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Sample records for savanna woodland soil

  1. 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 ...

  2. Restoration of temperate savannas and woodlands

    Science.gov (United States)

    Brice B. Hanberry; John M. Kabrick; Peter W. Dunwiddie; Tibor Hartel; Theresa B. Jain; Benjamin O. Knapp

    2017-01-01

    Savannas and woodlands are open forest phases that occur along a gradient between grasslands and closed canopy forests. These ecosystems are characterized by open to nearly closed canopies of overstorey trees, relatively sparse midstorey and understorey woody vegetation, and dense, species-rich ground flora. In contrast to closed forests, the dominant and codominant...

  3. Silviculture to restore oak savannas and woodlands

    Science.gov (United States)

    Daniel C. Dey; John M. Kabrick; Callie J. Schweitzer

    2017-01-01

    Variability in historic fire regimes in eastern North America resulted in an array of oak natural communities that were dominant across the region. In the past century, savannas and woodlands have become scarce because of conversion to agriculture or development of forest structure in the absence of fire. Their restoration is a primary goal for public agencies and...

  4. 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...

  5. Chemical changes to nonaggregated particulate soil organic matter following grassland-to-woodland transition in a subtropical savanna

    Science.gov (United States)

    Filley, Timothy R.; Boutton, Thomas W.; Liao, Julia D.; Jastrow, Julie D.; Gamblin, David E.

    2008-09-01

    Encroachment of thorn woodlands into grasslands of southern Texas has resulted in greater aboveground and belowground biomass and greater soil organic carbon (SOC) stocks. Our previous studies showed that a large percentage of the SOC accrued under invading woody clusters was not stabilized within protective soil aggregates or on mineral-surfaces. Here we evaluated lignin and cutin- and suberin-derived substituted fatty acid (SFA) chemistry to determine if the accrual of nonaggregated particulate organic matter (POM) in woodlands was promoted by inherently greater recalcitrance of tissues from woody versus grass species, and if there was selective input of aboveground versus belowground plant carbon to POM. Woody clusters exhibited reduced concentrations of cutin-derived SFA and cinnamyl phenols within surface litter compared to fresh aboveground plant material. However, root litter exhibited relatively minor changes in biopolymer chemistry compared to fresh root tissue, suggesting it was either more stable or was refreshed at a greater rate. Between 14 and 105 years of woody plant encroachment, SFA in free POM fractions appeared to be consistently derived from root material while SFA within intraaggregate POM were increasingly derived from cutin sources. In addition, the shift from herbaceous to woody input was accompanied by enrichment in the amount of cutin and suberin-derived aliphatics with respect to lignin in both root and surface litter as well as nonaggregated POM. Woody plant encroachment at this site results in the rapid accrual of POM pools that are biochemically recalcitrant, providing a mechanism by which soil organic carbon can accumulate in this sandy soil system. Our results also lend further credence to the hypothesis that aliphatic biopolymers, particularly root-derived suberin, are important components of long-term soil organic carbon stabilization.

  6. Regional variations in biomass distribution in Brazilian savanna woodland

    Science.gov (United States)

    S.d.C. de Miranda; M. Bustamente; M. Palace; S. Hagen; M. Keller; L.G. Ferreira

    2014-01-01

    The Cerrado, the savanna biome in central Brazil, mostly comprised of woodland savanna, is experiencing intense and fast land use changes. To understand the changes in Cerrado carbon stocks, we present an overview of biomass distribution in different Cerrado vegetation types (i.e., grasslands, shrublands and forestlands). We surveyed 26 studies including 170 Cerrado...

  7. Importance of dry savanna woodlands in rural livelihoods and wildlife conservation in southeastern Zimbabwe

    NARCIS (Netherlands)

    Gandiwa, E.

    2011-01-01

    Increasing human population, economic challenges, climate change impacts are intensifying reliance by local communities on savanna woodlands in tropical regions. Knowledge of the importance and value of savanna woodland ecosystems to rural livelihoods and wildlife conservation is therefore needed to

  8. Restoration of temperate savannas and woodlands [Chapter 11

    Science.gov (United States)

    Brice B. Hanberry; John M. Kabrick; Peter W. Dunwiddie; Tibor Hartel; Theresa B. Jain; Benjamin O. Knapp

    2017-01-01

    Savannas and woodlands are open forest phases that occur along a gradient between grasslands and closed canopy forests. These ecosystems are characterized by open to nearly closed canopies of overstorey trees, relatively sparse midstorey and understorey woody vegetation, and dense, species-rich ground flora. In contrast to closed forests, the dominant and codominant...

  9. 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...

  10. Tree stocking affects winter bird densities across a gradient of savanna, woodland, and forest in the Missouri Ozarks

    Science.gov (United States)

    Sarah W. Kendrick; Frank R., III Thompson

    2013-01-01

    Savanna and woodland were historically prevalent in the midwestern United States, and managers throughout the area are currently attempting to restore these communities. Better knowledge of the responses of breeding and non-breeding birds to savanna and woodland restoration is needed to inform management.We surveyed abundance of winter resident birds across a gradient...

  11. Restoring grassland savannas from degraded pinyon-juniper woodlands: effects of mechanical overstory reduction and slash treatment alternatives.

    Science.gov (United States)

    Brockway, Dale G; Gatewood, Richard G; Paris, Randi B

    2002-02-01

    Although the distribution and structure of pinyon-juiper woodlands in the southwestern United States are thought to be the result of historic fluctuations in regional climatic conditions, more recent increases in the areal extent, tree density, soil erosion rates and loss of understory plant diversity are attributed to heavy grazing by domestic livestock and interruption of the natural fire regime. Prior to 1850, many areas currently occupied by high-density pinyon-juniper woodlands, with their degraded soils and depauperate understories, were very likely savannas dominated by native grasses and forbs and containing sparse tree cover scattered across the landscape. The purpose of this study was to evaluate the effectiveness of mechanical overstory reduction and three slash treatment alternatives (removal, clustering and scattering) followed by prescribed fire as techniques for restoring grassland savannas from degraded woodlands. Plant cover, diversity, biomass and nutrient status, litter cover and soil chemistry and erosion rates were measured prior to and for two years following experimental treatment in a degraded pinyon-juniper woodland in central New Mexico. Treatment resulted in a significant increase in the cover of native grasses and, to a lesser degree, forbs and shrubs. Plant species richness and diversity increased most on sites where slash was either completely removed or scattered to serve as a mulch. Although no changes in soil chemistry or plant nutrient status were observed, understory biomass increased over 200% for all harvest treatments and was significantly greater than controls. While treatment increased litter cover and decreased soil exposure, this improvement did not significantly affect soil loss rates. Even though all slash treatment alternatives increased the cover and biomass of native grasses, scattering slash across the site to serve as a mulch appears most beneficial to improving plant species diversity and conserving site resources.

  12. 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

  13. 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...

  14. Dynamics of the leaf-litter arthropod fauna following fire in a neotropical woodland savanna.

    Science.gov (United States)

    Vasconcelos, Heraldo L; Pacheco, Renata; Silva, Raphael C; Vasconcelos, Pedro B; Lopes, Cauê T; Costa, Alan N; Bruna, Emilio M

    2009-11-09

    Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade) were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover) and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover). Although these effects were transitory, there is evidence that the increasingly prevalent fire return interval of

  15. Dynamics of the leaf-litter arthropod fauna following fire in a neotropical woodland savanna.

    Directory of Open Access Journals (Sweden)

    Heraldo L Vasconcelos

    Full Text Available Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover. Although these effects were transitory, there is evidence that the increasingly prevalent fire

  16. Vegetation structure characteristics and relationships of Kalahari woodlands and savannas

    CSIR Research Space (South Africa)

    Privette, JL

    2004-03-01

    Full Text Available modeling has become widespread (e.g., Potter et al., 1993, 1998; Sellers et al., 1996). Nevertheless, knowledge of vegetation canopy struc- ture remains incomplete in many remote areas, such as sub-Saharan Africa. First, comparatively small changes... 929 460 Colophospermum mopane woodland with patches of Terminalia sericea thicket Harry Oppenheimer Okavango Research Centre; Measurements were 3km east of a permanent flux tower 23.591E Okwa River Crossing, Botswana 22.411S 1089 407 Open Kalahari...

  17. Seasonal variations in methane and nitrous oxide emissions factors in northern Australian savanna woodlands

    Science.gov (United States)

    Meyer, C. P.(Mick); Cook, Garry; Reisen, Fabienne; Russell-Smith, Jeremy; Maier, Stefan; Schatz, Jon; Yates, Cameron; Watt, Felicity

    2010-05-01

    Burning of savannas and grasslands consumes more than one third of the total annual biomass burning globally. In Australia, savanna fires emit annually from 2% to 4% of Australia's greenhouse gas emissions. This has led to efforts to reduce savanna burning emissions through early season prescribed burning. These programs aim to change the fire seasonality from predominantly high intensity late season fires which are characterized by low levels of patchiness and high burning efficiencies to early-season fires characterized by low intensity, a high degree of patchiness and low burning efficiency. The result is a net reduction in fire area and associated carbon emissions. Mitigation of greenhouse gas emissions is predicated on there being little change in methane (CH4) or nitrous oxide (N2O) emission factors (EFs) as the fire season progresses, however, recent analysis of the emission characteristics of African savanna fires by Korontzi et al., indicates CH4-EF, in particular, could decline substantially as the fire season progresses. If this also occurs in Australian savanna woodlands, then the current mitigation strategy could be ineffective. To address the issue a series of field campaigns were undertaken in the savanna woodlands of Western Arnhem land, Australia to quantify the variability in CH4 and N2O EFs throughout the fire season. This study compared CH4 and N2O EFs measured in smoke sampled from prescribed burning in late June/early July with those from late season fires in early October. It concentrated on the two major vegetation classes in Western Arnhemland; eucalypt open woodland, in which the fuel is composed predominantly tree leaf-litter supplemented by senescent native Sorghum, and sandstone heaths which are dominated by Spinifex hummocks. There were no significant differences in CH4 EFs between early or late season fires, however there were substantial differences between vegetation classes. The woodland emitted 0.3% of fuel carbon as CH4 compared

  18. 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...

  19. Southwestern U. S. juniper savanna and piñon-juniper woodland communities: Ecological history and natural range of variability

    Science.gov (United States)

    Brian F. Jacobs

    2008-01-01

    Juniper savanna and pinon-juniper woodland communities collectively represent a widespread and diverse vegetation type that occupies foothill and mesa landforms at middle elevations in semi-arid portions of the American Southwest. Ecological understanding and proper management of these juniper and pinon types requires local knowledge of component species, site history...

  20. Rapid assessment and mapping of tree cover in southern African savanna woodlands using a new iPhone App and Landsat 8 imagery

    Science.gov (United States)

    Fuller, D. O.

    2016-12-01

    Tree cover is a key parameter in climate modeling. It strongly influences CO2 exchanges between the land surface and atmosphere and surface energy balance. We measured percent woody canopy cover (PWCC) in the savanna woodlands of eastern Zambia over a 10-day period in May 2016 using a new iPhone App (CanopyApp) and related these field measurements to Landsat 8 (L8) Band 4 (red) imagery acquired approximately the same time. We then used parameters from the band 4 digital numbers (DNs)-PWCC linear regression to derive a new map of PWCC for the entire L8 scene. Consistent with theory and previous empirical studies, we found that the relationship between L8 band 4 DNs- PWCC was negative and linear (r2 = 0.61, p sufficient to estimate PWCC when spectral contrast exists between the grass, soil and tree layers during the austral fall period in southern African savannas.

  1. Classification and mapping of the composition and structure of dry woodland and savanna in the eastern Okavango Delta

    Directory of Open Access Journals (Sweden)

    Michelle J. Tedder

    2013-02-01

    Full Text Available The dry woodland and savanna regions of the Okavango Delta form a transition zone between the Okavango Swamps and the Kalahari Desert and have been largely overlooked in terms of vegetation classification and mapping. This study focused on the species composition and height structure of this vegetation, with the aim of identifying vegetation classes and providing a vegetation map accompanied by quantitative data. Two hundred and fifty-six plots (50 m × 50 m were sampled and species cover abundance, total cover and structural composition were recorded. The plots were classified using agglomerative, hierarchical cluster analysis using group means and Bray-Curtis similarity and groups described using indicator species analysis. In total, 23 woody species and 28 grass species were recorded. Acacia erioloba and Colophospermum mopane were the most common woody species, whilst Urochloa mossambicensis, Panicum maximum, Dactyloctenium gigantiumand Eragrostis lehmanniana were the most widespread grasses. Eleven vegetation types were identified, with the most widespread being Short mixed mopane woodland, Tall mopane woodland and Tall mixed mopane woodland, covering 288.73 km2 (28%, 209.14 km2 (20% and 173.30 km2 (17% of the area, respectively. Despite their extensive area, these three vegetation types were the least species-rich, whilst Palm thornveld, Short mixed broadleaf woodland and Open mixed Acacia woodland were the most taxonomically variable. By contrast, Closed mixed Acacia woodland and Closed Acacia–Combretum woodland had the most limited distribution, accounting for less than 1% of the mapped area each.Conservation implications: The dry woodland and savanna vegetation of the Okavango Delta comprises a much wider suite of plant communities than the Acacia-dominated and Mopane-dominated classifications often used. This classification provided a more detailed understanding of this vegetation and essential background information for monitoring

  2. Land-use changes alter radiative energy and water vapor fluxes of a tall-grass Andropogon field and a savanna-woodland continuum in the Orinoco lowlands.

    Science.gov (United States)

    San José, José; Montes, Rubén; Grace, John; Nikonova, Nina; Osío, Anaís

    2008-03-01

    Changes in land use in the Orinoco lowlands affect the daily trends of energy and water vapor fluxes. We analyzed these fluxes along a disturbance gradient beginning from a cultivated tall-grass Andropogon field (S1) and extending over three savanna sites with increasing woody cover over herbaceous vegetation. The savanna sites encompass a herbaceous savanna (S2), a tree savanna (S3) and a woodland savanna (S4). In the wet season, there were differences in the radiation budget: seasonally averaged albedo for S1 (0.17) exceeded that of S2-S4 (0.13-0.14). Eddy covariance fluxes indicate that the partitioning of the daily net radiation (Rn) into sensible and latent heat (lambda E) fluxes depends on land use. During the wet season, evapotranspiration (i.e., lambda E) over the S1-S4 sites accounted for a variable fraction of Rn (i.e., 0.75, 0.52, 0.67 and 0.68, respectively). Therefore, the Bowen ratio was typically below 1. As the dry season progressed, the lambda E/Rn ratio decreased markedly with increasing air and canopy temperatures and air humidity mole fraction deficit. The maximum evaporation rate over the S1-S4 sites was 3.2, 2.5, 3.5 and 4.1 mm day(-1), respectively, and the annual values were 721, 538, 771 and 732 mm year(-1), respectively, equivalent to 49, 65, 52 and 88% of the rainfall. Soil water content fell from a maximum above 0.28 in the wet season to 0.030, 0.026, 0.030 and 0.028 m(3) m(-3) at sites S1-S4, respectively, in the dry season. Leaf area index was greatly reduced as herbaceous vegetation dried out.

  3. Hillslope soil movement in the oak savannas of the Southwestern Borderlands Region

    Science.gov (United States)

    Aaron Kauffman

    2009-01-01

    Oak woodlands and savannas comprise more than 31,000 square miles (80,290 square kilometers) in the southwestern United States and northern Mexico and provide various resources including forage for livestock, wildlife habitat, fuelwood, and recreational areas. Increased woody-plant encroachment into the more open savanna ecosystems has presented a problem to managers...

  4. Land Cover Change in Northern Botswana: The Influence of Climate, Fire, and Elephants on Semi-Arid Savanna Woodlands

    Directory of Open Access Journals (Sweden)

    John Tyler Fox

    2017-10-01

    Full Text Available Complex couplings and feedback among climate, fire, and herbivory drive short- and long-term patterns of land cover change (LCC in savanna ecosystems. However, understanding of spatial and temporal LCC patterns in these environments is limited, particularly for semi-arid regions transitional between arid and more mesic climates. Here, we use post-classification analysis of Landsat TM (1990, ETM+ (2003, and OLI (2013 satellite imagery to classify and assess net and gross LCC for the Chobe District, a 21,000 km2 area encompassing urban, peri-urban, rural, communally-managed (Chobe Enclave, and protected land (Chobe National Park, CNP, and six protected forest reserves. We then evaluate spatiotemporal patterns of LCC in relation to precipitation, fire detections (MCD14M, 2001–2013 from the Moderate Resolution Imaging Spectroradiometer (MODIS, and dry season elephant (Loxodonta africana aerial survey data (2003, 2006, 2012, 2013. Woodland cover declined over the study period by 1514 km2 (16.2% of initial class total, accompanied by expansion of shrubland (1305 km2, 15.7% and grassland (265 km2, 20.3%. Net LCC differed importantly in protected areas, with higher woodland losses observed in forest reserves compared to the CNP. Loss of woodland was also higher in communally-managed land for the study period, despite gains from 2003–2013. Gross (class changes were characterized by extensive exchange between woodland and shrubland during both time steps, and a large expansion of shrubland into grassland and bare ground from 2003–2013. MODIS active fire detections were highly variable from year to year and among the different protected areas, ranging from 1.8 fires*year−1/km2 in the Chobe Forest Reserve to 7.1 fires*year−1/km2 in the Kasane Forest Reserve Extension. Clustering and timing of dry season fires suggests that ignitions were predominately from anthropogenic sources. Annual fire count was significantly related to total annual rainfall

  5. Woody overstorey effects on soil carbon and nitrogen pools in South African savanna

    Science.gov (United States)

    A. T. Hudak; C. A. Wessman; T. R. Seastedt

    2003-01-01

    Woody plant encroachment in savannas may alter carbon (C) and nitrogen (N) pools over the longterm, which could have regional or global biogeochemical implications given the widespread encroachment observed in the vast savanna biome. Soil and litter %C and %N were surveyed across four soil types in two encroached, semiarid savanna landscapes in northern South Africa....

  6. Dinâmica físico-hídrica de uma toposseqüência de solos sob Savana Florestada (Cerradão em Assis, SP Soil water dynamics in a toposequence under Savanna Woodland (Cerradão in Assis, SP, Brazil

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Pinto Juhász

    2006-06-01

    ção espacial do mosaico vegetacional.The aim of this study was to characterize the morphological, physical and hydraulic soil properties in a toposequence under native plant cover in a permanent observation plot of 320 x 320 m installed in the Assis Ecological Station, São Paulo State, Brazil. The plot is covered by a remnant Savanna Woodland (Cerradão vegetation of the southern border zone of the great Cerrado domain. The bi-dimensional geometry (horizontal and vertical of the soil horizons in a toposequence provided details on the soil morphology. The soil water dynamics in the native plants environment was studied through determination of the soil-water retention curves as well as soil particle-size distribution, and saturated soil hydraulic conductivity using the Guelph permeameter. Soil moisture was measured in situ using a WCR sensor. Soil moisture and rainfall distribution were monitored from November 2003 to November 2004. The soils were classified, from the summit down to the footslope, as Rhodic Haplustox, Typic Haplustox and Epiaquic Haplustult. The high clay content in the subsurface horizon of the Epiaquic Haplustult, when compared to the Oxisols with greater sand content, determines less drainage, greater water retention and lower hydraulic conductivity. The soil moisture in this layer never attained the saturation during the study period. Soil water dynamics were influenced by relief conditions, as evidenced by the continuous lateral color transition, soil texture and structure, and by rainfall. At the soil surface, the soil moisture oscillation is closely related to the rain events. In the subsurface, this effect is less intense, and lagged in time. The water availability along the toposequence is limited in the dry season and in part of the wet season. The floristic characteristics of the forest formation and its mosaic distribution in the plot can be explained by the seasonal water availability.

  7. Soil clay content and fire frequency affect clustering in savanna trees in South African savannas

    OpenAIRE

    Groen, T.A.; Langevelde, van, F.; Vijver, van de, L.P.L.; N. Govender; Prins, H.H.T.

    2008-01-01

    In this paper, we investigate which factors determine tree clustering in Southern African savannas. This was tested by measuring clustering of trees using the T-squared sampling method in plots of the Kruger National Park experimental burning programme in South Africa. Fire return interval is the main treatment in these plots, but also several auxiliary determining parameters like clay content in the soil, diameter of tree canopies, understorey composition, tree species diversity and average ...

  8. Microbial Diversity in Cerrado Biome (Neotropical Savanna) Soils.

    Science.gov (United States)

    de Castro, Alinne Pereira; Sartori da Silva, Maria Regina Silveira; Quirino, Betania Ferraz; da Cunha Bustamante, Mercedes Maria; Krüger, Ricardo Henrique

    2016-01-01

    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.

  9. 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.

  10. 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)

    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. PMID:26066508

  11. Modeling pulsed soil respiration in an African savanna ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhaosheng; Neff, Jason C.; Hanan, Niall P.

    2015-01-01

    Savannas cover 60% of the African continent and play an important role in the global carbon (C) emissions from fire and land use. To better characterize the biophysical controls over soil respiration in these settings, half-hourly observations of volumetric soil-water content, temperature, and the concentration of carbon dioxide (CO2) at different soil depths were continually measured from 2005 to 2007 under trees ("sub-canopy") and between trees ("inter-canopy") in a savanna vegetation near Skukuza, Kruger National Park, South Africa. The measured soil climate and CO2 concentration data were assimilated into a process-based model that estimates the CO2 production and flux with coupled dynamics of dissolved organic C (DOC) and microbial biomass C. Our results show that temporal and spatial variations in CO2 flux were strongly influenced by precipitation and vegetation cover, with two times greater CO2 flux in the subcanopy plots (similar to 2421 g CO2 m(-2) yr(-1)) than in the inter-canopy plots (similar to 1290 g CO2 m(-2) yr(-1)). Precipitation influenced soil respiration by changing soil temperature and moisture; however, our modeling analysis suggests that the pulsed response of soil respiration to precipitation events (known as "Birch effect") is a key control on soil fluxes at this site. At this site, "Birch effect" contributed to approximately 50% and 65% of heterotrophic respiration or 20% and 39% of soil respiration in the sub-canopy and inter-canopy plots, respectively. These results suggest that pulsed response of respiration to precipitation events is an important component of the C cycle of savannas and should be considered in both measurement and modeling studies of carbon exchange in similar ecosystems. (C) 2014 Elsevier B.V. All rights reserved.

  12. 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.

  13. Group dynamics of zebra and wildebeest in a woodland savanna: effects of predation risk and habitat density.

    Directory of Open Access Journals (Sweden)

    Maria Thaker

    Full Text Available BACKGROUND: Group dynamics of gregarious ungulates in the grasslands of the African savanna have been well studied, but the trade-offs that affect grouping of these ungulates in woodland habitats or dense vegetation are less well understood. We examined the landscape-level distribution of groups of blue wildebeest, Connochaetes taurinus, and Burchell's zebra, Equus burchelli, in a predominantly woodland area (Karongwe Game Reserve, South Africa; KGR to test the hypothesis that group dynamics are a function of minimizing predation risk from their primary predator, lion, Panthera leo. METHODOLOGY/PRINCIPAL FINDINGS: Using generalized linear models, we examined the relative importance of habitat type (differing in vegetation density, probability of encountering lion (based on utilization distribution of all individual lions in the reserve, and season in predicting group size and composition. We found that only in open scrub habitat, group size for both ungulate species increased with the probability of encountering lion. Group composition differed between the two species and was driven by habitat selection as well as predation risk. For both species, composition of groups was, however, dominated by males in open scrub habitats, irrespective of the probability of encountering lion. CONCLUSIONS/SIGNIFICANCE: Distribution patterns of wildebeest and zebra groups at the landscape level directly support the theoretical and empirical evidence from a range of taxa predicting that grouping is favored in open habitats and when predation risk is high. Group composition reflected species-specific social, physiological and foraging constraints, as well as the importance of predation risk. Avoidance of high resource open scrub habitat by females can lead to loss of foraging opportunities, which can be particularly costly in areas such as KGR, where this resource is limited. Thus, landscape-level grouping dynamics are species specific and particular to the

  14. 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

  15. 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...

  16. 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, ...

  17. Soil clay content and fire frequency affect clustering in savanna trees in South African savannas

    NARCIS (Netherlands)

    Groen, T.A.; Langevelde, van F.; Vijver, van de C.A.D.M.; Govender, N.; Prins, H.H.T.

    2008-01-01

    In this paper, we investigate which factors determine tree clustering in Southern African savannas. This was tested by measuring clustering of trees using the T-squared sampling method in plots of the Kruger National Park experimental burning programme in South Africa. Fire return interval is the

  18. Multilocus phylogeography of a widespread savanna-woodland-adapted rodent reveals the influence of Pleistocene geomorphology and climate change in Africa's Zambezi region.

    Science.gov (United States)

    McDonough, Molly M; Šumbera, Radim; Mazoch, Vladimír; Ferguson, Adam W; Phillips, Caleb D; Bryja, Josef

    2015-10-01

    Understanding historical influences of climate and physiographic barriers in shaping patterns of biodiversity remains limited for many regions of the world. For mammals of continental Africa, phylogeographic studies, particularly for West African lineages, implicate both geographic barriers and climate oscillations in shaping small mammal diversity. In contrast, studies for southern African species have revealed conflicting phylogenetic patterns for how mammalian lineages respond to both climate change and geologic events such as river formation, especially during the Pleistocene. However, these studies were often biased by limited geographic sampling or exclusively focused on large-bodied taxa. We exploited the broad southern African distribution of a savanna-woodland-adapted African rodent, Gerbilliscus leucogaster (bushveld gerbil) and generated mitochondrial, autosomal and sex chromosome data to quantify regional signatures of climatic and vicariant biogeographic phenomena. Results indicate the most recent common ancestor for all G. leucogaster lineages occurred during the early Pleistocene. We documented six divergent mitochondrial lineages that diverged ~0.270-0.100 mya, each of which was geographically isolated during periods characterized by alterations to the course of the Zambezi River and its tributaries as well as regional 'megadroughts'. Results demonstrate the presence of a widespread lineage exhibiting demographic expansion ~0.065-0.035 mya, a time that coincides with savanna-woodland expansion across southern Africa. A multilocus autosomal perspective revealed the influence of the Kafue River as a current barrier to gene flow and regions of secondary contact among divergent mitochondrial lineages. Our results demonstrate the importance of both climatic fluctuations and physiographic vicariance in shaping the distribution of southern African biodiversity. © 2015 John Wiley & Sons Ltd.

  19. Detection of soil erosion with Thematic Mapper (TM) satellite data within Pinyon-Juniper woodlands

    Science.gov (United States)

    Price, Kevin Paul

    1987-01-01

    Pinyon-Juniper woodlands dominate approximately 24.3 million hectares (60 million acres) in the western United States. The overall objective was to test the sensitivity of the LANDSAT Thematic Mapper (TM) spectral data for detecting varying degrees of soil erosion within the Pinyon-Juniper woodlands. A second objective was to assess the potential of the spectral data for assigning the Universal Soil Loss Equation (USLE) crop management (C) factor values to varying cover types within the woodland. Thematic Mapper digital data for June 2, 1984 on channels 2, 3, 4, and 5 were used. Digital data analysis was performed using the ELAS software package. Best results were achieved using CLUS, an unsupervised clustering algorithm. Fifteen of the 40 Pinyon-Juniper signatures were identified as being relatively pure Pinyon-Juniper woodland. Final analysis resulted in the grouping of the 15 signatures into three major groups. Ten study sites were selected from each of the three groups and located on the ground. At each site the following field measurements were taken: percent tree canopy and percent understory cover, soil texture, total soil loss, and soil erosion rate estimates. A technique for measuring soil erosion within Pinyon-Juniper woodlands was developed. A theoretical model of site degradation after Pinyon-Juniper invasion is presented.

  20. The impact of broadleaved woodland on water resources in lowland UK: I. Soil water changes below beech woodland and grass on chalk sites in Hampshire

    Directory of Open Access Journals (Sweden)

    J. Roberts

    2005-01-01

    Full Text Available The possible effects of broadleaved woodland on recharge to the UK Chalk aquifer have led to a study of evaporation and transpiration from beech woodland (Black Wood and pasture (Bridgets Farm, growing in shallow soils above chalk in Hampshire. Eddy correlation measurements of energy balance components above both the forest and the grassland enabled calculation of latent heat flux (evaporation and transpiration as a residual. Comparative measurements of soil water content and soil water potential in 9 m profiles under both forest and grassland found changes in soil water content down to 6 m at both sites; however, the soil water potential measurements showed upward movement of water only above a depth of about 2 m. Below this depth, water continued to drain and the soil water potential measurements showed downward movement of water at both sites, notwithstanding significant negative soil water potentials in the chalk and soil above. Seasonal differences occur in the soil water content profiles under broadleaved woodland and grass. Before the woodland foliage emerges, greater drying beneath the grassland is offset in late spring and early summer by increased drying under the forest. Yet, when the change in soil water profiles is at a maximum, in late summer, the profiles below woodland and grass are very similar. A comparison of soil water balances for Black Wood and Bridgets Farm using changes in soil water contents, local rainfall and evaporation measured by the energy balance approach allowed drainage to be calculated at each site. Although seasonal differences occurred, the difference in cumulative drainage below broadleaved woodland and grass was small.

  1. Impacts of wildfire severity on hydraulic conductivity in forest, woodland, and grassland soils (Chapter 7)

    Science.gov (United States)

    Daniel G. Neary

    2011-01-01

    Forest, woodland, and grassland watersheds throughout the world are major sources of high quality water for human use because of the nature of these soils to infiltrate, store, and transmit most precipitation instead of quickly routing it to surface runoff. This characteristic of these wildland soils is due to normally high infiltration rates, porosities, and hydraulic...

  2. Remote sensing-based soil water balance to estimate Mediterranean holm oak savanna (dehesa) evapotranspiration under water stress conditions

    Science.gov (United States)

    Campos, Isidro; Villodre, Julio; Carrara, Arnaud; Calera, Alfonso

    2013-06-01

    This paper aims to present the use of a remote sensing-based soil water balance to estimate holm oak woodland evapotranspiration (ET). The model is based on the assimilation of MODIS reflectance-based vegetation indices in the dual crop coefficient methodology. A daily water balance was performed on the root zone soil to estimate plant water stress. The methodology was evaluated with respect to the actual ET measured by eddy covariance in Mediterranean holm oak savanna (dehesa) for five consecutive years (2004-2008). The model adequately reproduced the absolute values and tendencies measured at daily and weekly periods. Root mean square error (RMSE) was 0.50 mm/day for daily values and 2.70 mm/week for weekly accumulated values. The analysis demonstrated the presence of a long period of water stress during the summer and at the beginning of fall. Measured ET dropped during these periods, and the model replicated this tendency accurately, reaching a stress coefficient value close to 0.2. To be operative, the proposed method required low ground data (reference evapotranspiration and precipitation) and the results indicated a simple, robust method that can be used to map ET and water stress in the dehesa ecosystem.

  3. Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) satellite data

    Science.gov (United States)

    Price, Kevin P.; Ridd, Merrill K.

    1991-01-01

    The sensitivity of Landsat TM data for detecting soil erosion within pinyon-juniper woodlands, and the potential of the spectral data for assigning the universal soil loss equation (USLE) crop managemnent (C) factor to varying cover types within the woodlands are assessed. Results show greatly accelerated rates of soil erosion on pinyon-juniper sites. Percent cover by pinyon-juniper, total soil-loss, and total nonliving ground cover accounted for nearly 70 percent of the variability in TM channels 2, 3, 4, and 5. TM spectral data were consistently better predictors of soil erosion than the biotic and abiotic field variables. Satellite data were more sensitive to vegetation variation than the USLE C factor, and USLE was found to be a poor predictor of soil loss on pinyon-juniper sites. A new string-to-ground soil erosion prediction technique is introduced.

  4. RELATIONSHIP OF MICROBIAL COMMUNITY STRUCTURE AND CARBON DYNAMICS IN SOILS FROM BRAZILIAN SAVANNAS

    Science.gov (United States)

    Fertilization is a widespread management practice in savanna areas of central Brazil (Cerrado) that are undergoing rapid agricultural land use changes. We conducted field and laboratory studies in soils with added fertilizers to determine the effect that fertilization of native a...

  5. Impact of some savanna trees on soil quality on smallholder farms in ...

    African Journals Online (AJOL)

    Soil nutrient decline has become a major issue of concern to researchers in the semi-arid region of Nigeria. This condition is further exacerbated by worsening climate and declining environmental quality, amplified by huge population pressure on limited resources. This research investigates the impact of some key savanna ...

  6. Processes preventing nocturnal equilibration between leaf and soil water potential in tropical savanna woody species.

    Science.gov (United States)

    Sandra Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Jose A. Hinojosa; William A. Hoffman; Augusto C. Franco

    2004-01-01

    The impact of nocturnal water loss and recharge of stem water storage on predawn disequilibrium between leaf (ΨL) and soil (Ψ S) water potentials was studied in three dominant tropical savanna woody species in central Brazil (Cerrado). Sap flow continued throughout the night during the dry season and...

  7. Tree shade effects on soils and environmental factors in a Savanna ...

    African Journals Online (AJOL)

    Tree shade effects on soils and environmental factors in a Savanna of Senegal. LE Akpo, VA Goudiaby, M Grouzis, HN Le Houerou. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · http://dx.doi.org/10.4314/wajae.v7i1.45647.

  8. Rainfall, soil moisture, and runoff dynamics in New Mexico pinon-juniper woodland watersheds

    Science.gov (United States)

    Carlos Ochoa; Alexander Fernald; Vincent Tidwell

    2008-01-01

    Clearing trees in pinon-juniper woodlands may increase grass cover and infiltration, leading to reduced surface runoff and erosion. This study was conducted to evaluate pinon-juniper hydrology conditions during baseline data collection in a paired watershed study. We instrumented six 1.0 to 1.3 ha experimental watersheds near Santa Fe, NM to collect rainfall, soil...

  9. Microsite and time since prescribed fire's influence on soil microbiology in a pinyon woodland

    Science.gov (United States)

    Benjamin M. Rau; Robert R. Blank; Tye Morgan

    2008-01-01

    Pinyon-juniper (Pinus monophylla Torr. & Frém.? Juniperus osteosperma Torr.) encroachment into sagebrush grasslands is a continuing problem in the Western United States. Prescribed burning has been suggested to slow woodland encroachment. We examined surface soil microbial community structure using Phospholipid Fatty Acid (PLFA...

  10. Factors affecting soil fauna feeding activity in a fragmented lowland temperate deciduous woodland.

    Directory of Open Access Journals (Sweden)

    Jake E Simpson

    Full Text Available British temperate broadleaf woodlands have been widely fragmented since the advent of modern agriculture and development. As a result, a higher proportion of woodland area is now subject to edge effects which can alter the efficiency of ecosystem functions. These areas are particularly sensitive to drought. Decomposition of detritus and nutrient cycling are driven by soil microbe and fauna coactivity. The bait lamina assay was used to assess soil fauna trophic activity in the upper soil horizons at five sites in Wytham Woods, Oxfordshire: two edge, two intermediate and one core site. Faunal trophic activity was highest in the core of the woodland, and lowest at the edge, which was correlated with a decreasing soil moisture gradient. The efficiency of the assay was tested using four different bait flavours: standardised, ash (Fraxinus excelsior L., oak (Quercus robur L., and sycamore (Acer pseudoplatanus L.. The standardised bait proved the most efficient flavour in terms of feeding activity. This study suggests that decomposition and nutrient cycling may be compromised in many of the UK's small, fragmented woodlands in the event of drought or climate change.

  11. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Directory of Open Access Journals (Sweden)

    Wei Wang

    Full Text Available Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008 from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR, shrubland (SH, as well as in evergreen coniferous (EC, deciduous coniferous (DC and deciduous broadleaved forest (DB, to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  12. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Science.gov (United States)

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Zeng, Hui; Fang, Jingyun

    2013-01-01

    Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC) dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008) from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR), shrubland (SH), as well as in evergreen coniferous (EC), deciduous coniferous (DC) and deciduous broadleaved forest (DB), to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  13. Anchor chaining’s influence on soil hydrology and seeding success in burned piñon-juniper woodlands

    Science.gov (United States)

    Broadcast seeding is one of the most commonly used rehabilitation treatments for the restoration of burned piñon (Pinus ssp.) and juniper (Juniperus spp.) woodlands, but the success rate of this treatment is notoriously low. In piñon-juniper woodlands, post-fire soil water repellency can impair rese...

  14. 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.

  15. Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) data

    Science.gov (United States)

    Price, Kevin P.

    1993-01-01

    Multispectral measurements collected by Landsat Thematic Mapper (TM) were correlated with field measurements, direct soil loss estimates, and Universal Soil Loss Equation (USLE) estimates to determine the sensitivity of TM data to varying degrees of soil erosion in pinyon-juniper woodland in central Utah. TM data were also evaluated as a predictor of the USLE Crop Management C factor for pinyon-juniper woodlands. TM spectral data were consistently better predictors of soil erosion factors than any combination of field factors. TM data were more sensitive to vegetation variations than the USLE C factor. USLE estimates showed low annual rates of erosion which varied little among the study sites. Direct measurements of rate of soil loss using the SEDIMENT (Soil Erosion DIrect measureMENT) technique, indicated high and varying rates of soil loss among the sites since tree establishment. Erosion estimates from the USLE and SEDIMENT methods suggest that erosion rates have been severe in the past, but because significant amounts of soil have already been eroded, and the surface is now armored by rock debris, present erosion rates are lower. Indicators of accelerated erosion were still present on all sites, however, suggesting that the USLE underestimated erosion within the study area.

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

    African Journals Online (AJOL)

    ... people on adoption of mixed farming and land use and soil properties because they tend to affect each other. Fulani nomads and arable farmers should be encouraged to co-exist harmoniously with farming communities as this would encourage sustainable crop production in low to moderate fertile soils of the tropics.

  17. Soil Black Carbon Loss and Sediment Black Carbon Accumulation in a Central Texas Woodland

    Science.gov (United States)

    Schieve, E. A.; Hockaday, W. C.; White, J. D.

    2016-12-01

    The Balcones Canyonlands National Wildlife Refuge is located along the eastern edge of the Edwards Plateau in Texas, and was established in 1992 for the purpose of conserving habitat for two endangered bird species. The landscape is composed of hilly, mesa-valley terrain, which is mostly covered by grasslands and woodlands dominated by juniper with intermingling of various oak species. Based on historical photo analysis and tree fire scar dendrochronology, the area has experienced major land use changes over the last century due to wildfire, logging, and drought affecting soil stability and woodland species composition. A previous study on soil black carbon showed that site-specific soil erosion potential and time since last fire may act as controls on soil black carbon concentrations. However, the black carbon transport flux, depositional fate, or the magnitude of soil erosion effects upon the black carbon budget are unconstrained at the watershed scale. To address this, we sampled the sediments accumulating in small ponds constructed during the 1950's for livestock watering. We are quantifying black carbon in sediments using solid-state 13C nuclear magnetic resonance spectroscopy. Preliminary data suggest that the pond sediments are a black carbon sink. Black carbon comprises 15 % - 25 %, of the sedimentary organic carbon, as substantial enrichment relative to soils within the watershed. We will present an early assessment of the black carbon erosion and sediment accumulation rates in first- and second-order watersheds.

  18. 1100 years of human impact on woodland and soils in Kjarardalur, West Iceland

    Science.gov (United States)

    Gísladóttir, Guðrún; Erlendsson, Egill; Lal, Rattan

    2013-04-01

    Prior to the Norse settlement of Iceland around AD 874 climate was the principal control of ecosystem variability. Since then, drastic changes have been imposed on the island's ecosystem through human activities. Unsustainable land use has reduced vegetation coverage, altered floral composition and accelerated soil erosion, especially in conjunction with harsh climate. Healthy ecosystem, soil and vegetation, is not only an important resource to meet human demands but also a prominent sink of atmospheric CO2. In contrast, soil erosion and land degradation are major sources of atmospheric CO2. This study discusses the impact of human activities and climate change on vegetation, soil erosion, and soil organic carbon (SOC) in West Iceland. Analyses conducted include pollen in Histosols, soil properties, soil accumulation rates and SOC in Histosols and Andosols. Our data demonstrate a pre-settlement landscape that was not entirely stable, where relatively small differences in climate may have caused subtle changes to the terrestrial environment. However, the early colonists and subsequent occupants altered the environment significantly. The magnitude of alteration was spatially variable depending on land management. The vegetation and soil data demonstrate a swift transformation of environmental conditions across AD 874. The most profound impacts include reduction in birch woodland and concurrent decline of important habitat for fragile understory, which facilitated soil exposure and reduced soil quality. After about 300 years, land degradation-anticipated management towards enhanced sustainability was probably adopted at one of the farming properties in the study area, allowing for soil recovery after a period of drastic decline. At other properties unsustainable land use continued to degrade the terrestrial ecosystem. The late-Medieval climatic change and introduction of the Little-Ice age exerted added strain on the environments over the entire area, resulting in

  19. Decreased summer drought affects plant productivity and soil carbon dynamics in Mediterranean woodland

    Science.gov (United States)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-06-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. The throughfall manipulation experiment started in 2004 and we report data up to the 2009 growing season. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 50 % and 220 %, respectively, as compared to control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction of precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodland. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long term soil C stocks.

  20. Decreased summer drought affects plant productivity and soil carbon dynamics in a Mediterranean woodland

    Science.gov (United States)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-09-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.

  1. Soil and water conservation practices in the savanna of northern ...

    African Journals Online (AJOL)

    The challenge posed by the loss of several hectarage of farmlands on account of natural or human-induced ecological problems in terms of food security and sustenance of natural agro-ecosystems is enormous, especially for the resource low-income farmers. Adoption of soil and water conservation measures by farmers is ...

  2. Ecohydrological controls on soil moisture and hydraulic conductivity within a pinyon-juniper woodland

    Science.gov (United States)

    Lebron, I.; Madsen, M.D.; Chandler, D.G.; Robinson, D.A.; Wendroth, O.; Belnap, J.

    2007-01-01

    The impact of pinyon-juniper woodland encroachment on rangeland ecosystems is often associated with a reduction of streamflow and recharge and an increase in soil erosion. The objective of this study is to investigate vegetational control on seasonal soil hydrologic properties along a 15-m transect in pinyon-juniper woodland with biocrust. We demonstrate that the juniper tree controls soil water content (SWC) patterns directly under the canopy via interception, and beyond the canopy via shading in a preferred orientation, opposite to the prevailing wind direction. The juniper also controls the SWC and unsaturated hydraulic conductivity measured close to water saturation (K(h)) under the canopy by the creation of soil water repellency due to needle drop. We use this information to refine the hydrologic functional unit (HFU) concept into three interacting hydrologic units: canopy patches, intercanopy patches, and a transitional unit formed by intercanopy patches in the rain shadow of the juniper tree. Spatial autoregressive state-space models show the close relationship between K(h) close to soil water saturation and SWC at medium and low levels, integrating a number of influences on hydraulic conductivity. Copyright 2007 by the American Geophysical Union.

