changes, we measured the sensitivity of Quercus spp. radial growth to Palmer Drought Severity Index (PDSI). Tree growth sensitivity to climate can vary according to many factors, including: stand structure, available moisture, and tree age. To control for these factors, we sampled tree growth-climate responses at sites in both open and closed forests, and at both low and high annual precipitation. Within each site, we compared growth responses to climate between trees established under high CO2 conditions after 1950 (high CO2 young), and tree established before 1950 under low CO2 levels (low CO2 young). At most sites, low CO2 young have a higher drought sensitivity than higher CO2 young. These changes in the sensitivity to drought are consistent with CO2 enhancement of water use efficiency. Furthermore, these differences in drought sensitivity are higher at sites with high temperature and low precipitation, suggesting that the alleviation of drought is more likely in hot and dry regions. Thus, if CO2 enhancement is indeed occurring in these systems, lower growth sensitivity to drought in hot and dry regions could favor increased forest growth. If

  9. Sports Injuries in Brazilian Blind Footballers

    OpenAIRE

    Silva, MPME; Morato, MP; Bilzon, JLJ; Duarte, E

    2013-01-01

    The purpose of this study was to assess the characteristics and prevalence of sports-related injuries in visually disabled athletes of the Brazilian football 5-a-side team. The participants were 13 male athletes, all classified as B1 visual class, members of the Brazilian team, who played in five consecutive international competitions. Data were collected using the Brazilian Paralympic Committee and the Brazilian Confederation of Sports for the Blind report form. From the total of 13 athletes...

  10. Three-dimensional woody vegetation structure across different land-use types and land-use intensities in a semi-arid savanna

    CSIR Research Space (South Africa)

    Fisher, J

    2009-07-01

    Full Text Available Factors influencing woody savanna vegetation structure across a land-use gradient of intensity (highly and lightly utilized communal rangeland) and type (national protected area, private game reserve and communal rangelands) were investigated. Small...

  11. Malaria and Tropical Travel

    Centers for Disease Control (CDC) Podcasts

    2008-05-15

    Malaria is a serious mosquito-borne disease that can lead to death. This podcast discusses malaria risk when traveling to tropical areas, as well as how to protect yourself and your family from malaria infection.  Created: 5/15/2008 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 5/29/2008.

  12. [Tropical causes of epilepsy].

    Science.gov (United States)

    Carod-Artal, F J

    Eighty-five percent of all epileptics live in tropical regions. Prenatal risk factors, traumatic brain injuries and different parasitic infestations of the central nervous system (CNS) are the reasons behind the high prevalence of epilepsy. This work reviews the main parasitic infestations causing epilepsy in the tropics. Neurocysticercosis is the main cause of focal epilepsy in early adulthood in endemic areas (30-50%). All the phases of cysticerci (viable, transitional and calcified) are associated with epileptic seizures. Anti-cysticercus treatment helps get rid of cysticerci faster and reduces the risk of recurrence of seizures in patients with viable cysts. Symptomatic epilepsy can be the first manifestation of neuroschistosomiasis in patients without any systemic symptoms. The pseudotumoral form can trigger seizures secondary to the presence of granulomas and oedemas in the cerebral cortex. The eggs of Schistosoma japonicum are smaller, reach the CNS more easily and trigger epileptic seizures more frequently. Toxocariasis and sparganosis are other parasitic infestations that can give rise to symptomatic seizures. The risk factors for suffering chronic epilepsy after cerebral malaria are a positive familial history of epilepsy and a history of episodes of fever and cerebral malaria that began with coma or which progressed with multiple, prolonged epileptic seizures. About 20% of patients with cerebral infarction secondary to Chagas disease present late vascular epilepsy as a complication. Very few studies have been conducted to examine the prognosis, risk of recurrence and modification of the natural course of seizures associated with tropical parasitic infestations, except for the case of neurocysticercosis.

  13. Long term precipitation chemistry and wet deposition in a remote dry savanna site in Africa (Niger

    Directory of Open Access Journals (Sweden)

    C. Galy-Lacaux

    2009-03-01

    Full Text Available Long-term precipitation chemistry have been recorded in the rural area of Banizoumbou (Niger, representative of a semi-arid savanna ecosystem. A total of 305 rainfall samples ~90% of the total annual rainfall were collected from June 1994 to September 2005. From ionic chromatography, pH major inorganic and organic ions were detected. Rainwater chemistry is controlled by soil/dust emissions associated with terrigeneous elements represented by SO42−, Ca2+, Carbonates, K+ and Mg2+. It is found that calcium and carbonates represent ~40% of the total ionic charge. The second highest contribution is nitrogenous, with annual Volume Weighed Mean (VWM for NO3 and NH4+ concentrations of 11.6 and 18.1 μeq.l−1, respectively. This is the signature of ammonia sources from animals and NOx emissions from savannas soil-particles rain-induced. The mean annual NH3 and NO2 air concentration are of 6 ppbv and 2.6 ppbv, respectively. The annual VWM precipitation concentration of sodium and chloride are both of 8.7 μeq.l−1 which reflects the marine signature of monsoonal and humid air masses. The median pH value is of 6.05. Acidity is neutralized by mineral dust, mainly carbonates, and/or dissolved gases such NH3. High level of organic acidity with 8μeq.l−1 and 5.2 μeq.l−1 of formate and acetate were also found. The analysis of monthly Black Carbon emissions and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR values show that both biogenic emission from vegetation and biomass burning could explain the rainfall organic acidity content. The interannual variability of the VWM concentrations around the mean (1994–2005 is between ±5% and ±30% and mainly due to variations of sources strength and rainfall spatio-temporal distribution. From 1994 to 2005

  14. Genetic Divergence in Eucalyptus camaldulensis Progenies in the Savanna Biome in Mato Grosso, Brazil.

    Directory of Open Access Journals (Sweden)

    Reginaldo Brito da Costa

    Full Text Available Assessing the parental genetic differences and their subsequent prediction of progeny performance is an important first step to assure the efficiency of any breeding program. In this study, we estimate the genetic divergence in Eucalyptus camaldulensis based on the morphological traits of 132 progenies grown in a savanna biome. Thus, a field experiment was performed using a randomized block design and five replications to compare divergences in total height, commercial height, diameter at breast height, stem form and survival rate at 48 months. Tocher's clustering method was performed using the Mahalanobis and Euclidian distances. The Mahalanobis distance seemed more reliable for the assessed parameters and clustered all of the progenies into fourteen major groups. The most similar progenies (86 accessions were clustered into Group I, while the most dissimilar (1 progeny represented Group XIV. The divergence analysis indicated that promising crosses could be made between progenies allocated in different groups for high genetic divergence and for favorable morphological traits.

  15. Spatial-temporal distribution of fire-protected savanna physiognomies in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Marcelo H.O. Pinheiro

    2010-06-01

    Full Text Available The analysis of the influence of edaphic finer textures, as a facilitating factor for the expansion of forest formations in the absence of fire, was possible thanks to rare characteristics found in a savanna fragment located in the State of São Paulo, Brazil. The total suppression of fire for over four decades, and the occurrence of two savanna physiognomies, cerrado sensu stricto and cerradão, allowed the conduction of this study based on the hypothesis that cerradão, a physiognomy of forest aspect consisting of fire-sensitive tree and shrubs species, is favored by fire absence and higher soil hydric retention capacity. Edaphic samples were collected from a regular grid of 200 m² for the production of isopletic maps of the distribution of clay, fine sand, coarse sand and silt edaphic textures by the geostatistic method of ordinary kriging. Changes in the areas occupied by both savanna physiognomies, defined on the basis of aerial photographs taken over a period of 43 years, were assessed through mean variation rates. Besides corroborating the hypothesis of edaphic hydric retention as a facilitating factor for the expansion of forest physiognomies in savanna areas, we were able to infer the positive influence of higher precipitation on the increase in cerradão expansion rates.A influência de texturas edáficas finas, como fator de facilitação para a expansão de formações florestais sobre áreas savânicas, através da maior retenção hídrica edáfica, na ausência de incêndios, foi possível ser estudada graças às características encontradas em um fragmento savânico com 38,8 ha, situado em Corumbataí (SP. A supressão total do fogo por quatro décadas, e a ocorrência de duas fisionomias, cerrado sensu stricto e cerradão, permitiram a condução deste estudo. Amostras de solo foram coletadas em uma grade regular de 200 m², abrangendo toda a área do fragmento. Foram produzidos mapas iso-pléticos, com a distribuição das

  16. Assessing diet in savanna herbivores using stable carbon isotope ratios of faeces

    Directory of Open Access Journals (Sweden)

    D. Codron

    2005-06-01

    Full Text Available In African savannas, browse-based resources (@3 plants are isotopically distinct from grasses (@4 plants. The carbon isotopic composition of the basic plant diet is recorded in animal tissues. Mammal faeces are a readily accessible, non-invasive, sample material for temporally resolved dietary reconstructions. Faeces, however, include both undigested plant matter and waste, hence accuracy of dietary calculations could potentially be compromised by shifts in plant isotopic values related to seasonal or spatial differences, or by variability in the isotopic differences between faeces and diet. A controlled feeding study of four ungulate species showed a small, consistent difference between diet and faeces of-0.9 o, irrespective of whether the diet was @3 or C4-based. Results from faeces oftaxa known to be pure grazers, pure browsers, and mixed-feeders from the Kruger National Park were entirely consistent with their diets, but the accuracy of dietary reconstructions is enhanced with data from local plant communities.