  3. Soil moisture redistribution as a mechanism of facilitation in savanna tree-shrub clusters.

    Science.gov (United States)

    Zou, C B; Barnes, P W; Archer, S; McMurtry, C R

    2005-08-01

    Plant-soil water relations were examined in the context of a selective removal study conducted in tree-shrub communities occupying different but contiguous soil types (small discrete clusters on shallow, duplex soils versus larger, extensive groves on deep, sandy soils) in a subtropical savanna parkland. We (1) tested for the occurrence of soil moisture redistribution by hydraulic lift (HL), (2) determined the influence of edaphic factors on HL, and (3) evaluated the significance of HL for overstory tree-understory shrub interactions. Diel cycling and nocturnal increases in soil water potential (Psisoil), characteristic signatures of HL, occurred intermittently throughout an annual growth cycle in both communities over a range of moisture levels (Psisoil=-0.5 to -6.0 MPa) but only when soils were distinctly stratified with depth (dry surface/wet deep soil layers). The magnitude of mean (+/-SE) diel fluctuations in Psisoil (0.19+/-0.01 MPa) did not differ on the two community types, though HL occurred more frequently in groves (deep soils) than clusters (shallow soils). Selective removal of either Prosopis glandulosa overstory or mixed-species shrub understory reduced the frequency of HL, indicating that Prosopis and at least one other woody species was conducting HL. For Zanthoxylum fagara, a shallow-rooted understory shrub, Prosopis removal from clusters decreased leaf water potential (Psileaf) and net CO2 exchange (A) during periods of HL. In contrast, overstory removal had neutral to positive effects on more deeply-rooted shrub species (Berberis trifoliolata and Condalia hookeri). Removal of the shrub understory in groves increased A in the overstory Prosopis. Results indicate the following: (a) HL is common but temporally dynamic in these savanna tree-shrub communities; (b) edaphic factors influencing the degree of overstory/understory development, rooting patterns and soil moisture distribution influence HL; (c) net interactions between overstory and

  4. Rangeland degradation in savannas of South Africa: spatial patterns of soil and vegetation

    Science.gov (United States)

    Sandhage-Hofmann, Alexandra; Löffler, Jörg; du Preez, Chris; Kotzé, Elmarie; Weijers, Stef; Wundram, Dirk; Zacharias, Maximilan; Amelung, Wulf

    2017-04-01

    Extensive bush encroachment by Acacia mellifera and associated woody species at semi-arid and arid sites are the most notable forms of rangeland degradation in savannas of South Africa. Concerns are growing over the threat of suppression and loss of nutritious perennial grass species. Grazing and different rangeland management systems (communal and freehold) are considered to be of major importance for degradation, but the process of encroachment is not restricted to communal land. A vegetation change is mostly accompanied by changes in soil properties, where soils in savanna systems can profit from woody species due to litter fall, root distribution, shadow and animal resting time. Savannas are very heterogeneous systems with high spatial variation of patches with wood, herbaceous species and bare ground. We hypothesized that the spatial patterns of soil properties in South Africás rangelands are controlled by present or past vegetation, modulated by the tenure systems with higher rangeland degradation in communal areas. To test this, we sampled soils at communal and commercial land in the Kuruman area of South Africa with the following design: three farms per tenure system, 6 randomly chosen plots (100x100m) per farm, and 25 soil samples (0-10 cm) per plot, each in a 5x5m sampling area. At every sampling point, information of overlying vegetation was recorded (species or bare soil, canopy size, height). For each sampling area, if present, trees/ shrubs were sampled and their ages estimated through the counting of annual growth rings. For each plot, high resolution UAV aerial photos were taken to evaluate the extent of bush encroachment. Analyses involved main physical and chemical soil parameters and isotopic analyses. The results of a rough aerial image classification (grass, woody species, bare ground) revealed significant differences between the tenure systems with higher coverage of bare ground and shrubs at communal farms, and higher grass cover at

  5. EFFECT OF ORGANIC AND INORGANIC SOIL AMENDMENTS ON SOIL PHYSICAL AND CHEMICAL PROPERTIES IN A WEST AFRICA SAVANNA AGROECOSYSTEM

    Directory of Open Access Journals (Sweden)

    Joshua. Olalekan. Ogunwole

    2009-11-01

    Full Text Available Long-term agroecosystem productivity has stirred up the need to develop and implement nutrient management strategies that maintain and protect soil resources. In an attempt to address this, the current study involved the incorporation of residues of Centrosema pascuorum, Lablab purpureus and Parkia biglobosa. In addition, an inorganic fertilizer amended soil and, a maize/Lablab purpureus intercrop, along with the control (no amendment was included. The treatments were replicated three times and the site had been under continuous cultivation for eight years in a savanna Alfisol. Soil quality (physical and chemical indicators were examined for treatments effects. Dry macroaggregate turnover increased by 7% under C. pascuorum amended soils. This same treatment had more water-stable large microaggregates and a 40% increase in aggregated silt and clay content. Soil bulk density and saturated hydraulic conductivity reduced in nutrient management practices involving residue incorporation. However, soil organic carbon, total soil nitrogen, exchangeable Ca2+ and Mg2+ concentration were highest with soil receiving C. pascuorum. Crop residue management practices involving incorporation of C. pascuorum significantly improved soil physical and chemical properties of the study area.

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

    Science.gov (United States)

    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...

  7. 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).

  8. Local climatic conditions constrain soil yeast diversity patterns in Mediterranean forests, woodlands and scrub biome.

    Science.gov (United States)

    Yurkov, Andrey M; Röhl, Oliver; Pontes, Ana; Carvalho, Cláudia; Maldonado, Cristina; Sampaio, José Paulo

    2016-02-01

    Soil yeasts represent a poorly known fraction of the soil microbiome due to limited ecological surveys. Here, we provide the first comprehensive inventory of cultivable soil yeasts in a Mediterranean ecosystem, which is the leading biodiversity hotspot for vascular plants and vertebrates in Europe. We isolated and identified soil yeasts from forested sites of Serra da Arrábida Natural Park (Portugal), representing the Mediterranean forests, woodlands and scrub biome. Both cultivation experiments and the subsequent species richness estimations suggest the highest species richness values reported to date, resulting in a total of 57 and 80 yeast taxa, respectively. These values far exceed those reported for other forest soils in Europe. Furthermore, we assessed the response of yeast diversity to microclimatic environmental factors in biotopes composed of the same plant species but showing a gradual change from humid broadleaf forests to dry maquis. We observed that forest properties constrained by precipitation level had strong impact on yeast diversity and on community structure and lower precipitation resulted in an increased number of rare species and decreased evenness values. In conclusion, the structure of soil yeast communities mirrors the environmental factors that affect aboveground phytocenoses, aboveground biomass and plant projective cover. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Woodland dynamics as a result of settlement relocation on Pleistocene sandy soils in The Netherlands (200 BC – 1400 AD).

    NARCIS (Netherlands)

    Groenewoudt, B.; Spek, Mattheus

    2015-01-01

    In this paper we investigate the potential of charcoal kilns as indicators (proxy data) of the interaction between settlement dynamics and the history of woodland presence, composition and structure. The results demonstrate that in our research area (Pleistocene sandy soils of the Netherlands)

  10. Impact of a prescribed fire on soil water repellency in a Banksia woodland (Western Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Miller, Ben; Tangney, Ryan; Miller, Russell; González-Pérez, José A.; Jiménez-Morillo, Nicasio T.; Zavala, Lorena M.; Jordán, Antonio

    2016-04-01

    INTRODUCTION The Swan Coastal plain of Western Australia is dominated by fire-prone banksia woodland (Burrows and McCaw, 1990). In these areas, prescription burning is often used to reduce the risk of wildfires, by reducing available fuels (Boer et al., 2009). Little research has been conducted on the effects of prescription burning on Banksia woodlands, and, in particular, information on the impacts on soil properties and soil water repellency (SWR) is scarce. Here, we have studied the impact of fire on SWR in a Banksia woodland and monitored its evolution in the medium-term. It is expected that results are useful for management and restoration of fire-affected Banksia woodlands. METHODS An experimental fire was conducted on May 7th 2015 in Kings Park, Perth, Western Australia. The fire affected an area of 6 ha of mixed Banksia/Allocasuarina woodland under moderate fire intensity. At the time of ignition, the wind speed below the canopy was 1.2 km/h. During the prescribed burning, air temperatures were on average 20 ± 1 °C and relative humidity ranged between 45 and 55% (measured using a Kestrel portable weather station). Fuel moisture averaged 11.8% (measured using Wiltronics moisture meter) and soil moisture at 1 cm deep ranged from 0.1% to 8.6% (measured with a PR2 soil profile probe attached to a HH2 data logger). Temperatures greater than 120 °C were measured 1 cm below the soil surface using iButton temperature sensors. SWR was measured under lab conditions in oven-dry samples (48 h, 105 °C) with the water drop penetration time (WDPT) test. Soil microbial activity was determined with the 1-day CO2 test that is based on the measurement of the CO2 burst produced after moistening dry soil (Muñoz-Rojas et al., 2016). PRELIMINARY RESULTS AND DISCUSSION SWR was severe in the control (mean WDPT = 2608 s) and pre-burned areas (2722 s). One week after the prescribed fire, persistence of soil water repellency remained stable in the burned area (2402 s). In

  11. The influence of soil resources and plant traits on invasion and restoration in a subtropical woodland

    Science.gov (United States)

    Yelenik, Stephanie G.; D'Antonio, Carla M.; August-Schmidt, Elizabeth

    2017-01-01

    It has been shown in some cases that nitrogen (N) addition to soil will increase abundance of plant invaders because many invaders have traits that promote rapid growth in response to high resource supply. Similarly, it has been suggested, and sometimes shown, that decreasing soil N via carbon (C) additions can facilitate native species recovery. Yet all species are unlikely to respond to resource supply in the same way. We asked how soil nutrients and competition affect native and exotic woody species in a restoration experiment where we added N or C, and crossed soil manipulation with the manipulation of dominant exotic grass abundance in a Hawaiian subtropical woodland. We related changes in survival and growth of outplanted individuals to native/exotic status and plant traits. As a group, N-fixers showed reduced survival compared to non-fixers in response to added N, with Morella faya (exotic) and Acacia koa (native) having dramatic negative responses. Among non-fixers, species with greater foliar %N had more positive survival responses to increasing soil N. Specific leaf area was not predictive of responses to nutrients or competition. In general, responses to carbon addition were weak, although reducing competition from existing exotic grasses was beneficial for all outplanted species, with N-fixers showing the most positive response. We conclude that commonly used restoration strategies to clear exotic species or lower soil resources with C addition will most greatly benefit N-fixing species, which themselves may be unwanted invaders. Thus statements about the influence of increased soil N on invasions should be carefully dissected by considering the traits (such as N-fixation status) of the regional species pool.

  12. Changes in fire-derived soil black carbon storage in a subhumid woodland

    Science.gov (United States)

    Yao, Jian; Hockaday, William C.; Murray, Darrel B.; White, Joseph D.

    2014-09-01

    Fire-derived black carbon (BC) in soil, including charcoal, represents an important part in terrestrial carbon cycling due to its assumed long persistence in soil. Soil BC concentrations for a woodland in central Texas, USA, was found from study plots with a fire scar dendrochronology spanning 100 years. BC values were initially determined from 13C nuclear magnetic resonance (NMR) spectroscopy. The NMR-based BC concentrations were used to calibrate midinfrared vibrational spectra (MIRS) for evaluation as a less expensive and expedient technique. However, unexpectedly high BC values from the MIRS method were found for sites without evidence of fire for the past 100 years. Estimation of BC from NMR technique showed mean BC concentration of 2.73 ± 3.06 g BC kg-1 (0.91 ± 0.51 kg BC m-2) for sites with fire occurrence within the last 40 years compared with BC values of 1.21 ± 1.70 g BC kg-1 soil (0.18 ± 0.14 kg BC m-2) for sites with fire 40-100 years ago. Sites with no tree ring evidence of fire during the last 100 years had the lowest mean soil BC concentration of 0.05 ± 0.11 g BC kg-1 (0.02 ± 0.03 kg BC m-2). Molecular proxies of stability (lignin/N) and decomposition (Alkyl C/O-Alkyl C) showed no differences across the sites, indicating low potential for BC mineralization. Modeled soil erosion and time since fire from fire scar data showed that soil BC concentrations were inversely correlated. These results suggest that the addition of BC may be limited by topography and timing of fire.

  13. Changes in Fire-Derived Soil Black Carbon Storage in a Sub-humid Woodland

    Science.gov (United States)

    White, J. D.; Yao, J.; Murray, D. B.; Hockaday, W. C.

    2014-12-01

    Fire-derived black carbon (BC) in soil, including charcoal, represents a potentially important fraction of terrestrial carbon cycling due to its presumed long persistence in soil. Interpretation of site BC retention is important for assessing feedbacks to ecosystem processes including nutrient and water cycling. However, interaction between vegetation disturbance, BC formation, and off site transport may exist that complicate interpretation of BC addition to soils from wildfire or prescribed burns directly. To investigate the relationship between disturbance and site retention on soil BC, we determined BC concentrations for a woodland in central Texas, USA, from study plots in hilly terrain with a fire scar dendrochronology spanning 100 years. BC values were determined from 13C nuclear magnetic resonance (NMR) spectroscopy. Estimated values showed mean BC concentration of 2.73 ± 3.06 g BC kg-1 (0.91 ± 0.51 kg BC m-2) for sites with fire occurrence within the last 40 years compared with BC values of1.21 ± 1.70 g BC kg-1 soil (0.18 ± 0.14 kg BC m-2) for sites with fire 40 - 100 years ago. Sites with no tree ring evidence of fire during the last 100 years had the lowest mean soil BC concentration of 0.05 ± 0.11 g BC kg-1 (0.02 ± 0.03 kg BC m-2). Molecular proxies of stability (lignin/N) and decomposition (Alkyl C/O-Alky C) showed no differences across the sites, indicating that low potential for BC mineralization. Modeled soil erosion and time since fire from fire scar data showed that soil BC concentrations were inversely correlated. A modified the ecosystem process model, Biome-BGC, was also used simulate the effects of fire disturbance with different severities and seasonality on C cycling related to the BC production, effect on soil water availability, and off-site transport. Results showed that BC impacts on ecosystem processes, including net ecosystem exchange and leaf area development, were predominantly related to fire frequency. Site BC loss rates were

  14. Hydraulic lift as a determinant of tree-grass coexistence on savannas.

    Science.gov (United States)

    Yu, Kailiang; D'Odorico, Paolo

    2015-09-01

    The coexistence of woody plants and grasses in savannas is determined by a complex set of interacting factors that determine access to resources and demographic dynamics, under the control of external drivers and vegetation feedbacks with the physical environment. Existing theories explain coexistence mainly as an effect of competitive relations and/or disturbances. However, theoretical studies on the way facilitative interactions resulting from hydraulic lift affect tree-grass coexistence and the range of environmental conditions in which savannas are stable are still lacking. We investigated the role of hydraulic lift in the stability of tree-grass coexistence in savannas. To that end, we developed a new mechanistic model that accounts for both competition for soil water in the shallow soil and fire-induced disturbance. We found that hydraulic lift favors grasses, which scavenge the water lifted by woody plants. Thus, hydraulic lift expands (at the expenses of woodlands) the range of environmental conditions in which savannas are stable. These results indicate that hydraulic lift can be an important mechanism responsible for the coexistence of woody plants and grasses in savannas. Grass facilitation by trees through the process of hydraulic lift could allow savannas to persist stably in mesic regions that would otherwise exhibit a forest cover. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  15. 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

  16. Soil water repellency as a vegetation-driven strategy for soil moisture sequestration in Banksia woodlands (Western Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, José A.; Zavala, Lorena M.; Stevens, Jason; Jordán, Antonio

    2016-04-01

    Water repellency is a property of some soils that inhibits or delays the rainwater infiltration. When a surface or subsurface soil horizon is water repellent, water is retained for periods of time that vary according to the severity of hydrophobicity, soil moisture and other parameters. Water repellency is caused by hydrophobic organic substances released by plant residues, roots or soil microorganisms. Certain abiotic agents, like fire, can increase the severity of soil water repellency in certain cases. Under water-repellent conditions, water can infiltrate only when the pressure of the water column is high enough or when macropores allow it. These macropores may be formed by galleries excavated by animals, dead roots or gaps between aggregate or rock fragments. Banksia plants have a dimorphic root morphology. Proteoid roots are formed by clusters of densely compacted short lateral rootlets that radiate from the parent root. These clusters spread just some centimeters below the soil surface constituting a thick dense sheet of roots and are known to secrete large amounts of organic acids and phenolics to increase the uptake of P and other minerals. In contrast, the parent root penetrates soil deeply, reaching the water table. Sandy soils below banksia woodlands from Western Australia coastal dunes show a characteristic vertical distribution of water repellency. We observed that the first soil layer (just some millimeters of depth) was formed by a wettable sand particles transported by wind, covering a wettable or subcritically water-repellent subsurface layer (0-20 cm). A second soil layer (20-40 cm) was formed by a severely water-repellent layer with aggregates bulked by dominant banksia proteoid roots. Below this layer, soil water repellency decreased with depth until soil material rendered wettable at depths between 40 and 80 cm under field conditions. It is hypothesized that banksia roots are capable of inducing soil water repellency, causing the occurrence of

  17. Soil organic matter pools in a tropical savanna under agroforestry system in Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Carvalho Leite

    2014-08-01

    Full Text Available This study aimed at quantifying total organic carbon stocks and its pools in Acrisol under agroforestry systems with six (AFS6 and thirteen years old (AFS13, slash-and-burn agriculture (SBA and savanna native forest (SNF in northeastern Brazil. Soil samples were collected at 0-0.05 m, 0.05-0.10 m, 0.10-0.20 m and 0.20-0.40 m depths in the dry and rainy seasons to evaluate total organic carbon (TOC stocks and labile carbon (LC, fulvic acid fraction (C-FAF, humic acid fraction (C-HAF, humin (C-HF and microbial biomass carbon (Cmic contents. Additionally, carbon management index (CMI was determined. Higher TOC stocks (97.7 and 81.8 Mg ha-1 for the 0-0.40 m depth in the dry and rainy seasons, respectively and LC, humic substances and Cmic contents were observed in the AFS13 in all the depths. CMI also was higher in the AFS13 (0-0. 05 m: 158 and 86; 0.05-0.10 m: 171 and 67, respectively for the dry and rainy seasons especially when compared to the SBA (0-0.05 m: 5.6 and 5.4; 0.05-0.10 m: 5.3 and 5.8, respectively for dry and rainy seasons. The agroforestry systems increased soil quality through the conservation of organic matter and can be considered an excellent strategy to assurance sustainability in tropical soil of Northeastern Brazil

  18. Estimating aboveground biomass in Kalahari woodlands: inferring soil erosional and distributional processes

    Science.gov (United States)

    Wingate, Vladimir

    2017-04-01

    Maps which accurately quantify vegetation carbon, or above ground biomass (AGB) and its changes, are not only essential for ecosystem monitoring, but also for understanding controls on ecosystem carbon, associated soil organic carbon (SOC) and the global carbon cycle. Throughout the rangelands of Namibia, two vegetation cover change processes are widespread, firstly, deforestation and forest degradation, and secondly, the encroachment of the herbaceous and grassy layers by woody strata. Both processes effect a range of key ecosystem services, including SOC dynamics by facilitating erosion and altering soil re-distributional processes. Yet, the spatial and temporal intensity of these vegetation change processes and hence their effect on SOC, remain poorly quantified. This study therefore aims to distinguish and map the extent of both deforestation and woody thickening and associated AGB changes, and gain an understanding of the spatial distribution of land degradation risk areas. We map AGB at two periods (2007 and 2015) for part of the Namibian Kalahari woodland savannah, by modelling forest inventory measurements as a function of a fusion of radar and optical satellite imagery. We then process a change detection and validate both individual and change maps using independent field and satellite data. Results show widespread increases and declines in both areal extent and quantity of AGB, suggesting (i) important vegetation change processes (i.e. both deforestation and woody thickening), and (ii) associated changes in soil quality. Indeed, woody thickening has been found to mask land degradation, through the replacement of herbaceous layers with hardy shrubs, leading to increases in erosional processes. These results are in agreement with previous studies, which identify both extensive greening and small-scale deforestation. Keywords: Soil Organic Carbon, Erosion, deposition, Above Ground Biomass; Savannah; Rangeland; Carbon; Remote Sensing; Change detection

  19. Shifts in soil fungal communities in Tuber melanosporum plantations over a 20-year transition from agriculture fields to oak woodlands

    Directory of Open Access Journals (Sweden)

    Liu Bing

    2016-04-01

    Full Text Available Aim of study: To explore the diversity of soil fungi found in black truffle (Tuber melanosporum plantations following the introduction of the mycorrhizal-colonized host tree, (Quercus ilex, through the development of the brûlé and production of mature sporocarps.Area of study: This research was carried out province of Teruel, Aragon (central eastern Spain.Material and Methods: Soil samples from 6 plantations were collected beneath Q. ilex trees inoculated with T. melanosporum, of 3, 5, 7, 10, 14 and 20 years after out planting in truffle plantations. Soil DNA was extracted, PCR-amplified and sequenced to compare soil fungi present at different ages.Main results: As tree age increased, we observed an increased frequency of T. melanosporum (from 8% to 71% of sequenced colonies and concomitant decrease in the combined frequency of Fusarium spp. and Phoma spp. (from 64% to 3%.Research highlights: There are important shifts in species richness and in functional groups in the soil fungal communities in maturing black truffle-oak woodland plantations. The observed inverse relationship between the frequency of soil endophytic and/or pathogenic fungi and that of the mycorrhizal mutualist T. melanosporum provides support to continue a deeper analysis of shifts in fungal communities and functional groups where there is a transition from agriculture fields to woodlands.Abbreviations used: Ectomycorrhiza (ECM fungus; Vesicular arbuscular mycorrhiza (VAM; Operational taxonomic unit (OTU.

  20. Shifts in soil fungal communities in Tuber melanosporum plantations over a 20-year transition from agriculture fields to oak woodlands

    Energy Technology Data Exchange (ETDEWEB)

    Bing, L.; Fischer, C.R.; Bonet, J.A.; Castaño, C.; Colinas, C.

    2016-07-01

    Aim of study: To explore the diversity of soil fungi found in black truffle (Tuber melanosporum) plantations following the introduction of the mycorrhizal-colonized host tree, (Quercus ilex), through the development of the brûlé and production of mature sporocarps. Area of study: This research was carried out province of Teruel, Aragon (central eastern Spain). Material and Methods: Soil samples from 6 plantations were collected beneath Q. ilex trees inoculated with T. melanosporum, of 3, 5, 7, 10, 14 and 20 years after out planting in truffle plantations. Soil DNA was extracted, PCR-amplified and sequenced to compare soil fungi present at different ages. Main results: As tree age increased, we observed an increased frequency of T. melanosporum (from 8% to 71% of sequenced colonies) and concomitant decrease in the combined frequency of Fusarium spp. and Phoma spp. (from 64% to 3%). Research highlights: There are important shifts in species richness and in functional groups in the soil fungal communities in maturing black truffle-oak woodland plantations. The observed inverse relationship between the frequency of soil endophytic and/or pathogenic fungi and that of the mycorrhizal mutualist T. melanosporum provides support to continue a deeper analysis of shifts in fungal communities and functional groups where there is a transition from agriculture fields to woodlands. (Author)

  1. Influence of Vegetation Cover on Rain Pulse Responses in Semi-Arid Savannas in Central Texas

    Science.gov (United States)

    Litvak, M.; Heilman, J.; McInnes, K.; Thijs, A.; Kjelgaard, J.

    2007-12-01

    Savannas in central Texas are dominated by live oak (Quercus virginiana) and Ashe juniper (Juniperus asheii) underlain by perennial, C3/C4 grasslands, and are increasingly becoming juniper and mesquite dominated due to overgrazing and suppression of wildfires. Since 2004, we have been investigating how carbon, water and energy exchange in these rain-limited savannas respond to rainfall variability and this observed vegetation change. In semi-arid regions, rainfall pulses provide inputs of soil moisture and trigger biotic activity in the form of plant gas exchange and microbial metabolism as well as water dependent physical processes in the soil. Each of these components has a different characteristic response curve to soil moisture and integrates soil water content over a different range of depths. Here we focus on examining how the observed increase of woody species in central Texas savannas alters the response of net ecosystem exchange and its components, ecosystem respiration and gross ecosystem exchange, to rain pulses. Using data we have collected over the last three years from three Ameriflux tower sites at Freeman Ranch near San Marcos, TX (C3/C4 grassland, juniper/mesquite savanna with 50 percent woody cover, and oak/juniper woodland), we quantify the responses of both ecosystem respiration and daily carbon uptake to rainfall pulses throughout the year. Specifically, we look at the enhancement and persistence of ecosystem respiration and carbon uptake responses following a pulse, and isolate the main controlling factors on the observed response: seasonality, antecedent soil moisture and temperature, or previous pulses. In all three land covers, the general response to precipitation pulses is a respiration pulse followed by an increase in total carbon uptake. Differences in pulse responses observed at the savanna site compared to the grassland and woodland sites can be explained, in part, by the observed differences in rooting structure and photosynthetic

  2. Adaptation of soil nitrifiers to very low nitrogen level jeopardizes the efficiency of chemical fertilization in west african moist savannas.

    Science.gov (United States)

    Assémien, Féline L; Pommier, Thomas; Gonnety, Jean T; Gervaix, Jonathan; Le Roux, Xavier

    2017-08-31

    The moist savanna zone covers 0.5 × 10 6 km 2 in West Africa and is characterized by very low soil N levels limiting primary production, but the ecology of nitrifiers in these (agro)ecosystems is largely unknown. We compared the effects of six agricultural practices on nitrifier activity, abundance and diversity at nine sites in central Ivory Coast. Treatments, including repeated fertilization with ammonium and urea, had no effect on nitrification and crop N status after 3 to 5 crop cycles. Nitrification was actually higher at low than medium ammonium level. The nitrifying community was always dominated by ammonia oxidizing archaea and Nitrospira. However, the abundances of ammonia oxidizing bacteria, AOB, and Nitrobacter increased with fertilization after 5 crop cycles. Several AOB populations, some affiliated to Nitrosospira strains with urease activity or adapted to fluctuating ammonium levels, emerged in fertilized plots, which was correlated to nitrifying community ability to benefit from fertilization. In these soils, dominant nitrifiers adapted to very low ammonium levels have to be replaced by high-N nitrifiers before fertilization can stimulate nitrification. Our results show that the delay required for this replacement is much longer than ever observed for other terrestrial ecosystems, i.e. > 5 crop cycles, and demonstrate for the first time that nitrifier characteristics jeopardize the efficiency of fertilization in moist savanna soils.

  3. Combining airborne laser scanning and Landsat data for statistical modeling of soil carbon and tree biomass in Tanzanian Miombo woodlands.

    Science.gov (United States)

    Egberth, Mikael; Nyberg, Gert; Næsset, Erik; Gobakken, Terje; Mauya, Ernest; Malimbwi, Rogers; Katani, Josiah; Chamuya, Nurudin; Bulenga, George; Olsson, Håkan

    2017-12-01

    Soil carbon and biomass depletion can be used to identify and quantify degraded soils, and by using remote sensing, there is potential to map soil conditions over large areas. Landsat 8 Operational Land Imager satellite data and airborne laser scanning data were evaluated separately and in combination for modeling soil organic carbon, above ground tree biomass and below ground tree biomass. The test site is situated in the Liwale district in southeastern Tanzania and is dominated by Miombo woodlands. Tree data from 15 m radius field-surveyed plots and samples of soil carbon down to a depth of 30 cm were used as reference data for tree biomass and soil carbon estimations. Cross-validated plot level error (RMSE) for predicting soil organic carbon was 28% using only Landsat 8, 26% using laser only, and 23% for the combination of the two. The plot level error for above ground tree biomass was 66% when using only Landsat 8, 50% for laser and 49% for the combination of Landsat 8 and laser data. Results for below ground tree biomass were similar to above ground biomass. Additionally it was found that an early dry season satellite image was preferable for modelling biomass while images from later in the dry season were better for modelling soil carbon. The results show that laser data is superior to Landsat 8 when predicting both soil carbon and biomass above and below ground in landscapes dominated by Miombo woodlands. Furthermore, the combination of laser data and Landsat data were marginally better than using laser data only.

  4. Interaction of vegetative cover and N addition on soil CO2 efflux in an oak savanna ecosystem

    Science.gov (United States)

    Morris, Kendalynn; Wutzler, Thomas; Poehlmann, Marco; Nair, Richard; Migliavacca, Mirco; Schrumpf, Marion

    2017-04-01

    Numerous fertilization experiments have demonstrated that nitrogen (N) addition leads to shifts in soil respiration. In forest ecosystems N addition typically results in decreased soil respiration, while grasslands generally have the opposite response. Neither result is universal because the direction of the response is dictated by site-specific soil and vegetation properties. The MaNiP large scale nutrient manipulation experiment aims at studying ecosystem properties, such as soil respiration, by altering nitrogen (N) and phosphorus (P) stoichiometry. The experimental site is a dehesa, an oak-savanna ecosystem in Extremadura, Spain. The tree-grass structure results in a mosaic of two distinct soils coexisting within the same parent material and climatic conditions. Soils beneath trees are richer in organic matter, have a higher C:N, and a relatively well developed A-horizon compared to soils in the open grassland. This offers an ideal opportunity to study how soil properties modify responses to stoichiometric shifts. We established automated respiration chambers in both of these soil types within plots fertilized with N and where no nitrogen was added (Control). By comparing the magnitude of near continuous CO2 fluxes in these chambers with onsite Eddy Covariance Towers, we can quantify the relative contribution of soils under trees and in open grassland to ecosystem respiration and how the nutrient treatments moderate their responses to seasonal fluctuations in temperature and moisture. Preliminary results suggest that soil respiration increased with fertilization and that fluxes underneath tree canopies are more responsive, likely due to higher C content and microclimatic properties. Further analysis will determine if fertilization influences annual cycles in respiration or the sensitivity of respiration to climatic drivers and pulses (e.g., rain). Our initial conclusion is that vegetation cover modifies the interaction of soil C and N cycle in this ecosystem.

  5. 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...

  6. Plant identity and shallow soil moisture are primary drivers of stomatal conductance in the savannas of Kruger National Park

    Science.gov (United States)

    Tobin, Rebecca L.

    2018-01-01

    Our goal was to describe stomatal conductance (gs) and the site-scale environmental parameters that best predict gs in Kruger National Park (KNP), South Africa. Dominant grass and woody species were measured over two growing seasons in each of four study sites that represented the natural factorial combination of mean annual precipitation [wet (750 mm) or dry (450 mm)] and soil type (clay or sand) found in KNP. A machine-learning (random forest) model was used to describe gs as a function of plant type (species or functional group) and site-level environmental parameters (CO2, season, shortwave radiation, soil type, soil moisture, time of day, vapor pressure deficit and wind speed). The model explained 58% of the variance among 6,850 gs measurements. Species, or plant functional group, and shallow (0–20 cm) soil moisture had the greatest effect on gs. Atmospheric drivers and soil type were less important. When parameterized with three years of observed environmental data, the model estimated mean daytime growing season gs as 68 and 157 mmol m-2 sec-1 for grasses and woody plants, respectively. The model produced here could, for example, be used to estimate gs and evapotranspiration in KNP under varying climate conditions. Results from this field-based study highlight the role of species identity and shallow soil moisture as primary drivers of gs in savanna ecosystems of KNP. PMID:29373605

  7. Opportunities and challenges to capturing the multiple potential benefits of REDD+ in a traditional transnational savanna-woodland region in West Africa.

    Science.gov (United States)

    Olsson, E Gunilla A; Ouattara, Syna

    2013-04-01

    The REDD+ scheme of the United Nations intends to offer developing countries financial incentives to reduce the rates of deforestation and forest degradation for reducing global CO2 emissions. This is combined with building carbon stocks in existing wooded ecosystems and fostering other soil, biodiversity and water conservation objectives. Successful application of REDD+ to the Xylophone Triangle of West Africa faces substantial challenges and risks to both meeting REDD+ objectives and to the local people's rights and livelihoods. The transnationality of the culturally coherent area requires collaboration of three national governments. The opportunities, however, are great to capitalize on the region's biodiversity, the well-developed traditional ecological knowledge and the use of local medicinal plants as an integral part of the agro-ecosystem. Possibilities open to, not only sequester carbon, but also to increase the resilience of the ecosystem and of independent rural livelihoods in the face of climate change and globalization.

  8. The influence of vegetation covers on soil moisture dynamics at high temporal resolution in scattered tree woodlands of Mediterranean climate

    Science.gov (United States)

    Lozano-Parra, Javier; Schnabel, Susanne; Ceballos-Barbancho, Antonio

    2015-04-01

    Soil water is a key factor that controls the organization and functioning of dryland ecosystems. However, in spite of its great importance in ecohydrological processes, most of the studies focus on daily or longer timescales, while its dynamics at shorter timescales are very little known. The main objective of this work was to determine the role of vegetation covers (grassland and tree canopy) in the soil hydrological response using measurements with high temporal resolution in evergreen oak woodland with Mediterranean climate. For this, soil water content was monitored continuously with a temporal resolution of 30 minutes and by means of capacitance sensors, mainly for the hydrological years 2010-2011 and 2011-2012. They were installed at 5, 10 and 15 cm, and 5 cm above the bedrock and depending on soil profile. This distribution along the soil profile is justified because soils are generally very shallow and most of the roots are concentrated in the upper layer. The sensors were gathered in 8 soil moisture stations in two contrasting situations characterized by different vegetation covers: under tree canopy and in open spaces or grasslands. Soil moisture variations were calculated at rainfall event scale at top soil layer and deepest depth by the difference between the final and initial soil moisture registered by a sensor at the finish and the beginning of the rainfall event, respectively. Besides, as soil moisture changes are strongly influenced by antecedent conditions, different antecedent soil moisture conditions or states, from driest to wettest, were also defined. The works were carried out in 3 experimental farms of the Spanish region of Extremadura. Results obtained revealed that rainwater amount bypassing vegetation covers and reaching the soil may temporarily be modified by covers according to precipitation properties and antecedent environmental conditions (from dry to wet) before the rain episode. Rainfall amounts triggering a positive soil

  9. Are fire, soil fertility and toxicity, water availability, plant functional diversity, and litter decomposition related in a Neotropical savanna?

    Science.gov (United States)

    Carvalho, Gustavo Henrique; Batalha, Marco Antônio; Silva, Igor Aurélio; Cianciaruso, Marcus Vinicius; Petchey, Owen L

    2014-07-01

    Understanding how biodiversity and ecosystem functioning respond to changes in the environment is fundamental to the maintenance of ecosystem function. In realistic scenarios, the biodiversity-ecosystem functioning path may account for only a small share of all factors determining ecosystem function. Here, we investigated the strength to which variations in environmental characteristics in a Neotropical savanna affected functional diversity and decomposition. We sought an integrative approach, testing a number of pairwise hypotheses about how the environment, biodiversity, and functioning were linked. We used structural equation modelling to connect fire frequency, soil fertility, exchangeable Al, water availability, functional diversity of woody plants, tree density, tree height, and litter decomposition rates in a causal chain. We found significant effects of soil nutrients, water availability, and Al on functional diversity and litter decomposition. Fire did not have a significant direct effect on functional diversity or litter decomposition. However, fire was connected to both variables through soil fertility. Functional diversity did not influence rates of litter decomposition. The mediated effects that emerged from pairwise interactions are encouraging not only for predicting the functional consequences of changes in environmental variables and biodiversity, but also to caution against predictions based on only environmental or only biodiversity change.

  10. Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical Savanna.

    Science.gov (United States)

    Boutton, T W; Archer, S R; Midwood, A J

    1999-01-01

    Stable isotopes are often utilized as intrinsic tracers to study the effects of human land uses on the structural and functional characteristics of ecosystems. Here, we illustrate how stable isotopes of H, C, and O have been utilized to document changes in ecosystem structure and function using a case study from a subtropical savanna ecosystem. Specifically, we demonstrate that: (1) delta 13C values of soil organic carbon record a vegetation change in this ecosystem from C4 grassland to C3 woodland during the past 40-120 years, and (2) delta 2H and delta 18O of plant and soil water reveal changes in ecosystem hydrology that accompanied this grassland-to-woodland transition. In the Rio Grande Plains of North America, delta 13C values of plants and soils indicate that areas now dominated by C3 subtropical thorn woodland were once C4 grasslands. delta 13C values of current organic matter inputs from wooded landscape elements in this region are characteristic of C3 plants (-28 to -25/1000), while those of the associated soil organic carbon are higher and range from -20 to -15/1000. Approximately 50-90% of soil carbon beneath the present C3 woodlands is derived from C4 grasses. A strong memory of the C4 grasslands that once dominated this region is retained by delta 13C values of organic carbon associated with fine and coarse clay fractions. When delta 13C values are evaluated in conjunction with 14C measurements of that same soil carbon, it appears that grassland-to-woodland conversion occurred largely within the past 40-120 years, coincident with the intensification of livestock grazing and reductions in fire frequency. These conclusions substantiate those based on demographic characteristics of the dominant tree species, historical aerial photography, and accounts of early settlers and explores. Concurrent changes in soil delta 13C values and organic carbon content over the past 90 years also indicate that wooded landscape elements are behaving as sinks for

  11. Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape

    Science.gov (United States)

    Boutton, T. W.; Liao, J. D.

    2010-09-01

    Subtropical woodlands dominated by N-fixing tree legumes have largely replaced grasslands in the Rio Grande Plains, southwestern United States, during the past century. To evaluate the impact of this vegetation change on the N cycle, we measured the mass and isotopic composition (δ15N) of N in the soil system of remnant grasslands and woody plant stands ranging in age from 10 to 130 years. Nitrogen accumulated at linear rates following woody encroachment in the litter (0.10-0.14 g N m-2 yr-1), roots (0.63-0.98 g N m-2 yr-1), and soils (0.75-3.50 g N m-2 yr-1), resulting in a 50%-150% increase in N storage in the soil system (0-30 cm) in woody stands older than 60 years. Simultaneous decreases in soil δ15N of up to 2‰ in the upper 30 cm of the profile are consistent with a scenario in which N inputs have exceeded losses following woody encroachment and suggest N accrual was derived from symbiotic N fixation by tree legumes and/or differential atmospheric N deposition to wooded areas. Vertical uplift and lateral transfer of N by the more deeply and intensively rooted woody plants may have contributed to N accumulation in wooded areas, but soil δ15N values are inconsistent with this explanation. N accumulation following woody encroachment may alter soil N availability, species interactions and successional dynamics, flux rates of key trace gases such as NOX and N2O and ecosystem C sequestration. Given the geographic dimensions of woody encroachment, these results may have implications for atmospheric composition and the climate system.

  12. What Controls the Extent of Tropical Forest? An 8-year Experiment to Understand the Response of Savanna-Forest Boundaries to Climate, Soils, and Fire in Central Brazil

    Science.gov (United States)

    Hoffmann, W.; Franco, A. C.; Haridasan, M.; Geiger, E.; Gotsch, S. G.

    2015-12-01

    Tropical savanna-forest boundaries are considered to be sensitive indicators of climate change, but direct tests of this are lacking, which limits our ability to predict the future of these two biomes. We used an ecosystem experiment at a savanna-forest boundary to compare the importance of seasonal drought and soil nutrients for limiting forest expansion. We set up twelve 70m x 10 plots, each extending across the biome boundary. Water and nutrient treatments were randomly assigned to these plots in a factorial experiment. The water treatment consisted of a control (no added water) or irrigation (60 mm per week throughout the dry season to eliminate soil water deficit), and the nutrient treatment consisted of a control (no added nutrients or a complete NPK + micronutrients added twice per year to minimize nutrient deficits). After four years, the study site was burned, allowing us to examine interactions with the primary disturbance at savanna-forest boundaries. Tree growth and forest expansion were strongly limited by nutrients, but not water. Nutrient addition doubled rates of tree diameter growth over 4 years (2.4 mm/yr versus 1.1 mm/yr) growth, but irrigation had no detectable effect (1.9 mm/yr versus 1.7 mm/yr). Long-term fire suppression at the site had allowed forest tree species to establish in savanna, and these had more than a 3-fold greater growth rate than savanna species. The higher productivity of forest species was offset by greater biomass loss during fire, but within 3 years these losses were largely recovered. Nutrient limitation, combined with the slow growth of savanna tree species, greatly slows canopy closure in this environment, predisposing the savanna to remain in an open state under occasional burning. These results challenge the perception that rainfall is the primary factor limiting the natural distribution of tropical forest. Climate change is likely to cause a shift in the biome boundary only it is accompanied with a changing fire

  13. Vegetation-induced soil water repellency as a strategy in arid ecosystems. A geochemical approach in Banksia woodlands (SW Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, Jose Antonio; Zavala, Lorena M.; Stevens, Jason; Jordan, Antonio

    2016-04-01

    Introduction Banksia woodlands (BW) are iconic ecosystems of Western Australia (WA) composed by an overstorey dominated by Proteaceae, e.g. Banksia menziesii and Banksia attenuata, in combination with other species, such as Eucalyptus spp., Verticordia spp. or Melaleuca spp. Although located in very poor dune soils, BW provide numerous ecosystem services and sustain a high biodiversity. In this area, annual rainfall is relatively high (about 800 mm) but permeability of the sandy substrate leads to a functionally arid ecosystem. Currently, BW are threatened by sand mining activities and urban expansion; therefore conservation and restoration of these woodlands are critical. Despite numerous efforts, the success of restoration plans is usually poor mostly due to the high sensitivity to drought stress and poor seedling survival rates (5-30%) (Benigno et al., 2014). A characteristic feature of BW is their root architecture, formed by a proteoid (cluster) system that spreads to form thick mats below the soil surface, favouring the uptake of nutrients (especially, P), and preventing soil erosion. Root exudates are related to numerous plant functions, as they facilitate penetration of roots in soil and enhance the extraction of scarce mineral nutrients and its further assimilation. Exudates may also interact directly with soil or indirectly through microbial mediated events being also related to soil water repellency (SWR; Lozano et al, 2014). Knowledge about the specific compounds able to induce SWR is limited (Doerr et al., 2000), but it is generally accepted that is caused by organic molecules coating the surface of soil mineral particles and aggregates (Jordán et al., 2013). Proteaceae release short-chained organic acids to enhance phosphate acquisition, which have been also reported to be related with SWR (Jiménez-Morillo et al., 2014). It is hypothesized that disruption of water dynamics in mature BW soils is underlying the failure of restoration plans. This

  14. Spatial variation in vegetation structure coupled to plant available water determined by two-dimensional soil resistivity profiling in a Brazilian savanna.

    Science.gov (United States)

    Ferreira, Joice N; Bustamante, Mercedes; Garcia-Montiel, Diana C; Caylor, Kelly K; Davidson, Eric A

    2007-08-01

    Tropical savannas commonly exhibit large spatial heterogeneity in vegetation structure. Fine-scale patterns of soil moisture, particularly in the deeper soil layers, have not been well investigated as factors possibly influencing vegetation patterns in savannas. Here we investigate the role of soil water availability and heterogeneity related to vegetation structure in an area of the Brazilian savanna (Cerrado). Our objective was to determine whether horizontal spatial variations of soil water are coupled with patterns of vegetation structure across tens of meters. We applied a novel methodological approach to convert soil electrical resistivity measurements along three 275-m transects to volumetric water content and then to estimates of plant available water (PAW). Structural attributes of the woody vegetation, including plant position, height, basal circumference, crown dimensions, and leaf area index, were surveyed within twenty-two 100-m(2) plots along the same transects, where no obvious vegetation gradients had been apparent. Spatial heterogeneity was evaluated through measurements of spatial autocorrelation in both PAW and vegetation structure. Comparisons with null models suggest that plants were randomly distributed over the transect with the greatest mean PAW and lowest PAW heterogeneity, and clustered in the driest and most heterogeneous transect. Plant density was positively related with PAW in the top 4 m of soil. The density-dependent vegetation attributes that are related to plot biomass, such as sum of tree heights per plot, exhibited spatial variation patterns that were remarkably similar to spatial variation of PAW in the top 4 m of soil. For PAW below 4 m depth, mean vegetation attributes, such as mean height, were negatively correlated with PAW, suggesting greater water uptake from the deep soil by plants of larger stature. These results are consistent with PAW heterogeneity being an important structuring factor in the plant distribution at the

  15. Soil Acidobacterial 16S rRNA Gene Sequences Reveal Subgroup Level Differences between Savanna-Like Cerrado and Atlantic Forest Brazilian Biomes

    Directory of Open Access Journals (Sweden)

    Elisa C. P. Catão

    2014-01-01

    Full Text Available 16S rRNA sequences from the phylum Acidobacteria have been commonly reported from soil microbial communities, including those from the Brazilian Savanna (Cerrado and the Atlantic Forest biomes, two biomes that present contrasting characteristics of soil and vegetation. Using 16S rRNA sequences, the present work aimed to study acidobacterial diversity and distribution in soils of Cerrado savanna and two Atlantic forest sites. PCA and phylogenetic reconstruction showed that the acidobacterial communities found in “Mata de galeria” forest soil samples from the Cerrado biome have a tendency to separate from the other Cerrado vegetation microbial communities in the direction of those found in the Atlantic Forest, which is correlated with a high abundance of Acidobacteria subgroup 2 (GP2. Environmental conditions seem to promote a negative correlation between GP2 and subgroup 1 (GP1 abundance. Also GP2 is negatively correlated to pH, but positively correlated to high Al3+ concentrations. The Cerrado soil showed the lowest Acidobacteria richness and diversity indexes of OTUs at the species and subgroups levels when compared to Atlantic Forest soils. These results suggest specificity of acidobacterial subgroups to soils of different biomes and are a starting point to understand their ecological roles, a topic that needs to be further explored.

  16. Vegetation and environmental controls on soil respiration in a pinon-juniper woodland

    Science.gov (United States)

    Sandra A. White

    2008-01-01

    Soil respiration (RS) responds to changes in plant and microbial activity and environmental conditions. In arid ecosystems of the southwestern USA, soil moisture exhibits large fluctuations because annual and seasonal precipitation inputs are highly variable, with increased variability expected in the future. Patterns of soil moisture, and periodic severe drought, are...

  17. Woodland Detection.

    Science.gov (United States)

    Fischer, Richard B.

    1989-01-01

    Presents tips on nature observation during a woodland hike in the Adirondacks. Discusses engraver beetles and Dutch elm disease, birds' nests, hornets' nests, caterpillar webs, deer and bear signs, woodpecker holes, red squirrels, porcupine and beaver signs, and galls. (SV)

  18. Understorey productivity in temperate grassy woodland responds to soil water availability but not to elevated [CO2 ].

    Science.gov (United States)

    Collins, L; Bradstock, R A; Resco de Dios, V; Duursma, R A; Velasco, S; Boer, M M

    2018-01-07

    Rising atmospheric [CO2 ] and associated climate change are expected to modify primary productivity across a range of ecosystems globally. Increasing aridity is predicted to reduce grassland productivity, though rising [CO2 ] and associated increases in plant water use efficiency may partially offset the effect of drying on growth. Difficulties arise in predicting the direction and magnitude of future changes in ecosystem productivity, due to limited field experimentation investigating climate and CO2 interactions. We use repeat near-surface digital photography to quantify the effects of water availability and experimentally manipulated elevated [CO2 ] (eCO2 ) on understorey live foliage cover and biomass over three growing seasons in a temperate grassy woodland in south-eastern Australia. We hypothesised that (i) understorey herbaceous productivity is dependent upon soil water availability, and (ii) that eCO2 will increase productivity, with greatest stimulation occurring under conditions of low water availability. Soil volumetric water content (VWC) determined foliage cover and growth rates over the length of the growing season (August - March), with low VWC (changes. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  19. Estimating CH4 emission from paddy managed soils in southern guinea savanna zone of Nigeria using an integrated approach

    Science.gov (United States)

    Akpeokhai, Agatha; Menz, Gunter; Thonfeld, Frank; Akinluyi, Francis

    2016-04-01

    ESTIMATING CH4 EMISSION FROM PADDY MANAGED SOILS IN SOUTHERN GUINEA SAVANNA ZONE OF NIGERIA USING AN INTEGRATED APPROACH Akpeokhai Agatha 1, Menz Gunter 1, Thonfeld Frank 1, Akinluyi Francis 2 1 Remote Sensing Research Group (RSRG), Geography Institute, University of Bonn, Germany. 2 Department Remote Sensing and Geo-Science Information System, School of Earth and Mineral Science, Federal University of Technology, Akure Nigeria. Methane is one of the most important greenhouse gases as it has the second greatest climate forcing potential. Paddy fields have been identified to be sources of methane and Nigerian paddies are not left out. In Nigeria, the guinea savanna region is regarded as the bread basket of the nation and this area is one of the major rice producing regions in Nigeria. Its location in the food basket region of the country makes this part a very important study site. However, since Nigerian paddies contribute to methane emission by how much do these paddies contribute to the emissions? Also, so far, there limited studies on methane from rice fields in West Africa thus making this study a very important start off point. To answer this huge question, methane emission will be estimated using an integrated approach in the North Central part of Nigeria. Land use change cultivated to rice was analysed using Remote sensing techniques to determine the changes in land cultivated to rice. Methane emission from these identified rice fields will be estimated using the IPCC Tier 1 set of equations. First relevant indices (Normalized Differential Moisture Index, Normalized Differential Wetness Index and Rice Growth Vegetation Index) were generated to aid classification of rice fields using LANDSAT data from the USGS. Next the LANDSAT datasets were analyzed for land use change cultivated to rice from 1990 to 2014 to generate rice field maps. ERDAS Imagine, ARCGIS and ENVI tools were used to meet these spatial needs. Methane emissions from this region will be

  20. Seasonal selection of soil types and grass swards by roan antelope in a South African savanna.

    NARCIS (Netherlands)

    Heitkönig, I.M.A.; Owen-Smith, N.

    1997-01-01

    Roan antelope are distributed mainly in regions characterized by infertile soils, offering food of low quality. We hypothesized that roan may select localities with higher soil nutrient levels and/or grass swards with more favourable properties in terms of food abundance or quality than generally

  1. Liming and fertilisation in Pinus taeda plantations with severe nutrient deficiency in savanna soils

    Directory of Open Access Journals (Sweden)

    Araína Hulmann Batista

    2014-11-01

    Full Text Available Soils with high acidity and low exchangeable bases may be responsible for low yields of Pinus taeda in a forest plantation at Jaguariaíva, Paraná State, Brazil. The aim of this study was to evaluate the effect of liming and fertilisation, applied over litter, on two selected areas with Pinus taeda plantations. Soil, litter and pine needles were evaluated for K, Ca and Mg concentrations and soil acidity parameters. Seven treatments were applied: (i complete (N, P, K, Zn, Cu, B, Mo, and lime; (ii without N, P, and K; (iii without Zn, Cu, B, and Mo; (iv without K; (v without Zn; (vi without lime; and (vii control (without nutrients and lime. Soil samples were collected at five soil depths (0-5, 5-10, 10-20, 20-40 and 40-60 cm simultaneously with litter samples. Needles were also collected from the first and second pine flushes. Liming induced soil pH, Ca2+, and Mg2+ increases, and the opposite was observed for Al3+ and Al saturation. Fertilisation increased soil exchangeable K+ concentrations and needle and litter K concentrations. The low Ca and Mg concentrations found in the plant needles might be attributable to their low mobility.

  2. Soil development mediated by traditional practices shape the stand structure of Spanish juniper woodland

    Directory of Open Access Journals (Sweden)

    Javier de la Fuente-Leon

    2014-03-01

    Full Text Available Aim of study: Assessing the effect of soil development on the stand structure of a Spanish juniper forest traditionally shaped by livestock browsing and wood extraction. Area of study: Berlanga de Duero (Soria, Castilla y León, Spain.Material and Methods: A stand inventory served to record stand structure. Tree age, height, DBH, basal area, and overbark volume were determined in each plot. Results were pooled considering two well-differentiated degrees of soil evolution. One-way ANOVAs (and Tukey’s test and regressions between growth parameters were performed to assess significant differences between growth performances on both types of soils. Research highlights: Deeper soils yielded significant higher plant density and stand stock figures than stony shallower profiles despite the intense past livestock activity in the area; and single tree-size was also significantly greater. Non-significant differences were found for merchantable junipers age (≈120-160 years. Wood extraction and livestock browsing should be limited on shallower soils to allow soil and forest evolution; as well as to preserve the genetic pool better adapted to hardest growing conditions.Keywords: livestock browsing; forest development; Juniperus thurifera L.; soil evolution; stand stock.

  3. Dynamics of Biopolymer Turnover in Soil Physical Fractions Following Land-Cover yChange in a Subtropical Savanna

    Science.gov (United States)

    Filley, T. R.; Gamblin, D.; Wang, Y.; Liao, J.; Boutton, T.; Jastrow, J.

    2004-12-01

    Changes in the apportionment of organic carbon and nitrogen among soil physical yfractions following land-cover shifts are of critical importance to the debate surrounding ythe capacity of terrestrial ecosystems to store or release greenhouse gases. For example, ythe difference between the mean residence times (MRTs) of light particulate organic ymatter (POM) vs. silts and clays is typically quite large, with silt and clay associated yorganic matter having the longest MRTs and the greatest likelihood to contribute to long yterm carbon storage. A few studies in agricultural and forest systems have demonstrated ythat biopolymer chemistry also varies along physical, as well as density, fractionation ygradients. We quantified changes in biopolymer (lignin, suberin and cutin, and yhydrolysable amino acids) chemistry of size and density fractionated soil from the Rio yGrande Plains of Texas where C4 grasslands (d13C = -14 %) have undergone succession yto subtropical thorn woodland dominated by C3 trees/shrubs (d13C = -27 %) over the ypast 150 years. This natural isotopic distinction was used to determine MRTs of free ylight organic matter (density less than 1.0 g/cc), macroaggregate (greater than 250 um), ymicroaggregate (53-250 um) and silt+clay (less than 53 um) fractions (see Liao et al., ythis session) which were then related to their specific biopolymer chemistries. Our yresults illustrate that lignin and aliphatic biopolymers (as measured by hydroxyl fatty yacids) are apportioned differently among size/density fractions and along the successional ychronosequence. Lignin is incorporated into all soil fractions soon after woody yencroachment, whereas aliphatic components are slow to be incorporated in the silt and yclay fractions. The lignin components that do become associated with silts and clays are, yin general, highly oxidized. Differences in foliar chemistry among the plant sources yindicate selective movement of leaf cutins into POM, macro- and microaggregate

  4. [Testaceans (Testacea, Protozoa) of taiga soils in Western Siberia (Surgut woodland)].

    Science.gov (United States)

    Rakhleeva, A A

    2002-01-01

    We studied population structure of testaceans of automorphic and hydromorphic soils in the middle taiga of Western Siberia. Rich testacean fauna has been revealed. It was represented to a similar extent as compared to the soils of Ciscaucasian Russia. The bryophilic group was the most typical for the region, since its representatives inhabited the predominating hydromorphic soils of bogs. The typical species included Amphitrema flavum, Heleopera petricola, Placocista spinosa, Trigonopyxis arcula, Centropyxis laevigata, Nebela tincta, Arcella catinus, as well as other moss forms. Flood plain proved to be the richest by testacean species variability among the studied habitats. The set of species here included both representatives of watershed and typical aquatic forms present due to the flood conditions of a given area. The highest quantitative indices of the testacean complexes were revealed in the forest area soils. Quadrulella quadrigera Deflandre, 1936 has been found in a flood plain area for the first time in Russia.

  5. Soil C and N patterns in a semiarid piñon-juniper woodland: Topography of slope and ephemeral channels add to canopy-intercanopy heterogeneity

    Science.gov (United States)

    Law, Darin J.; Breshears, David D.; Ebinger, Michael H.; Meyer, Clifton W.; Allen, Craig D.

    2012-01-01

    Carbon and nitrogen are crucial to semiarid woodlands, determining decomposition, production and redistribution of water and nutrients. Carbon and nitrogen are often greater beneath canopies than intercanopies. Upslope vs. downslope position and ephemeral channels might also cause variation in C and N. Yet, few studies have simultaneously evaluated spatial variation associated with canopy–intercanopy patches and topography. We estimated C and N upslope and downslope in an eroding piñon–juniper woodland for canopies beneath piñons (Pinus edulis) and junipers, (Juniperus monosperma), intercanopies, and ephemeral channels. Soil C and N in the surface and profile beneath canopies exceeded that of intercanopies and channels. Relative to intercanopies, channels had more profile C upslope but less downslope (profile N was not significant). Relative to upslope, profile C downslope for intercanopies was greater and for channels was less (profile N was not significant). Relative to profile, surface soil C and N exhibited less heterogeneity. Although some topographic heterogeneity was detected, results did not collectively support our redistribution hypotheses, and we are unable to distinguish if this heterogeneity is due to in situ or redistribution effects. Nonetheless, results highlight finer topographical spatial variation in addition to predominant canopy and intercanopy variation that is applicable for semiarid woodland management.

  6. A Comparison of Management Strategies in the Oak Woodlands of Spain and California

    Science.gov (United States)

    Lynn Huntsinger; James W. Bartolome; Paul F. Starrs

    1991-01-01

    The characteristics, uses, and management of oak woodlands and savannas in California and southern Spain are compared. There are many similarities between the Spanish dehesa and the California oak woodland. Both are located in Mediterranean climate zones, and are used predominantly for livestock grazing. However the Spanish dehesa is a more diverse and long-standing...

  7. Fire regimes and variability in aboveground woody biomass in miombo woodland

    NARCIS (Netherlands)

    Saito, Makoto; Luyssaert, Sebastiaan; Poulter, Ben; Williams, Mathew; Ciais, Philippe; Bellassen, Valentin; Ryan, Casey M.; Yue, Chao; Cadule, Patricia; Peylin, Philippe

    2014-01-01

    This study combined a process-based ecosystem model with a fire regime model to understand the effect of changes in fire regime and climate pattern on woody plants of miombo woodland in African savanna. Miombo woodland covers wide areas in Africa and is subject to frequent anthropogenic fires. The

  8. Effects of fire on soil nitrogen dynamics and microbial biomass in savannas of Central Brazil

    Directory of Open Access Journals (Sweden)

    Nardoto Gabriela Bielefeld

    2003-01-01

    Full Text Available The objective of this work was to study the effects of fire on net N mineralization and soil microbial biomass in burned and unburned cerrado stricto sensu sites. The study was carried out from April 1998 to April 2000. The pH values were significantly higher in the burned site while soil moisture content was significantly higher in the unburned site (P<0.05. The soil C/N ratio was 22/1 and the available NO3-N ranged between 1.5 and 2.8 mg kg-¹ dry weight. However, the NH4-N concentration ranged between 3 and 34 mg kg-1 dry weight in the burned site and between 3 and 22 mg kg-1 dry weight in the unburned site. The NH4-N increased after fire, but no significant changes were observed for NO3-N (P<0.05. The NO3-N accumulation occurred in short periods during the rainy season. The rates of net N mineralization increased during the rainy season while reductions in soil microbial biomass were observed at both sites. This suggested that the peak in microbial activities occurred with the first rain events, with an initial net immobilization followed by net mineralization. Both sites presented the same pattern for mineralization/immobilization, however, the amount of inorganic-N cycled annually in unburned site was 14.7 kg ha-1 per year while the burned site presented only 3.8 kg ha-¹ of inorganic-N, one year after the burning.

  9. Soil Organic Matter Dynamics Following Land-Cover Change in a Subtropical Savanna: Insights from Soil Physical Fractionation and Stable Isotopes

    Science.gov (United States)

    Liao, J. D.; Boutton, T. W.; Jastrow, J. D.

    2004-12-01

    Soil physical structure is an important determinant of soil organic carbon (SOC) storage and turnover due to differential accessibility of SOC to decomposer organisms. Techniques for physical fractionation of soil organic matter in conjunction with isotopic analyses (d13C, d15N) of those soil fractions have been used to (a) determine where organic C is stored relative to aggregate structure, (b) identify sources of SOC, (c) quantify turnover rates of SOC in specific soil fractions, and (d) evaluate organic matter quality. We used these two complementary approaches to characterize soil C storage and dynamics in the Rio Grande Plains of southern Texas where C3 trees and shrubs (d13C = -27 o/oo) have largely replaced C4 grasslands (d13C = -14 o/oo) over the past 100-200 yr. Using a chronosequence approach, soils were collected from remnant grasslands (Time 0) and from woody plant stands ranging in age from 10-130 yr. We separated soil organic matter into specific size/density fractions and determined their C and N concentrations and natural d13C and d15N values. Rates of whole-soil C and N storage in the upper 15 cm of the soil profile averaged 10-30 g C/m2/yr and 1-3 g N/m2/yr, respectively, over the past 130 yr of woodland development. These rates of accumulation have increased soil C and N pool sizes in older wooded areas by 80-200 o/o relative to remnant grasslands. The relative proportions of the free light fraction (density less than 1.0 g/cc) and macroaggregate fraction (greater than 250 um) increased linearly with time following woody plant invasion of grassland. Conversely, the relative proportions of free microaggregate (53-250 um) and free silt+clay (less than 53 um) fractions decreased linearly with time after woody invasion, likely reflecting incorporation of these fractions into macroaggregates. C and N concentrations in all soil fractions increased with time following woody invasion, but most of the C and N accumulated in light (density less than 1.85 g

  10. Characterization of soil bacterial assemblies in Brazilian savanna-like vegetation reveals acidobacteria dominance.

    Science.gov (United States)

    Araujo, Janaina F; de Castro, Alinne P; Costa, Marcos M C; Togawa, Roberto C; Júnior, Georgios J Pappas; Quirino, Betania F; Bustamante, Mercedes M C; Williamson, Lynn; Handelsman, Jo; Krüger, Ricardo H

    2012-10-01

    The Brazilian Cerrado is the second largest biome in Brazil and is considered a biodiversity hotspot. In this work, we compared the bacterial communities in Cerrado soil associated with four types of native vegetation (Cerrado Denso, Cerrado sensu stricto, Campo Sujo, and Mata de Galeria) by ribosomal RNA intergenic spacer analysis, terminal fragment restriction length polymorphism and pyrosequencing. The fingerprinting results were very similar. The bacterial communities of Cerrado Denso and Cerrado sensu stricto grouped together and were distinct from those in Campo Sujo and Mata de Galeria. Pyrosequencing generated approximately 40,000 16S rRNA gene sequences per sample and allowed the identification of 17 phyla in soil samples under Cerrado vegetation. Acidobacteria were dominant in all areas studied with a relative frequency of 40-47 %, followed closely by Proteobacteria accounting for 34-40 % of the sequences. Results from all molecular techniques used suggested that the bacterial communities of Cerrado sensu stricto and Cerrado Denso are very similar to each other, while Campo Sujo forms a separate group, and Mata de Galeria is the most distinct with higher species richness. This is the first extensive study of native Cerrado soil microbiota, an important but endangered biome.

  11. 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

  12. How switches and lags in biophysical regulators affect spatial-temporal variation of soil respiration in an oak-grass savanna

    Science.gov (United States)

    Baldocchi, Dennis; Tang, Jianwu; Xu, Liukang

    2006-06-01

    Complex behavior, associated with soil respiration of an oak-grass savanna ecosystem in California, was quantified with continuous measurements of CO2 exchange at two scales (soil and canopy) and with three methods (overstory and understory eddy covariance systems, soil respiration chambers, and a below-ground CO2 flux gradient system). To partition soil respiration into its autotrophic and heterotrophic components, we exploited spatial gradients in the landscape and seasonal variations in rainfall. During the dry summer, heterotrophic respiration was dominant in the senesced grassland area, whereas autotrophic respiration by roots and the feeding of microbes by root exudates was dominant under the trees. A temporal switch in soil respiration occurred in the spring. But the stimulation of root respiration lagged the timing of leaf-out by the trees. Another temporal switch in soil respiration occurred at the start of autumn rains. This switch was induced by the rapid germination of grass seed and new grass growth. Isolated summer rain storms caused a pulse in soil respiration. Such rain events stimulated microbial respiration only; the rain was not sufficient to replenish soil moisture in the root zone or to germinate grass seed. Soil respiration lagged photosynthetic activity on hourly scales. The likely mechanism is the slow translocation of photosynthate to the roots and associated microbes. Another lag occurred on daily scales because of modulations in photosynthesis and stomatal conductance by the passage of dry and humid air masses.

  13. Changes in grass plant populations and temporal soil seed bank dynamics in a semi-arid African savanna: Implications for restoration.

    Science.gov (United States)

    Tessema, Zewdu K; de Boer, Willem F; Prins, Herbert H T

    2016-11-01

    The re-colonization or recovery of grass species after disappearance due to heavy grazing depends on the presence of persistent soil seed banks that might be accumulated over time from the aboveground vegetation. Moreover, successful plant recruitment is a function of seed production, seed germination and seedling survival, which can be mechanistically understood through studying the life cycle processes of grass species populations under field conditions. Therefore, we studied the number of germinable seeds, species richness and life-forms in the soil seed banks under light and heavy grazing conditions, and the changes in grass species populations in a semi-arid savanna of Ethiopia. Accordingly, a total of 103 species (15 perennial and 29 annual grasses, 6 legumes, 52 forbs and 1 woody species) emerged from the soil samples collected. Lightly grazed sites had a higher seed density compared with heavily grazed sites. The seed density increased over the first three months of soil sampling and decreased thereafter. Perennial grasses dominated the light grazing sites, whereas annual species dominated the heavily grazed sites, indicating that perennial grasses were replaced by annual species in the soil seed bank through grazing. The mean mortality rate from the seedling stage to adult plants was 65%. The seed-to-seedling stage was found to be the most critical transitional stage for grass survival. High seedling mortality in the aboveground vegetation and depletion of seeds in the soil seed banks as a result of sustained heavy grazing can lead to local extinction and disappearance of perennial grasses in semi-arid Ethiopian savannas. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Short-term effects of early-season fire on herbaceous composition, dry matter production and soil fertility in Guinea savanna, Nigeria

    Directory of Open Access Journals (Sweden)

    Oyedeji Stephen

    2016-01-01

    Full Text Available The ecological impact of fire regimes on plant diversity and soil fertility has become a subject of intense discussion, especially in savannas where recurring incidences are common. This study assessed the short-term effects of early-season fire on herbaceous composition, dry matter yield and soil fertility in the Guinea savanna belt of Nigeria. Data on ground cover, dry matter yield (DMY in plants and concentrations of C, N, P, K, Ca and Mg in soil were collected from 10 delineated subplots in the burned and unburned zones of four sites after annual wildfire had occurred. Ground cover was significantly higher in the burned zones, increasing progressively from January to April (dry season. Eleven herbaceous species in addition to 2 tree seedlings occurred and represented families of Asteraceae, Cyperaceae, Fabaceae and Poaceae. Digitaria nuda, Brachiaria lata, Daniellia oliveri and Aeschynomene indica were limited to the burnt zones while Cyperus tuberosus, Mariscus alternifolius and Rottboellia cochinchinensis were restricted to the unburned zones. DMY ranged from 0.32 g m-2 (Desmodium tortuosum to 52.96 g m-2 (Megathyrsus maximus. Average biomass in the burned and unburned sites was 35.86 g m-2 and 28.42 g m-2, respectively. Soil C, N and P concentrations decreased (positive deterioration index - DI, while those of K, Ca and Mg improved (negative DI in the burned sites. Burning altered the growth (ground cover and composition of plant species in the short term, and could significantly influence soil nutrient dynamics in the long term, especially with recurring fire events.

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

    CSIR Research Space (South Africa)

    Ferrar, P

    1982-09-01

    Full Text Available on their biology are given. Most of the species occur in the flatter areas of Burkea savanna; three are restricted to open land near the turfvlei" Tfie broad-leaved woodland of Maroelakop lacks two species but has two others restricted. Acacia patches (including...

  16. Soils mediate the impact of fine woody debris on invasive and native grasses as whole trees are mechanically shredded into firebreaks in piñon-juniper woodlands

    Science.gov (United States)

    Aanderud, Zachary T.; Schoolmaster, Donald R.; Rigby, Deborah; Bybee, Jordon; Campbell, Tayte; Roundy, Bruce A.

    2017-01-01

    To stem wildfires, trees are being mechanically shredded into firebreaks with the resulting fine woody debris (FWD) potentially exerting immense control over soil and plants. We linked FWD-induced changes in microbial activity and nutrient availability to the frequency of Bromus tectorum and three native, perennial grasses across 31 piñon-juniper woodlands, UT, USA. Using a series of mixed models, we found that FWD increased the frequency of three of the four grasses by at least 12%. Deep, as opposed to shallow, soils mediated frequencies following FWD additions but only partially explained the variation in Bromus and Pseudoroegneria spicata. Although fertile areas associated with tree-islands elicited no response, FWD-induced increases in nitrogen mineralization in deep soils (15–17 cm) caused the frequency of the exotic and Pseudoroegneria to rise. Higher phosphorus availability in FWD-covered surface soils (0–2 cm) had no impact on grasses. FWD altered deep soil respiration, and deep and shallow microbial biomass structuring Pseudoroegneria frequencies, suggesting that microorganism themselves regulated Pseudoroegneria. The positive effects of FWD on grass frequencies intensified over time for natives but diminished for Bromus. Our results demonstrate that microorganisms in deeper soils helped mediate species-specific responses to disturbance both facilitating exotic invasion and promoting native establishment.

  17. Determinants of seasonal changes in availability of food patches for elephants (Loxodonta africana in a semi-arid African savanna

    Directory of Open Access Journals (Sweden)

    Bruce W. Clegg

    2017-06-01

    Full Text Available Loss of biodiversity caused by impact of elephants (Loxodonta africana on African woodlands may require a management response, but any action should be based on an understanding of why elephants choose to utilise trees destructively. Comprehension of elephant feeding behaviour requires consideration of the relative value of the plant groups they may potentially consume. Profitability of available food is partly determined by the time to locate a food patch and, therefore, as a foundation for understanding the influence of food availability on diet selection, key controls on the density of grass, forb, and browse patches were investigated across space and time in a semi-arid African savanna. Density of food patches changed seasonally because plant life-forms required different volumes of soil water to produce green forage; and woody plants and forbs responded to long-term changes in soil moisture, while grasses responded to short-term moisture pulses. Soil texture, structure of woody vegetation and fire added further complexity by altering the soil water thresholds required for production of green forage. Interpolating between regularly-timed, ground-based measurements of food density by using modelled soil water as the predictor in regression equations may be a feasible method of quantifying food available to elephants in complex savanna environments.

  18. Pinyon-juniper woodlands

    Science.gov (United States)

    Gottfried, Gerald J.; Swetnam, Thomas W.; Allen, Craig D.; Betancourt, Julio L.; Chung-MacCoubrey, Alice L.; Finch, Deborah M.; Tainter, Joseph A.

    1995-01-01

    since the introduction of livestock and fire control. This relates to whether tree densities have been increasing or whether trees are invading grasslands and, to a lesser extent, drier ponderosa pine (Pinus ponderosa) forests. In areas where woodlands were heavily used by American Indians for fuelwood prior to European contact, the advance of pinyon and juniper could represent the slow recovery from intensive use (Samuels and Betancourt 1982). There are numerous questions regarding declines in watershed condition related to changes in pinyon-juniper tree stand densities and to the density and composition of understory vegetation. There are different opinions about proper management of woodland ecosystems. Should these lands be managed for a single resource, such as forage for livestock production, or managed for sustained production of multiple resource products and amenities? Depending on site and stand conditions, the woodlands can produce variable quantities of fuelwood, pinyon nuts, wildlife habitat, forage for livestock, and cover for watershed protection. Management must also consider increasing recreational demands, threatened and endangered species, and protection of archeological sites. Many pinyon-juniper woodland watersheds in New Mexico have unsatisfactory soil and watershed conditions (USDA Forest Service 1993); managers must develop restoration procedures that recognize the value of woodland ecosystems. The concerns, questions, and conflicts surrounding management of pinyon-juniper lands, as well as the ecological foundations of ecosystem management, require that all interested parties reevaluate attitudes toward the woodlands. Ecosystem management goals and concepts recognize diversity. Pinyonjuniper woodlands are diverse, and stand characteristics and site productivities vary. Management objectives and prescriptions must evaluate the potential of each site, and decisions must be based on sound scientific information. This information is often

  19. 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

  20. Water repellent soils following prescribed burning treatments and a wildfire in the oak savannas of the Malpai Borderlands Region

    Science.gov (United States)

    Cody L. Stropki; Peter F. Ffolliott; Gerald J. Gottfried

    2009-01-01

    Water repellent (hydrophobic) soils impact the infiltration process of a water budget by restricting the movement of water into and through a soil body. The infiltration of water into a water repellent soil can be inhibited or completely impeded in which case much of the incoming precipitation reaching the soil surface becomes overland flow. One mechanism causing the...

  1. Post-fire interactions between soil water repellency, soil fertility and plant growth in soil collected from a burned piñon-juniper woodland

    Science.gov (United States)

    Fernelius, Kaitlynn J.; Madsen, Matthew D.; Hopkins, Bryan G.; Bansal, Sheel; Anderson, Val J.; Eggett, Dennis L.; Roundy, Bruce A.

    2017-01-01

    Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO3eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.

  2. Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees.

    Science.gov (United States)

    Sandra J. Bucci; Guillermo Goldstein; Frederick C. Meinzer; Augusto C. Franco; Paula Campanello; Fabián G. Scholz

    2005-01-01

    Seasonal regulation of leaf water potential (ΨL) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday minimum Ψ...

  3. Factors influencing the adaptation and distribution of Colophospermum mopane in southern Africa’s mopane savannas – A review

    Directory of Open Access Journals (Sweden)

    Rudzani A. Makhado

    2014-07-01

    Full Text Available Colophospermum mopane is the dominant tree or shrub within mopane woodland in the subtropical areas of southern Africa’s savanna ecosystems. This article provided a review on the adaptation capabilities of mopane against fire, browsing activity and environmental stresses. It further reviewed and tested the extent to which rainfall, temperature, altitude and soil types had an effect on the distribution of mopane in southern Africa. Mopane is adapted to survive moisture stresses, low nutrient environments and even disturbances caused by fire and browsing by large herbivores through its physical, physiological and chemical responses. Adaptation of mopane to various stresses enables it to dominate the low-lying areas of southern Africa’s savannas. The distribution of mopane is best associated with low to moderate rainfall (R2 = 0.38, high temperature (R2 = 0.42, low altitudes (R2 = 0.44 and a variety of soil types. An increase in the annual rainfall (> 800 mm and altitude (> 800 m.a.s.l., coupled with a reduction in the minimum temperature and acidic soil, limits the distribution of mopane. Mopane in South Africa occurs under similar environmental conditions to those in Zimbabwe and Zambia, but quite different from those in Angola, Namibia, Mozambique, Malawi and Botswana where mopane occurs.

  4. Woodlands Grazing Issues in Mediterranean Basin

    Science.gov (United States)

    Campos, P.

    2009-04-01

    In Mediterranean basin, woodlands grazing still continue to be important commercial owners' benefits. These owners manage woodlands vegetations as if they were not at risk of degradation and declining. Frequently, no temporally grazing set-aside is taken into account to avoid overgrazing of annual and perennial vegetations. Although less common, in the northern shore of Mediterranean basin undergrazing might increase the frequency and the number of catastrophic forest fires. This under/over grazing regime occurs in the Mediterranean basin woodlands with contrasted differences on land property rights, local economies and government livestock policy incentives. Spain and Tunisia are examples of these Mediterranean livestock contrasts. Most of Spanish Mediterranean woodlands and livestock herds are large private ownerships and owners could maintain their lands and livestock herds properties on the basis of moderate cash-income compensation against land revaluation and exclusive amenity self-consumption. The later is less tangible benefit and it could include family land legacy, nature enjoyment, country stile of life development, social status and so on. In public woodlands, social and environmental goals -as they are cultural heritage, biodiversity loss mitigation, soil conservation and employment- could maintain market unprofitable woodlands operations. Last three decades Spanish Mediterranean woodlands owners have increased the livestock herds incentivized by government subsidies. As result, grazing rent is pending on the level of European Union and Spanish government livestock subsidies. In this context, Spanish Mediterranean woodlands maintain a high extensive livestock stoking population, which economy could be called fragile and environmentally unsustainable because forest degradation and over/under grazing practices. Tunisian Mediterranean woodlands are state properties and livestock grazing is practice as a free private regimen. Livestock herds are small herd

  5. Cork oak woodlands patchiness

    DEFF Research Database (Denmark)

    Costa, Augusta; Madeira, Manuel; Plieninger, Tobias

    2014-01-01

    The cork oak (Quercus suber L.) woodlands of the agroforestry landscapes of Southwestern Iberia are undergoing drastic change due to severe natural and anthropogenic disturbances. These may eventually result in woodland loss or deforestation, the final step of an ongoing process of woodland...... woodlands exhibited similar trends of decreasing fractional canopy cover and decreasing number of larger patches. Patchiness rather than fractional canopy cover seems, however, to be potentially more useful as a signature of imminent oak woodlands deforestation, given that its contrast before and after...

  6. Pairwise comparison of soil organic particle-size distributions in native savannas and Eucalyptus plantations in Congo

    OpenAIRE

    D'Annunzio, R.; Conche, Sofian; Landais, D; Saint André, L.; Joffre, R.; Barthès, Bernard

    2008-01-01

    Conversion of native vegetation into fast-growing tree plantations is known to affect soil organic matter (SOM): soil carbon (C) and nitrogen (N) content and their distribution in particle-size fractions can be modified in various ways depending on numerous factors, such as soil properties, SOM levels prior to conversion, climatic conditions, silvicultural practices and fire occurrence. Since 1978, 43,000 ha of clonal eucalyptus plantations have been established on sandy coastal plains under ...

  7. Ecosystem vs. community recovery 25 years after grass invasions and fire in a subtropical woodland

    Science.gov (United States)

    D'Antonio, Carla M.; Yelenik, Stephanie G.; Mack, Michelle C.

    2017-01-01

    Despite a large body of research documenting invasive plant impacts, few studies have followed individual invaded sites over decades to observe how they change, and none have contrasted how compositional impacts from invasion compare to ecosystem-process impacts over a multi-decadal time-scale. Using direct measurements of plant density and composition and of ecosystems processes, we evaluate how ecosystem structure, above-ground net primary production (ANPP), and above-ground and soil nutrient pools compare over 25 years since fire and C4 grass invasions disrupted seasonally dry Hawaiian woodlands. We compare structure and function between primary woodland that has never burned and is largely native species-dominated, with sites that had been the same woodland type but burned in alien-grass-fuelled fires in the 1970s and 1980s. The sites have not experienced fires since 1987. We report here that woody plant composition and structure continue to be dramatically changed by the initial invasions and fires that occurred 25 years ago and invaders continue to dominate in burned sites. This is reflected in continued low plant carbon pools in burned compared to unburned sites. Yet ANPP and N storage, which were dramatically lower in the initial decade after invasive-grass fuelled fires, have increased and are now indistinguishable from values measured in intact woodlands. Soil carbon pools were resilient to both invasion and fire initially and over time. Above-ground net primary production has recovered because of invasion of burned sites by a non-native N-fixing tree rather than because of recovery of native species. This invasive N-fixing tree is unlikely to return C storage of the invaded sites to those of unburned woodland because of its tissue and growth characteristics and its interactions with invasive grasses. It does not facilitate native species but rather promotes a persistent invasive grass/N-fixer savanna. Synthesis. We conclude that fire, an unusual

  8. [Effects of tree species transfer on soil dissolved organic matter pools in a reforested Chinese fir (Cunninghamia lanceolata) woodland].

    Science.gov (United States)

    Wan, Xiao-Hua; Huang, Zhi-Qun; He, Zong-Ming; Hu, Zhen-Hong; Yu, Zai-Peng; Wang, Min-Huang; Yang, Yu-Sheng; Fan, Shao-Hui

    2014-01-01

    Based on the comparison between reforested 19-year-old Mytilaria laosensis and Cunninghamia lanceolata plantations on cut-over land of C. lanceolata, effects of tree species transfer on soil dissolved organic matter were investigated. Cold water, hot water and 2 mol x L(-1) KCl solution were used to extract soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) from 0-5, 5-10 and 10-20 cm soil layers. In M. laosensis plantaion, the concentrations of soil DOC extracted by cold water, hot water and 2 mol L(-1) KCl solutions were significantly higher than that in C. lanceolata plantation. In the 0-5 and 5-10 cm layers, the concentrations of soil DON extracted by cold water and hot water in M. laosensis plantation were significantly higher than that in C. lanceolata plantation. The extracted efficiencies for DOC and DON were both in order of KCl solution > hot water > cold water. In the 0-5 cm layers, soil microbial biomass carbon (MBC) under M. laosensis was averagely 76.3% greater than under C. lanceolata. Correlation analysis showed that there were significant positive relationships between hot water extractable organic matter and soil MBC. Differences in the sizes of soil DOC and DON pools between the M. laosensis and C. lanceolata forests might be attributed to the quality and quantity of organic matter input. The transfer from C. lanceolata to M. laosensis could improve soil fertility in the plantation.

  9. Soil aggregation, organic carbon and CO2 emission in different land uses in Brazilian Savanna, Triangulo Mineiro region

    Directory of Open Access Journals (Sweden)

    Camila Silva Borges

    2015-07-01

    Full Text Available Soil aggregation and carbon distribution are important indicators of soil quality. Moreover, these attributes are closely related to CO2 fluxes in the soil-atmosphere interface. We sought to evaluate soil aggregation, organic carbon distribution and CO2 evolution in different land uses of Minas Gerais Triangle. Four different land uses were selected: (1 Panicum maximum, (2 Panicum maximum Jacqvr. (Tanzânia, (3 sugarcane, and (4 native Cerrado (control. In each land-use type, soil samples from a 0-10 cm layer were collected. The samples were air-dried and sieved in order to obtain aggregates sized 4-2 mm. The samples were submitted to wet-sieving to evaluate stability and also to obtain aggregates of different sizes: 4-2 mm; 2-1 mm; 1-0.5 mm; and 0.5-0.25 mm. Total organic carbon, humic substances and texture were determined for each aggregate size fraction. The CO2 emission was measured in field and lab conditions, both by the capture in NaOH solution method. The native Cerrado and Panicum maximum Jacqvr. (Tanzânia areas (mostly clay showed the highest soil aggregation. The conventional soil tillage adopted in sugarcane areas contributed significantly to aggregate disruption. In all of the areas, the largest aggregates had higher organic carbon and humic substances. Organic carbon content and soil texture seem to be closely associated with CO2 emissions in the areas studied.

  10. Bioaugmentation and biostimulation as strategies for the bioremediation of a burned woodland soil contaminated by toxic hydrocarbons: a comparative study.

    Science.gov (United States)

    Andreolli, Marco; Lampis, Silvia; Brignoli, Pierlorenzo; Vallini, Giovanni

    2015-04-15

    In this work, the natural attenuation strategy (no soil amendments done) was compared with two different bioremediation approaches, namely bioaugmentation through soil inoculation with a suspension of Trichoderma sp. mycelium and biostimulation by soil addition with a microbial growth promoting formulation, in order to verify the effectiveness of these methods in terms of degradation efficiency towards toxic hydrocarbons, with particular attention to the high molecular weight (HMW) fraction, in a forest area impacted by recent wildfire in Northern Italy. The area under investigation, divided into three parcels, was monitored to figure out the dynamics of decay in soil concentration of C₁₂₋₄₀ hydrocarbons (including isoalkanes, cycloalkanes, alkyl-benzenes and alkyl-naphthalenes besides PAHs) and low molecular weight (LMW) PAHs, following the adoption of the foregoing different remediation strategies. Soil hydrocarbonoclastic potential was even checked by characterizing the autochthonous microbial cenoses. Field experiments proved that the best performance in the abatement of HMW hydrocarbons was reached 60 days after soil treatment through the biostimulation protocol, when about 70% of the initial concentration of HMW hydrocarbons was depleted. Within the same time, about 55% degradation was obtained with the bioaugmentation protocol, whilst natural attenuation allowed only a 45% removal of the starting C12-40 hydrocarbon fraction. Therefore, biostimulation seems to significantly reduce the time required for the remediation, most likely because of the enhancement of microbial degradation through the improvement of nutrient balance in the burned soil. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Transpiration of oak trees in the oak savannas of the Southwestern Borderlands region

    Science.gov (United States)

    Peter F. Ffolliott; Cody L. Stropki; Aaron T. Kauffman; Gerald J. Gottfried

    2008-01-01

    Transpiration of oak trees on the Cascabel watersheds in the savannas on the eastern slope of the Peloncillo Mountains in southwestern New Mexico has been estimated by the sap-flow method. Transpiration represents the largest loss of gross precipitation falling on a watershed in approximations of water budgets for the more densely stocked oak woodlands of the...