  17. Biomass burning aerosols in a savanna region of the Ivory Coast

    International Nuclear Information System (INIS)

    Cachier, H.; Ducret, J.; Bremond, M.P.; Yoboue, V.; Lacaux, J.P.; Gaudichet, A.; Baudet, J.

    1991-01-01

    In order to characterize the biomass burning particulate emissions, the authors sampled aerosols at Lamto in the wooded savanna of the Ivory Coast, during periods when the atmosphere is primarily influenced by various prescribed nearby or distant fires. They present here the results of parallel analyses which focus on the problem of tracing biomass burning aerosols at different levels of investigation. Soluble ion measurements give evidence of enhanced levels of various cations (potassium, calcium) and anions (sulfate, nitrate, oxalate), and the appearance of detectable oxalate concentrations. Further indication is obtained by analytical transmission electron microscopy of the small individual particles focusing on their trace element content. In addition, studies of the bulk carbonaceous content of the particles appear to provide primarily some possible indicators of the fire variability such as the isotropic composition fraction in the carbonaceous material (Cb to Ct ratio)

  18. Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

    Directory of Open Access Journals (Sweden)

    William J Platt

    Full Text Available Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature. We used nonparametric cluster analyses of a 17-year (1993-2009 data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires over a 13-year period with fire records (1997-2009. Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with

  19. Ecosystem properties of semiarid savanna grassland in West Africa and its relationship with environmental variability.

    Science.gov (United States)

    Tagesson, Torbern; Fensholt, Rasmus; Guiro, Idrissa; Rasmussen, Mads Olander; Huber, Silvia; Mbow, Cheikh; Garcia, Monica; Horion, Stéphanie; Sandholt, Inge; Holm-Rasmussen, Bo; Göttsche, Frank M; Ridler, Marc-Etienne; Olén, Niklas; Lundegard Olsen, Jørgen; Ehammer, Andrea; Madsen, Mathias; Olesen, Folke S; Ardö, Jonas

    2015-01-01

    The Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ data. The studied variables include hydroclimatic variables, species composition, albedo, normalized difference vegetation index (NDVI), hyperspectral characteristics (350-1800 nm), surface reflectance anisotropy, brightness temperature, fraction of absorbed photosynthetic active radiation (FAPAR), biomass, vegetation water content, and land-atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable for investigating relationships between ecosystem properties and hydroclimatic variables for semiarid savanna ecosystems of the region. There were strong interannual, seasonal and diurnal dynamics in NEE, with high values of ~-7.5 g C m(-2)  day(-1) during the peak of the growing season. We found neither browning nor greening NDVI trends from 2002 to 2012. Interannual variation in species composition was strongly related to rainfall distribution. NDVI and FAPAR were strongly related to species composition, especially for years dominated by the species Zornia glochidiata. This influence was not observed in interannual variation in biomass and vegetation productivity, thus challenging dryland productivity models based on remote sensing. Surface reflectance anisotropy (350-1800 nm) at the peak of the growing season varied strongly depending on wavelength and viewing angle thereby having implications for the design of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics

  20. Within-population isotopic niche variability in savanna mammals: disparity between carnivores and herbivores

    Directory of Open Access Journals (Sweden)

    Daryl eCodron

    2016-02-01

    Full Text Available Large mammal ecosystems have relatively simple food webs, usually comprising three – and sometimes only two – trophic links. Since many syntopic species from the same trophic level therefore share resources, dietary niche partitioning features prominently within these systems. In African and other subtropical savannas, stable carbon isotopes readily distinguish between herbivore species for which foliage and other parts of dicot plants (13C-depleted C3 vegetation are the primary resource (browsers and those for which grasses (13C-enriched C4 vegetation are staples (grazers. Similarly, carbon isotopes distinguish between carnivore diets that may be richer in either browser, grazer, or intermediate-feeding prey. Here, we investigate levels of carbon and nitrogen isotopic niche variation and niche partitioning within populations (or species of carnivores and herbivores from South African savannas. We emphasize predictable differences in within-population trends across trophic levels: we expect that herbivore populations, which require more foraging effort due to higher intake requirements, are far less likely to display within-population resource partitioning than carnivore populations. Our results reveal generally narrower isotopic niche breadths in herbivore than carnivore populations, but more importantly we find lower levels of isotopic differentiation across individuals within herbivore species. While these results offer some support for our general hypothesis, the current paucity of isotopic data for African carnivores limits our ability to test the complete set of predictions arising from our hypothesis. Nevertheless, given the different ecological and ecophysiological constraints to foraging behaviour within each trophic level, comparisons across carnivores and herbivores, which are possible within such simplified foodwebs, make these systems ideal for developing a process-based understanding of conditions underlying the evolution of