  12. Reptile and amphibian responses to restoration of fire-maintained pine woodlands

    Science.gov (United States)

    Roger W Perry; D. Craig Rudolph; Ronald E. Thill

    2009-01-01

    Fire-maintained woodlands and savannas are important ecosystems for vertebrates in many regions of the world. These ecosystems are being restored by forest managers, but little information exists on herpetofaunal responses to this restoration in areas dominated by shortleaf pine (Pinus echinata). We compared habitat characteristics and...

  13. Carbono orgânico e biomassa microbiana do solo em plantios de Acacia mangium no Cerrado de Roraima Soil organic carbon and soil microbial biomass in Acacia mangium plantation in the Savanna of Roraima

    Directory of Open Access Journals (Sweden)

    Sara Magda Oliveira Simões

    2010-03-01

    Full Text Available O objetivo do estudo foi avaliar os efeitos de plantios de Acacia mangium, localizados no cerrado em Roraima, sobre o carbono orgânico e biomassa microbiana do solo. Foram realizadas amostragens de solo nas profundidades de 0-20 cm e 20-40 cm em dois plantios de A. mangium com cerca de cinco anos de idade, e em duas áreas de Cerrado nativo consideradas referência. Um dos plantios de A. mangium (localizado na Fazenda Cigolina correspondeu a um plantio homogêneo (espa��amento de 3,6 m entre linhas e 2,0 m entre plantas enquanto que o outro (localizado no Campo Experimental Água Boa - CEAB correspondeu a um plantio em faixas com duas linhas de plantio (espaçamento de 6 m entre linhas, 2,5 m entre plantas e cerca de 30 m entre faixas. As amostras de solo foram analisadas quanto ao carbono orgânico, carbono da biomassa microbiana, respiração basal do solo e quociente metabólico, além de atributos químicos de fertilidade. Foi verificado que os plantios de A. mangium não proporcionaram aumentos significativos do carbono orgânico do solo em comparação às áreas de referência. Entretanto, na média geral, esses plantios proporcionaram aumento do carbono da biomassa microbiana do solo e redução do quociente metabólico, indicando a possibilidade de acúmulo de carbono orgânico no solo em longo prazo. Também foi observado que, em comparação ao plantio da fazenda Cigolina e às áreas de referência, o carbono microbiano do solo foi maior e acompanhado de menor quociente metabólico no plantio de A. mangium no CEAB, mostrando que a estrutura de plantio exerceu influência sobre a biomassa microbiana do solo.The aim of this study was to evaluate the effects of Acacia mangium plantation in the Roraima's Savanna, on soil organic carbon and soil microbial biomass. Soil samplings were collected on the depths of 0-20 cm and 20-40 cm in two Acacia mangium plantation sites, about five years old, and in two sites of native savanna as

  14. Spatio-Temporal Dynamics in Land Use and Habitat Fragmentation within a Protected Area Dedicated to Tourism in a Sudanian Savanna of West Africa

    Directory of Open Access Journals (Sweden)

    Dimobe Kangbéni

    2017-01-01

    Full Text Available Nazinga Game Ranch (NGR is a reserve in Burkina Faso involving local communities for securing biodiversity through sustainable management. Yet, its ecosystems are threatened by increasing number of elephants and illegal human activities. Renowned as a model of wildlife participatory management, NGR has mainly been studied for its animal wildlife only. The aim of this study was to uncover ecological effects of recent land management on savanna habitats including tourism, and to conclude on more sustainable options, land use/land cover (LULC changes and vegetation dynamics in NGR were analyzed. This was accomplished with multi-temporal change detection using Landsat images of 1984, 2002 and 2013 to map seven representative LULC classification categories, and quantitative indices of landscape metrics. The results showed that the LULC dynamics in NGR from 1984 to 2013 was mainly characterized by an expansion of gallery forest, tree savanna and agricultural area and a reduction of shrub savanna, woodland and bare soils. From 2002 to 2013, fragmentation in all land cover types increased at the landscape level, whereas at the class level, it decreased for woodland. Our findings provided evidence of habitat degradation in NGR, due to extensive agriculture, tourism and growing of elephants’ population. According to the original management goals and the purposes of the reserve, both fauna and tourism are to be maintained and sustained in a sustainable way. Adaptation of land use and targeted wildlife management are the main requirements for avoiding further degradation of vegetation and thus of the existence basis of local inhabitants, animals and tourism.

  15. Season mediates herbivore effects on litter and soil microbial abundance and activity in a semi-arid woodland

    Science.gov (United States)

    Aimee T. Classen; Steven T. Overby; Stephen C. Hart; George W. Koch; Thomas G. Whitham

    2007-01-01

    Herbivores can directly impact ecosystem function by altering litter quality of an ecosystem or indirectly by shifting the composition of microbial communities that mediate nutrient processes. We examined the effects of tree susceptibility and resistance to herbivory on litter microarthropod and soil microbial communities to test the general hypothesis that herbivore...

  16. Seasonal changes of water carbon relations in savanna ecosystems

    Science.gov (United States)

    Kutsch, W. L.; Merbold, L.; Archibald, S.

    2011-12-01

    During evolution plant species have developed different strategies to optimize the water carbon relations. These stratgies summarize to ecosystem properties. As an example we show how tropical and subtropical savannas and woodlands can respond flexibly to changes in temperature and water availability and thus optimize carbon and water fluxes between land surface and atmosphere. Several phenomena are presented and discussed in this overview from African flux sites in Zambia, Burkina Faso and South Africa: Pre-rain leaf development: Many trees developed new leaves before the first rain appeared. As a consequence of this early timing of leaf flush, the phenological increase of photosynthetic capacity (Amax) was steeper than in temperate forests. Mid-term response of conductance and photosynthesis to soil water relations: The regulation of canopy conductance was temporally changing in two ways: changes due to phenology during the course of the growing season and short-term (hours to days) acclimation to soil water conditions. The most constant parameter was water use efficiency. It was influenced by water vapour pressure deficit (VPD) during the day, but the VPD response curve of water usage only changed slightly during the course of the growing season, and decreased by about 30% during the transition from wet to dry season. The regulation of canopy conductance and photosynthetic capacity were closely related. This observation meets recent leaf-level findings that stomatal closure triggers down-regulation of Rubisco during drought. Our results may show the effects of these processes on the ecosystem scale. Furthermore, we observed that the close relationship between stomatal conductance and photosynthesis resulted in different temperature optima of GPP that were close to the average daytime temperature. Adaptation of respiration to rain pulses: Finally, the response of respiration to rain pulses showed changes throughout the growing season. The first rain events early

  17. The impact of broadleaved woodland on water resources in lowland UK: III. The results from Black Wood and Bridgets Farm compared with those from other woodland and grassland sites

    Directory of Open Access Journals (Sweden)

    J. Roberts

    2005-01-01

    Full Text Available In the United Kingdom the planting of broadleaved woodland has led to concerns about the impact on water resources. Comparative studies, typically using soil water measurements, have been established to compare water use of broadleaved woodland and grassland. The diversity of outcomes from these studies makes it difficult to make any consistent prediction of the hydrological impact of afforestation. Most studies have shown greater drying of soils under broadleaved woodland than under grass. However, two studies in a beech wood growing on shallow soils above chalk at Black Wood, Micheldever, Hampshire showed little overall difference between broadleaved woodland and grass, either in soil water abstraction or in evaporation. Two factors are thought to contribute to the different results from Black Wood. It is known that evaporation can be considerably enhanced at the edges of woodlands or in small areas of woodlands. The studies at Black Wood were made well within a large area of fairly uniform woodland. Other studies in which a difference occurred in soil drying between broadleaved woodland and grass used measurements made in small areas of woodlands or at woodland edges. Another important difference between comparison of woodland at Black Wood and grassland growing nearby, also on shallow soils above Chalk, compared to other broadleaved woodland/grass comparisons, growing on other geologies, is the influence of the Chalk. Although vegetation such as grass (and woodland does not populate the chalk profusely with roots, water can be removed from the Chalk by the roots which proliferate at the soil/chalk interface and which can generate upward water movement within the Chalk. Published work showed that only in a very dry summer did the evaporation from grass growing on shallow soils above chalk fall below potential. In broadleaved woodland/grass comparisons on non-chalky soils it is possible that moisture deficits in the soil below the grass may

  18. [Vertical distribution characteristics of N2O emission in tea garden and its adjacent woodland].

    Science.gov (United States)

    Fan, Li-chao; Han, Wen-yan; Li, Xin; Li, Zhi-xin

    2015-09-01

    In this study, we determined the vertical distribution of N2O emission rates in tea soils and its adjacent woodland soils. The results showed that total nitrogen contents, N2O fluxes and cumulative emissions in the tea garden and woodland decreased with the increasing depth of the soil layer, and their average values were greater in tea garden than in woodland. Generally, pH, soil water soluble organic nitrogen (WSON), soil microbial biomass nitrogen (MBN), NO(3-)-N and NH(4+)-N contents had a downward trend with the increasing depth of soil layer. The WSON, MBN, NO(3-)-N and NH(4+)-N contents from each soil layer were greater in tea garden than in woodland, but the pH value in tea garden was lower than that in woodland. The N2O emission rate was significantly positively related with TN, MBN and NH(4+)-N contents, but not with pH value. The N2O emission rate was significantly correlated with WSON content in woodland, but not in tea garden. The N20 emission rate was significantly correlated with NO(3-)-N concentration in tea garden, but not in woodland. WSON/TN and N2O-N/SMBN were averagely greater than in tea garden in woodland, and SMBN/TN was opposite. These results indicated that tea soil was not conducive to accumulate nitrogen pool, maintain soil quality and its sustainable use compared to woodland.

  19. Edaphic characterization of a forest savanna ecotone in southeastern Brazil.

    OpenAIRE

    Pinheiro, Marcelo H. Ongaro; Arantes, Sayonara A. do Couto Moreno; Jimenez-Rueda, Jairo R.; Monteiro, Reinaldo

    2009-01-01

    This study was motivated by the scarcity of studies involving descriptions of edaphic horizons in the transition from savanna to forest. It aims at comparing the chemical features and the texture of savanna and forest soils in one ecotone, and at considering possible edaphic infl uences on vegetation. In areas pertaining to the Botanical Garden of Bauru, State of São Paulo, two-meter deep pits were opened in different parts of a seasonal semi-deciduous forest and of a forested savanna to dire...

  20. Chemical and biological quality of the soil in different systems of use in the savanna environment = Qualidade química e biológica do solo em diferentes sistemas de uso em ambiente de savana

    Directory of Open Access Journals (Sweden)

    Valdinar Ferreira Melo

    2017-06-01

    Full Text Available Environmental concern has led the agricultural community to search soil management systems aimed at maintaining or improving the quality of agricultural soils. The objective of this study was to evaluate soil quality (QS, by means of chemical and microbiological attributes under different use systems, natural savannah, planting sugarcane, forestation with sabiá, intercropping manioc + corn + beans cowpea (MCB and coconut planting. The study was developed in the Campus Cauamé UFRR. In each area were opened four mini-trench and soil samples collected at depths from 0.0 to 0.05 m, 0.05 to 0.10 m, 0.10 to 0.20 me from 0.20 to 0.40 m. The samples were subjected to chemical analysis, soil organic matter (SOM and microbiological. Noting that forms land use provide improved soil fertility and of the content of MOS, when compared with the natural conditions of savannas, these being more Evident in the layers of 0.00 -0.05 and 0.05 - 0.10 m, with emphasis on cultivation in an MMF consortium. The CA and MMF management systems were efficient the use of MOS, and could be used as form of MO increase in savanna soils in Roraima. The MMF, CA and FS systems presented Increased C-BMS, with greater evidence in the first layers (0.0-0.05 and 0.05-0.10 m. As forms of proportional land use, to some extent, improved soil fertility and MOS Compared with the natural conditions of the savanna hnoting that land use forms provide improved soil fertility and of the content of MOS, when compared with the natural conditions of savannas. = A preocupação ambiental tem levado a comunidade agrícola a buscar manejos que visam a manutenção ou melhoria da qualidade dos solos agrícolas. Objetivou-se com este trabalho avaliar a qualidade do solo (QS, por meio de atributos químicos e microbiológicos, submetido a diferentes sistemas de uso, sendo: pomar de coqueiros (CO, cultivo de cana-de-açúcar (CA, cultivo em consórcio de mandioca, milho e feijão-caupi (MMF

  1. Seasonal abundance of soil-surface arthropods in relation to some meteorological and edaphic variables of the grassland and tree-planted areas in a tropical semi-arid savanna

    Science.gov (United States)

    Vikram Reddy, M.; Venkataiah, B.

    1990-03-01

    Seasonality of relative population abundance in different groups of soil-surface arthropods was investigated monthly by pit-fall traps during a 2-year period in the grassland and tree-planted areas of a tropical semi-arid savanna at Warangal (south India). Densities of most groups were lowest during summer and highest during the rainy season. They were less abundant during winter. Arthropods were recorded in higher numbers in tree-planted compared to grassland areas. Certain arthropods that were found only during part of the year were recorded for a longer period in the tree-planted area. Formicidae, Monomorium indicum Forel, Crematogaster sp. and Pachycondyla? tesserinoda (Emery), and Coleoptera, Pachycera sp. reached maximum densities in the rainy season and minimum numbers during winter and summer in the grassland area. However, these species had lower densities during the rainy season and reached maximum densities during winter and summer in the tree-planted area. The seasonal abundance of arthropods showed significant linear correlations with different abiotic environmental variables such as rainfall, soil moisture, organic matter, soil and air temperatures, soil pH, relative humidity at the soil surface, and potassium and phosphorus of surface soil. Soil moisture and rainfall were generally the strongest correlates with densities, particularly in the grassland area.

  2. Brevitalea aridisoli, B. deliciosa and Arenimicrobium luteum, three novel species of Acidobacteria subdivision 4 (class Blastocatellia) isolated from savanna soil and description of the novel family Pyrinomonadaceae.

    Science.gov (United States)

    Wüst, Pia K; Foesel, Bärbel U; Geppert, Alicia; Huber, Katharina J; Luckner, Manja; Wanner, Gerhard; Overmann, Jörg

    2016-09-01

    Three novel strains of the phylum Acidobacteria (Ac_11_E3T, Ac_12_G8T and Ac_16_C4T) were isolated from Namibian semiarid savanna soils by a high-throughput cultivation approach using low-nutrient growth media. 16S rRNA gene sequence analysis placed all three strains in the order Blastocatellales of the class Blastocatellia (Acidobacteria subdivision 4). However, 16S rRNA gene sequence similarities to their closest relative Pyrinomonas methylaliphatogenes K22T were ≤90 %. Cells of strains Ac_11_E3T, Ac_12_G8T and Ac_16_C4T were Gram-staining-negative and non-motile and divided by binary fission. Ac_11_E3T and Ac_16_C4T formed white colonies, while those of Ac_12_G8T were orange-yellowish. All three strains were aerobic chemoorganoheterotrophic mesophiles with a broad pH range for growth. All strains used a very limited spectrum of carbon and energy sources for growth, with a preference for complex proteinaceous substrates. The major respiratory quinone was MK-8. The major shared fatty acid was iso-C15 : 0. The DNA G+C contents of strains Ac_11_E3T, Ac_12_G8T and Ac_16_C4T were 55.9 mol%, 66.9 mol% and 54.7 mol%, respectively. Based on these characteristics, the two novel genera Brevitaleagen. nov. and Arenimicrobiumgen. nov. are proposed, harboring the novel species Brevitaleaaridisoli sp. nov. (Ac_11_E3T=DSM 27934T=LMG 28618T), Brevitalea deliciosa sp. nov. (Ac_16_C4T=DSM 29892T=LMG 28995T) and Arenimicrobium luteum sp. nov. (Ac_12_G8T=DSM 26556T=LMG 29166T), respectively. Since these novel genera are only distantly related to established families, we propose the novel family Pyrinomonadaceaefam. nov. that accommodates the proposed genera and the genus Pyrinomonas(Crowe et al., 2014).

  3. Sustainable Land Management for the Oxisols of the Latin American Savannas: Dynamics of Soil Organic Matter and Indicators of Soil Quality

    OpenAIRE

    Thomas, R. (ed.); Ayarza, M. (ed.)

    1999-01-01

    Metadata only record This publication is a collection of state-of-the-art scientific findings on the dynamics of soil organic matter in the Oxisol savannahs (Cerrados) of central Brazil. These savannahs represent the second largest biome in South America and one of the most rapidly expanding agricultural frontiers. These projects have produced several potential indicators of soil health for the major Oxisol types in the Brazilian Cerrados.

  4. Ecophysiology of forest and savanna vegetation

    OpenAIRE

    Lloyd, J.; Goulden, M. L.; Ometto, J. P.; Patino, S.; Fyllas, N. M.; Quesada, C. A.

    2013-01-01

    Ecophysiological characteristics of forest and savanna vegetation are compared in an attempt to understand how physiological differences within and between these vegetation types relate to their geographical distributions. A simple ordination first shows that although precipitation exerts a key effect on Amazonian vegetation distributions, soil characteristics are also important. In particular, it is found that under similar precipitation regimes, deciduous forests tend to occur on more ferti...

  5. Effects of soil and space on the woody species composition and vegetation structure of three Cerrado phytophysiognomies in the Cerrado-Amazon transition.

    Science.gov (United States)

    Maracahipes-Santos, L; Lenza, E; Santos, J O; Mews, H A; Oliveira, B

    2017-11-01

    The Cerrado Biome is considered one of the world's biodiversity hotspots because of its rich biodiversity, the high level of endemism and the increasing threat. The Cerrado is composed by a mosaic of different vegetation types, including physiognomies that vary from grasslands (campo limpo) to savannas (typical cerrado or cerrado sensu stricto) and cerrado woodlands (cerradão). However, the factors that determine the composition of the Cerrado's flora and the structure of the physiognomies that compose this biome are still poorly understood. Here, we investigate the influence of the chemical and granulometric properties of the soil and the effect of geographic distance on the occurrence and abundance of woody species in three Cerrado phytophysiognomies - cerrado woodland (cerradão), dense cerrado savanna and typical cerrado savanna - in the Cerrado-Amazon transition. We tested the hypothesis that the edaphic characteristics and geographic space determine the species composition and the structure of the woody vegetation of these three phytophysiognomies. We demonstrate that the dissimilarities in the structure and composition of the three sites were determined more by space (13% of explanation) than edaphic properties (1%), but primarily by the interaction between these two factors (26%). We conclude that, in situations where the chemical and granulometric properties of the soil are relatively homogeneous, as we found in the present study, geographic distance between sites has a greater influence than variation in the substrate's properties on modelling the occurrence and abundance of the woody plant species in the Cerrado.

  6. Managing pinyon-juniper woodlands

    Science.gov (United States)

    Gerald J. Gottfried; Kieth E. Severson

    1994-01-01

    A renewed interest in pinyon-juniper woodlands has accelerated debate regarding management of this unique ecosystem. Should these woodlands be managed only to provide livestock forage through overstory removal-popular programs in the 1950s and 1960s-or should they be managed for production of multiple resource products and amenities? Pinyon-juniper woodlands have...

  7. 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

  8. Soil dehydrogenase in a land degradation-rehabilitation gradient: observations from a savanna site with a wet/dry seasonal cycle.

    Science.gov (United States)

    Doi, Ryoichi; Ranamukhaarachchi, Senaratne Leelananda

    2009-01-01

    Soil dehydrogenase activity is a good indicator of overall microbial activity in soil, and it can serve as a good indicator of soil condition. However, seasonal changes in soil moisture content may have an effect on soil dehydrogenase activity, making an accurate assessment of soil condition difficult. In this study, we attempted to determine the significance of soil dehydrogenase activity for assessing soil condition, and we attempted to find a way to account for the influence of soil moisture content on soil dehydrogenase activity.' Soils were sampled in dry evergreen forest (original vegetation), bare ground (severely degraded) and Acacia plantation plots established on bare ground in 1986 and 1987 in Sakaerat, Thailand. Soil physico-chemical characteristics and dehydrogenase activity in the Acacia plantation soil had few differences from those in the evergreen forest soil. Soil dehydrogenase activity varied significantly between the bare ground and the forests regardless of the season (wet or dry), while the season did not produce a significant variation in soil dehydrogenase activity, as determined by repeated measures analysis of variance (p=0.077). The physico-chemical data provided the first principal component as a good measure of soil fertility. Values of soil dehydrogenase activity significantly correlated to scores of the soil samples of the first principal component (R=0.787, prehabilitative effects of reforestation in this part of Thailand.

  9. Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes

    National Research Council Canada - National Science Library

    Platt, William J; Orzell, Steve L; Slocum, Matthew G

    2015-01-01

    ... (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...

  10. 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

  11. Soil dehydrogenase in a land degradation-rehabilitation gradient: observations from a savanna site with a wet/dry seasonal cycle

    Directory of Open Access Journals (Sweden)

    Ryoichi Doi

    2009-06-01

    Full Text Available Soil dehydrogenase activity is a good indicator of overall microbial activity in soil, and it can serve as a good indicator of soil condition. However, seasonal changes in soil moisture content may have an effect on soil dehydrogenase activity, making an accurate assessment of soil condition difficult. In this study, we attempted to determine the significance of soil dehydrogenase activity for assessing soil condition, and we attempted to find a way to account for the influence of soil moisture content on soil dehydrogenase activity. Soils were sampled in dry evergreen forest (original vegetation, bare ground (severely degraded and Acacia plantation plots established on bare ground in 1986 and 1987 in Sakaerat, Thailand. Soil physico-chemical characteristics and dehydrogenase activity in the Acacia plantation soil had few differences from those in the evergreen forest soil. Soil dehydrogenase activity varied significantly between the bare ground and the forests regardless of the season (wet or dry, while the season did not produce a significant variation in soil dehydrogenase activity, as determined by repeated measures analysis of variance (p=0.077. The physico-chemical data provided the first principal component as a good measure of soil fertility. Values of soil dehydrogenase activity significantly correlated to scores of the soil samples of the first principal component (R=0.787, p<0.001. We found that soil dehydrogenase activity is a useful indicator of the extent of soil degradation and the rehabilitative effects of reforestation in this part of Thailand. Rev. Biol. Trop. 57 (1-2: 223-234. Epub 2009 June 30.

  12. Perdas de solo e água em plantio de Acacia mangium wild e savana em Roraima, norte da Amazônia Soil and water losses in Acacia mangium wild plantations and natural savanna in Roraima, northern Amazon

    Directory of Open Access Journals (Sweden)

    Luciana da Silva Barros

    2009-04-01

    Acacia mangium are being increasingly implemented. The purpose of this study was the in situ determination of soil and water losses in commercial stands of Acacia mangium and compare them with those under native savanna. The experiment was conducted on a Red-Yellow Argisol (Ultisol in the region of Serra da Lua where Gerlach sediment and water collectors were installed. Soil density, texture, penetration resistance and infiltration rate were determined. All climate data were recorded by an automatic weather station placed within the experimental area. The experiment had a randomized block design with three treatments: one-year-old Acacia stand (P1, four-year-old Acacia stand (P4; and native savanna (SV. All experimental data were collected within one year. Results indicated that greater soil and water losses occurred in younger Acacia plantations (P1, followed by savanna (SV and four-year-old Acacia stands (P4. This was attributed to great soil exposure just after planting, when Acacia trees had not yet developed a good soil cover in these sealing-prone soils. The peak of soil and water loss occurred between April and August, and the practice of downslope planting aggravated soil erosion in Acacia stands. Soil bulk density or organic matter contents were not considered good management indicators for this area.

  13. Ecophysiology of forest and savanna vegetation

    Science.gov (United States)

    Lloyd, J.; Goulden, M. L.; Ometto, J. P.; Patiño, S.; Fyllas, N. M.; Quesada, C. A.

    Ecophysiological characteristics of forest and savanna vegetation are compared in an attempt to understand how physiological differences within and between these vegetation types relate to their geographical distributions. A simple ordination first shows that although precipitation exerts a key effect on Amazonian vegetation distributions, soil characteristics are also important. In particular, it is found that under similar precipitation regimes, deciduous forests tend to occur on more fertile soils than do cerrado vegetation types. A high subsoil clay content is also important in allowing the existence of semievergreen forests at only moderate rainfall. Such observations are consistent with biome specific physiological characteristics. For example, deciduous trees have higher nutrient requirements than do evergreen ones which also tend to have characteristics associated with severe water deficits such as a low specific leaf area. Nutrient contents and photosynthetic rates are lower than for savanna than for forest species with several ecosystem characteristics suggesting a primary limitation of nitrogen on savanna productivity. By contrast, phosphorus seems to constrain the productivity of most Amazonian forest types. Differentiation is made between the fast-growing, high-nutrient-requiring forest types of western Amazonia and their counterparts in eastern Amazonia, which tend to occupy infertile but deeper soils of high water-holding ability. On the basis of observed physiological characteristics of the various vegetation forms, it is argued that, should Amazonian precipitation decline sharply in the future, the slower growing forests of eastern Amazonia will transform directly into an evergreen cerrado type vegetation but with the more fertile western Amazonian forests being replaced by some form of drought-deciduous vegetation.

  14. Simultaneous assimilation of satellite and eddy covariance data for improving terrestrial water and carbon simulations at a semi-arid woodland site in Botswana

    Directory of Open Access Journals (Sweden)

    T. Kato

    2013-02-01

    Full Text Available Terrestrial productivity in semi-arid woodlands is strongly susceptible to changes in precipitation, and semi-arid woodlands constitute an important element of the global water and carbon cycles. Here, we use the Carbon Cycle Data Assimilation System (CCDAS to investigate the key parameters controlling ecological and hydrological activities for a semi-arid savanna woodland site in Maun, Botswana. Twenty-four eco-hydrological process parameters of a terrestrial ecosystem model are optimized against two data streams separately and simultaneously: daily averaged latent heat flux (LHF derived from eddy covariance measurements, and decadal fraction of absorbed photosynthetically active radiation (FAPAR derived from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS.

    Assimilation of both data streams LHF and FAPAR for the years 2000 and 2001 leads to improved agreement between measured and simulated quantities not only for LHF and FAPAR, but also for photosynthetic CO2 uptake. The mean uncertainty reduction (relative to the prior over all parameters is 14.9% for the simultaneous assimilation of LHF and FAPAR, 8.5% for assimilating LHF only, and 6.1% for assimilating FAPAR only. The set of parameters with the highest uncertainty reduction is similar between assimilating only FAPAR or only LHF. The highest uncertainty reduction for all three cases is found for a parameter quantifying maximum plant-available soil moisture. This indicates that not only LHF but also satellite-derived FAPAR data can be used to constrain and indirectly observe hydrological quantities.

  15. Water economy of Neotropical savanna trees: six paradigms revisited.

    Science.gov (United States)

    Goldstein, Guillermo; Meinzer, Frederick C; Bucci, Sandra J; Scholz, Fabian G; Franco, Augusto C; Hoffmann, William A

    2008-03-01

    Biologists have long been puzzled by the striking morphological and anatomical characteristics of Neotropical savanna trees which have large scleromorphic leaves, allocate more than half of their total biomass to belowground structures and produce new leaves during the peak of the dry season. Based on results of ongoing interdisciplinary projects in the savannas of central Brazil (cerrado), we reassessed the validity of six paradigms to account for the water economy of savanna vegetation. (1) All savanna woody species are similar in their ability to take up water from deep soil layers where its availability is relatively constant throughout the year. (2) There is no substantial competition between grasses and trees for water resources during the dry season because grasses exclusively explore upper soil layers, whereas trees access water in deeper soil layers. (3) Tree species have access to abundant groundwater, their stomatal control is weak and they tend to transpire freely. (4) Savanna trees experience increased water deficits during the dry season despite their access to deep soil water. (5) Stomatal conductance of savanna species is low at night to prevent nocturnal transpiration, particularly during the dry season. (6) Savanna tree species can be classified into functional groups according to leaf phenology. We evaluated each paradigm and found differences in the patterns of water uptake between deciduous and evergreen tree species, as well as among evergreen tree species, that have implications for regulation of tree water balance. The absence of resource interactions between herbaceous and woody plants is refuted by our observation that herbaceous plants use water from deep soil layers that is released by deep-rooted trees into the upper soil layer. We obtained evidence of strong stomatal control of transpiration and show that most species exhibit homeostasis in maximum water deficit, with midday water potentials being almost identical in the wet and dry

  16. Private Woodland Owners' Perspectives on Multifunctionality in English Woodlands

    Science.gov (United States)

    Urquhart, Julie; Courtney, Paul; Slee, Bill

    2012-01-01

    Increasing emphasis is being placed in forest policies to deliver public goods such as biodiversity, recreation, landscape and carbon sequestration, alongside timber production. In light of this, it is important to understand how woodland owners themselves perceive their role in delivering these multiple benefits. With up to 80% of woodland in…

  17. 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

  18. Vegetation structure and small-scale pattern in Miombo Woodland, Marondera, Zimbabwe

    Directory of Open Access Journals (Sweden)

    B. M. Campbell

    1995-10-01

    Full Text Available The aim ol this paper is to describe woodland structure and small-scale patterning of woody plants at a miombo site, and to relate these to past disturbance and soil properties. Brachystegia spiciformis Benth. and Julbemardia globiflora (Benth. Troupin were the most frequent woody plants at the five hectare site, with size-class distributions which were markedly skewed towards the smaller size classes. The vegetation structure at the site and the increase in basal area over the past thirty years point to considerable disturbance prior to the present protected status. Six woodland subtypes were identified, grouped into two structural types: open and closed woodland. The distribution of woodland subtypes related closely to certain soil properties. It was hypothesized that the distribution of open and closed woodland is stable and a positive feedback mechanism by which this occurs is postulated.

  19. Characteristics and behavior of a cool-season prescribed fire in the oak savannas of the Southwestern Borderlands

    Science.gov (United States)

    Karen A. Koestner; Daniel G. Neary; Gerald J. Gottfired; Ruben Morales

    2008-01-01

    Oak-savannas and woodlands comprise over 80,000 km2 (31,000 mi2) in the mountains and high valleys of the southwestern United States and northern Mexico (Figure 1). Fire, which was once the most important natural disturbance in this system, has been excluded due to over-grazing and fire suppression practices. This has resulted in ecosystem changes and fuel...

  20. Household Anthropogenic Pollutants Against Soil Respiration Erin Murphy EnvironMentors - AggieMentor -Trent Ichiuji University of California Davis / Woodland High School

    Science.gov (United States)

    Murphy, E.; Ichiuji, T.

    2013-12-01

    Macroscopic organisms have been largely studied for carbon dioxide release rate and the effect that human development has had on these rates. However, the majority of biomass on Earth is microbes found on the Earth's surface, in the waterways and in soil. As for pollution, a single drop of weak acid is unlikely to kill on the skin of a large animal, yet this could be catastrophic to a colony of microbes. This experiment studied the effect of anthropogenic pollution on soil respiration using toxins that could easily infiltrate our soil and water systems. This project specifically examined common household chemicals in conjunction with Putah Creek soil. The tested toxins were Mobil 1 motor oil, Windex window cleaner, Ajax dish soap, and Dawn antibacterial dish soap. Six samples of Putah Creek soil were collected in jars. Four soil samples were exposed to toxins, while the remaining two were the control and glucose replicates. The control included soil damped by water, while the glucose replicate included both water and glucose. The glucose replicate was included because of its known ability to encourage respiration. A 20 mL NaCl base trap was added to each jar before being sealed. The jars were aerated once a week before titration. The 1.0 N NaCl from each jar of each week was titrated with 0.5 N HCl. The initial prediction for this experiment was that the glucose would raise the respiration levels, and that the control with no glucose would fall. Five weeks of recording the respiration levels confirmed our hypothesis that household toxins are detrimental to the soil microbial community over time. A similar experiment employed heavy metals instead of household toxins. The experiment showed that soil respiration and ATP content were strongly affected by the heavy metal content present in the soil. (Vanhala, Ahtiainen, 1994). This project will raise awareness of the negative effect of improper disposal of seemingly harmless materials. The next step of the project would

  1. Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes: e0116952

    National Research Council Canada - National Science Library

    William J Platt; Steve L Orzell; Matthew G Slocum

    2015-01-01

    ... (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...

  2. A floristic classification of the vegetation of a forest-savanna boundary in southeastern Zimbabwe

    Directory of Open Access Journals (Sweden)

    I. Mapaure

    1997-12-01

    Full Text Available The vegetation of Chirinda Forest boundary was classified into eight types using Two-way Indicator Species Analysis (TWINSPAN and Detrended Correspondence Analysis (DCA. The moist forest comprises three types:  Strychnos mellodora-Chrysophyllum gonmgosanum Forest on deep dolerite soils; Chrysophyllum gorungosanum-Myrianthus holstii Forest on shallow dolerite soils; and  Teclea iiobilis-Ehretia cymosa Forest on drier, but deep dolerite soils. The non-forest vegetation comprises five types: Themeda triandra Grassland on shallow dolerite soils; Psidium guajava Bushland on sandstone; Bridelia micrantha-Harungana madagascariensis Mixed Woodland not restricted to any one particular soil type; Acacia karroo- Heteropyxis dehniae Woodland on shallow soils derived from sandstone but sometimes on dolerite; and  Julbemardia globiflora-Brachystegia spiciformis (Miombo Woodland on sandstone.

  3. A floristic classification of the vegetation of a forest-savanna boundary in southeastern Zimbabwe

    Directory of Open Access Journals (Sweden)

    I. Mapaure

    1997-10-01

    Full Text Available The vegetation of Chirinda Forest boundary was classified into eight types using Two-way Indicator Species Analysis (TWINSPAN and Detrended Correspondence Analysis (DCA. The moist forest comprises three types:  Strychnos mellodora-Chrysophyllum gonmgosanum Forest on deep dolerite soils; Chrysophyllum gorungosanum-Myrianthus holstii Forest on shallow dolerite soils; and  Teclea iiobilis-Ehretia cymosa Forest on drier, but deep dolerite soils. The non-forest vegetation comprises five types: Themeda triandra Grassland on shallow dolerite soils; Psidium guajava Bushland on sandstone; Bridelia micrantha-Harungana madagascariensis Mixed Woodland not restricted to any one particular soil type; Acacia karroo- Heteropyxis dehniae Woodland on shallow soils derived from sandstone but sometimes on dolerite; and  Julbemardia globiflora-Brachystegia spiciformis (Miombo Woodland on sandstone.

  4. Soil nutrient ecology associated with Acacia sieberana at different ...

    African Journals Online (AJOL)

    Keywords: Acacia sieberana; Ecosystems; Fertile islands; Mycorrhizas; Panicum maximum; Patchiness; Plant growth parameters; Savanna; Soil fertility; Soil mycorrhizal infectivity; Soil nutrients; Soil properties; Tree density; Trees; soil; ecology; paperbark acacia; botany; nutrients; mycorrhiza; kwazulu-natal; south africa; ...

  5. Modelling fire frequency in a Cerrado savanna protected area.

    Science.gov (United States)

    Pereira Júnior, Alfredo C; Oliveira, Sofia L J; Pereira, José M C; Turkman, Maria Antónia Amaral

    2014-01-01

    Covering almost a quarter of Brazil, the Cerrado is the world's most biologically rich tropical savanna. Fire is an integral part of the Cerrado but current land use and agricultural practices have been changing fire regimes, with undesirable consequences for the preservation of biodiversity. In this study, fire frequency and fire return intervals were modelled over a 12-year time series (1997-2008) for the Jalapão State Park, a protected area in the north of the Cerrado, based on burned area maps derived from Landsat imagery. Burned areas were classified using object based image analysis. Fire data were modelled with the discrete lognormal model and the estimated parameters were used to calculate fire interval, fire survival and hazard of burning distributions, for seven major land cover types. Over the study period, an area equivalent to four times the size of Jalapão State Park burned and the mean annual area burned was 34%. Median fire intervals were generally short, ranging from three to six years. Shrub savannas had the shortest fire intervals, and dense woodlands the longest. Because fires in the Cerrado are strongly responsive to fuel age in the first three to four years following a fire, early dry season patch mosaic burning may be used to reduce the extent of area burned and the severity of fire effects.

  6. Modelling fire frequency in a Cerrado savanna protected area.

    Directory of Open Access Journals (Sweden)

    Alfredo C Pereira Júnior

    Full Text Available Covering almost a quarter of Brazil, the Cerrado is the world's most biologically rich tropical savanna. Fire is an integral part of the Cerrado but current land use and agricultural practices have been changing fire regimes, with undesirable consequences for the preservation of biodiversity. In this study, fire frequency and fire return intervals were modelled over a 12-year time series (1997-2008 for the Jalapão State Park, a protected area in the north of the Cerrado, based on burned area maps derived from Landsat imagery. Burned areas were classified using object based image analysis. Fire data were modelled with the discrete lognormal model and the estimated parameters were used to calculate fire interval, fire survival and hazard of burning distributions, for seven major land cover types. Over the study period, an area equivalent to four times the size of Jalapão State Park burned and the mean annual area burned was 34%. Median fire intervals were generally short, ranging from three to six years. Shrub savannas had the shortest fire intervals, and dense woodlands the longest. Because fires in the Cerrado are strongly responsive to fuel age in the first three to four years following a fire, early dry season patch mosaic burning may be used to reduce the extent of area burned and the severity of fire effects.

  7. Modelling Fire Frequency in a Cerrado Savanna Protected Area

    Science.gov (United States)

    Pereira Júnior, Alfredo C.; Oliveira, Sofia L. J.; Pereira, José M. C.; Turkman, Maria Antónia Amaral

    2014-01-01

    Covering almost a quarter of Brazil, the Cerrado is the world’s most biologically rich tropical savanna. Fire is an integral part of the Cerrado but current land use and agricultural practices have been changing fire regimes, with undesirable consequences for the preservation of biodiversity. In this study, fire frequency and fire return intervals were modelled over a 12-year time series (1997–2008) for the Jalapão State Park, a protected area in the north of the Cerrado, based on burned area maps derived from Landsat imagery. Burned areas were classified using object based image analysis. Fire data were modelled with the discrete lognormal model and the estimated parameters were used to calculate fire interval, fire survival and hazard of burning distributions, for seven major land cover types. Over the study period, an area equivalent to four times the size of Jalapão State Park burned and the mean annual area burned was 34%. Median fire intervals were generally short, ranging from three to six years. Shrub savannas had the shortest fire intervals, and dense woodlands the longest. Because fires in the Cerrado are strongly responsive to fuel age in the first three to four years following a fire, early dry season patch mosaic burning may be used to reduce the extent of area burned and the severity of fire effects. PMID:25054540

  8. Woody Plant Invasion of Grassland: Storage and Turnover of Carbon in Soil Physical Fractions

    Science.gov (United States)

    Liao, J. D.; Boutton, T. W.; Jastrow, J. D.

    2003-12-01

    Woody plant encroachment is common in many grassland and savanna regions around the world. In the Rio Grande Plains of southern Texas, subtropical thorn woodlands dominated by C3 trees and shrubs (d13C = -27 o/oo) have largely replaced C4 grasslands (d13C = -14 o/oo) over the past 150 y. This vegetation change has resulted in increased soil organic carbon (SOC) storage. To elucidate mechanisms of SOC sequestration and turnover in this system, we separated soil organic matter into specific physical (size, density) fractions and determined natural d13C values of carbon in these fractions. Using a chronosequence approach, soils were collected from remnant grasslands (Time 0) and from woody plant stands ranging in age from 10-130 y. The free light-fraction (density less than 1 g/cm3) increased from 1 o/o of whole-soil weight in grasslands to 2-4 o/o of whole-soil weight in wooded landscape elements. The macroaggregate fraction (greater than 250 um) of soil in the 0-15 cm depth increment increased from less than 10 o/o of whole-soil dry weight in grasslands to more than 30 o/o of whole-soil weight in older woodlands. In contrast, the microaggregate fraction (53-250 um) decreased from 80 o/o of whole-soil weight in grasslands to 60 o/o of whole-soil weight after 80-130 y of woodland development. The decrease in microaggregates with increasing stand age likely reflects their incorporation into the macroaggregate fraction. Carbon contents (g C within a fraction per kg of whole soil) of all soil physical fractions (except free silt and clay) increased linearly with increasing woodland age, and were greatest in macroaggregates. Based on changes in natural C-13 abundance, mean residence times (1/k) for microaggregate carbon (326 y) were significantly greater than those for macroaggregate carbon (76 y), indicating that the older carbon associated with microaggregates is biochemically recalcitrant and/or physically protected. These results indicate that the interactions between

  9. Tree cover, tree height and bare soil cover differences along a land use degradation gradient in semi-arid savannas, South Africa

    CSIR Research Space (South Africa)

    Mathieu, R

    2009-07-01

    Full Text Available impacted communal sites. Generally communal areas have altered tree height distribution but in diverse way depending on the geology or the level of human utilization. Bare soil cover was generally found to be quite low (10%) in all different land uses...

  10. 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%.

  11. 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.

  12. Earthworm Populations in Savannas of the Orinoco Basin. A Review of Studies in Long-Term Agricultural-Managed and Protected Ecosystems

    Directory of Open Access Journals (Sweden)

    Danilo López-Hernández

    2012-04-01

    Full Text Available Earthworm biomass and production in savannas are limited by seasonal precipitation and the lack of organic and nutrient resources; I hypothesize that after a long-term protection of savanna from fire and agricultural activities drastic changes in the physical and chemical characteristics of the soil occur with a concomitant increase in earthworm abundance and activities. Similar changes might occur after a long-term fertilization of savannas with manure. This review article considers the earthworm communities and other soil quality indices in Trachypogon savannas of the Orinoco Basin in an organic agricultural forestal savanna (OAFS amended with compost over forty years in Puerto Ayacucho, Venezuela, and in an Experimental Station long-term protected (PS from fire and cattle raising from more than four decades in Central Llanos, Venezuela, comparison is made with results from similar savannas. Long-term additions of organic manure or a long protection have induced significant changes in the soil physical and chemical properties of the natural savanna (NS soils that induce a significant increase in the density and biomass of earthworm populations. On the other hand, the protection of the savanna promotes an improvement in the physical and chemical properties of the soil, which favors an increase in the density and biomass of earthworms in the PS compared with the NS subjected to recurrent burning and grazing. The results emphasize the importance of appropriate organic matter management and the relevance of earthworms in such agroecosystems.

  13. 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

  14. Grassland to woodland transitions: Dynamic response of microbial community structure and carbon use patterns

    Science.gov (United States)

    Creamer, Courtney A.; Filley, Timothy R.; Boutton, Thomas W.; Rowe, Helen I.

    2016-06-01

    Woodland encroachment into grasslands is a globally pervasive phenomenon attributed to land use change, fire suppression, and climate change. This vegetation shift impacts ecosystem services such as ground water allocation, carbon (C) and nutrient status of soils, aboveground and belowground biodiversity, and soil structure. We hypothesized that woodland encroachment would alter microbial community structure and function and would be related to patterns in soil C accumulation. To address this hypothesis, we measured the composition and δ13C values of soil microbial phospholipids (PLFAs) along successional chronosequences from C4-dominated grasslands to C3-dominated woodlands (small discrete clusters and larger groves) spanning up to 134 years. Woodland development increased microbial biomass, soil C and nitrogen (N) concentrations, and altered microbial community composition. The relative abundance of gram-negative bacteria (cy19:0) increased linearly with stand age, consistent with decreases in soil pH and/or greater rhizosphere development and corresponding increases in C inputs. δ13C values of all PLFAs decreased with time following woody encroachment, indicating assimilation of woodland C sources. Among the microbial groups, fungi and actinobacteria in woodland soils selectively assimilated grassland C to a greater extent than its contribution to bulk soil. Between the two woodland types, microbes in the groves incorporated relatively more of the relict C4-C than those in the clusters, potentially due to differences in below ground plant C allocation and organo-mineral association. Changes in plant productivity and C accessibility (rather than C chemistry) dictated microbial C utilization in this system in response to shrub encroachment.

  15. 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...

  16. Trends in savanna structure and composition along an aridity gradient in the Kalahari

    CSIR Research Space (South Africa)

    Scholes, RJ

    2002-06-01

    Full Text Available more than 10% of the area; savannas as having a cover by trees greater than 10% but less than 33%, and woodlands by having a tree cover greater than 33% but less than 66%. ?Broad-leafed? refers to the leaves or leaflets of the dominant woody species... being larger than about 20 mm (major axis); fine-leafed is smaller than 20 mm, and usually less than 2 mm. Deciduous means that > 90% of all tree and shrub leaves are lost for at least three months, evergreen means that > 80% of tree leaf is retained...

  17. Cascading ecohydrological transitions: Multiple changes in vegetation and hydrology over the past 500 years for a semiarid forest/woodland boundary zone in New Mexico, USA

    Science.gov (United States)

    Allen, Craig D.

    2010-05-01

    On decadal and centennial time scales, multiple drivers can cause substantial changes in vegetation cover, which can trigger associated changes in runoff and erosion patterns and processes, with consequent feedbacks to the vegetation - cumulatively this can lead to a cascading series of non-equilibrial ecosystem changes through time. The work reported here provides a relatively detailed 500-year perspective of such changes on the mesas the eastern Jemez Mountains in northern New Mexico (USA), which today exhibit vegetation transitions along an elevational gradient between semiarid ponderosa pine (Pinus ponderosa) forests, mixed woodlands dominated by piñon (Pinus edulis) and one-seed juniper (Juniperus monosperma), and juniper savannas. Using multiple lines of evidence, a history of major ecosystem changes since ca. 1500 A.D. is reconstructed for a dynamic transition zone on one such mesa (Frijolito Mesa). Evidence includes intensive archaeological surveys, dendrochronological reconstructions of the demographic and spatial patterns of establishment and mortality for these three main tree species, dendrochronological reconstructions of fire regimes and climate patterns, broad-scale mapping of vegetation changes from historic aerial photographs since 1935, monitoring of vegetation from permanent transects since 1991, detailed soil maps and interpretations, intensive ecohydrological studies since 1993 on portions of this mesa, and research on the ecosystem effects of an experimental tree-thinning experiment conducted in 1997. Frijolito Mesa was fully occupied by large numbers of Native American farmers from the A.D. 1200's until the late 1500's, when they left these mesas for settlements in the adjoining Rio Grande Valley. Archaeological evidence and tree ages indicate that the mesa was likely quite deforested when abandoned, followed by episodic tree establishment dominated by ponderosa pine during the Little Ice Age. By the late 1700's Frijolito Mesa included

  18. 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 (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 savanna tree sizes do not occur in either coarse sands or heavy clays. When examining the occurrence of

  19. 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....

  20. Factors influencing woodlands of southwestern North Dakota

    Science.gov (United States)

    Michele M. Girard; Harold Goetz; Ardell J. Bjugstad

    1987-01-01

    Literature pertaining to woodlands of southwestern North Dakota is reviewed. Woodland species composition and distribution, and factors influencing woodland ecosystems such as climate, logging, fire, and grazing are described. Potential management and improvement techniques using vegetation and livestock manipulation have been suggested.

  1. Pinyon/juniper woodlands [Chapter 4

    Science.gov (United States)

    Robin J. Tausch; Sharon Hood

    2007-01-01

    Pinyon-juniper woodlands occur in 10 states and cover large areas in many of them. These woodlands can be dominated by several species of pinyon pine (Pinus spp. L.) and juniper (Juniperus spp. L.) (Lanner 1975; Mitchell and Roberts 1999; West 1999a). A considerable amount of information is available on the expansion of the woodlands that has occurred over large parts...

  2. Indiana residents' perceptions of woodland management

    Science.gov (United States)

    Daniel J. Witter; Shannon M. Amberg; David J. Case; Phillip T. Seng

    2013-01-01

    A 2009 telephone survey of 1,402 Indiana adults was conducted to assess opinions regarding woodland management. Forty-eight percent said they were "very concerned" about the health and productivity of Indiana's woodlands, and 45 percent, "somewhat concerned." Almost half (47 percent) thought that the state's woodlands are held in about...

  3. Comparison of Infiltrability Measurements in the Thornbush Savanna, Namibia

    Science.gov (United States)

    Classen, Nikolaus; Gröngröft, Alexander; Eschenbach, Annette

    2010-05-01

    Large proportions of Namibian Savannas are affected by strong bush encroachment leading to a reduction in grazing capacity. Especially woody plant encroachment is expected to have an impact on hydrology by increasing plant transpiration, bare soil evaporation and reducing soil water availability (HUXMAN et al. 2005). Although the processes are not fully understood, the role of soil water balance is highlighted by many studies. Especially the small-scale interactions of vegetation and soil are of high relevance. To characterize the water balance of different sites in the Namibian thornbush savanna long-term studies were conducted. In addition we applied three methods to quantify the infiltration rate (IR) at four central Namibian thornbush savanna sites differing in soil texture and vegetation type: a single ring (own construction, 14 cm inner diameter), a disc-infiltrometer (Eijkelkamp Agrisearch Equipment BV) and a hood infiltrometer (UGT Umwelt-Geräte-Technik GmbH). At each site, the measurements we conducted along short transect lines (15 m) in positions with differing plant influence (canopy of Acacia trees and shrubs, grass and dwarf-shrub tussocks, bare soil, termitaria). All three methods resulted in different mean IR as well as spatial distribution patterns. Using statistical analysis by ANOVA, dominant controlling variables were elaborated. The poster will demonstrate which of the methods is defensible with respect to the research question. References : HUXMAN, T. E., B. P. WILCOX, et al. (2005): Ecohydrological implications of woody plant encroachment. Ecology 86(2): 308-319. Acknowledgment: The work was founded by BMBF within the Project Biota South (support code 01LC 0624 A2).

  4. Are the long-term effects of mesobrowsers on woodland dynamics substitutive or additive to those of elephants?

    Science.gov (United States)

    O'Kane, Christopher A. J.; Duffy, Kevin J.; Page, Bruce R.; Macdonald, David W.

    2011-09-01

    The large spectrum of existing literature on browser-woodland dynamics, both from savanna and temperate biomes, converges towards concluding that all browsers importantly impact woody plants. In this context a crucial question in the current debate about reintroducing elephant culling, is whether the long-term effects of elephants and mesobrowsers are similar. If the two groups impact the same woody species in the same habitats, sufficiently high biomass-densities of mesobrowsers may, following removal of elephants, continue to heavily impact earlier life-history stages of the same suite of woody plants that elephant impacted, preventing these species from maturing. Thus, as existing mature trees die from natural causes and fade from the system, a similar end-point for woodland structure and composition is achieved. We reviewed 49 years of literature on the savanna browser guild, performing a meta-analysis on the disparate data on the guild's woody plant species use (3677 records) and habitat use (894 records). Mesobrowsers' and elephants' extensive overlap in habitat use and staple woody species diet, together with evidence of their influencing each others' abundance and of their dietary separation increasing with resource depletion, implies that the two groups impact the same core woody species in the same habitats. It therefore seems probable that high biomass-density mesobrowsers may have a long-term substitutive effect to that of elephant on woodland dynamics. Consequently management wanting a particular state of savanna woodland, should consider the biomass-density of both groups, rather than just focus on the system's perceived keystone species. Such principles may also apply to temperate and other systems.

  5. The development of an approach to assess critical loads of acidity for woodland habitats in Great Britain

    Directory of Open Access Journals (Sweden)

    S. J. Langan

    2004-01-01

    Full Text Available Alongside other countries that are signatories to the UNECE Convention Long Range Transboundary on Air Pollution, the UK is committed to reducing the impact of air pollution on the environment. To advise and guide this policy in relation to atmospheric emissions of sulphur and nitrogen, a critical load approach has been developed. To assess the potential impact of these pollutants on woodland habitats a steady state, simple mass balance model has been parameterised. For mineral soils, a Ca:Al ratio in soil solution has been used as the critical load indicator for potential damage. For peat and organic soils critical loads have been set according to a pH criterion. Together these approaches have been used with national datasets to examine the potential scale of acidification in woodland habitats across the UK. The results can be mapped to show the spatial variability in critical loads of the three principal woodland habitat types (managed coniferous, managed broadleaved/ mixed woodland and unmanaged woodland. The results suggest that there is a wide range of critical loads. The most sensitive (lowest critical loads are associated with managed coniferous followed by unmanaged woodland on peat soils. Calculations indicate that at steady state, acid deposition inputs reported for 1995–1997 result in a large proportion of all the woodland habitats identified receiving deposition loads in excess of their critical load; i.e. critical loads are exceeded. These are discussed in relation to future modelled depositions for 2010. Whilst significant widespread negative impacts of such deposition on UK woodland habitats have not been reported, the work serves to illustrate that if acid deposition inputs were maintained and projected emissions reductions not achieved, the long-term sustainability of large areas of woodland in the UK could be compromised. Keywords: critical loads, acid deposition, acidification, woodland, simple mass balance model

  6. The characterisation and management of greenhouse gas emissions from fires in northern Australian savannas

    Science.gov (United States)

    Cook, G. D.; Liedloff, A. C.; Richards, A. E.; Meyer, M.

    2016-12-01

    Australia is the only OECD country with a significant area of tropical savannas within it borders. Approximately 220 000 km2 of these savannas burn every year releasing 2 to 4 % of Australia's accountable greenhouse gas emissions. Reduction in uncertainty in the quantification of these emissions of methane and nitrous has been fundamental to improving both the national GHG inventory and developing approaches to better manage land to reduce these emissions. Projects to reduce pyrogenic emissions have been adopted across 30% of Australia's high rainfall savannas. Recent work has focussed on quantifying the additional benefit of increased carbon stocks in fine fuel and coarse woody debris (CWD) resulting from improvements in fire management. An integrated set of equations have been developed to enable seemless quantification of emissions and sequestration in these frequently burnt savannas. These show that increases in carbon stored in fine fuel and CWD comprises about 3 times the emissions abatement from improvements in fire management that have been achieved in a project area of 28 000 km2. Future work is focussing on improving the understanding of spatial and temporal variation in fire behaviour across Australia's savanna biome, improvements in quantification of carbon dynamics of CWD and improved quantification of the effects of fire on carbon dynamics in soils of the savannas.

  7. Carbon Accumulation and Nitrogen Pool Recovery during Transitions from Savanna to Forest in Central Brazil

    Science.gov (United States)

    Pellegrini, A.; Hoffmann, W. A.; Franco, A. C.

    2014-12-01

    The expansion of tropical forest into savanna may potentially be a large carbon sink, but little is known about the patterns of carbon sequestration during transitional forest formation. Moreover, it is unclear how nutrient limitation, due to extended exposure to firedriven nutrient losses, may constrain carbon accumulation. Here, we sampled plots that spanned a woody biomass gradient from savanna to transitional forest in response to differential fire protection in central Brazil. These plots were used to investigate how the process of transitional forest formation affects the size and distribution of carbon (C) and nitrogen (N) pools. This was paired with a detailed analysis of the nitrogen cycle to explore possible connections between carbon accumulation and nitrogen limitation. An analysis of carbon pools in the vegetation, upper soil, and litter shows that the transition from savanna to transitional forest can result in a fourfold increase in total carbon (from 43 to 179 Mg C/ha) with a doubling of carbon stocks in the litter and soil layers. Total nitrogen in the litter and soil layers increased with forest development in both the bulk (+68%) and plant-available (+150%) pools, with the most pronounced changes occurring in the upper layers. However, the analyses of nitrate concentrations, nitrate : ammonium ratios, plant stoichiometry of carbon and nitrogen, and soil and foliar nitrogen isotope ratios suggest that a conservative nitrogen cycle persists throughout forest development, indicating that nitrogen remains in low supply relative to demand. Furthermore, the lack of variation in underlying soil type (>20 cm depth) suggests that the biogeochemical trends across the gradient are driven by vegetation. Our results provide evidence for high carbon sequestration potential with forest encroachment on savanna, but nitrogen limitation may play a large and persistent role in governing carbon sequestration in savannas or other equally fire-disturbed tropical

  8. Firewise Landscaping for Woodland Homes

    OpenAIRE

    Close, David

    2015-01-01

    A home in a woodland setting is surrounded by flammable vegetation. Firewise landscaping can help you create a defensible space or buffer zone around your home. This publication details landscaping zones which should be used when planning for fire protections and rates common landscaping plants by flammability.

  9. 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.

  10. Soil Properties and Yam Performance in Differently Tilled Soils in ...

    African Journals Online (AJOL)

    Soil Properties and Yam Performance in Differently Tilled Soils in Auchi Area, Edo State of Nigeria. ... Nigerian Journal of Soil Science ... is to investigate soil properties and tillage requirement for yam on silty loam soils of derived savanna zone of Edo State, Nigeria and determine soil properties influencing yam performance ...

  11. Ciclagem de nutrientes por plantas de cobertura na entressafra em um solo de cerrado Nutrient cycling in off-season cover crops on a Brazilian savanna soil

    Directory of Open Access Journals (Sweden)

    Carlo Adriano Boer

    2007-09-01

    Full Text Available O objetivo deste trabalho foi avaliar o acúmulo e a liberação de nutrientes (N, P, K, Ca, Mg e S de resíduos culturais de plantas de cobertura na entressafra, em condições de Cerrado. O experimento foi conduzido em um Latossolo Vermelho distroférrico com textura argilosa. As plantas de cobertura avaliadas foram: amaranto (Amaranthus cruentus L., milheto (Pennisetum glaucum L. e capim-pé-de-galinha (Eleusine coracana (L. Gaertn.. O delineamento experimental utilizado foi o de blocos ao acaso, no esquema de parcelas subdivididas, com quatro repetições. Na fase de florescimento das espécies, foi avaliada a produção de matéria seca e o acúmulo de nutrientes. A fim de avaliar a liberação de nutrientes dos resíduos culturais, o material vegetal de cada espécie foi acondicionado em sacolas de náilon, as quais foram dispostas sobre o solo e seu conteúdo analisado em intervalos de 30 dias, até 240 dias após sua instalação. As maiores quantidades de nutrientes acumulados na fitomassa das plantas de cobertura foram observadas no milheto e no capim-pé-de-galinha. O potássio foi o nutriente acumulado em maior quantidade, chegando a atingir 416,9 kg ha-1 no milheto. As maiores taxas de liberação de nutrientes foram observadas nos resíduos culturais do amaranto.The objective of this work was to evaluate the accumulation and the liberation of nutrients (N, P, K, Ca, Mg and S of cultural residues by three species of cover crops, in off-season. Tested cover crops were amaranthus (Amaranthus cruentus L., pearl millet (Pennisetum glaucum L. and finger millet (Eleusine coracana (L. Gaertn.. The experiment was carried out in a Typic Haplorthox clay texture soil. A randomized block desing in a split-plot array in time, with four replications, was used. At the flowering of the species, the production of dry matter and the accumulation of nutrients were evaluated. Proportional samples of dry matter of each cover crop species were placed in

  12. Atmospheric nitrogen budget in Sahelian dry savannas

    Directory of Open Access Journals (Sweden)

    C. Delon

    2010-03-01

    Full Text Available The atmospheric nitrogen budget depends on emission and deposition fluxes both as reduced and oxidized nitrogen compounds. In this study, a first attempt at estimating the Sahel nitrogen budget for the year 2006 is made, through measurements and simulations at three stations from the IDAF network situated in dry savanna ecosystems. Dry deposition fluxes are estimated from measurements of NO2, HNO3 and NH3 gaseous concentrations and from simulated dry deposition velocities, and wet deposition fluxes are calculated from NH4+ and NO3 concentrations in samples of rain. Emission fluxes are estimated including biogenic emission of NO from soils (an Artificial Neural Network module has been inserted into the ISBA-SURFEX surface model, emission of NOx and NH3 from domestic fires and biomass burning, and volatilization of NH3 from animal excreta. Uncertainties are calculated for each contribution of the budget.

    This study uses original and unique data from remote and hardly-ever-explored regions.The monthly evolution of oxidized N compounds shows that emission and deposition increase at the beginning of the rainy season because of large emissions of biogenic NO (pulse events. Emission of oxidized compounds is dominated by biogenic emission from soils (domestic fires and biomass burning of oxidized compounds account for 0 to 13% at the most at the annual scale, depending on the station, whereas emission of NH3 is dominated by the process of volatilization from soils. At the annual scale, the average gaseous dry deposition accounts for 47% of the total estimated deposition flux, for both oxidized and reduced compounds. The average estimated wet plus dry deposition flux in dry savanna ecosystems is 7.5±1.8 kgN ha−1 yr−1, with approximately 30% attributed to oxidized compounds, and the rest attributed

  13. A Crown Cover Chart for Oak Savannas

    Science.gov (United States)

    Jay Law; Paul Johnson; Gary Houf

    1994-01-01

    Although oak savannas have been defined in many ways, they are characterized by scattered trees, largely comprised of oaks, and a sparse ground layer rich in grasses and forbs (Haney and Apfelbaum 1990). Nuzzo (1986, p. 11) more specifically defined oak savannas as plant communities "...dominated by oaks having between 10 and 80 percent canopy, with or without a...

  14. African savanna-forest boundary dynamics

    DEFF Research Database (Denmark)

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

    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 i...

  15. 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.

  16. 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

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

    African Journals Online (AJOL)

    The effects of soil type and grazing on the tree:grass ratio in encroached Acacia mellifera-dominated savannas in the Northern Cape, South Africa, were investigated by means of vegetation classification and analyses of sequential aerial photographs. Acacia mellifera never occurred on clay pans, and in low numbers only in ...

  18. 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...

  19. 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.

  20. Group composition and activity patterns of brown-nosed coatis in savanna fragments, Mato Grosso do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    EMJ. Costa

    Full Text Available The Parque Estadual do Prosa (PEP, in Campo Grande, MS, is an urban fragment of savanna (cerrado and tall savanna woodland (cerradão, with an area of 1,335 km², where the population density of brown-nosed coatis is 33.71 individuals/km². Our results suggest that seasonality at the PEP causes changes in the availability of resources for coatis, altering their home range areas, their dispersion patterns and their daily behaviour. And our observations regarding male-band associations, agonistic interactions between bands and their daily behaviour emphasize the plasticity of coati social structure, and its potential for future comparative studies.

  1. Four millennia of woodland structure and dynamics at the Arctic treeline of eastern Canada.

    Science.gov (United States)

    Auger, Sarah; Payette, Serge

    2010-05-01

    Paleoecological analysis using complementary indicators of vegetation and soil can provide spatially explicit information on ecological processes influencing trajectories of long-term ecosystem change. Here we document the structure and dynamics of an old-growth woodland before and after its inception 1000 years ago. We infer vegetation and soil characteristics from size and age distributions of black spruce (Picea mariana (Mill.) B.S.P.), soil properties, plant fossils, and paleosols. Radiocarbon ages of charcoal on the ground and in the soil indicate that the fire return interval was approximately 300 years between 2750 and 1000 cal. yr BP. No fire evidence was found before and after this period despite the presence of spruce since 4200 cal. yr BP. The size structures of living and dead spruce suggest that the woodland is in equilibrium with present climate in absence of fire. Tree establishment and mortality occurred regularly since the last fire event around 950 cal. yr BP. Both layering and occasional seeding have contributed to stabilize the spatial distribution of spruce over the past 1000 years. Since initial afforestation, soil development has been homogenized by the changing spatial distribution of spruce following each fire. We conclude that the history of the woodland is characterized by vegetation shifts associated with fire and soil disturbances and by millennial-scale maintenance of the woodland's structure despite changing climatic conditions.

  2. Potential hominin plant foods in northern Tanzania: semi-arid savannas versus savanna chimpanzee sites.

    Science.gov (United States)

    Copeland, Sandi R

    2009-10-01

    Savanna chimpanzees are useful as referential models for early hominins, and here potential differences between chimpanzee and early hominin ecology is the focus. Whereas chimpanzees inhabit only a handful of modern African savannas, there is evidence that early hominins occupied relatively more open and arid savannas than those in which chimpanzees live. In order to help expand potential models of early hominin palaeoecology beyond savanna chimpanzee-like scenarios, and to provide a basis for future modeling and testing of actual hominin diets, this study compares the types of plant foods available in modern semi-arid savannas of northern Tanzania to plant foods at savanna chimpanzee sites. The semi-arid savannas are not occupied by modern chimpanzees, but are potentially similar to environments occupied by some early hominins. Compared to savanna chimpanzee habitats, the northern Tanzania semi-arid savanna has a lower density and fewer species of trees that produce fleshy fruits. Additionally, the most abundant potential hominin plant foods are seasonally available Acacia seeds/pods and flowers, grass seeds, and the underground parts of marsh plants, as evidenced by vegetation surveys and by studies of the diets of baboons that forage in similar areas. The information from this study should be useful for framing hypotheses about hominin diets for sites with palaeoenvironmental contexts similar to those of the northern Tanzania semi-arid savannas and for contextualising tests of actual hominin diets (e.g., those based on dental microwear or isotopes).

  3. 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

  4. Disaggregating tree and grass phenology in tropical savannas

    Science.gov (United States)

    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

  5. Wildlife response to stand structure of deciduous woodlands

    Science.gov (United States)

    Robert A. Hodorff; Carolyn Hull Sieg; Raymond L. Linder

    1988-01-01

    Deciduous woodlands provide important habitat for wildlife but comprise Fraxinus pennsylvanica) woodlands in northwestern South Dakota. Closed-canopy stands were multilayered communities with dense...

  6. Patterns in volatile organic compound emissions along a savanna-rainforest gradient in central Africa

    Science.gov (United States)

    Klinger, L. F.; Greenburg, J.; Guenther, A.; Tyndall, G.; Zimmerman, P.; M'bangui, M.; Moutsamboté, J.-M.; Kenfack, D.

    1998-01-01

    In temperate regions the chemistry of the lower troposphere is known to be significantly affected by biogenic volatile organic compounds (VOCs) emitted by plants. The chemistry of the lower troposphere over the tropics, however, is poorly understood, in part because of the considerable uncertainties in VOC emissions from tropical ecosystems. Present global VOC models predict that base emissions of isoprene from tropical rainforests are considerably higher than from savannas. These global models of VOC emissions which rely mainly on species inventories are useful, but significant improvement might be made with more ecologically based models of VOC emissions by plants. Ecosystems along a successional transect from woodland savanna to primary rainforest in central Africa were characterized for species composition and vegetation abundance using ground surveys and remotely sensed data. A total of 336 species (mostly trees) at 13 sites were recorded, and 208 of these were measured for VOC emissions at near-optimal light and temperature conditions using a leaf cuvette and hand-held photoionization detector (PID). A subset of 59 species was also sampled using conventional VOC emission techniques in order to validate the PID technique. Results of ecological and VOC emission surveys indicate both phylogenetic and successional patterns along the savanna-rainforest transect. Genera and families of trees which tend to emit isoprene include Lophira, Irvingia, Albizia, Artocarpus, Ficus, Pterocarpus, Caesalpiniaceae, Arecaceae, and Moraceae. Other taxa tend to contain stored VOCs (Annonaceae and Asteraceae). Successional patterns suggest that isoprene emissions are highest in the relatively early successional Isoberlinia forest communities and progressively decrease in the later successional secondary and primary rainforest communities. Stored VOCs appear to increase along the savanna-rainforest succession, but these data are more tentative. These findings are consistent with

  7. 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

    ,500 Ha among the different savanna ecosystem types. Highest frequencies and largest burned areas occur in the less accessible well-drained savannas of the southern part of the region. The analysis also reveals a close relationship between land tenure and fire regimes, with highest frequencies in Indigenous Reserves, followed by private land ranches and National Parks, indicating that most fires are human induced. By 2000 more than 500k hectares of natural savannas were transformed to sown pastures (Brachiaria spp.), and some 100k hectares were planted with oil palm and irrigated rice. Such changes have taken place in more accessible areas and slightly better soils. In areas subject to land use change and intensification a significant reduction in fire frequency can be observed. Because such land use changes have been occurring in savanna types with better soils and higher aerial biomass values, the average effect on reduction of C-emissions is some 30 to 50% larger than the effect on fire area reduction. Our results indicate a reduction of fire frequencies greater than 80% in areas where savannas were replaced by introduced Brachiaria pastures. However the reduction in C emissions from fire reduction in these pastures is exceeded by the parallel emissions from the increase in the cattle stocking rates with a net effect of an additional emission of 0.5 Gt.CO2 equivalents. We make preliminary projections of future emission trends based on the land use change model, and we discuss the likely effects of future sources and sinks of C expected from the increase of irrigated rice crops and from projected oil palm and timber plantations.

  8. Deciphering the distribution of the savanna biome

    CSIR Research Space (South Africa)

    Lehmann, CER

    2011-07-01

    Full Text Available ?mberg, 2004). But C4 grasslands also displaced forests, 12 thickets and shrublands; biomes that coexist with savanna in modern landscapes, and define the 13 modern limits of savannas (Keeley & Rundel, 2005). Inter-conversion between savanna and 14..., and forests will be referred to 20 collectively as ?closed-canopy ecosystems,? even if they do not possess a truly closed canopy. 21 4 The defining characteristic of these systems is that the cover of woody plants is sufficiently 22 dense to shade out C4...

  9. 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

  10. Local-Scale Mapping of Biomass in Tropical Lowland Pine Savannas Using ALOS PALSAR

    Directory of Open Access Journals (Sweden)

    Dimitrios Michelakis

    2014-09-01

    Full Text Available Fine-scale biomass maps offer forest managers the prospect of more detailed and locally accurate information for measuring, reporting and verification activities in contexts, such as sustainable forest management, carbon stock assessments and ecological studies of forest growth and change. In this study, we apply a locally validated method for estimating aboveground woody biomass (AGWB from Advanced Land Observing Satellite (ALOS Phased Array-type L-band Synthetic Aperture Radar (PALSAR data to produce an AGWB map for the lowland pine savannas of Belize at a spatial resolution of 100 m. Over 90% of these woodlands are predicted to have an AGWB below 60 tha−1, with the average woody biomass of these savannas estimated at 23.5 tha−1. By overlaying these spatial estimates upon previous thematic mapping of national land cover, we derive representative average biomass values of ~32 tha−1 and ~18 tha−1 for the previously qualitative classes of “denser” and “less dense” tree savannas. The predicted average biomass, from the mapping for savannas woodlands occurring within two of Belize’s larger protected areas, agree closely with previous biomass estimates for these areas based on ground surveys and forest inventories (error ≤20%. However, biomass estimates derived for these protected areas from two biomass maps produced at coarser resolutions (500 m and 1000 m from global datasets overestimated biomass (errors ≥275% in each dataset. The finer scale biomass mapping of both protected and unprotected areas provides evidence to suggest that protection has a positive effect upon woody biomass, with the mean AGWB higher in areas protected and managed for biodiversity (protected and passively managed (PRPM, 29.5 tha−1 compared to unprotected areas (UPR, 23.29 tha−1. These findings suggest that where sufficient ground data exists to build a reliable local relationship to radar backscatter, the more detailed biomass mapping that can be

  11. Nutrient Cycling in Managed and Unmanaged Oak Woodland-Grass Ecosystems

    Science.gov (United States)

    Randy Dahlgren; Michael J. Singer

    1991-01-01

    The influence of oak trees and grazing on nutrient cycling in oak woodland-grass ecosystems was examined at the Sierra Foothill Range Field Station in the northern-Sierra Nevada foothills of California. Nutrient concentrations in ecosystem waterflows (precipitation, canopy throughfall, and soil solutions) were monitored in a non-managed natural area and in an adjacent...

  12. Ecohydrology of pinon-juniper woodlands in the Jemez Mountains, New Mexico: Runoff, erosion, and restoration

    Science.gov (United States)

    Craig D. Allen

    2008-01-01

    (Please note, this is an extended abstract only) Woodlands of pinon (Pinus edulis) and oneseed juniper (Juniperus monosperma) in the Jemez Mountains at Bandelier National Monument in northern New Mexico exhibit greatly accelerated rates of soil erosion, triggered by historic land use practices (livestock grazing and fire suppression). This erosion is degrading these...

  13. Arbuscular mycorrhizal associations in Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands of Northern Ethiopia.

    NARCIS (Netherlands)

    Emiru Birhane, E.B.; Kuyper, T.W.; Sterck, F.J.; Bongers, F.

    2010-01-01

    This study assessed the arbuscular mycorrhizal (AM) status of Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands in relation to season, management and soil depth in Ethiopia. We studied 43 woody species in 52 plots in three areas. All woody species were colonized by AM fungi,

  14. 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.

  15. 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 the sustainable management of this ecosystem service is essential to energy security and poverty alleviation. Strong dependence on fuelwood and resulting high levels of extraction has raised concerns about a looming “fuelwood-crisis” at local and national scales...

  16. Molecular identification of Entamoeba species in savanna woodland chimpanzees (Pan troglodytes schweinfurthii).

    Science.gov (United States)

    Jirků-Pomajbíková, Kateřina; Čepička, Ivan; Kalousová, Barbora; Jirků, Milan; Stewart, Fiona; Levecke, Bruno; Modrý, David; Piel, Alex K; Petrželková, Klára J

    2016-05-01

    To address the molecular diversity and occurrence of pathogenic species of the genus Entamoeba spp. in wild non-human primates (NHP) we conducted molecular-phylogenetic analyses on Entamoeba from wild chimpanzees living in the Issa Valley, Tanzania. We compared the sensitivity of molecular [using a genus-specific polymerase chain reaction (PCR)] and coproscopic detection (merthiolate-iodine-formaldehyde concentration) of Entamoeba spp. We identified Entamoeba spp. in 72 chimpanzee fecal samples (79%) subjected to species-specific PCRs for six Entamoeba species/groups (Entamoeba histolytica, Entamoeba nuttalli, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba coli and Entamoeba polecki ST2). We recorded three Entamoeba species: E. coli (47%), E. dispar (16%), Entamoeba hartmanni (51%). Coproscopically, we could only distinguish the cysts of complex E. histolytica/dispar/moshkovskii/nuttalli and E. coli. Molecular prevalence of entamoebas was higher than the prevalence based on the coproscopic examination. Our molecular phylogenies showed that sequences of E. dispar and E. coli from Issa chimpanzees are closely related to sequences from humans and other NHP from GenBank. The results showed that wild chimpanzees harbour Entamoeba species similar to those occurring in humans; however, no pathogenic species were detected. Molecular-phylogenetic methods are critical to improve diagnostics of entamoebas in wild NHP and for determining an accurate prevalence of Entamoeba species.

  17. Management of California Oak Woodlands: Uncertainties and Modeling

    Science.gov (United States)

    Jay E. Noel; Richard P. Thompson

    1995-01-01

    A mathematical policy model of oak woodlands is presented. The model illustrates the policy uncertainties that exist in the management of oak woodlands. These uncertainties include: (1) selection of a policy criterion function, (2) woodland dynamics, (3) initial and final state of the woodland stock. The paper provides a review of each of the uncertainty issues. The...

  18. Comparison of the driving forces of spring phenology among savanna landscapes by including combined spatial and temporal heterogeneity

    Science.gov (United States)

    Zhu, Likai; Southworth, Jane; Meng, Jijun

    2015-10-01

    Understanding spatial and temporal dynamics of land surface phenology (LSP) and its driving forces are critical for providing information relevant to short- and long-term decision making, particularly as it relates to climate response planning. With the third generation Global Inventory Monitoring and Modeling System (GIMMS3g) Normalized Difference Vegetation Index (NDVI) data and environmental data from multiple sources, we investigated the spatio-temporal changes in the start of the growing season (SOS) in southern African savannas from 1982 through 2010 and determined its linkage to environmental factors using spatial panel data models. Overall, the SOS occurs earlier in the north compared to the south. This relates in part to the differences in ecosystems, with northern areas representing high rainfall and dense tree cover (mainly tree savannas), whereas the south has lower rainfall and sparse tree cover (mainly bush and grass savannas). From 1982 to 2010, an advanced trend was observed predominantly in the tree savanna areas of the north, whereas a delayed trend was chiefly found in the floodplain of the north and bush/grass savannas of the south. Different environmental drivers were detected within tree- and grass-dominated savannas, with a critical division being represented by the 800 mm isohyet. Our results supported the importance of water as a driver in this water-limited system, specifically preseason soil moisture, in determining the SOS in these water-limited, grass-dominated savannas. In addition, the research pointed to other, often overlooked, effects of preseason maximum and minimum temperatures on the SOS across the entire region. Higher preseason maximum temperatures led to an advance of the SOS, whereas the opposite effects of preseason minimum temperature were observed. With the rapid increase in global change research, this work will prove helpful for managing savanna landscapes and key to predicting how projected climate changes will affect

  19. Preliminary research on environmental impact of woodland grazing by pigs

    Directory of Open Access Journals (Sweden)

    Danilo Mani

    2010-01-01

    Full Text Available 6 castrate pigs about 30 kg live weight each entered in a fence into hilly woodland area. The pigs were bred until about 140 kg live weight. After 10 months of pasture breeding, the environmental damages (cover ground, plants and soil characteristics by rooting and trampling were evaluated. The damages to cover ground and to shrubs and to physical structure (Fissures and Aggregate stability caused hydro-geological instability with soil erosion and landslides. Removing surface layers of soil caused considerable loss of organic matter (Total Organic Carbon and Total Nitrogen, microbial activity (Microbial ATP and breathing and enzyme activity changes (Total β−glucosidase and Extra cellular β−glucosidase. Damages to native plants are different in relation to the root and the trunk kinds, and to the palatability of leaves and apexes which result inversely related whit the abundance of disagreeable substances content (ADL, Tannins, Resins, Latex.

  20. The impact of broadleaved woodland on water resources in lowland UK: II. Evaporation estimates from sensible heat flux measurements over beech woodland and grass on chalk sites in Hampshire

    Directory of Open Access Journals (Sweden)

    J. Roberts

    2005-01-01

    Full Text Available The impact on recharge to the Chalk aquifer of substitution of broadleaved woodland for pasture is a matter of concern in the UK. Hence, measurements of energy balance components were made above beech woodland and above pasture, both growing on shallow soils over chalk in Hampshire. Latent heat flux (evaporation was calculated as the residual from these measurements of energy balances in which sensible heat flux was measured with an eddy correlation instrument that determined fast response vertical wind speeds and associated temperature changes. Assessment of wind turbulence statistics confirmed that the eddy correlation device performed satisfactorily in both wet and dry conditions. There was excellent agreement between forest transpiration measurements made by eddy correlation and stand level tree transpiration measured with sap flow devices. Over the period of the measurements, from March 1999 to late summer 2000, changes in soil water content were small and grassland evaporation and transpiration estimated from energy balance-eddy flux measurements were in excellent agreement with Penman estimates of potential evaporation. Over the 18-month measurement period, the cumulative difference between broadleaved woodland and grassland was small but evaporation from the grassland was 3% higher than that from the woodland. In the springs of 1999 and 2000, evaporation from the grassland was greater than that from the woodland. However, following leaf emergence in the woodland, the difference in cumulative evaporation diminished until the following spring.

  1. Savanna vegetation-fire-climate relationships differ among continents

    CSIR Research Space (South Africa)

    Lehmann, CER

    2014-01-01

    Full Text Available Ecologists have long sought to understand the factors controlling the structure of savanna vegetation. Using data from 2154 sites in savannas across Africa, Australia, and South America, we found that increasing moisture availability drives...

  2. The social value of carbon sequestered in Great Britain's woodlands

    Energy Technology Data Exchange (ETDEWEB)

    Brainard, Julii; Bateman, Ian J.; Lovett, Andrew A. [Centre for Social and Economic Research on the Global Environment, School of Environmental Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom)

    2009-02-15

    The economic value of carbon storage associated with British woodland is calculated. Models were developed to estimate C flux associated with live trees, forest floor litter, soils, wood products, harvest, fossil fuel used in manufacturing and C displacement from biofuels and products for representative British plantation species: Sitka spruce (Picea sitchensis) and beech (Fagus sylvatica). Map databases of publicly and privately owned woodlands were compiled for Great Britain. Carbon flux was determined for individual woodland sites, and monetised using candidate parameters for the social discount rate (1, 3, 3.5 or 5%) and social value of carbon (USD109.5, USD1, USD10 or USD17.10/t). A conventional discount function was applied. Final results are expressed as Net Present Values, for the base year 2001, with discounting commencing in 2002. The minimum suggested NPV (discount rate = 3% and social value of carbon = USD1) of GB woodlands already existing in 2001 is USD82 million, with a further USD72 million that might be added by future afforestation. These figures rise dramatically if a discount rate of 1% and social value of sequestered carbon = USD109.5/t are assumed. The calculated total value of C stored in British woodland depends significantly on parameter assumptions, especially about appropriate discount rate and social value of sequestered carbon. (author)

  3. Características físicas, químicas e conteúdo de água em solos convertidos de savana para plantio de Acacia mangium. = Physical and chemical characteristics and soil humidity by converting savanna to Acacia mangium crop, Roraima State, Brazil.

    Directory of Open Access Journals (Sweden)

    Maria Ivonilde Leitão de Souza

    2010-06-01

    Full Text Available Os quarenta mil quilômetros quadrados de savana (cerrado em Roraima vêm sendo substituídos por agricultura, pecuária e florestamento, portanto, objetivou-se avaliar o efeito da conversão da savana nativa para plantios de Acacia mangium, com diferentes idades, em diferentes classes de solos e profundidades dos solos nas características químicas, físicas e no teor de água do solo. O trabalho foi conduzido em duas fazendas do Empreendimento Ouro Verde Agrosilvopastoril Ltda, no município do Cantá, RR, em plantios de Acacia mangium com até quatro anos de implantação comparado a condição natural (savana. As áreas situam-se em solos da classe Latossolo Amarelo distrófico (Fazenda Tuquinha e Argissolo Amarelo distrófico (Fazenda Garimpeira e as variáveis foram avaliadas nas profundidades de 0 - 30; 30 - 60 e 60 - 90 cm. As variáveis analisadas foram: pH, bases trocáveis, alumínio trocável, H+ + Al3+, fósforo, sódio, Matéria Orgânica do Solo (MOS, granulometria, densidade do solo e teor de água no solo. Em geral, os solos são de baixa fertilidade natural, verificando-se que a implantação de Acaciamangium não apresentou alterações químicas positivas no solo, revelando uma tendência de aumento da umidade do solo coma idade de plantio de Acacia mangium. = The forty thousand square kilometers of savannah (cerrado in Roraima State, Brazil, are being replaced by agriculture and forestry. The purpose of this study was to evaluate the effect of native savanna conversion to plantationsof Acacia mangium at different ages, classes and soil depths on chemical and physical attribute and water content of soil. Thisresearch was done in two farms of Ouro Verde Agrossilvopastoril Ltda., in the city of Cantá – RR, with up to four year oldAcacia mangium crops at Tuquinha`s farm and at Garimpeira`s farm, and in natural savanna conditions. The collected samples were of dystrophic yellow Latosol (Tuquinha farm and dystrophic yellow

  4. Holocene semi-arid oak woodlands in the Irano-Anatolian region of Southwest Asia: natural or anthropogenic?

    Science.gov (United States)

    Asouti, Eleni; Kabukcu, Ceren

    2014-04-01

    It is commonly accepted that, following the end of the Pleistocene, semi-arid deciduous oak woodlands did not spread in the Irano-Anatolian region of Southwest Asia as quickly as they did in the Levantine Mediterranean littoral, despite the fact that climatic improvement occurred broadly at the same time in both regions. Prehistoric impacts on woodland vegetation (such as woodcutting, burning and clearance for cultivation), the harsh continental climate of inland Southwest Asia and its distance from late Pleistocene arboreal refugia have all been discussed in the literature as likely causes of the delay. In this paper we argue that semi-arid deciduous oak woodlands should not be viewed as part of the “natural” vegetation of the Irano-Anatolian region that has been progressively destroyed by millennia of human activities since the Neolithic. They represent instead one of the earliest anthropogenic vegetation types in Southwest Asia, one that owes its very existence to prehistoric landscape practices other scholars commonly label as “destructive”. Drawing on anthracological, pollen and modern vegetation data from central Anatolia we describe how the post-Pleistocene species-rich and structurally diverse temperate semi-arid savanna grasslands were gradually substituted by low-diversity, even-aged Quercus-dominated parklands and wood pastures in the course of the early Holocene. Economic strategies that encouraged the establishment and spread of deciduous oaks included sheep herding that impacted on grass and forb vegetation, the controlling of competing arboreal vegetation through woodcutting, and woodland management practices such as coppicing, pollarding and shredding that enhanced Quercus vegetative propagation, crown and stem growth. Understanding the origin and evolution of the Irano-Anatolian semi-arid oak woodlands of Southwest Asia is of critical importance for reconstructing the changing ecologies and geographical distributions of the progenitors of

  5. Monitoring vegetation dynamics and carbon stock density in miombo woodlands.

    Science.gov (United States)

    Ribeiro, Natasha S; Matos, Céu N; Moura, Isabel R; Washington-Allen, Robert A; Ribeiro, Ana I

    2013-11-09

    The United Nation's Program for Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to reduce the 20% contribution to global emissions of greenhouse gases from the forest sector, offering a financial value of the carbon stored in forests as an incentive for local communities. The pre-requisite for the setup of a participatory REDD + Program is the monitoring, reporting and verification (MRV) of baseline carbon stocks and their changes over time. In this study, we investigated miombo woodland's dynamics in terms of composition, structure and biomass over a 4-year period (2005-2009), and the Carbon Stock Density (CSD) for the year 2009. The study was conducted in the Niassa National Reserve (NNR) in northern Mozambique, which is the 14th largest protected area in the world. Mean tree density distributed across 79 species increased slightly between 2005 and 2009, respectively, from 548 to 587 trees ha-1. Julbernardia globiflora (Benth.) was the most important species in this area [importance value index (IVI2005= 61 and IVI2009 = 54)]. The woodlands presented an inverted J-shaped diametric curve, with 69% of the individuals representing the young cohort. Woody biomass had a net increase of 3 Mg ha-1 with the highest growth observed in Dyplorhynchus condilocarpon (Müll.Arg.) Pichon (0.54 Mg ha-1). J. globiflora had a net decrease in biomass of 0.09 Mg ha-1. Total CSD density was estimated at ca. 67 MgC ha-1 ± 24.85 with soils (average 34.72 ± 17.93 MgC ha-1) and woody vegetation (average 29.8 MgC ha-1 ± 13.07) representing the major carbon pools. The results point to a relatively stable ecosystem, but they call for the need to refocus management activities. The miombo woodlands in NNR are representative of the woodlands in the eco-region in terms of vegetation structure and composition. They experienced net increase in woody biomass, a considerable recruitment level and low mortality. According to our results, NNR

  6. [Bioecological characteristics of earthworm populations (Oligochaeta: Glossoscolecidae) in a natural and a protected savanna in the central Llanos of Venezuela].

    Science.gov (United States)

    Hernández, Luis; Ojeda, Alonso; López-Hernández, Danilo

    2012-09-01

    In tropical savannas, the earthworm communities have a predominant role since they regulate the soil structure and dynamics of the organic matter. To study the effect on earthworm populations in two differently managed savannas, we compared the general aspects of the biology and ecology of earthworm populations from a 40 years protected savanna (SP) with no fire or cattle raising at the Estaci6n Biol6gica de los Llanos, Venezuela (EBLL), and a natural savanna (SNI), under normal burning and cattle raising management conditions. Sampling was carried out at the end of the dry season (April), and at the peak of the wet season (July-August). The main physical properties of soils per system were estimated. In each system, in plots of 90x90m, five fixed sampling units were selected at random; and at each sampling point one soil monolith of 25x25x30cm was collected per unit. Earthworms were extracted using the hand sorting extraction method; and the flotation method was used to estimate the density of cocoons. The earthworms were classified in different ecological categories considering their pigmentation, size and depth profile distribution. As a result of the savanna protection, physical parameters were modified in relation to SNI. The SP soils had higher soil moisture when compared to SNI. Soil moisture varied with depth during the dry season since, after the start of the rainy season, the soil was saturated. Field capacity in the SP was greater than that in the SNI. The surface apparent bulk density of soil was lower in the SP respect SNI, reflecting a lower soil compaction. Total average for the density and biomass of earthworms differed greatly, showing higher values in the SP. The earthworm density average in SP ranged between 25.6-85 individuals/m2 and the average biomass between 6.92-23.23g/m2. While in SNI, earthworms were only found in August, with a mean density of 22.40individuals/m2 and a mean biomass of 5.17g/m2. The vertical distribution pattern was only

  7. Subsistence strategies of two "savanna" chimpanzee populations: the stable isotope evidence.

    Science.gov (United States)

    Schoeninger, M J; Moore, J; Sept, J M

    1999-12-01

    Twenty-two chimpanzee hair samples collected from night nests at two different "savanna" sites were analyzed for carbon and nitrogen stable isotope ratios represented as delta13C and delta15N values. The first at Ugalla, Tanzania is a miombo woodland with grass groundcover and small patches of forest. The second at Ishasha, Democratic Republic of the Congo is a habitat composed of riverine gallery forest, semideciduous thicket forest, wooded grassland, and grassland. Based on comparative data from other primates, Ugalla hair delta13C values suggest that the chimpanzees are feeding primarily in the woodland rather than in forest patches or on grassland foods (grasses or grammivorous fauna). Similar comparisons indicate that the Ishasha chimpanzees are feeding within the forests and not in more open areas. In addition, the Ugalla chimpanzees had delta15N values that indicate extensive ingestion of leguminous flowers, seeds, and/or leaves. The Ishasha samples show a range encompassing three trophic levels. Two samples with the most positive values may indicate a nursing signal or vertebrate-feeding. Three individuals with intermediate values are similar to those in omnivorous nonhuman primate species. The four individuals with the lowest values are very similar to those in herbivorous monkeys. Stable isotope ratios permit time-averaged and habitat-specific dietary comparisons among sites, even without habituation or detailed foraging observations.

  8. Interactions between Canopy Structure and Herbaceous Biomass along Environmental Gradients in Moist Forest and Dry Miombo Woodland of Tanzania.

    Directory of Open Access Journals (Sweden)

    Deo D Shirima

    Full Text Available We have limited understanding of how tropical canopy foliage varies along environmental gradients, and how this may in turn affect forest processes and functions. Here, we analyse the relationships between canopy leaf area index (LAI and above ground herbaceous biomass (AGBH along environmental gradients in a moist forest and miombo woodland in Tanzania. We recorded canopy structure and herbaceous biomass in 100 permanent vegetation plots (20 m × 40 m, stratified by elevation. We quantified tree species richness, evenness, Shannon diversity and predominant height as measures of structural variability, and disturbance (tree stumps, soil nutrients and elevation as indicators of environmental variability. Moist forest and miombo woodland differed substantially with respect to nearly all variables tested. Both structural and environmental variables were found to affect LAI and AGBH, the latter being additionally dependent on LAI in moist forest but not in miombo, where other factors are limiting. Combining structural and environmental predictors yielded the most powerful models. In moist forest, they explained 76% and 25% of deviance in LAI and AGBH, respectively. In miombo woodland, they explained 82% and 45% of deviance in LAI and AGBH. In moist forest, LAI increased non-linearly with predominant height and linearly with tree richness, and decreased with soil nitrogen except under high disturbance. Miombo woodland LAI increased linearly with stem density, soil phosphorous and nitrogen, and decreased linearly with tree species evenness. AGBH in moist forest decreased with LAI at lower elevations whilst increasing slightly at higher elevations. AGBH in miombo woodland increased linearly with soil nitrogen and soil pH. Overall, moist forest plots had denser canopies and lower AGBH compared with miombo plots. Further field studies are encouraged, to disentangle the direct influence of LAI on AGBH from complex interrelationships between stand

  9. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species

    NARCIS (Netherlands)

    Barbosa, E.R.; Tomlinson, K.W.; Carvalheiro, L.G.; Kirkman, K.; Bie, de S.; Prins, H.H.T.; Langevelde, van F.

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect

  10. Determinants of woody cover in African savannas

    NARCIS (Netherlands)

    Sankaran, M.; Hanan, N.P.; Scholes, R.J.; Ratnam, J.; Augustine, D.J.; Cade, B.S.; Gignoux, J.; Higgins, S.I.; Roux, Le X.; Ludwig, F.; Ardo, J.; Banyikwa, F.; Bronn, A.; Bicini, 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

  11. Wildlife resources of the West African savanna

    NARCIS (Netherlands)

    Bie, de S.

    1991-01-01

    The wild fauna in Africa is a renewable resource and its overexploitation has led to the depletion of animal populations. This thesis focusses on the ecological characterization of the ungulate community of the West African savanna, with special reference to the Biosphere Reserve 'Boucle du

  12. Savanna browse production. 1: Determinants and measurement ...

    African Journals Online (AJOL)

    With the rapid expansion of wildlife ranching and conservation in South African savannas and the resultant increase in multi-species grazing and browsing systems, information on browse production potential is essential for determination of carrying capacity. This study, conducted on three game reserves in the northern ...

  13. Unsustainable fuelwood extraction from South African savannas

    CSIR Research Space (South Africa)

    Wessels, Konrad J

    2013-01-01

    Full Text Available 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...

  14. 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.

  15. Contributions of microbial activity and ash deposition to post-fire nitrogen availability in a pine savanna

    OpenAIRE

    Ficken, Cari D.; Wright, Justin P.

    2017-01-01

    Many ecosystems experience drastic changes to soil nutrient availability associated with fire, but the magnitude and duration of these changes are highly variable among vegetation and fire types. In pyrogenic pine savannas across the southeastern United States, pulses of soil inorganic nitrogen (N) occur in tandem with ecosystem-scale nutrient losses from prescribed burns. Despite the importance of this management tool for restoring and maintaining fire-dependent plant commu...

  16. Unravelling ecosystem functions at the Amazonia-Cerrado transition: II. Carbon stocks and CO2 soil efflux in cerradão forest undergoing ecological succession

    Science.gov (United States)

    Peixoto, Karine S.; Marimon-Junior, Ben Hur; Marimon, Beatriz S.; Elias, Fernando; de Farias, Josenilton; Freitag, Renata; Mews, Henrique A.; das Neves, Eder C.; Prestes, Nayane Cristina C. S.; Malhi, Yadvinder

    2017-07-01

    The transition region between two major South American biomes, the Amazon forest and the Cerrado (Brazilian savanna), has been substantially converted into human-modified ecosystems. Nevertheless, the recovery dynamics of ecosystem functions in this important zone of (ecological) tension (ZOT) remain poorly understood. In this study, we compared two areas of cerradão (a forest-woodland of the Brazilian savanna; Portuguese augmentative of cerrado), one in secondary succession (SC) and one adjacent and well preserved (PC), to test whether the ecosystem functions lost after conversion to pasture were restored after 22 years of regeneration. We tested the hypothesis that the increase in annual aboveground biomass in the SC would be greater than that in the PC because of anticipated successional gains. We also investigated soil CO2 efflux, litter layer content, and fine root biomass in both the SC and PC. In terms of biomass recovery our hypothesis was not supported: the biomass did not increase in the successional area over the study period, which suggested limited capacity for recovery in this key ecosystem compartment. By contrast, the structure and function of the litter layer and root mat were largely reconstituted in the secondary vegetation. Overall, we provide evidence that 22 years of secondary succession were not sufficient for these short and open forests (e.g., cerradão) in the ZOT to recover ecosystem functions to the levels observed in preserved vegetation of identical physiognomy.

  17. Non-equilibrium hillslope dynamics and irreversible landscape changes at a shifting pinyon-juniper woodland ecotone

    Science.gov (United States)

    McAuliffe, Joseph R.; McFadden, Leslie D.; Roberts, Leah M.; Wawrzyniec, Tim F.; Scuderi, Louis A.; Meyer, Grant A.; King, Matthew P.

    2014-11-01

    Pinyon-juniper woodlands of the western United States frequently exist within topographically complex landscapes where varied slope aspect yields substantial, local microclimate variation. Vegetation composition and cover typically change markedly along the gradient of relatively mesic northern aspects to more xeric southern aspects. Ecohydrological processes including precipitation runoff, soil moisture storage, and erosion are strongly influenced by vegetation. In certain cases, reduction of plant cover may set self-enhancing feedbacks in motion that lead to further declines of both vegetation and soils, and in some cases, replacement of woodlands with more xerophytic vegetation. The first place such change is likely to occur is in the ecotone between the drier southern aspects and moister north aspects. We studied vegetation, soils, and soil erosion in two small (1-2 ha) drainage basins in northeastern Arizona where pinyon-juniper woodlands occupy northern aspects, grading to shrub-dominated vegetation on more xeric southern aspects. Mapping of soil thickness, use of tree-root exposure to measure long-term soil erosion rates, and data on tree mortality and establishment indicate that the ecotone between woodland and more xerophytic vegetation has apparently been shifting for centuries, with a reduction in woodland vegetation. Erosion rates on xeric aspects ranged from 14 to 23 cm per century in one basin and as much as 60 cm per century in the other basin. In contrast, mesic aspects showed either no net soil losses over the last several centuries or rates significantly less than on the xeric aspects. Exposure of small roots (soils. The contrasting sets of self-enhancing feedback dynamics on xeric vs. mesic aspects not only produce different states in vegetation and soils, they also set in motion the production of pronounced geomorphic contrasts that probably require centuries to millennia to develop. The ongoing ecohydrological transitions in the more xeric

  18. The influence of arbuscular mycorrhizae and light on Wisconsin (USA) sand savanna understories 2. Plant competition.

    Science.gov (United States)

    Landis, Frank C; Gargas, Andrea; Givnish, Thomas J

    2005-11-01

    Wisconsin (USA) oak savannas are endangered plant communities that have remarkably high plant species diversity. To investigate factors underlying this richness, we experimentally investigated the potentially interacting effects of light gradients and arbuscular mycorrhizal fungi (AMF) on plant competition in the greenhouse, using a fully randomized block design. We used four plant species, soil, and AMF from a remnant sand savanna, under two light and five AMF treatments. Plants were grown four per pot under two competition treatments (either one or four species per pot) for 20 weeks. Using ANOVA, we found that all species showed significant treatment effects on total and shoot biomass, primarily due to differences in competition and light, less to AMF. However, effects were the opposite of predictions. Putatively mycorrhizal plants showed neutral to negative responses to AMF, and a nonmycorrhizal species outcompeted AMF species in infected pots. We concluded that our experimental setup of small pots, sandy soil, and long growing period had induced parasitism by the AMF on susceptible hosts. This unexpected result is consistent with field data from the sand savanna, and may help explain how nonmycorrhizal plants can compete successfully with AMF species in established, species-rich communities.

  19. Local versus landscape-scale effects of savanna trees on grasses

    Science.gov (United States)

    Riginos, C.; Grace, J.B.; Augustine, D.J.; Young, T.P.

    2009-01-01

    1. Savanna ecosystems - defined by the coexistence of trees and grasses - cover more than one-fifth the world's land surface and harbour most of the world's rangelands, livestock and large mammal diversity. Savanna trees can have a variety of effects on grasses, with consequences for the wild and domestic herbivores that depend on them. 2.Studies of these effects have focused on two different spatial scales. At the scale of individual trees, many studies have shown net positive effects of trees on sub-canopy grass nutrient concentrations and biomass. At the landscape scale, other studies have shown negative effects of high tree densities on grass productivity. These disparate results have led to different conclusions about the effects of trees on forage quality and ungulate nutrition in savannas. 3.We integrate these approaches by examining the effects of trees on grasses at both spatial scales and across a range of landscape-scale tree densities. 4.We quantified grass biomass, species composition and nutrient concentrations in these different contexts in an Acacia drepanolobium savanna in Laikipia, Kenya. Individual trees had positive effects on grass biomass, most likely because trees enrich soil nitrogen. Grass leaf phosphorus in sub-canopy areas, however, was depressed. The effects of individual trees could explain the effects of increasing landscape-scale tree cover for the biomass of only two of the four dominant grass species. 5.The negative effects of trees on grass and soil phosphorus, combined with depressed grass productivity in areas of high tree cover, suggest that ungulate nutrition may be compromised in areas with many trees. 6.Synthesis. We conclude that few, isolated trees may have positive local effects on savanna grasses and forage, but in areas of high tree density the negative landscape-scale effects of trees are likely to outweigh these positive effects. In savannas and other patchy landscapes, attempts to predict the consequences of changes

  20. Woodland in Practical Skills Therapeutic Education

    Science.gov (United States)

    Mata, Paula; Gibons, Kenneth; Mata, Fernando

    2016-01-01

    Modern urban life provides less opportunities to contact with nature, which is a potential cause of developmental deviances in children. We investigated the potential therapeutic effect of woodlands, within the context of Practical Skills Therapeutic Education at the Ruskin Mill College, UK. Data on physical and emotional perceptions were…

  1. Alien plant invasions in European woodlands

    NARCIS (Netherlands)

    Wagner, Viktoria; Chytrý, Milan; Jiménez-Alfaro, Borja; Pergl, Jan; Hennekens, Stephan; Biurrun, Idoia; Knollová, Ilona; Berg, Christian; Vassilev, Kiril; Rodwell, John S.; Škvorc, Željko; Jandt, Ute; Ewald, Jörg; Jansen, Florian; Tsiripidis, Ioannis; Botta-Dukát, Zoltán; Casella, Laura; Attorre, Fabio; Rašomavičius, Valerijus; Ćušterevska, Renata; Schaminée, Joop H.J.; Brunet, Jörg; Lenoir, Jonathan; Svenning, Jens Christian; Kącki, Zygmunt; Petrášová-Šibíková, Mária; Šilc, Urban; García-Mijangos, Itziar; Campos, Juan Antonio; Fernández-González, Federico; Wohlgemuth, Thomas; Onyshchenko, Viktor; Pyšek, Petr

    2017-01-01

    Aim: Woodlands make up a third of European territory and carry out important ecosystem functions, yet a comprehensive overview of their invasion by alien plants has never been undertaken across this continent. Location: Europe. Methods: We extracted data from 251,740 vegetation plots stored in the

  2. Thermoregulatory capabilities of the woodland dormouse ...

    African Journals Online (AJOL)

    The woodland dormouse, Graphiurus murinus, in common with many other small rodents, enters torpor under conditions of food deprivation and low temperatures. Its thermoregulatory capabilities under more favourable conditions, however, have not been investigated. We measured metabolism and thermoregulation in ...

  3. 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

  4. 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

  5. Prediction and scale in savanna ecosystems.

    Science.gov (United States)

    Staver, A Carla

    2017-10-13

    Contents I. II. III. IV. V. VI. References SUMMARY: Savannas are highly variable systems, and predicting variation, especially in the tree layer, represents a major unresolved challenge for forecasting biosphere responses to global change. Prediction to date has focused on disentangling interactions between resource limitation and chronic disturbances to identify what determines local savanna vegetation heterogeneity. By focusing at too fine a scale, this approach overlooks: sample size limitation arising from sparse tree distributions; stochasticity in demographic and environmental processes that is preserved as heterogeneity among tree populations with slow dynamics; and spatial self-organization. Renewed focus on large (1-50 ha) permanent plots and on spatial patterns of tree-layer variability at even larger landscape spatial scales (≥1000s of ha) promises to resolve these limitations, consistent with the goal of predicting large-scale biosphere responses to global change. © 2017 The Author. New Phytologist © 2017 New Phytologist Trust.

  6. 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.

  7. Macrofauna invertebrada do solo em sistema integrado de produção agropecuária no Cerrado = Soil invertebrate macrofauna in an integrated livestock production system in the Brazilian savanna

    Directory of Open Access Journals (Sweden)

    Rogério Ferreira da Silva

    2008-12-01

    Full Text Available O trabalho teve como objetivo avaliar a densidade e diversidade da macrofauna invertebrada do solo de um sistema de produção envolvendo a rotação lavoura e pecuária, sob plantio direto. O trabalho foi conduzido no Município de Dourados, Estado do Mato Grosso do Sul, num LATOSSOLO VERMELHO Distroférrico típico, em parcelas commonocultivo e preparo convencional do solo, sistema integrado lavoura/pecuária em plantio direto e pastagem contínua, e um fragmento de vegetação nativa. As avaliações foram realizadas em quatro épocas distintas: janeiro/2002, junho/2002, janeiro/2003 e julho/2003, conforme o método recomendado pelo programa “Tropical Soil Biology and Fertility” (TSBF. Os sistemas com menor interferência antrópica apresentaram maior abundância e riqueza da comunidade da macrofauna invertebrada do solo.The objective of this work was to evaluate the density and diversity of soil invertebrate macrofauna in a crop-livestock rotation production system under no-tillage. The field experiment was performed in Dourados, Mato Grosso do Sul State, Brazil, on a Typic Hapludox soil, in parcels under a conventional monoculturesystem, a crop-livestock rotation system under no-tillage and continuous pasture, and a native vegetation fragment. The evaluations were conducted in January 2002, June 2002, January 2003 and July 2003, according to the method recommended by the Tropical SoilBiology and Fertility (TSBF program. Systems with less anthropic interference showed greater abundance and richness of soil invertebrate macrofauna.

  8. Methane uptake by a selection of soils in Ghana with different land use

    DEFF Research Database (Denmark)

    Priemé, Anders; Christensen, Søren

    1999-01-01

    We measured the oxidation of atmospheric methane in tropical soils in Ghana covering a moisture gradient from the moist forest zone to the savanna zone at the onset of the rainy season. Land use at the sites covered undisturbed (forest and savanna) and cultivated soil, including burning. Generally......, the methane oxidation rates in the tropical forest and savanna soils were low (range from 9 to 26 µg CH4 m-2 h-1) compared to, for example temperate forest soils. In the savanna soil, annual fire had decreased soil methane oxidation rates to 5 µg CH4 m-2 h-1 compared to 9 µg CH4 m-2 h-1 at a site...... h-1 after the rain. These rates are comparable to other reports from arable soils in tropical and temperate regions. Thus arable agriculture and, to a lesser extent, biomass burning decreased methane oxidation rates by the investigated soils....

  9. Understanding plant-to-plant interactions for soil resources in multilayered Iberian dehesas

    Science.gov (United States)

    Moreno, G.; Rolo, V.; Cubera, E.; López-Díaz, L.

    2009-04-01

    Iberian dehesa is usually defined as two-layered silvopastoral system, where native grasses cohabit with a scattered widely-space tree layer. In the last two decades, an intense debate has been developed on the sustainability of this simplified type of dehesa. While some authors argue that that the forest cycle has been disrupted in most dehesas, where the lack of regeneration is an inherent problem to their exploitation, other authors have showed that dehesa degradation is easily reversible if certain abandonment is periodically exerted. The coexistence of two-layered plots with multilayered plots (encroached open woodlands) and mono-layered plots (either closed forest or mono-pasture/monocrops) has been a common feature of dehesas, as result of a systematic combination of agricultural, pastoral, and forestry uses. Different structures of vegetation depend on land use, giving a mosaic at both estate and landscape scales. These mosaic-type systems allow finding several scenarios of plant-to-plant interactions, mostly at belowground level. A key issue for sustainable management of oak woodland is to understand the complexity of the plant-to-plant relationships and their consequences in the ecosystem functioning in terms of productivity and stability. The competitive abilities of component systems are modified by the environment conditions. Dehesas, as most savanna systems, exhibit a low rainfall with high variability within and between years as well as a high evaporative demand during the summer. Indeed, water availability is one of the major ecological factors influencing either natural savannas or man-made open woodlands. Although most of the available studies have focused different aspects of the mature tree-grass interactions, we also present here some recent results on tree-tree, tree-shrub, shrub-seedling and seedling-grass interactions, explained mostly in terms of competition for soil water and nutrients. Trees can modify the soil and microclimate

  10. Response of carbon fluxes to water relations in a savanna ecosystem in South Africa

    Directory of Open Access Journals (Sweden)

    W. L. Kutsch

    2008-12-01

    Full Text Available The principal mechanisms that connect carbon fluxes with water relations in savanna ecosystems were studied by using eddy covariance method in a savanna ecosystem at Kruger National Park, South Africa. Since the annual drought and rewetting cycle is a major factor influencing the function of savanna ecosystems, this work focused on the close inter-connection between water relations and carbon fluxes. Data from a nine-month measuring campaign lasting from the early wet season to the late dry season were used.

    Total ecosystem respiration showed highest values at the onset of the growing season, a slightly lower plateau during the main part of the growing season and a continuous decrease during the transition towards the dry season.

    The regulation of canopy conductance was changed in two ways: changes due to phenology during the course of the growing season and short-term acclimation to soil water conditions.

    The most constant parameter was water use efficiency that was influenced by VPD during the day but the VPD response curve of water usage did change only slightly during the course of the growing season and decreased by about 30% during the transition from wet to dry season.

    The regulation of canopy conductance and photosynthetic capacity were closely related. This observation meets recent leaf-level findings that stomatal closure triggers down-regulation of Rubisco during drought. Our results may show the effects of these processes on the ecosystem scale.

  11. Influence of competition and rainfall manipulation on the growth responses of savanna trees and grasses.

    Science.gov (United States)

    February, Edmund C; Higgins, Steven I; Bond, William J; Swemmer, Louise

    2013-05-01

    In this study, we explored how rainfall manipulation influenced competitive interactions between grasses and juvenile trees (small nonreproductive trees capable of resprouting) in savanna. To do this, we manipulated rainfall amount in the field using an incomplete factorial experiment that determined the effects of rainfall reduction, no manipulation, rainfall addition, and competition between grasses and trees on grass and tree growth. As response variables, we focused on several measures of tree growth and Disc Pasture Meter settling height as an estimate of grass aboveground biomass. We conducted the study over four years, at two sites in the Kruger National Park, South Africa. Our results show that rainfall manipulation did not have substantial effects on any of the measures of tree growth we considered. However, trees at plots where grasses had been removed grew on average 15 cm more in height and 1.3-1.7 times more in basal area per year than those in plots with grasses. Grass biomass was not influenced by the presence of trees but was significantly and positively influenced by rainfall addition. These findings were not fundamentally influenced by soil type or by prevailing precipitation, suggesting applicability of our results to a wide range of savannas. Our results suggest that, in savannas, increasing rainfall serves to increase the competitive pressure exerted by grasses on trees. The implication is that recruitment into the adult tree stage from the juvenile stage is most likely in drought years when there is little competition from grass for resources and grass fuel loads are low.

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

    African Journals Online (AJOL)

    Modelling annual evapotranspiration in a semi-arid, African savanna: functional convergence theory, MODIS LAI and the Penman–Monteith equation. ... and, when used independently of the eddy covariance data, ETMODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.

  13. Water economy of neotropical savanna trees: six paradigms revisited.

    Science.gov (United States)

    Guillermo Goldstein; Fredrick C. Meinzer; Sandra J. Bucci

    2008-01-01

    Biologists have long been puzzled by the striking morphological and anatomical characteristics of Neotropical savanna trees which have large scleromorphic leaves, allocate more than half of their total biomass to belowground structures and produce new leaves during the peak of the dry season. Based on results of ongoing interdisciplinary projects in the savannas of...

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

    NARCIS (Netherlands)

    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

  15. 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

  16. 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...

  17. Fragmentation patterns of evergreen oak woodlands in Southwestern Iberia

    DEFF Research Database (Denmark)

    Costa, A.; Madeira, M.; Lima Santos, J.

    2014-01-01

    Mediterranean evergreen oak woodlands (composed of Quercus suber L. and Quercus rotundifolia Lam.) are becoming increasingly fragmented in the human-modified landscapes of Southwestern Portugal and Spain. Previous studies have largely neglected to assess the spatial changes of oak woodlands...... in relation to their surrounding landscape matrix, and to characterize and quantify woodland boundaries and edges. The present study aims to fill this gap by analyzing fragmentation patterns of oak woodlands over a 50-year period (1958-2007) in three landscapes. Using archived aerial imagery from 1958, 1995...... and 2007, for two consecutive periods (1958-1995 and 1995-2007), we calculated a set of landscape metrics to compare woodland fragmentation over time. Our results indicated a continuous woodland fragmentation characterized by their edge dynamics. From 1958 to 2007, the replacement of open farmland...

  18. The influence of arbuscular mycorrhizae and light on Wisconsin (USA) sand savanna understories 1. Plant community composition.

    Science.gov (United States)

    Landis, Frank C; Gargas, Andrea; Givnish, Thomas J

    2005-11-01

    To explain the complex community composition found in Wisconsin (USA) oak savannas, we investigated potentially interacting effects of light gradients and arbuscular mycorrhizal fungi (AMF) on community composition in the greenhouse, using a fully randomized block experimental design. We used plant species, soil, and AMF from a remnant sand savanna in setting up the experiment, using two light and five AMF treatments. Eleven plant species were seeded into 80 microcosms, and they were grown together for 20 weeks. Plant numbers and biomass were measured, and Simpson's index was calculated for both. Data were analyzed using ANOVA and nonparametric ANOVA. We found significant light effects on biomass and on numbers of four species. There were no treatment effects on Simpson's index, and only Schizachyrium numbers showed a significant AMF effect. These findings are consistent with results from other studies of the sand savanna, and, collectively, these data suggest that plant community composition in this species-rich savanna is not strongly influenced by arbuscular mycorrhizae. This is a novel finding with important implications for understanding interactions between plant and AMF diversity in wild communities.

  19. How does fire intensity and frequency affect miombo woodland tree populations and biomass?

    Science.gov (United States)

    Ryan, Casey M; Williams, Mathew

    2011-01-01

    Miombo woodlands are the largest savanna in the world and dominate southern Africa. They are strongly influenced by anthropogenic fires and support the livelihoods of over 100 million people. Managing the fire regime of these flammable systems is difficult, but crucial for sustaining biodiversity, ecosystem services, and carbon stocks. Fire intensity is more easily manipulated than fire frequency, because suppression is expensive and ineffective. However, there are important issues relating fire intensity to impacts on woody vegetation that need to be understood to inform management approaches. Such impacts include the links between fire intensity, tree top-kill, resprouting, and regrowth rates. Here we present results from a fire experiment in Mozambican miombo; the results of a 50-year fire experiment in Zimbabwean miombo; and observations of forest structure at a dry-forest site in Mozambique. We synthesize these data with a process-based gap model of stem growth, regeneration, and mortality; this model explicitly considers the effect of different frequencies and intensities of fire. We use the model, tested against the field data, to explore the sensitivity of woodland tree populations and biomass to fire intensity and frequency. The fire experiments show that large (> 5 cm dbh) stems are vulnerable to fire, with top-kill rates of up to 12% in intense fires. In contrast to idealized physical representations of tree mortality, stems of > 10 cm dbh did not gain further protection from fire with increasing dbh. Resprouting was very common and not obviously linked to fire intensity. The modeling showed that miombo tree populations and biomass are very sensitive to fire intensity, offering opportunities for effective management. At any achievable fire return interval (biomass. Model predictions and field experiments show that no tree biomass can be sustained under annual fires.

  20. 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

    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. 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). 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 further development and application of spatially explicit time series

  1. Beyond precipitation: physiographic gradients dictate the relative importance of environmental drivers on Savanna vegetation.

    Directory of Open Access Journals (Sweden)

    Miguel A Campo-Bescós

    Full Text Available 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

  2. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species.

    Directory of Open Access Journals (Sweden)

    Eduardo R M Barbosa

    Full Text Available Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use. Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall and nutrient availability (no fertilisation vs. fertilisation affects seedlings' above-ground biomass production and leaf-nutrient concentrations (N, P and K of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf

  3. Short-term effect of nutrient availability and rainfall distribution on biomass production and leaf nutrient content of savanna tree species.

    Science.gov (United States)

    Barbosa, Eduardo R M; Tomlinson, Kyle W; Carvalheiro, Luísa G; Kirkman, Kevin; de Bie, Steven; Prins, Herbert H T; van Langevelde, Frank

    2014-01-01

    Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation vs. fertilisation) affects seedlings' above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broad-leafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly. Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes in leaf nutrient concentration

  4. Phosphate-induced cadmium adsorption in a tropical savannah soil ...

    African Journals Online (AJOL)

    The influence of phosphate (P) on cadmium (Cd) adsorption was examined in a savanna soil with long history of different fertilizer amendment. The soil was incubated with P at 0, 250 and 500 mg P kg-1 soil and left to equilibrate for 2 weeks. Cd was added to the P-incubated soil at concentrations ranging from 27, 49 and ...

  5. Soils

    Science.gov (United States)

    Emily Moghaddas; Ken Hubbert

    2014-01-01

    When managing for resilient forests, each soil’s inherent capacity to resist and recover from changes in soil function should be evaluated relative to the anticipated extent and duration of soil disturbance. Application of several key principles will help ensure healthy, resilient soils: (1) minimize physical disturbance using guidelines tailored to specific soil types...

  6. The effects of soil conditions and grazing strategy on plant species ...

    African Journals Online (AJOL)

    The tree:grass ratio of savannas is important, especially in the semi-arid savannas of South Africa. An increase in tree cover leads to reduced productivity and profitability of rangelands. We investigated the effects of soil type and grazing strategy on the presence and distribution of plant species in the Kimberley Triangle ...

  7. Relationships of pinon juniper woodland expansion and climate trends in the Walker Basin, Nevada

    Science.gov (United States)

    Donald, Jonathon

    Landscapes are in constant flux. Vegetation distributions have changed in conjunction with climate, driven by factors such as Milankovitch cycles and atmospheric composition. Until recently, these changes have occurred gradually. Human populations are altering Earth's systems, including atmospheric composition and land use. This is altering vegetation distributions at landscape scales due to changes in species potential niche, as well as current and historical alteration of their realized niche. Vegetation shifts have the potential to be more pronounced in arid and mountainous environments as resources available to plants such as soil moisture are more limiting. In the Great Basin physiographic region of the western United States, woody encroachment of pinon juniper (Pinus monophylla & Juniperus osteosperma) woodlands is well known, but the drivers of its expansion are not well understood across elevational gradients. Predominant theories of future vegetation distribution change due to a changing climate, predict that montane species will move upslope in response to increasing temperatures. In pinon juniper woodlands, the focus has been on downslope movement of woodlands into other ecosystem types. The drivers for this are typically thought to be historical land uses such as grazing and fire exclusion. However, infilling and establishment is occurring throughout its distribution and relatively little attention has been paid to woodland movement uphill. This study focuses on two mountain ranges within the Walker Lake Basin, so as to understand changes occurring along the full gradient of pinon juniper woodlands, from lower to upper treeline, on both the western and eastern side of the ranges. The overall goal of this study was to understand trends of change (increasing, decreasing canopy density) in pinon juniper woodlands and determine if these trends were related to climate change trends. Trends in both vegetation and climate were analyzed for the entire

  8. Biodiversity of Soil Microbial Communities Following Woody Plant Invasion of Grassland: An Assessment Using Molecular Methods

    Science.gov (United States)

    Kantola, I. B.; Gentry, T. J.; Filley, T. R.; Boutton, T. W.

    2012-12-01

    Woody plants have encroached into grasslands, savannas, and other grass-dominated ecosystems throughout the world during the last century. This dramatic vegetation change is likely driven by livestock grazing, altered fire frequencies, elevated atmospheric CO2 concentrations, and/or changes in atmospheric deposition patterns. Woody invasion often results in significant changes in ecosystem function, including alterations in above- and belowground primary productivity, soil C, N, and P storage and turnover, and the size and activity of the soil microbial biomass pool. The purpose of this study was to examine the relationships and interactions between plant communities and soil microbial communities in the Rio Grande Plains region of southern Texas where grasslands have been largely replaced by woodlands. Research was conducted along a successional chronosequence representing the stages of woody plant encroachment from open grassland to closed-canopy woodland. To characterize soil microbial community composition, soil samples (0-7.5 cm) were collected in remnant grasslands (representing time 0) and near the centers of woody plant clusters, groves, and drainage woodlands ranging in age from 10 to 130 yrs. Ages of woody plant stands were determined by dendrochronology. Community DNA was extracted from each soil sample with a MoBio PowerMax Soil DNA isolation kit. The DNA concentrations were quantified on a NanoDrop ND-1000 spectrophotometer and diluted to a standard concentration. Pyrosequencing was performed by the Research and Testing Laboratory (Lubbock, TX) according to Roche 454 Titanium chemistry protocols. Samples were amplified with primers 27F and 519R for bacteria, and primers ITS1F and ITS4 for fungi. Sequences were aligned using BioEdit and the RDP Pipeline and analyzed in MOTHUR. Non-metric multidimensional scaling of the operational taxonomic units identified by pyrosequencing revealed that both bacterial and fungal community composition were

  9. 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

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

    Science.gov (United States)

    Whitley, Rhys; Beringer, Jason; Hutley, Lindsay B.; Abramowitz, Gabriel; De Kauwe, Martin G.; Evans, Bradley; Haverd, Vanessa; Li, Longhui; Moore, Caitlin; Ryu, Youngryel; Scheiter, Simon; Schymanski, Stanislaus J.; Smith, Benjamin; Wang, Ying-Ping; Williams, Mathew; Yu, Qiang

    2017-10-01

    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 benchmarking and

  11. the Role of Species, Structure, and Biochemical Traits in the Spatial Distribution of a Woodland Community

    Science.gov (United States)

    Adeline, K.; Ustin, S.; Roth, K. L.; Huesca Martinez, M.; Schaaf, C.; Baldocchi, D. D.; Gastellu-Etchegorry, J. P.

    2015-12-01

    The assessment of canopy biochemical diversity is critical for monitoring ecological and physiological functioning and for mapping vegetation change dynamics in relation to environmental resources. For example in oak woodland savannas, these dynamics are mainly driven by water constraints. Inversion using radiative transfer theory is one method for estimating canopy biochemistry. However, this approach generally only considers relatively simple scenarios to model the canopy due to the difficulty in encompassing stand heterogeneity with spatial and temporal consistency. In this research, we compared 3 modeling strategies for estimating canopy biochemistry variables (i.e. chlorophyll, carotenoids, water, dry matter) by coupling of the PROSPECT (leaf level) and DART (canopy level) models : i) a simple forest representation made of ellipsoid trees, and two representations taking into account the tree species and structural composition, and the landscape spatial pattern, using (ii) geometric tree crown shapes and iii) detailed tree crown and wood structure retrieved from terrestrial lidar acquisitions. AVIRIS 18m remote sensing data are up-scaled to simulate HyspIRI 30m images. Both spatial resolutions are validated by measurements acquired during 2013-2014 field campaigns (cover/tree inventory, LAI, leaf sampling, optical measures). The results outline the trade-off between accurate and abstract canopy modeling for inversion purposes and may provide perspectives to assess the impact of the California drought with multi-temporal monitoring of canopy biochemistry traits.

  12. 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.

  13. 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 CO2 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 CO2, 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 CO2 assimilation leading to higher GPP. However, CO2 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.

  14. Influencing woodland management using web-based technology

    Science.gov (United States)

    William R. Thomas; Jeffrey W. Stringer

    2011-01-01

    The University of Kentucky, Department of Forestry Extension delivered hosted Web-based forestry educational programs ("webinars") in 2009 to promote woodland management in Kentucky and engage county extension agents in forestry programming. These webinars were hosted by county extension agents and attended by woodland owners. This hosted webinar approach was...

  15. Predicting Polylepis distribution: vulnerable and increasingly important Andean woodlands

    OpenAIRE

    Zutta, Brian R.; Phillip W. Rundel; Sassan Saatchi; Jorge D. Casana; Paul Gauthier Gauthier; Aldo Soto; Yessenia Velazco; Wolfgang Buermann

    2012-01-01

    Polylepis woodlands are a vital resource for preserving biodiversity and hydrological functions, which will be altered by climate change and challenge the sustainability of local human communities. However, these highaltitude Andean ecosystems are becoming increasingly vulnerable due to anthropogenic pressure including fragmentation, deforestation and the increase in livestock. Predicting the distribution of native woodlands has become increasingly important to counteract the negative effects...

  16. Oak woodlands and other hardwood forests of California, 1990s.

    Science.gov (United States)

    K.L. Waddell; T.M. Barrett

    2005-01-01

    This report provides a multiownership assessment of oak woodlands and other hardwood forests in California, excluding only reserved lands outside of national forests. Because sampling intensity on woodlands was doubled from the previous 1981-84 inventory, and because national forests were inventoried, this is the most complete assessment to date for California...

  17. Coarse woody debris in oak woodlands of California.

    Science.gov (United States)

    William D. Tietje; Karen L. Waddell; Justin K. Vreeland; Charles L. Bolsinger

    2002-01-01

    An extensive forest inventory was conducted to estimate the amount and distribution of coarse woody debris (CWD) on 5.6 million ac of woodlands in California that are outside of national forests and reserved areas. Woodlands consist primarily of oak (Quercus spp.) types and are defined as forestland incapable of producing commercial quantities of...

  18. Removal of pinyon-juniper woodlands on the Colorado Plateau

    Science.gov (United States)

    Michael Peters; Neil S. Cobb

    2008-01-01

    (Please note, this is an abstract only) Pinyon-Juniper (PJ) woodland is the 3rd largest vegetation type in the United States, covering 35.5% of the Colorado Plateau, it is the largest vegetation type administered by the Bureau of Land Management (BLM) on the Colorado Plateau. These woodlands have been increasing dramatically in density and extent over the last 100...

  19. Oak woodland conservation management planning in southern CA - lessons learned

    Science.gov (United States)

    Rosi Dagit

    2015-01-01

    The California Oak Woodlands Conservation Act (AB 242 2001) established requirements for the preservation and protection of oak woodlands and trees, and allocated funding managed by the Wildlife Conservation Board. In order to qualify to use these funds, counties and cities need to adopt an oak conservation management plan. Between 2008 and 2011, a team of concerned...

  20. Economic incentives for oak woodland preservation and conservation

    Science.gov (United States)

    Rosi Dagit; Cy Carlberg; Christy Cuba; Thomas Scott

    2015-01-01

    Numerous ordinances and laws recognize the value of oak trees and woodlands, and dictate serious and expensive consequences for removing or harming them. Unfortunately, the methods used to calculate these values are equally numerous and often inconsistent. More important, these ordinances typically lack economic incentives to avoid impacts to oak woodland values...

  1. Silvics and silviculture in the southwestern pinyon-juniper woodlands

    Science.gov (United States)

    Gerald J. Gottfried

    2004-01-01

    Southwestern pinyon-juniper and juniper woodlands cover large areas of the western United States. The woodlands have been viewed as places of beauty and sources of valuable resource products or as weed-dominated landscapes that hinder the production of forage for livestock. They are special places because of the emotions and controversies that encircle their management...

  2. Multi-Sensor Model-Data Assimilation for Improved Modeling of Savanna Carbon and Water Budgets

    Science.gov (United States)

    Barrett, D. J.; Renzullo, L. J.; Guerschman, J.; Hill, M. J.

    2007-12-01

    Model-data assimilation methods are increasingly being used to improve model predictions of carbon pools and fluxes, soil profile moisture contents, and evapotranspiration at catchment to regional scales. In this talk, I will discuss the development of model-data assimilation methods for application to parameter and state estimation problems in the context of savanna carbon and water cycles. A particular focus of this talk will be on the integration of in situ datasets and multiple types of satellite observations with radiative transfer, surface energy balance, and carbon budget models. An example will be drawn from existing work demonstrating regional estimation of soil profile moisture content based on multiple satellite sensors. The data assimilation scheme comprised a forward model, observation operators, multiple observation datasets and an optimization scheme. The forward model propagates model state variables in time based on climate forcing, initial conditions and model parameters and includes processes governing evapotranspiration, water budget and carbon cycle processes. The observation operators calculate modeled land surface temperature and microwave brightness temperatures based on the state variables of profile soil moisture and soil surface layer soil moisture at less than 2.5 cm depth. Satellite observations used in the assimilation scheme are surface brightness temperatures from AMSR-E (passive microwave at 6.9GHz at horizontal polarization) and from AVHRR (thermal channels 4 & 5 from NOAA-18), and land surface reflectances from MODIS Terra (channels 1 and 2 at 250m resolution). These three satellite sensors overpass at approximately the same time of day and provide independent observations of the land surface at different wavelengths. The observed brightness temperatures are used as constraints on the coupled energy balance/microwave radiative transfer model, and a canopy optical model was inverted to retrieve leaf area indices from observed

  3. Effects of breeding habitat (woodland versus urban) and metal pollution on the egg characteristics of great tits (Parus major).

    Science.gov (United States)

    Hargitai, Rita; Nagy, Gergely; Nyiri, Zoltán; Bervoets, Lieven; Eke, Zsuzsanna; Eens, Marcel; Török, János

    2016-02-15

    In an urban environment, birds are exposed to metals, which may accumulate in their tissues and cause oxidative stress. Female birds may eliminate these pollutants through depositing them into eggs, thus eggs become suitable bioindicators of pollution. In this study, we aimed to analyse whether eggshell spotting pattern, egg volume, eggshell thickness and egg yolk antioxidant (lutein, tocopherol, retinol and selenium) levels were related to the breeding area (woodland versus urban) and the metal levels in the eggshell of a small passerine species, the great tit (Parus major). In the urban habitat, soil and eggshells contained higher concentrations of metals, and soil calcium level was also higher than that in the woodland. Eggshell spotting intensity and egg volume did not differ between eggs laid in the woodland and the urban park, and these traits were not related to the metal levels of the eggshell, suggesting that these egg characteristics are not sensitive indicators of metal pollution. A more aggregated eggshell spotting distribution indicated a higher Cu concentration of the eggshell. We found that eggshells were thinner in the less polluted woodland habitat, which is likely due to the limited Ca availability of the woodland area. Great tit eggs laid in the urban environment had lower yolk lutein, retinol and selenium concentrations, however, as a possible compensation for these lower antioxidant levels, urban females deposited more tocopherol into the egg yolk. It appears that females from different breeding habitats may provide similar antioxidant protection for their offspring against oxidative damage by depositing different specific dietary antioxidants. Egg yolk lutein and retinol levels showed a negative relationship with lead concentration of the eggshell, which may suggest that lead had a negative impact on the amount of antioxidants available for embryos during development in great tits. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Flood regime and water table determines tree distribution in a forest-savanna gradient in the Brazilian Pantanal.

    Science.gov (United States)

    Ferreira-Júnior, Walnir G; Schaefer, Carlos E G R; Cunha, Cátia N; Duarte, Temilze G; Chieregatto, Luiz C; Carmo, Flávia M S

    2016-01-01

    This study aimed to recognized the preferential location of species of the tree sinusiae in response to a moisture gradient in Pantanal Matogrossense, Brazil. We established sampling plots of arboreal sinusiae along a soil moisture and flood gradient. Piezometers were installed, allowing monthly measurements of water table depth and flood height during one year. Detrended Correspondence Analysis, Gradient Direct Analysis, Multi-response Permutation Procedures and Indicator Species Analysis were performed to evaluate the effect of moisture gradient on tree distribution. The annual variation of water table is shallower and similar in Seasonally Flooded Forest and Termite Savanna, with increasing depths in Open Savanna, Savanna Forest and Dry Forest. Circa 64% of the species were characterized as having a preferential location in "terrestrial habitats normally not subjected to inundation", while 8% preferentially occur in "wet habitats". Lowest tree richness in flood-affected vegetation types is related to both present-day high climatic seasonality and Late Pleistocene dry paleoclimates in the Pantanal wetland. The tree distribution across different formations in the Pantanal shows a direct relationship with soil moisture gradient.

  5. Status of woodland caribou in Alberta

    Directory of Open Access Journals (Sweden)

    J. Edmonds

    1998-03-01

    Full Text Available A recent review of woodland caribou {Rangifer tarandus caribou status in Alberta estimated that there are between 3600 and 6700 caribou occupying 113 000 km2 of habitat. There are two ecotypes of caribou in Alberta; the mountain ecotype in the west central region and the boreal ecotype primarily in the north. Mountain caribou populations are stable or declining and boreal populations, where data are available, appear to be stable or declining slowly. A major initiative in caribou management in Alberta has been the development of the Woodland Caribou Conservation Strategy. This document was developed over two and a half years by a committee of multi-stakeholder representatives. The past five years has seen an increase in baseline inventory and applied research jointly funded by government, industry and universities, addressing a wide range of management issues from caribou response to logging to interactions of moose, wolves and caribou in the boreal ecosystem. Land use conflicts on caribou range remain high with timber harvesting, oil and gas development, peat moss extraction, coal mining, agricultural expansion and increasing road access overlapping. Cumulative effects of these disturbances are poorly understood and have received little attention to date.

  6. Humans and elephants as treefall drivers in African savannas

    CSIR Research Space (South Africa)

    Mograbi, PJ

    2017-01-01

    Full Text Available elephant Loxodonta africana alter woody vegetation in savannas through removal of large trees and activities that may increase shrub cover. Interactive effects of both humans and elephants with fire may also alter vegetation structure and composition. Here...

  7. Savanna woody vegetation classification – now in 3-D

    CSIR Research Space (South Africa)

    Fisher, JT

    2013-05-01

    Full Text Available The co-existence of woody plants and grasses characterize savannas, with the horizontal and vertical spatial arrangement of trees creating a heterogeneous biotic environment. To understand the influence of biogeophysical drivers on the spatial...

  8. 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.

  9. Lidar remote sensing of savanna biophysical attributes

    Science.gov (United States)

    Gwenzi, David

    Although savanna ecosystems cover approximately 20 % of the terrestrial land surface and can have productivity equal to some closed forests, their role in the global carbon cycle is poorly understood. This study explored the applicability of a past spaceborne Lidar mission and the potential of future missions to estimate canopy height and carbon storage in these biomes. The research used data from two Oak savannas in California, USA: the Tejon Ranch Conservancy in Kern County and the Tonzi Ranch in Santa Clara County. In the first paper we used non-parametric regression techniques to estimate canopy height from waveform parameters derived from the Ice Cloud and land Elevation Satellite's Geoscience Laser Altimeter System (ICESat-GLAS) data. Merely adopting the methods derived for forests did not produce adequate results but the modeling was significantly improved by incorporating canopy cover information and interaction terms to address the high structural heterogeneity inherent to savannas. Paper 2 explored the relationship between canopy height and aboveground biomass. To accomplish this we developed generalized models using the classical least squares regression modeling approach to relate canopy height to above ground woody biomass and then employed Hierarchical Bayesian Analysis (HBA) to explore the implications of using generalized instead of species composition-specific models. Models that incorporated canopy cover proxies performed better than those that did not. Although the model parameters indicated interspecific variability, the distribution of the posterior densities of the differences between composition level and global level parameter values showed a high support for the use of global parameters, suggesting that these canopy height-biomass models are universally (large scale) applicable. As the spatial coverage of spaceborne lidar will remain limited for the immediate future, our objective in paper 3 was to explore the best means of extrapolating

  10. Carbon stocks, greenhouse gas emissions and water balance of Sudanese savannah woodlands in relation to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Alam, S. A.

    2013-06-01

    Understanding the carbon (C) sequestration potential of drylands requires knowledge of the stocks of C in soils and biomass and on the factors affecting them. The overall aim of the study was to determine and evaluate the variation in the C stocks and water balance of Acacia savannah woodlands across the dryland (arid and semi-arid) region (10-16 deg N; 21-36 deg E) of the former Sudan (now mainly in the Republic of the Sudan) and how they are related to climatic factors and may be affected by climate change. The role played by small but numerous brick making industries on woodland deforestation in the region and greenhouse gas production was also investigated. The study region is often referred to as the gum belt because it is the world's major source of gum Arabic, which is harvested from Acacia trees. The soils in the centre and west of the region are mainly Arenosols (sandy soils) and those in the eastern part are mainly Vertisols (clay soils). The soils are C poor and often in a degraded state. This dissertation consists of a summary section and four articles (Study I, II, III and IV). Study I focuses on fuelwood consumption by the brick making industries (BMIs) and associated deforestation and greenhouse gas (GHG) emissions. In Study II the C densities (g C m-2) of the woodland tree biomass and soil (1 m) for 39 map sheets covering the study region were determined from national forest inventory data and global soil databases and the dependence on mean annual precipitation (MAP) and mean annual temperature (MAT) determined. The water balance of savannah woodlands for the same 39 map sheets was modelled in Study III and the variation in water balance components across the region evaluated. The potential impacts of climate change on woodland biomass C density and water-use (actual evapotranspiration, AET) was analysed for eight of the map sheets in Study IV. Sudanese BMIs consume a considerable amount of fuelwood that mainly comes from unsustainably managed

  11. Land clearing and greenhouse gas emissions from Jatropha biofuels on African Miombo Woodlands

    Energy Technology Data Exchange (ETDEWEB)

    Romijn, Henny A., E-mail: h.a.romijn@tue.nl [Technology and Development Studies, Faculty of Industrial Engineering and Innovation Sciences, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2011-10-15

    The paper investigates greenhouse gas (GHG) emissions from land use change associated with the introduction of large-scale Jatropha curcas cultivation on Miombo Woodland, using data from extant forestry and ecology studies about this ecosystem. Its results support the notion that Jatropha can help sequester atmospheric carbon when grown on complete wastelands and in severely degraded conditions. Conversely, when introduced on tropical woodlands with substantial biomass and medium/high organic soil carbon content, Jatropha will induce significant emissions that offset any GHG savings from the rest of the biofuel production chain. A carbon debt of more than 30 years is projected. On semi-degraded Miombo the overall GHG balance of Jatropha is found to hinge a lot on the extent of carbon depletion of the soil, more than on the state of the biomass. This finding points to the urgent need for detailed measurements of soil carbon in a range of Miombo sub-regions and similar tropical dryland ecosystems in Asia and Latin America. Efforts should be made to clarify concepts such as 'degraded lands' and 'wastelands' and to refine land allocation criteria and official GHG calculation methodologies for biofuels on that basis.

  12. What lies beneath: detecting sub-canopy changes in savanna woodlands using a three-dimensional classification method

    CSIR Research Space (South Africa)

    Fisher, JT

    2015-07-01

    Full Text Available of Technology, 54 Lomb Memorial Drive, Rochester, New York 14623, USA; 6Remote Sensing Research Unit, Council for Scientific and Industrial Research (CSIR)-Meraka Institute, P.O. Box 395, Pretoria 0001, South Africa; 7Centre for Geoinformation Science..., Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Cnr Lynnwood and University Roads, Hatfield 0083, Pretoria, South Africa; 8Ecosystems Earth Observations, Natural Resources & Environment, Council for Scientific...

  13. Effects of charcoal production on soil biodiversity and soil physical ...

    African Journals Online (AJOL)

    ... radius around the kilns in Sudanian or Guinean savanna areas while this radius is 5 m in Semi-deciduous forest. The soil fauna assessment permitted to record 81 micro-organisms belonging essentially to the Beetles, Hymenoptera, Heteroptera, Diptera, Orthoptera, Myriapods, Homoptera, Acarians, Nematodes, Isoptera, ...

  14. 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.

  15. The genome of woodland strawberry (Fragaria vesca).

    Science.gov (United States)

    Shulaev, Vladimir; Sargent, Daniel J; Crowhurst, Ross N; Mockler, Todd C; Folkerts, Otto; Delcher, Arthur L; Jaiswal, Pankaj; Mockaitis, Keithanne; Liston, Aaron; Mane, Shrinivasrao P; Burns, Paul; Davis, Thomas M; Slovin, Janet P; Bassil, Nahla; Hellens, Roger P; Evans, Clive; Harkins, Tim; Kodira, Chinnappa; Desany, Brian; Crasta, Oswald R; Jensen, Roderick V; Allan, Andrew C; Michael, Todd P; Setubal, Joao Carlos; Celton, Jean-Marc; Rees, D Jasper G; Williams, Kelly P; Holt, Sarah H; Ruiz Rojas, Juan Jairo; Chatterjee, Mithu; Liu, Bo; Silva, Herman; Meisel, Lee; Adato, Avital; Filichkin, Sergei A; Troggio, Michela; Viola, Roberto; Ashman, Tia-Lynn; Wang, Hao; Dharmawardhana, Palitha; Elser, Justin; Raja, Rajani; Priest, Henry D; Bryant, Douglas W; Fox, Samuel E; Givan, Scott A; Wilhelm, Larry J; Naithani, Sushma; Christoffels, Alan; Salama, David Y; Carter, Jade; Lopez Girona, Elena; Zdepski, Anna; Wang, Wenqin; Kerstetter, Randall A; Schwab, Wilfried; Korban, Schuyler S; Davik, Jahn; Monfort, Amparo; Denoyes-Rothan, Beatrice; Arus, Pere; Mittler, Ron; Flinn, Barry; Aharoni, Asaph; Bennetzen, Jeffrey L; Salzberg, Steven L; Dickerman, Allan W; Velasco, Riccardo; Borodovsky, Mark; Veilleux, Richard E; Folta, Kevin M

    2011-02-01

    The woodland strawberry, Fragaria vesca (2n = 2x = 14), is a versatile experimental plant system. This diminutive herbaceous perennial has a small genome (240 Mb), is amenable to genetic transformation and shares substantial sequence identity with the cultivated strawberry (Fragaria × ananassa) and other economically important rosaceous plants. Here we report the draft F. vesca genome, which was sequenced to ×39 coverage using second-generation technology, assembled de novo and then anchored to the genetic linkage map into seven pseudochromosomes. This diploid strawberry sequence lacks the large genome duplications seen in other rosids. Gene prediction modeling identified 34,809 genes, with most being supported by transcriptome mapping. Genes critical to valuable horticultural traits including flavor, nutritional value and flowering time were identified. Macrosyntenic relationships between Fragaria and Prunus predict a hypothetical ancestral Rosaceae genome that had nine chromosomes. New phylogenetic analysis of 154 protein-coding genes suggests that assignment of Populus to Malvidae, rather than Fabidae, is warranted.

  16. Evaluation of the soil organic carbon, nitrogen and available ...

    African Journals Online (AJOL)

    The upland soils of the Nigerian savanna zones are low in fertility and their agricultural potentials for sustainable crops and livestock production is low. The surface soils of the area are sandy loam dominated by low activity clay and low content of organic matter. The soils are also shallow in nature and they have higher ...

  17. The Woodlands: Una forma diferente de gobernar

    Directory of Open Access Journals (Sweden)

    Raquel Insa-Ciriza

    2010-06-01

    Full Text Available The Woodlands (Texas es uno de los mejores ejemplos de éxito de los partenariados público-privados entre el Departamento de Urbanismo y Vivienda Americano (Department of Housing and Urban Development, US - HUD y la empresa privada. The Woodlands, que fue creada como una «Nueva Ciudad» por la compañía Mitchell Energy & Development Corporation, ha ido creciendo y creando una masa crítica de residentes, trabajadores, su propio sentido de comunidad y lo más importante, su propia forma de gobierno. Es el único caso en Estados Unidos de ciudad gobernada por asociaciones privadas. Estas asociaciones, representadas por un Consejo de Administración, proveen la mayoría de los servicios públicos a los ciudadanos. En este artículo se muestra lo que llamo «complicidad ciudadana» basada en lo que el Nuevo Servicio Público define como gobierno basado en la comunidad. Ellos no están reinventando ninguna clase de gobierno, lo que están haciendo es crear una nueva forma de gobierno en la que los ciudadanos prefieren tomar el mando que servir. El estudio del caso que muestro nos ayuda a entender cómo una mayor participación de los ciudadanos en las tareas de la administración local puede hacer disminuir visiblemente el poder del promotor en el desarrollo de una Nueva Ciudad. Esta complicidad ciudadana se traduce en términos de implicación de los miembros de la comunidad en el crecimiento y en el Gobierno de la ciudad

  18. Stand biomass and volume estimation for Miombo woodlands at ...

    African Journals Online (AJOL)

    , Tanzania ignored small branches and small trees. Consequently, this study was carried out to develop new individual tree volume and biomass equations, and assess current regeneration status, biodiversity and yield of miombo woodlands ...

  19. Plant establishment and soil microenvironments in Utah juniper masticated woodlands

    Science.gov (United States)

    Kert R. Young

    2012-01-01

    Juniper (Juniperus spp.) encroachment into sagebrush (Artemisia spp.) and bunchgrass communities has reduced understory plant cover and allowed juniper trees to dominate millions of hectares of semiarid rangelands. Trees are mechanically masticated or shredded to decrease wildfire potential and increase desirable understory plant cover. When trees are masticated after...

  20. Seasonal variations in phosphorus fractions in semiarid sandy soils under different vegetation types

    Science.gov (United States)

    Qiong Zhao; Dehui Zeng; Zhiping Fan; Zhanyuan Yu; Yalin Hu; Jianwei Zhang

    2009-01-01

    We investigated the seasonal patterns of soil phosphorus (P) fractions under five vegetation types – Ulmus macrocarpa savanna, grassland, Pinus sylvestris var. mongolica plantation, Pinus tabulaeformis plantation, and Populus simonii plantation ...

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

    Science.gov (United States)

    Priyadarshini, K V R; Prins, Herbert H T; de Bie, Steven; Heitkönig, Ignas M A; Woodborne, Stephan; Gort, Gerrit; Kirkman, Kevin; Fry, Brian; de Kroon, Hans

    2014-04-01

    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 (15)N tracer additions to investigate possible redistribution of N by trees to grasses. Foliar stable N isotope ratio (δ(15)N) values were consistent with trees and grasses using mycorrhiza-supplied N in all seasons except in the wet season when they switched to microbially fixed N. The dependence of trees and grasses on mineralized soil N seemed highly unlikely based on seasonal variation in mineralization rates in the Kruger Park region. Remarkably, foliar δ(15)N values were similar for all three tree species differing in the potential for N fixation through nodulation. The tracer experiment showed that N was redistributed by trees to understory grasses in all seasons. Our results suggest that the redistribution of N from trees to grasses and uptake of N was independent of water redistribution. Although there is overlap of N sources between trees and grasses, dependence on biological sources of N coupled with redistribution of subsoil N by trees may contribute to the coexistence of trees and grasses in semi-arid savannas.

  2. Determinants of woody encroachment and cover in African savannas.

    Science.gov (United States)

    Devine, Aisling P; McDonald, Robbie A; Quaife, Tristan; Maclean, Ilya M D

    2017-04-01

    Savanna ecosystems are an integral part of the African landscape and sustain the livelihoods of millions of people. Woody encroachment in savannas is a widespread phenomenon but its causes are widely debated. We review the extensive literature on woody encroachment to help improve understanding of the possible causes and to highlight where and how future scientific efforts to fully understand these causes should be focused. Rainfall is the most important determinant of maximum woody cover across Africa, but fire and herbivory interact to reduce woody cover below the maximum at many locations. We postulate that woody encroachment is most likely driven by CO 2 enrichment and propose a two-system conceptual framework, whereby mechanisms of woody encroachment differ depending on whether the savanna is a wet or dry system. In dry savannas, the increased water-use efficiency in plants relaxes precipitation-driven constraints and increases woody growth. In wet savannas, the increase of carbon allocation to tree roots results in faster recovery rates after disturbance and a greater likelihood of reaching sexual maturity. Our proposed framework can be tested using a mixture of experimental and earth observational techniques. At a local level, changes in precipitation, burning regimes or herbivory could be driving woody encroachment, but are unlikely to be the explanation of this continent-wide phenomenon.

  3. When is a ‘forest’ a savanna, and why does it matter?

    CSIR Research Space (South Africa)

    Ratnam, J

    2011-09-01

    Full Text Available Savannas are defined based on vegetation structure, the central concept being a discontinuous tree cover in a continuous grass understorey. However, at the high-rainfall end of the tropical savanna biome, where heavily wooded mesic savannas begin...

  4. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

    Directory of Open Access Journals (Sweden)

    Nicholas R Vaughn

    Full Text Available Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

  5. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

    Science.gov (United States)

    Vaughn, Nicholas R; Asner, Gregory P; Smit, Izak P J; Riddel, Edward S

    2015-01-01

    Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

  6. [Community characteristics of Hippophae rhamnoides forest and water and nutrient condition of the woodland in Loess hilly region].

    Science.gov (United States)

    Ruan, Chengjiang; Li, Daiqiong

    2002-09-01

    To improve the productivity of Hippophae rhamnoides forest and to manage the forest reasonably, the community characteristics of Hippophae rhamnoides and the water and nutrient condition of the woodland were analyzed. The results showed that Hippophae rhamnoides grew fast and its adaptability was strong. 4-5 years old Hippophae rhamnoides could form shrubs-grass community. The biomass 1-8 years old Hippophae rhamnoides increased rapidly, but that of 8-11 years old increased more slowly. Hippophae rhamnoides older than 11 years could keep reasonable community structure and higher primary productivity by natural thinning. The utilization of soil moisture by Hippophae rhamnoides could be classified into four layers as faint utilization layer of root system (0-20 cm), utilization of root system (20-300 cm), adjustment layer supplied by soil moisture (300-400 cm), and faint adjustment layer (400-500 cm). Due to the soil improvement by Hippophae rhamnoides and the water retaining by litter, the soil moisture of 1-1.5 m layer could be easy to restore. Hippophae rhamnoides could keep the balance of nutrition in the woodland through the fixation of nitrogen by root nodule and the decomposition of litter. In the 6-9 years old Hippophae rhamnoides plantation, the total nitrogen content of soil might be improved from 0.05-0.1% to 0.2%.

  7. Savanna chimpanzee (Pan troglodytes verus) nesting ecology at Bagnomba (Kedougou, Senegal).

    Science.gov (United States)

    Badji, L; Ndiaye, P I; Lindshield, S M; Ba, C T; Pruetz, J D

    2017-12-27

    We studied the nesting behavior of the critically endangered West African chimpanzee (Pan troglodytes verus). We assumed that the nesting data stemmed from a single, unhabituated community at the Bagnomba hill site in the savanna-woodlands of southeastern Senegal. The aim of this study was to examine chimpanzees' nesting habits in terms of the tree species utilized and sleeping nest heights. We recorded a total of 550 chimpanzee nests at Bagnomba between January 2015 and December 2015. The chimpanzees here made nests in particular tree species more often than others. The majority of nests (63%) were in two tree species: Diospyros mespiliformis and Pterocarpus erinaceus. The average height of nesting trees was 10.54 m (SD 3.91, range, 0.0-29.0 m) and average nest height was 7.90 m (SD 3.62, range, 0.0-25.0 m). The result of a linear regression analysis (r = 0.7874; n = 550; p < 0.05) is consistent with a preference for nesting at a particular height. Bagnomba chimpanzees rarely made ground nests (0.36% of nests), but the presence of any ground nesting was unexpected, given that at least one leopard (Panthera pardus) also occupied the hill. This knowledge will enable stakeholders involved in the protection of chimpanzees specifically and of biodiversity in general to better understand chimpanzee ecology and inform a conservation action plan in Senegal where the survival of this species is threatened.

  8. Land Cover Characterization in West Sudanian Savannas Using Seasonal Features from Annual Landsat Time Series

    Directory of Open Access Journals (Sweden)

    Jinxiu Liu

    2016-04-01

    Full Text Available With the increasing temporal resolution of medium spatial resolution data, seasonal features are becoming more readily available for land cover characterization. However, in the tropical regions, images can be severely contaminated by clouds during the rainy season and fires during the dry season, with possible effects to seasonal features. In this study, we evaluated the performance of seasonal features based on an annual Landsat time series (LTS of 35 images for land cover characterization in West Sudanian savanna woodlands. First, the burnt areas were detected and removed. Second, the reflectance seasonality was modelled using a harmonic model, and model parameters were used as inputs for land cover classification and tree crown cover prediction using the random forest algorithm. Furthermore, to study the sensitivity of the approach to the burnt areas, we repeated the analyses without the first step. Our results showed that seasonal features improved classification accuracy significantly from 68.7% and 66.1% to 76.2%, and decreased root mean square error (RMSE of tree crown cover predictions from 11.7% and 11.4% to 10.4%, in comparison to the dry and rainy season single date images, respectively. The burnt areas biased the seasonal parameters in near-infrared and shortwave infrared bands, and decreased the accuracy of classification and tree crown cover prediction, suggesting that burnt areas should be removed before fitting the harmonic model. We conclude that seasonal features from annual LTS improved land cover characterization performance, and the harmonic model, provided a simple method for computing annual seasonal features with burnt area removal.

  9. Farming Systems of the African Savanna

    International Development Research Centre (IDRC) Digital Library (Canada)

    Alternatively, if the cultivator cannot find more fertile land, the farming practices may be intensified by increasing the use of manures and fertilizers, by growing additional crops on the same land, and practicing simple soil conservation and other techniques that conserve and build up soil fertility. At present, the main ...

  10. The genome of woodland strawberry (Fragaria vesca)

    Science.gov (United States)

    Shulaev, Vladimir; Sargent, Daniel J; Crowhurst, Ross N; Mockler, Todd C; Folkerts, Otto; Delcher, Arthur L; Jaiswal, Pankaj; Mockaitis, Keithanne; Liston, Aaron; Mane, Shrinivasrao P; Burns, Paul; Davis, Thomas M; Slovin, Janet P; Bassil, Nahla; Hellens, Roger P; Evans, Clive; Harkins, Tim; Kodira, Chinnappa; Desany, Brian; Crasta, Oswald R; Jensen, Roderick V; Allan, Andrew C; Michael, Todd P; Setubal, Joao Carlos; Celton, Jean-Marc; Rees, D Jasper G; Williams, Kelly P; Holt, Sarah H; Ruiz Rojas, Juan Jairo; Chatterjee, Mithu; Liu, Bo; Silva, Herman; Meisel, Lee; Adato, Avital; Filichkin, Sergei A; Troggio, Michela; Viola, Roberto; Ashman, Tia-Lynn; Wang, Hao; Dharmawardhana, Palitha; Elser, Justin; Raja, Rajani; Priest, Henry D; Bryant, Douglas W; Fox, Samuel E; Givan, Scott A; Wilhelm, Larry J; Naithani, Sushma; Christoffels, Alan; Salama, David Y; Carter, Jade; Girona, Elena Lopez; Zdepski, Anna; Wang, Wenqin; Kerstetter, Randall A; Schwab, Wilfried; Korban, Schuyler S; Davik, Jahn; Monfort, Amparo; Denoyes-Rothan, Beatrice; Arus, Pere; Mittler, Ron; Flinn, Barry; Aharoni, Asaph; Bennetzen, Jeffrey L; Salzberg, Steven L; Dickerman, Allan W; Velasco, Riccardo; Borodovsky, Mark; Veilleux, Richard E; Folta, Kevin M

    2012-01-01

    The woodland strawberry, Fragaria vesca (2n = 2x = 14), is a versatile experimental plant system. This diminutive herbaceous perennial has a small genome (240 Mb), is amenable to genetic transformation and shares substantial sequence identity with the cultivated strawberry (Fragaria × ananassa) and other economically important rosaceous plants. Here we report the draft F. vesca genome, which was sequenced to ×39 coverage using second-generation technology, assembled de novo and then anchored to the genetic linkage map into seven pseudochromosomes. This diploid strawberry sequence lacks the large genome duplications seen in other rosids. Gene prediction modeling identified 34,809 genes, with most being supported by transcriptome mapping. Genes critical to valuable horticultural traits including flavor, nutritional value and flowering time were identified. Macrosyntenic relationships between Fragaria and Prunus predict a hypothetical ancestral Rosaceae genome that had nine chromosomes. New phylogenetic analysis of 154 protein-coding genes suggests that assignment of Populus to Malvidae, rather than Fabidae, is warranted. PMID:21186353

  11. Status of woodland caribou in Saskatchewan

    Directory of Open Access Journals (Sweden)

    Jim Rettie

    1998-03-01

    Full Text Available Recent research has shown that woodland caribou in Saskatchewan exist as relatively separate populations within a metapopulation. Preliminary analyses show that individuals within all populations are selecting peatland habitat types (i.e., fens and bogs throughout the year. Despite an absence of hunting, populations south of the Precambrian shield appear to be declining slowly, while those on the southern margin of the shield may be declining more rapidly. The apparent population decline is likely due to high rates of predation, especially on neonates. To maintain viable caribou populations in the region, forestry operations must be managed to maintain adequate amounts of preferred habitat types and connections among populations. At a coarse scale, preferred habitat is that which acts as a refuge from predators. Additional information is required to categorize specific peatland types, as data in the existing provincial forest inventory are inadequate for both selection analysis and management purposes. Ongoing research into revisions to the forest inventory and analyses of bog and fen types selected by caribou are needed to focus future management strategies.

  12. Keeping your forest soils healthy and productive.

    Science.gov (United States)

    Ole T. Helgerson; Richard E. Miller

    2008-01-01

    Soils are an integral structural part of your woodland and the larger forest ecosystem. Important forest soil functions include:Providing water, nutrients, and physical support for the growth of trees and other forest plantsAllowing an exchange of carbon dioxide, oxygen, and other gasses that affect root growth and...

  13. Woodland recovery following drought-induced tree mortality across an environmental stress gradient.

    Science.gov (United States)

    Redmond, Miranda D; Cobb, Neil S; Clifford, Michael J; Barger, Nichole N

    2015-10-01

    Recent droughts and increasing temperatures have resulted in extensive tree mortality across the globe. Understanding the environmental controls on tree regeneration following these drought events will allow for better predictions of how these ecosystems may shift under a warmer, drier climate. Within the widely distributed piñon-juniper woodlands of the southwestern USA, a multiyear drought in 2002-2004 resulted in extensive adult piñon mortality and shifted adult woodland composition to a juniper-dominated, more savannah-type ecosystem. Here, we used pre- (1998-2001) and 10-year post- (2014) drought stand structure data of individually mapped trees at 42 sites to assess the effects of this drought on tree regeneration across a gradient of environmental stress. We found declines in piñon juvenile densities since the multiyear drought due to limited new recruitment and high (>50%) juvenile mortality. This is in contrast to juniper juvenile densities, which increased over this time period. Across the landscape, piñon recruitment was positively associated with live adult piñon densities and soil available water capacity, likely due to their respective effects on seed and water availability. Juvenile piñon survival was strongly facilitated by certain types of nurse trees and shrubs. These nurse plants also moderated the effects of environmental stress on piñon survival: Survival of interspace piñon juveniles was positively associated with soil available water capacity, whereas survival of nursed piñon juveniles was negatively associated with perennial grass cover. Thus, nurse plants had a greater facilitative effect on survival at sites with higher soil available water capacity and perennial grass cover. Notably, mean annual climatic water deficit and elevation were not associated with piñon recruitment or survival across the landscape. Our findings reveal a clear shift in successional trajectories toward a more juniper-dominated woodland and highlight the

  14. Soil erosion and sediment yield from the degraded Mzinga River ...

    African Journals Online (AJOL)

    Soil erosion measurements and sediment yield modelling were done to monitor land use practices that contribute to catchment degradation. The results showed very high soil erosion losses on agricultural lands (33 tons/ha) and low soil losses from fallow (4.8 tons/ha) and degraded miombo woodlands (2.4 tons/ha).

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Pinheiro, M H O; Monteiro, R

    2010-02-01

    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.

  17. Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes

    Science.gov (United States)

    Platt, William J.; Orzell, Steve L.; Slocum, Matthew G.

    2015-01-01

    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 timing of

  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. Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

    Science.gov (United States)

    Platt, William J; Orzell, Steve L; Slocum, Matthew G

    2015-01-01

    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 timing of

  20. Under-utilisation of organic wastes during brownfield regeneration to community woodland: tackling the barriers.

    Science.gov (United States)

    Ashwood, Francis E; Doick, Kieron J; Atkinson, Gail E; Chenoweth, Jonathan

    2014-01-01

    The regeneration of brownfield land to greenspace is a governmental policy objective of many European countries. Healthy vegetation establishment and growth is an essential component of successful greenspace establishment, and research has shown that a planting medium of an appropriate standard for supporting vegetation can be created through amendment of soil-forming materials with organic wastes. However, failed regeneration projects suggest that barriers may exist that prevent the use of suitable quality soil materials. The aim of this research was to identify barriers to the use of organic wastes for improving soil materials for brownfield regeneration to community woodland. We conducted interviews with a range of professionals experienced in regeneration to greenspace, and used content analysis on interview transcripts. A diverse set of barriers was revealed, including a low technical awareness among some professional groups of how to improve soil quality, coupled with a low awareness of the published technical guidance. Other barriers include regulatory and project management issues, which influence the timings and economics of raising brownfield soil quality. We highlight areas in which future efforts may be focused to improve the quality of planting media used in land regeneration. Such effort will improve the sustainability of greenspaces created and complement effective management of organic waste streams.

  1. Body weight measurements and correlation relationship in Savanna ...

    African Journals Online (AJOL)

    The aim of this study was to investigate the effect of age at castration, type of birth and sex on body weight, body linear measurements and correlation between body weight and body length, chest length, height-at-withers, facial length and fore and hind leg lengths of semi-intensively managed Savanna Brown goats.

  2. Pasture Distribution In The Derived Savanna Area Of Ogun State ...

    African Journals Online (AJOL)

    A survey was carried out to estimate the distribution of pastures in 30 villages in the derived savanna area of Ogun State. Ten villages were selected in each of Odeda, Abeokuta South and Abeokuta North Local Government Area. Odeda Local Government Area had the highest population of pasture plants (36.3%) followed ...

  3. Quantifying Savanna Woody Cover in the Field and on Historical ...

    African Journals Online (AJOL)

    The proliferation of woody vegetation on open grass savannas constitutes degradation in rangeland quality. Historical high spatial resolution satellite imagery in archive provides possibilities for assessing increase in woody vegetation cover on the rangelands. This paper examines the quantification of woody vegetation in ...

  4. Spatial and temporal variation in a mesic savanna fire regime ...

    African Journals Online (AJOL)

    Umfolozi Park, a mesic savanna area in South Africa. The study focuses at the landscape scale of tens of kilometres and at the medium term temporal scale of decades. Variation in fire regime was analysed in relation to variation in annual rainfall ...

  5. 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.

  6. Bird diversity in the savanna habitats of Akagera National Park ...

    African Journals Online (AJOL)

    ... point counts and presence–absence surveys to estimate bird species richness and diversity in acacia savanna habitats of the park between 2009 and 2011. We recorded a total number of 301 species, of which 75% were resident and 22% migrant, including a large number of Palearctic visitors and Afrotropical migrants.

  7. Responses of savanna lawn and bunch grasses to water limitation

    NARCIS (Netherlands)

    van der Plas, Alfons; Zeinstra, Patricia; Veldhuis, Michiel; Fokkema, Rienk; Tielens, Elske; Howison, Ruth; Olff, Han

    The grass layer of African savannas consists of two main vegetation types: grazing lawns, dominated by short, mostly clonally reproducing grasses, and bunch grasslands, dominated by tall bunch grasses. This patchy distribution of vegetation types is mostly created by large herbivores, which

  8. Survival rates in West African savanna birds | Stevens | Ostrich ...

    African Journals Online (AJOL)

    Despite widespread interest in life histories and the comparison of parameters between tropical and temperate regions, there are still relatively few multispecies studies assessing annual survival in Afrotropical species. We used data from systematic mist-netting of savanna birds in Nigeria, between 2001 and 2008, ...

  9. 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 ...

  10. 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

  11. Seed predation by nocturnal rodents in an African savanna ecosystem

    African Journals Online (AJOL)

    The small mammal community in Acacia savanna consists of three omnivorous nocturnal rodent species, Mastomys natalensis, Saccostomus campestris and Aethomys chrysophilus, which eat varying proportions of seed in their diet. From a seed removal experiment, it was found that rodents preferentially selected Acacia ...

  12. Rate and pattern of bush encroachment in Eastern Cape savanna ...

    African Journals Online (AJOL)

    The rate and pattern of bush encroachment in the grasslands and savannas of the Kei Road-Komga region of the Eastern Cape were quantified by analysis of nine sets of aerial photographs taken between 1937 and 1986. Woody cover increased from 17% to 35% over this period. with most of the increase occurring after ...

  13. 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 ...

  14. Changes in Soil Chemical Properties and Lettuce Yield Response Following Incorporation of Biochar and Cow Dung to Highly Weathered Acidic Soils

    DEFF Research Database (Denmark)

    Agyei Frimpong, Kwame; Amoakwah, Emmanuel; Osei, Benjamin A

    2016-01-01

    imposed on two highly weathered, acidic soils from the coastal savanna and tropical rainforest agroecological zones of Ghana, respectively, to elucidate their effect on yield of lettuce. The study showed that application of biochar solely or in combination with cow dung increased soil pH, total organic...... improve soil chemical properties and lettuce yield if applied solely or in combination with cow dung....

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Woodlands or wastelands: examining the value of South Africa's ...

    African Journals Online (AJOL)

    third of South Africa. They are also home to one-quarter of the population, with 70 % of the former homelands being in the savanna biome. Consequently, they have the potential to make a marked contribution to the national economy, both in the ...

  17. 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. PMID:24066138

  18. Connecting above and below: the impacts of large wildlife loss and pastoralism on savanna carbon dynamics

    Science.gov (United States)

    Forbes, E. S.; Young, H. S.; Young, T.; Schimel, J.

    2016-12-01

    There is widespread evidence that large wildlife species contribute to ecosystem carbon efflux; however, their influence is not incorporated into traditional carbon models. As large wildlife loss continues in the Anthropocene and in the face of climate change, it becomes increasingly important to understand the impacts of their loss on ecosystem carbon. The charismatic, threatened wildlife in central Kenya's savanna provide an ideal framework for these questions. We compared differences in carbon efflux in the presence or absence of native herbivores and/or cattle, as a proxy for wildlife loss and the interaction of pastoralism. We measured carbon dynamics in situ with a closed-chamber system and microbial respiration rates in lab by incubating sampled soil. We discovered a significant effect of herbivore presence/absence on carbon efflux: incubated soils collected from plots with cattle only exhibit greater carbon accumulation and faster initial respiration rates than soils collected from plots with native herbivores and no cattle, native herbivores and cattle, and neither native herbivores nor cattle. When measured in situ, plots with no herbivores show higher efflux than plots with only native herbivores, and plots with both. The data also suggest that grazing pressure results in successively lower efflux. The differences in these studies imply that the impacts of large wildlife loss differ on microbial respiration as an isolated mechanism in ecosystem carbon exchange, and total carbon efflux. This is most likely because in situ efflux measurements encompass environmental variables as well as soil microbial respiration. The lab data suggest that cattle as the only herbivore causes greater soil microbial efflux compared to native herbivores alone, native herbivores with cattle, or no herbivores. The in situ data show that no herbivores results in increased carbon efflux, and suggest that increasing numbers of herbivores lowers efflux.These studies demonstrate

  19. 77 FR 33560 - Eastern Maine Railway Company-Trackage Rights Exemption-Woodland Rail, LLC

    Science.gov (United States)

    2012-06-06

    ... Surface Transportation Board Eastern Maine Railway Company--Trackage Rights Exemption-- Woodland Rail, LLC Pursuant to a written trackage rights agreement dated April 30, 2012, Woodland Rail, LLC (Woodland Rail... a rail line known as the Calais Industrial Track (the Line). The Line is approximately 11.83 track...

  20. Land Cover Change and Woodland Degradation in a Charcoal Producing Semi-Arid Area in Kenya

    NARCIS (Netherlands)

    Kiruki, H.M.; van der Zanden, E.H.; Malek, Z.; Verburg, P.H.

    2016-01-01

    Woodlands in Kenya are undergoing land cover change and degradation leading to loss of livelihoods. Uncontrolled charcoal production, although a livelihood source for communities living in woodland areas of Kenya, leads to woodland degradation. We used Landsat imagery, field plot data and household

  1. Age structure and expansion of pinon-juniper woodlands: a regional perspective in the Intermountain West

    Science.gov (United States)

    Richard F. Miller; Robin J. Tausch; E. Durant McArthur; Dustin D. Johnson; Stewart C. Sanderson

    2008-01-01

    Numerous studies have documented the expansion of woodlands in the Intermountain West; however, few have compared the chronology of expansion for woodlands across different geographic regions or determined the mix and extent of presettlement stands. We evaluated tree age structure and establishment for six woodlands in four ecological provinces in the central and...

  2. Avian use of successional cottonwood (Populus deltoides) woodlands along the middle Missouri River

    Science.gov (United States)

    Mark A. Rumble; John E. Gobeille

    2004-01-01

    Cottonwood (Populus deltoides) woodlands are important habitats for birds. Yet, little is known of the relations between bird habitat and succession in these woodlands. We studied the bird community in cottonwood woodlands from early to late seral stages along the Missouri River in central South Dakota from 1990 to 1992 to describe quantitative...

  3. Acid extractable mocronutrients (Mn and Zn) in selected soils of ...

    African Journals Online (AJOL)

    Consequently upon reports of Zinc (Zn) deficiency in some parts of Kwara State in the Guinea Savanna ecological zone of Nigeria, surface soil samples were analysed for native Manganese (Mn) and Zn contents of selected soils in Ilorin, Kwara State of Nigeria. Acid (0.1M HCl) extractable contents were determined using ...

  4. Field calibration of alfisol soil in Guinea Savannahof Northern ...

    African Journals Online (AJOL)

    ... for calibration of capacitance probe (Diviner2000) for use in alfisol soil in Northern Guinea Savanna of Nigeria. Changes in the resonant frequency of the circuit depend on changes in the capacitance of the soil-access tube system. Keywords: Capacitance probe, Diviner 2000, volumetric water contents,scale frequency.

  5. [Effects of land use change on soil active organic carbon in deep soils in Hilly Loess Plateau region of Northwest China].

    Science.gov (United States)

    Zhang, Shuai; Xu, Ming-Xiang; Zhang, Ya-Feng; Wang, Chao-Hua; Chen, Gai

    2015-02-01

    Response of soil active organic carbon to land-use change has become a hot topic in current soil carbon and nutrient cycling study. Soil active organic carbon distribution characteristics in soil profile under four land-use types were investigated in Ziwuling forest zone of the Hilly Loess Plateau region. The four types of land-use changes included natural woodland converted into artificial woodland, natural woodland converted into cropland, natural shrubland converted into cropland and natural shrubland converted into revegetated grassland. Effects of land-use changes on soil active organic carbon in deep soil layers (60-200 cm) were explored by comparison with the shallow soil layers (0-60 cm). The results showed that: (1) The labile organic carbon ( LOC) and microbial carbon (MBC) content were mainly concentrated in the shallow 0-60 cm soil, which accounted for 49%-66% and 71%-84% of soil active organic carbon in the profile (0-200 cm) under different land-use types. Soil active organic carbon content in shallow soil was significantly varied for the land-use changes types, while no obvious difference was observed in soil active organic carbon in deep soil layer. (2) Land-use changes exerted significant influence on soil active organic carbon, the active organic carbon in shallow soil was more sensitive than that in deep soil. The four types of land-use changes, including natural woodland to planted woodland, natural woodland to cropland, natural shrubland to revegetated grassland and natural shrubland to cropland, LOC in shallow soil was reduced by 10%, 60%, 29%, 40% and LOC in the deep layer was decreased by 9%, 21%, 12%, 1%, respectively. MBC in the shallow soil was reduced by 24% 73%, 23%, 56%, and that in the deep layer was decreased by 25%, 18%, 8% and 11%, respectively. (Land-use changes altered the distribution ratio of active organic carbon in soil profile. The ratio between LOC and SOC in shallow soil increased when natural woodland and shrubland were

  6. 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.

  7. Maize-grain legume intercropping for enhanced resource use efficiency and crop productivity in the Guinea savanna of northern Ghana.

    Science.gov (United States)

    Kermah, Michael; Franke, Angelinus C; Adjei-Nsiah, Samuel; Ahiabor, Benjamin D K; Abaidoo, Robert C; Giller, Ken E

    2017-11-01

    Smallholder farmers in the Guinea savanna practise cereal-legume intercropping to mitigate risks of crop failure in mono-cropping. The productivity of cereal-legume intercrops could be influenced by the spatial arrangement of the intercrops and the soil fertility status. Knowledge on the effect of soil fertility status on intercrop productivity is generally lacking in the Guinea savanna despite the wide variability in soil fertility status in farmers' fields, and the productivity of within-row spatial arrangement of intercrops relative to the distinct-row systems under on-farm conditions has not been studied in the region. We studied effects of maize-legume spatial intercropping patterns and soil fertility status on resource use efficiency, crop productivity and economic profitability under on-farm conditions in the Guinea savanna. Treatments consisted of maize-legume intercropped within-row, 1 row of maize alternated with one row of legume, 2 rows of maize alternated with 2 rows of legume, a sole maize crop and a sole legume crop. These were assessed in the southern Guinea savanna (SGS) and the northern Guinea savanna (NGS) of northern Ghana for two seasons using three fields differing in soil fertility in each agro-ecological zone. Each treatment received 25 kg P and 30 kg K ha -1 at sowing, while maize received 25 kg (intercrop) or 50 kg (sole) N ha -1 at 3 and 6 weeks after sowing. The experiment was conducted in a randomised complete block design with each block of treatments replicated four times per fertility level at each site. Better soil conditions and rainfall in the SGS resulted in 48, 38 and 9% more maize, soybean and groundnut grain yield, respectively produced than in the NGS, while 11% more cowpea grain yield was produced in the NGS. Sole crops of maize and legumes produced significantly more grain yield per unit area than the respective intercrops of maize and legumes. Land equivalent ratios (LERs) of all intercrop patterns were greater than

  8. Towards a Manitoba Hydro boreal woodland caribou strategy: Outcomes from Manitoba Hydro boreal woodland caribou workshop

    Directory of Open Access Journals (Sweden)

    Fiona E. Scurrah

    2012-03-01

    Full Text Available Manitoba Hydro is responsible for the continued supply of energy to meet the needs of the province and is committed to protecting the environment when planning the construction and operation of its facilities. Corporate policy dictates ongoing improvement of Environmental Management Systems (EMS in order to meet or surpass regulatory requirements. Environmental objectives are reviewed annually and programs are modified when necessary to address improvements in environmental performance. Manitoba Hydro plans and constructs major transmission projects throughout northern Manitoba which includes areas occupied by boreal woodland caribou. In recognition of the potential issues associated with hydro transmission construction in boreal caribou range, Manitoba Hydro hosted an expert workshop on May 8, 2007 to provide objective advice in the development of a draft corporate strategy that effectively directs targeted monitoring and research for environmental assessment and mitigation. The workshop focused on assessing the potential threats to boreal woodland caribou from a transmission line construction and operation perspective, and identifying appropriate approaches in site selection and environmental assessment (SSEA and long-term monitoring and research. A total of nine threat categories were reviewed to determine the degree and magnitude of potential effects that may result from transmission construction and operation; and of the original nine, five final threat categories were delineated. The main elements of the workshop provided strategic approaches for proactive pre-construction monitoring, research on recruitment and mortality for local populations impacted by ROWs and control areas, and various habitat monitoring, management, and mitigation techniques. Research and monitoring priorities have been identified and continued collaboration with Manitoba Conservation and other land users were also identified.

  9. Land-Use History and Contemporary Management Inform an Ecological Reference Model for Longleaf Pine Woodland Understory Plant Communities.

    Energy Technology Data Exchange (ETDEWEB)

    Brudvig, Lars A. [Department of Plant Biology, Michigan State University; Orrock, John L. [Department of Zoology, University of Wisconsin; Damschen, Ellen I. [Department of Zoology, University of Wisconsin; et al, et al

    2014-01-23

    Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils lol(which broadly structure these communities), and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together. and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients–i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes). Our study demonstrates the utility

  10. Land-use history and contemporary management inform an ecological reference model for longleaf pine woodland understory plant communities.

    Directory of Open Access Journals (Sweden)

    Lars A Brudvig

    Full Text Available Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils (which broadly structure these communities, and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients-i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes. Our study demonstrates

  11. Land-use history and contemporary management inform an ecological reference model for longleaf pine woodland understory plant communities.

    Science.gov (United States)

    Brudvig, Lars A; Orrock, John L; Damschen, Ellen I; Collins, Cathy D; Hahn, Philip G; Mattingly, W Brett; Veldman, Joseph W; Walker, Joan L

    2014-01-01

    Ecological restoration is frequently guided by reference conditions describing a successfully restored ecosystem; however, the causes and magnitude of ecosystem degradation vary, making simple knowledge of reference conditions insufficient for prioritizing and guiding restoration. Ecological reference models provide further guidance by quantifying reference conditions, as well as conditions at degraded states that deviate from reference conditions. Many reference models remain qualitative, however, limiting their utility. We quantified and evaluated a reference model for southeastern U.S. longleaf pine woodland understory plant communities. We used regression trees to classify 232 longleaf pine woodland sites at three locations along the Atlantic coastal plain based on relationships between understory plant community composition, soils (which broadly structure these communities), and factors associated with understory degradation, including fire frequency, agricultural history, and tree basal area. To understand the spatial generality of this model, we classified all sites together and for each of three study locations separately. Both the regional and location-specific models produced quantifiable degradation gradients-i.e., progressive deviation from conditions at 38 reference sites, based on understory species composition, diversity and total cover, litter depth, and other attributes. Regionally, fire suppression was the most important degrading factor, followed by agricultural history, but at individual locations, agricultural history or tree basal area was most important. At one location, the influence of a degrading factor depended on soil attributes. We suggest that our regional model can help prioritize longleaf pine woodland restoration across our study region; however, due to substantial landscape-to-landscape variation, local management decisions should take into account additional factors (e.g., soil attributes). Our study demonstrates the utility of

  12. LBA-ECO ND-07 Microbial Biomass in Cerrado Soils, Brasilia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the microbial biomass in soil samples collected from the Cerrado, a woodlands-savannah area, in Brasilia, Brazil. Microbial biomass was...

  13. LBA-ECO ND-07 Microbial Biomass in Cerrado Soils, Brasilia, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the microbial biomass in soil samples collected from the Cerrado, a woodlands-savannah area, in Brasilia, Brazil. Microbial biomass...

  14. Characterization of the Roraima savanna across of X-ray diffraction, thermomagnetic analysis and Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gilmar A.; Araujo, R.C.; Sergio, C.S. [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil)

    2012-07-01

    Full text: The technique of X-ray diffraction has great resolving power to determine the phases present in crystalline material, thereby enabling it to determine the elements present in the materials as well as changes in structure that they can suffer when subjected to various physical processes and/or chemical means. The research had as objective to characterize the mineralogy of iron oxides, silicon, aluminum and other minerals in the soil of five points of the Roraima savannah. The points where samples were collected are five municipalities in the state of Roraima. The area of sampling is part of the savanna in Roraima. The samples were collected. We analyzed samples from five points from the collection of natural soil in the locations listed. The samples were placed in a mill to a uniform grain size. After the milling process, the magnetic material was separated using a permanent magnet. Then the samples were analyzed by x-ray diffraction, thermomagnetic analysis and Moessbauer spectroscopy. Preliminary results of XRD showed the occurrence of phases of oxides of iron, silicon, aluminum and other phases less. Thermomagnetic analysis show that the magnetic phases are magnetite and hematite. The results of the Moessbauer spectroscopy indicates the reliability in the two prior art and confirmed the presence of the phases of oxides of iron present in the soil analyzed. (author)

  15. Land-Cover Legacy Effects on Arbuscular Mycorrhizal Abundance in Human and Wildlife Dominated Systems in Tropical Savanna

    Directory of Open Access Journals (Sweden)

    Geofrey E. Soka

    2016-01-01

    Full Text Available Arbuscular mycorrhizal fungi (AMF can be important mutualists to plant hosts in acquiring soil nutrients. Past work has not explored whether previous land-cover history influences current AMF abundance in croplands and whether different land-cover histories in grazed but not cultivated areas influence AMF. This study was conducted to assess the effects of land-cover history in and near Serengeti National Park on AMF abundance in areas with three different land uses. The results showed that land-cover history influenced a number of soil physicochemical properties following conversion of grassland to cropland or woodland to cropland during the past 27 years. Different original land cover generally did not significantly influence current AMF abundance in croplands or livestock-grazed soils. However, livestock-grazed current grasslands that were formerly woodlands had lower AMF abundance than sites that had been grasslands since 1984. These results suggest that lower AMF abundance in livestock-grazed and cropland areas as compared to protected wildlife-grazed areas may reflect reduced total carbon inputs and higher disturbance and are not strongly influenced by the legacy of previous land cover. Given that recent studies have detected legacy effects on AMF, such effects may reflect more the impact on the taxonomic composition of AMF rather than their total abundance.

  16. Germination strategy of the East African savanna tree Acacia tortilis

    NARCIS (Netherlands)

    Loth, P.E.; Boer, de W.F.; Heitkönig, I.M.A.; Prins, H.H.T.

    2005-01-01

    Germination of Acacia tortilis seeds strongly depends on micro-site conditions. In Lake Manyara National Park, Tanzania, Acacia tortilis occurs abundantly in recently abandoned arable fields and in elephant-mediated gaps in acacia woodland, but does not regenerate in grass swards or beneath

  17. Wildfire impact : natural experiment reveals differential short-term changes in soil microbial communities

    OpenAIRE

    Prendergast-Miller, Miranda Tendai; de Menezes, Alexandre B.; Macdonald, Lynne M.; Toscas, Peter; Bissett, Andrew; Baker, Geoff; Farrell, Mark; Richardson, Alan E.; Wark, Tim; Thrall, Peter H.

    2017-01-01

    A wildfire which overran a sensor network site provided an opportunity (a natural experiment) to monitor short-term post-fire impacts (immediate and up to three months post-fire) in remnant eucalypt woodland and managed pasture plots. The magnitude of fire-induced changes in soil properties and soil microbial communities was determined by comparing (1) variation in fire-adapted eucalypt woodland vs. pasture grassland at the burnt site; (2) variation at the burnt woodland-pasture sites with va...

  18. 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

  19. Seasonal variation of carbon fluxes in a sparse savanna in semi arid Sudan

    Directory of Open Access Journals (Sweden)

    El-Tahir Bashir

    2008-12-01

    Full Text Available Abstract Background Large spatial, seasonal and annual variability of major drivers of the carbon cycle (precipitation, temperature, fire regime and nutrient availability are common in the Sahel region. This causes large variability in net ecosystem exchange and in vegetation productivity, the subsistence basis for a major part of the rural population in Sahel. This study compares the 2005 dry and wet season fluxes of CO2 for a grass land/sparse savanna site in semi arid Sudan and relates these fluxes to water availability and incoming photosynthetic photon flux density (PPFD. Data from this site could complement the current sparse observation network in Africa, a continent where climatic change could significantly impact the future and which constitute a weak link in our understanding of the global carbon cycle. Results The dry season (represented by Julian day 35–46, February 2005 was characterized by low soil moisture availability, low evapotranspiration and a high vapor pressure deficit. The mean daily NEE (net ecosystem exchange, Eq. 1 was -14.7 mmol d-1 for the 12 day period (negative numbers denote sinks, i.e. flux from the atmosphere to the biosphere. The water use efficiency (WUE was 1.6 mmol CO2 mol H2O-1 and the light use efficiency (LUE was 0.95 mmol CO2 mol PPFD-1. Photosynthesis is a weak, but linear function of PPFD. The wet season (represented by Julian day 266–273, September 2005 was, compared to the dry season, characterized by slightly higher soil moisture availability, higher evapotranspiration and a slightly lower vapor pressure deficit. The mean daily NEE was -152 mmol d-1 for the 8 day period. The WUE was lower, 0.97 mmol CO2 mol H2O-1 and the LUE was higher, 7.2 μmol CO2 mmol PPFD-1 during the wet season compared to the dry season. During the wet season photosynthesis increases with PPFD to about 1600 μmol m-2s-1 and then levels off. Conclusion Based on data collected during two short periods, the studied ecosystem

  20. The ecology and management of the Miombo woodlands for ...

    African Journals Online (AJOL)

    There is new and increasing emphasis on the contribution of non-timber forest products (NTFPs) to improving the livelihoods of rural communities and therefore the need for sustainable management of forest ecosystems of the Miombo woodlands to ensure the continued availability of these NTFPs. This paper examines and ...

  1. Cryptic indirect effects of exurban edges on a woodland community

    Science.gov (United States)

    R. J. Warren; S. M. Pearson; S. Henry; K. Rossouw; J. P. Love; M. J. Olejniczak; Katherine Elliott; M. A. Bradford

    2015-01-01

    Exurban development (e.g., second homes) in woodlands spreads urban land use impacts beyond suburbs, but because exurban developments often retain many components of original ecosystem structure—such as a forest canopy rather than open lawn—their ecological impacts may be underestimated. Changes in seed-dispersing ant behavior prompted by exurban land use,...

  2. Impact of crop producer price change on quantities of woodland ...

    African Journals Online (AJOL)

    ... produced by these households will affect quantities of woodland products that are harvested. The data used for this study was mainly collected in a questionnaire survey that covered ten villages in the Romwe community in Chivi District, southern Zimbabwe. The Zimbabwe Science News Volume 36 (1+ 2) 2002, pp. 37-41 ...

  3. Physio-climatic classification of South Africa's woodland biome

    CSIR Research Space (South Africa)

    Fairbanks, DHK

    2000-07-01

    Full Text Available is carried out to determine class membership. The final map of custom physio-climatic regions is described, and these custom regions are compared with a vegetation potential map of the woodland types identified in the South African summer rainfall zone....

  4. The colonisation of woodland gaps by ferns and horsetails

    NARCIS (Netherlands)

    Bremer, P.

    2010-01-01

    In the Voorsterbos, a planted woodland on a former sea-floor (the Netherlands), artificial gaps within stands of Fagus sylvatica on boulder clay were monitored for five or six years after cutting. Ten fern species and three species of horsetail established in these gaps, with Dryopteris cristata,

  5. Diversity, Structure and Regeneration Status of the Woodland and ...

    African Journals Online (AJOL)

    This study was conducted on the woodland and riverine vegetation of Sire Beggo in Gololcha District, eastern Ethiopia with the aim of documenting the floristic composition, population structure and identifying major plant community types. ... Vegetation classification was performed using TWINSPAN software package.

  6. Recent land cover and use changes in Miombo woodlands of ...

    African Journals Online (AJOL)

    Forest and wood land ecosystems in Tanzania occupy more than 45% of the land area, more than two thirds of which made up of the Miombo woodland. The main form of land use in the Miombo region has long been shifting and small-scale sedentary cultivation. The lack of infrastructure and prevalence of deadly diseases ...

  7. A National Perspective on Women Owning Woodlands (WOW) Networks

    Science.gov (United States)

    Huff, Emily S.

    2017-01-01

    This article provides a national overview of women owning woodlands (WOW) networks and the barriers and successes they encounter. Qualitative interview data with key network leaders were used for increasing understanding of how these networks operate. Network leaders were all connected professionally, and all successful WOW networks involved…

  8. Decision-support tool for management of miombo woodlands: a ...

    African Journals Online (AJOL)

    The model complexity is well adapted to the data quality and abundance, and it is dependent on proxies of some main drivers of the dynamic processes. The development of the matrix model is a step forward facilitating better decisions in the management of miombo woodlands. However, data ranges used for calibrating ...

  9. Explaining the forest product selling behavior of private woodland owners

    Science.gov (United States)

    David N. Larsen; David A. Gansner; David A. Gansner

    1973-01-01

    A multiple-variable screening technique, AID, was used to explain the forest-product-sales behavior of private woodland owners. Results provide a basis for policy-related inferences and suggest an optimal strategy for encouraging sales of forest products.

  10. Teacher-in-Residence at the Woodland Park Zoo

    Science.gov (United States)

    Gantert, Robert L.

    1977-01-01

    Described is a field trip program to the Woodland Park Zoological Gardens, Seattle, Washington, which includes an indoor lecture-discussion and tours of the zoological facility led by docents. An educational survey revealed that fourth graders asked the greatest number of logical animal biology questions and had the highest interest in reading…

  11. Phytoecological study of Tetraclinis articulata in the woodland of ...

    African Journals Online (AJOL)

    Phytoecological study of Tetraclinis articulata in the woodland of Beni Affene, Sdamas Chergui (Tiaret, Algeria). M.E. Azzaoui, M Maatoug, M Berrayah. Abstract. The Mediterranean flora is definitely considered as an exceptional diversity that deserves particular attention to be conserved. This work aims to quantify the ...

  12. Estimating wood volume from canopy area in deciduous woodlands ...

    African Journals Online (AJOL)

    In this study we tested the predictive ability of canopy area in estimating wood volume in deciduous woodlands of Zimbabwe. The study was carried out in four sites of different climatic conditions. We used regression analysis to statistically quantify the prediction of wood volume from canopy area at species and stand level ...

  13. Changing C and N Levels of miombo woodland litter ...

    African Journals Online (AJOL)

    Litterfall was collected fortnightly from four-25 m2 cleared miombo woodland plots for five years. The litter was fractionated and compared for quantity, monthly distribution and concentrations of total C and N. Annual litterfall, starting at the beginning of the dry season (May) to the end of the rainy season (April), ranged from ...

  14. 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

  15. Trade-offs between savanna woody plant diversity and carbon storage in the Brazilian Cerrado.

    Science.gov (United States)

    Pellegrini, Adam F A; Socolar, Jacob B; Elsen, Paul R; Giam, Xingli

    2016-10-01

    Incentivizing carbon storage can be a win-win pathway to conserving biodiversity and mitigating climate change. In savannas, however, the situation is more complex. Promoting carbon storage through woody encroachment may reduce plant diversity of savanna endemics, even as the diversity of encroaching forest species increases. This trade-off has important implications for the management of biodiversity and carbon in savanna habitats, but has rarely been evaluated empirically. We quantified the nature of carbon-diversity relationships in the Brazilian Cerrado by analyzing how woody plant species richness changed with carbon storage in 206 sites across the 2.2 million km(2) region at two spatial scales. We show that total woody plant species diversity increases with carbon storage, as expected, but that the richness of endemic savanna woody plant species declines with carbon storage both at the local scale, as woody biomass accumulates within plots, and at the landscape scale, as forest replaces savanna. The sharpest trade-offs between carbon storage and savanna diversity occurred at the early stages of carbon accumulation at the local scale but the final stages of forest encroachment at the landscape scale. Furthermore, the loss of savanna species quickens in the final stages of forest encroachment, and beyond a point, savanna species losses outpace forest species gains with increasing carbon accumulation. Our results suggest that although woody encroachment in savanna ecosystems may provide substantial carbon benefits, it comes at the rapidly accruing cost of woody plant species adapted to the open savanna environment. Moreover, the dependence of carbon-diversity trade-offs on the amount of savanna area remaining requires land managers to carefully consider local conditions. Widespread woody encroachment in both Australian and African savannas and grasslands may present similar threats to biodiversity. © 2016 John Wiley & Sons Ltd.

  16. Air humidity as key determinant of morphogenesis and productivity of the rare temperate woodland fern Polystichum braunii.

    Science.gov (United States)

    Schwerbrock, R; Leuschner, C

    2016-07-01

    (1) Most ferns are restricted to moist and shady habitats, but it is not known whether soil moisture or atmospheric water status are decisive limiting factors, or if both are equally important. (2) Using the rare temperate woodland fern Polystichum braunii, we conducted a three-factorial climate chamber experiment (soil moisture (SM) × air humidity (RH) × air temperature (T)) to test the hypotheses that: (i) atmospheric water status (RH) exerts a similarly large influence on the fern's biology as soil moisture, and (ii) both a reduction in RH and an increase in air temperature reduce vigour and growth. (3) Nine of 11 morphological, physiological and growth-related traits were significantly influenced by an increase in RH from 65% to 95%, leading to higher leaf conductance, increased above- and belowground productivity, higher fertility, more epidermal trichomes and fewer leaf deformities under high air humidity. In contrast, soil moisture variation (from 66% to 70% in the moist to ca. 42% in the dry treatment) influenced only one trait (specific leaf area), and temperature variation (15 °C versus 19 °C during daytime) only three traits (leaf conductance, root/shoot ratio, specific leaf area); RH was the only factor affecting productivity. (4) This study is the first experimental proof for a soil moisture-independent air humidity effect on the growth of terrestrial woodland ferns. P. braunii appears to be an air humidity hygrophyte that, whithin the range of realistic environmental conditions set in this study, suffers more from a reduction in RH than in soil moisture. A climate warming-related increase in summer temperatures, however, seems not to directly threaten this endangered species. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Fuel composition influences fire characteristics and understorey hardwoods in pine savanna

    National Research Council Canada - National Science Library

    Ellair, Darin P; Platt, William J; Austin, Amy

    2013-01-01

    .... We experimentally manipulated amounts of pine and hickory leaves beneath understorey hickory stems in a pine savanna, measured temperatures during prescribed fires and assessed combustion of fuels...

  18. Relationship between soil oxidizable carbon and physical, chemical and mineralogical properties of umbric ferralsols

    Directory of Open Access Journals (Sweden)

    Flávio Adriano Marques

    2011-02-01

    Full Text Available The occurrence of Umbric Ferralsols with thick umbric epipedons (> 100 cm thickness in humid Tropical and Subtropical areas is a paradox since the processes of organic matter decomposition in these environments are very efficient. Nevertheless, this soil type has been reported in areas in the Southeast and South of Brazil, and at some places in the Northeast. Aspects of the genesis and paleoenvironmental significance of these Ferralsols still need a better understanding. The processes that made the umbric horizons so thick and dark and contributed to the preservation of organic carbon (OC at considerable depths in these soils are of special interest. In this study, eight Ferralsols with a thick umbric horizon (UF under different vegetation types were sampled (tropical rain forest, tropical seasonal forest and savanna woodland and their macromorphological, physical, chemical and mineralogical properties studied to detect soil characteristics that could explain the preservation of high carbon amounts at considerable depths. The studied UF are clayey to very clayey, strongly acidic, dystrophic, and Al-saturated and charcoal fragments are often scattered in the soil matrix. Kaolinites are the main clay minerals in the A and B horizons, followed by abundant gibbsite and hydroxyl-interlayered vermiculite. The latter was only found in UFs derived from basalt rock in the South of the country. Total carbon (TC ranged from 5 to 101 g kg-1 in the umbric epipedon. Dichromate-oxidizable organic carbon represented nearly 75 % of TC in the thick A horizons, while non-oxidizable C, which includes recalcitrant C (e.g., charcoal, contributed to the remaining 25 % of TC. Carbon contents were not related to most of the inorganic soil variables studied, except for oxalate-extractable Al, which individually explained 69 % (P < 0.001 of the variability of TC in the umbric epipedon. Clay content was not suited as predictor of TC or of the other studied C forms. Bulk

  19. Influence of plant community structure on vulnerability to drought of semiarid pine woodlands.

    Science.gov (United States)

    Moreno-Gutiérrez, Cristina; Battipaglia, Giovanna; Cherubini, Paolo; Saurer, Matthias; Siegwolf, Rolf; Querejeta, José Ignacio

    2010-05-01

    The growth, water status and water use efficiency of trees are sensitive to drought. The severity of drought experienced by trees can be magnified or diminished depending on plant community structure and density. This is especially important in semiarid environments. In dense afforested plantations, high inter-tree competition for soil water could increase the water stress of trees in comparison to plants in an open woodland. On the other hand, the shading effect of the tree canopy and the increased soil infiltration capacity in semiarid afforested stands could prevail over competition and buffer the drought effect. Thus, in dense afforested plantations, greater inter-tree competition but more favourable microclimatic conditions may have opposite effects, and the prevalence of one of them could depend on annual meteorological conditions. To test these hypotheses, we made a long term assessment (50 years) of tree ring growth and isotopic composition of Pinus halepensis in two nearby communities: an afforested pine stand and an open pine woodland with under storey (shrub land), both located in semiarid SE Spain (Murcia). We sampled 10 trees per site and we measured tree ring width. The individual time series were detrended and the mean chronology was calculated for each series. On selected five trees per location, the annual δ13C and δ18O were measured on cellulose extracted from latewood. The relationships between measured variables and meteorological (temperature and precipitation) data, provided by the Spanish Agency of Meteorology, were statistically assessed with linear regression analyses. We found a strong significant correlation between the standardized mean chronologies of pines in both communities. In both sites, the mean sensitivity of the mean chronologies was high: 0.37 in the open pine woodland (ow) and 0.54 in the afforested stand (as), suggesting that the individual growth series have a clear common signal. Our results show significant positive

  20. Soil catena along gypseous woodland in the middle Ebro Basin: soil properties and micromorphology relationships Propiedades del suelo y relaciones micromorfológicas de suelos yesosos forestales en el Valle medio del Ebro Propriedades do solo e relações micromorfológicas dos solos florestais gessosos no Vale do Ebro

    Directory of Open Access Journals (Sweden)

    Javier M Aznar

    2013-03-01

    Full Text Available Gypsisols, mainly distributed in arid lands, support a key economic activity and have attracted a lot of scientific interest due to their particular physical and chemical properties. For example, Gypsisols show a high erodibility, low fertility and a variable water holding capacity that can be attributed to different gypsum particle sizes. This study aims to describe some representative Gypsisols from the middle Ebro Basin. Five representative soil profiles (mainly Gypsisols by WRB were selected and sampled at different positions along a hillside where soils where developed on gyprock. Furthemore, it links micromorphological properties with soil water retention. Soils have a dominant loamy texture, more rarely stoney. Gypsum is abundant in all soil profiles, ranging from 6 to 84% with minimum values in Ah horizons and maximum in By and Cy. The soils have a low level of salinity and a very low cation exchange capacity (CEC. The soil organic matter (SOM is medium or abundant in the Ah horizons, otherwise it is low. Soil aggregate stability (SAS is related significantly and positively with SOM and porosity, which is also positively related with moisture retention at field capacity and saturation humidity. However, there is no significant correlation between porosity and permanent wilting point (PWP. Soil water retention is dependant on the gypsum percentage and textural class. Low levels of gypsum have no influence on water retention, but high gypsum levels (> 60% enhance the field capacity (FC and decrease PWP, especially when the gypsum is microcrystalline. Gypsum levels between 40 and 60% also increase available water contents (AWC due to a decrease in PWP. There is a positive and significant correlation between PWP and FC in Gypsisols, except for those which are loamy and have gypsum values over 40%. The higher available water capacity (AWC than expected is related to microcrystalline gypsum, predominant in the studied soils. These high AWC

  1. Modeling the health and productivity of Oak Savannas in central USA

    Science.gov (United States)

    Nightingale, J. M.; Hill, M. J.

    2012-12-01

    Oak species have a long history of domination in eastern North America and their present distribution in various regions exceeds that recorded in the original forests at the time of European settlement. The increase in oak during the late 18th and 19th centuries can be attributed to historical changes in disturbance regimes in the eastern biome. The expansion in oak distribution has occurred on xeric or nutrient-poor sites, which indicates the stress tolerance capabilities of many oak species. The aim of this research is to assess the health and productivity of the fragmented oak savannas that span from Texas north to the Canada border using statewide GAP, climate and MODIS data and the 3PGS (Physiological Principles Predicting Growth using satellite data) ecosystem process model. 3-PGS is a simple big-leaf productivity model that sets upper limits on monthly gross primary productivity (GPP) by determining the amount of photosynthetically active radiation absorbed (APAR) by vegetation and the photosynthetic capacity (LUE) of the canopy. The utilized portion of APAR is calculated by reducing total PAR by an amount determined by the most constraining of a series of environmental modifiers that affect gas exchange through stomata. These include: (a) high daytime atmospheric VPD; (b) soil water availability; and (c) the frequency of sub-freezing temperatures (precipitation, average temperature and vapor pressure deficit are obtained from the Daymet daily gridded surface data from Oak Ridge National Laboratory (ORNL). The fraction of APAR is obtained from the MODIS terra/aqua combined product. Monthly surfaces were derived for the study period 2003-2008 spanning available MODIS and Climate datasets. Soil properties for the entire U.S.A., derived from luster analysis of STATSGO soil parameters, terrain and climate observations were obtained from ORNL. Oak savannas within this region are identified using the statewide Gap Analysis Program data provided by USGS. Several

  2. Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland

    Directory of Open Access Journals (Sweden)

    J. H. Shim

    2013-07-01

    Full Text Available We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR. Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET was significantly related to post-pulse δR enrichment because the leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET/ES. In contrast, the soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought.

  3. Agricultural Systems Located in the Forest-Savanna Ecotone of the Venezuelan Amazonian. Are Organic Agroforestry Farms Sustainable?

    National Research Council Canada - National Science Library

    Hernández, Carmen Leonor; López-Hernández, Danilo; Netuzhilin, Igor; López-Contreras, Ana Yamila

    2009-01-01

    The savannas located in the forest-savanna ecotone in the Venezuelan Amazon have unfertile sandy ultisols and entisols which show a very low crop production unless they are supplemented with large amounts of fertiliser...

  4. 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

  5. Modelling global change impacts on soil carbon contents of agro-silvo-pastoral Mediterranean systems

    Science.gov (United States)

    Lozano-García, Beatriz; Muñoz-Rojas, Miriam; Parras-Alcántara, Luis

    2016-04-01

    To assess the impact of climate change on soil organic C (SOC) stocks in agro-silvo-pastoral environments, different models have been applied worldwide at local or regional scales, such as as RothC (Francaviglia et al., 2012) or CENTURY (Alvaro-Fuentes et al., 2012). However, some of these models may require a high number of input parameters or can underestimate the effect of soil depth. CarboSOIL (Muñoz-Rojas et al., 2013) is an empirical model based on regression techniques and developed to predict SOC contents at standard soil depths (0-25, 25-50 and 50-75 cm) under a range of climate and/or land use change scenarios. CarboSOIL has been successfully applied in different Mediterranean areas ,e.g. Southern Spain (Muñoz-Rojas et al., 2013; Abd-Elmabod et al., 2014), Northern Egypt (Muñoz-Rojas et al., 2014) and Italy (Muñoz-Rojas et al., 2015). In this study, CarboSOIL was applied in the Cardeña and Montoro mountain range Natural Park. This area covers 385 km2 and is located within Sierra Morena (Córdoba, South Spain) and has a semiarid Mediterranean climate. It is characterized by agro-silvo-pastoral systems. The Mediterranean evergreen oak woodland (MEOW-dehesa) is savanna-like open woodland ecosystem characterized by silvopastoral uses, being an ancient human modified Mediterranean landscape (Corral-Fernández et al., 2013; Lozano-García and Parras-Alcántara 2013). The most representative soils in the Cardeña and Montoro mountain range Natural Park are Cambisols, Regosols, Leptosols and Fluvisols. These soils are characterized by low fertility, poor physical conditions and marginal capacity for agricultural use, together with low organic matter (OM) content due to climate conditions (semiarid Mediterranean climate) and soil texture (sandy). The model was applied at different soil depths: 0-25, 25-50 and 50-75 cm (Parras-Alcántara et al., 2015) considering land use and climate changes scenarios based on available global climate models (IPPC, 2007). A

  6. Evaluation of changes in post-fire recharge under native woodland using hydrological measurements, modelling and remote sensing

    Science.gov (United States)

    Silberstein, Richard P.; Dawes, Warrick R.; Bastow, Trevor P.; Byrne, John; Smart, Natalie F.

    2013-05-01

    SummaryThis paper examines the use of a controlled fuel reduction burn in native woodland to increase recharge to a shallow aquifer system for water supply in south-western Australia. Soil moisture trends from neutron probe measurements and watertable dynamics from piezometers under adjacent burned and unburned plots were compared to determine the difference in recharge resulting from the fire. Remotely sensed evapotranspiration (ET) subtracted from rainfall was used to independently estimate groundwater and soil moisture recharge and compare against a physically based model of soil-water fluxes. The use of naturally occurring chemicals (n-alkanes and cycloalkanes) produced in the fire as tracers of the recharge pulse in the winter following the fire was tested. It was found that in the winter following the fire (annual rainfall 701 mm), water storage in the 9 m thick unsaturated zone increased by about 300 mm but recharge to the watertable was only about 60 mm. In the subsequent year (rainfall 630 mm), leaf area index in the burned woodland recovered to be about 10% less than the unburned plot, remotely sensed ET rose above that in the unburned plot and recharge was lower in the burned than unburned plot. This trend continued and, after 3 years, increased ET negated any early recharge gains, and there was a net decrease in recharge resulting from the fire. The combination of water balance measurements, modelling and remote sensing provides a robust method to gain hydrological understanding of recharge mechanisms. Further work is required to refine the use of burn residue chemicals as soil water tracers, particularly in improving instrument design for groundwater sample collection in fine textured soils. As climate continues to change and regions with growing water shortages seek innovative solutions, approaches such as controlled burning may be needed; however, in this example, the approach was unproductive and further the environmental consequences need to be

  7. Monitoring drought impact on Mediterranean oak savanna vegetation using remote sensing

    Science.gov (United States)

    González-Dugo, Maria P.; Carpintero, Elisabet; Andreu, Ana

    2015-04-01

    A holm oak savanna, known as dehesa in Spain and montado in Portugal, is the largest agroforest ecosystem in Europe, covering about 3 million hectares in the Iberian Peninsula and Greece (Papanastasis et al., 2004). It is considered an example of sustainable land use, supporting a large number of species and diversity of habitats and for its importance in rural development and economy (Plieninger et al., 2001). It is a combination between an agricultural and a naturally vegetated ecosystem, consisting of widely-spaced oak trees (mostly Quercus Ilex and Quercus suber) combined with a sub-canopy composed by crops, annual grassland and/or shrubs. It has a Mediterranean climate with severe periodic droughts. In the last decades, this system is being exposed to multiple threats derived from socio-economic changes and intensive agricultural use, which have caused environmental degradation, including tree decline, changes in soil properties and hydrological processes, and an increase of soil erosion (Coelho et al., 2004). Soil water dynamics plays a central role in the current decline and reduction of forested areas that jeopardizes the preservation of the system. In this work, a series of remotely sensed images since 1990 to present was used to evaluate the effect of several drought events occurred in the study area (1995, 2009, 2010/2011) on the tree density and water status. Data from satellites Landsat and field measurements have been combined in a spectral mixture model to assess separately the evolution of tree, dry grass and bare soil ground coverage. Only summer images have been used to avoid the influence of the green herbaceous layer on the analysis. Thermal data from the same sensors and meteorological information are integrated in a two source surface energy balance model to compute the Evaporative Stress Index (ESI) and evaluate the vegetation water status. The results have provided insights about the severity of each event and the spatial distribution of

  8. Litter dominates surface fluxes of carbonyl sulfide in a Californian oak woodland

    Science.gov (United States)

    Sun, Wu; Maseyk, Kadmiel; Lett, Céline; Seibt, Ulli

    2016-02-01

    Carbonyl sulfide (COS) is a promising tracer for partitioning terrestrial photosynthesis and respiration from net carbon fluxes, based on its daytime co-uptake alongside CO2 through leaf stomata. Because ecosystem COS fluxes are the sum of plant and soil fluxes, using COS as a photosynthesis tracer requires accurate knowledge of soil COS fluxes. At an oak woodland in Southern California, we monitored below-canopy surface (soil + litter) COS and CO2 fluxes for 40 days using chambers and laser spectroscopy. We also measured litter fluxes separately and used a depth-resolved diffusion-reaction model to quantify the role of litter uptake in surface COS fluxes. Soil and litter were primarily COS sinks, and mean surface COS uptake was small (˜1 pmol m-2 s-1). After rainfall, uptake rates were higher (6-8 pmol m-2 s-1), and litter contributed a significant fraction (up to 90%) to surface fluxes. We observed rapid concurrent increases in COS uptake and CO2 efflux following the onset of rain. The patterns were similar to the Birch effect widely documented for soils; however, both COS and CO2 flux increases originated mainly in the litter. The synchronous COS-CO2 litter Birch effect indicates that it results from a rapid increase in litter microbial activity after rainfall. We expect that the drying-rewetting cycles typical for mediterranean and other semiarid ecosystems create a pronounced seasonality in surface COS fluxes. Our results highlight that litter uptake is an important component of surface COS exchange that needs to be taken into account in ecosystem COS budgets and model simulations.

  9. Will ecosystem management supply woodland caribou habitat in northwestern Ontario?

    Directory of Open Access Journals (Sweden)

    David L. Euler

    1998-03-01

    Full Text Available Ecosystem management is emerging as an important concept in managing forests. Although the basic conceptual idea is not new, important defining principles are developing that elucidate some of the specific attributes of ecosystem management. These principles include: the maintenance of all ecosystems in the managed forest, rhe emulation of natural disturbance patterns on rhe landscape and the insurance that structure and function of forested ecosystems are conserved. Forest management has an impact on woodland caribou (Rangifer tarandus caribou, although the presence of wolves (Canis lupus and moose (Alces alces in the same northern ecosystems also affects the caribou-forestry interacrion. Specific management for caribou as a featured species has been proposed, based on managing large landscape blocks. Ecosystem management would also produce habitat in a manner that might accomplish the goal of conserving woodland caribou as well as maintaining other important ecosystem functions.

  10. Nutrients in an African Savanna: the consequences of supply heterogeneity for plants and animals

    NARCIS (Netherlands)

    Waal, van der C.

    2010-01-01

    In savannas, trees and grasses co-exist and share resources such as water and nutrients. The ratio between the tree and grass components (i.e., vegetation structure) importantly controls productivity, animal assemblages and earth-atmosphere feedbacks. As the structure of savanna vegetation is

  11. Effects of nutrients and shade on tree-grass interactions in an East African savanna.

    NARCIS (Netherlands)

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

    2001-01-01

    Savanna trees have a multitude of positive and negative effects on understorey grass production. but little is known about how these effects interact. We report on a fertilization and shading experiment carried out in a Tanzanian tropical city savanna around Acacia tortilis trees. In two years of

  12. 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 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...

  13. Textural analysis of historical aerial photography to characterize woody plant encroachment in South African savanna

    Science.gov (United States)

    Andrew T. Hudak; Carol A. Wessman

    1998-01-01

    Transitions from grassland to shrubland through woody plant encroachment result in potentially significant shifts in savanna ecosystem function. Given high resolution imagery, a textural index could prove useful for mapping woody plant densities and monitoring woody plant encroachment across savanna landscapes. Spatial heterogeneity introduced through mixtures of...

  14. Validation of BEHAVE fire behavior predictions in oak savannas using five fuel models

    Science.gov (United States)

    Keith Grabner; John Dwyer; Bruce Cutter

    1997-01-01

    Prescribed fire is a valuable tool in the restoration and management of oak savannas. BEHAVE, a fire behavior prediction system developed by the United States Forest Service, can be a useful tool when managing oak savannas with prescribed fire. BEHAVE predictions of fire rate-of-spread and flame length were validated using four standardized fuel models: Fuel Model 1 (...

  15. 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

  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. A condition metric for Eucalyptus woodland derived from expert evaluations.

    Science.gov (United States)

    Sinclair, Steve J; Bruce, Matthew J; Griffioen, Peter; Dodd, Amanda; White, Matthew D

    2018-02-01

    The evaluation of ecosystem quality is important for land-management and land-use planning. Evaluation is unavoidably subjective, and robust metrics must be based on consensus and the structured use of observations. We devised a transparent and repeatable process for building and testing ecosystem metrics based on expert data. We gathered quantitative evaluation data on the quality of hypothetical grassy woodland sites from experts. We used these data to train a model (an ensemble of 30 bagged regression trees) capable of predicting the perceived quality of similar hypothetical woodlands based on a set of 13 site variables as inputs (e.g., cover of shrubs, richness of native forbs). These variables can be measured at any site and the model implemented in a spreadsheet as a metric of woodland quality. We also investigated the number of experts required to produce an opinion data set sufficient for the construction of a metric. The model produced evaluations similar to those provided by experts, as shown by assessing the model's quality scores of expert-evaluated test sites not used to train the model. We applied the metric to 13 woodland conservation reserves and asked managers of these sites to independently evaluate their quality. To assess metric performance, we compared the model's evaluation of site quality with the managers' evaluations through multidimensional scaling. The metric performed relatively well, plotting close to the center of the space defined by the evaluators. Given the method provides data-driven consensus and repeatability, which no single human evaluator can provide, we suggest it is a valuable tool for evaluating ecosystem quality in real-world contexts. We believe our approach is applicable to any ecosystem. © 2017 State of Victoria.

  18. Severe dry winter affects plant phenology and carbon balance of a cork oak woodland understorey

    Science.gov (United States)

    Correia, A. C.; Costa-e-Silva, F.; Dubbert, M.; Piayda, A.; Pereira, J. S.

    2016-10-01

    Mediterranean climates are prone to a great variation in yearly precipitation. The effects on ecosystem will depend on the severity and timing of droughts. In this study we questioned how an extreme dry winter affects the carbon flux in the understorey of a cork oak woodland? What is the seasonal contribution of understorey vegetation to ecosystem productivity? We used closed-system portable chambers to measure CO2 exchange of the dominant shrub species (Cistus salviifolius, Cistus crispus and Ulex airensis), of the herbaceous layer and on bare soil in a cork oak woodland in central Portugal during the dry winter year of 2012. Shoot growth, leaf shedding, flower and fruit setting, above and belowground plant biomass were measured as well as seasonal leaf water potential. Eddy-covariance and micrometeorological data together with CO2 exchange measurements were used to access the understorey species contribution to ecosystem gross primary productivity (GPP). The herbaceous layer productivity was severely affected by the dry winter, with half of the yearly maximum aboveground biomass in comparison with the 6 years site average. The semi-deciduous and evergreen shrubs showed desynchronized phenophases and lagged carbon uptake maxima. Whereas shallow-root shrubs exhibited opportunistic characteristics in exploiting the understorey light and water resources, deep rooted shrubs showed better water status but considerably lower assimilation rates. The contribution of understorey vegetation to ecosystem GPP was lower during summer with 14% and maximum during late spring, concomitantly with the lowest tree productivity due to tree canopy renewal. The herbaceous vegetation contribution to ecosystem GPP never exceeded 6% during this dry year stressing its sensitivity to winter and spring precipitation. Although shrubs are more resilient to precipitation variability when compared with the herbaceous vegetation, the contribution of the understorey vegetation to ecosystem GPP can

  19. Effects of Litter Removal and Addition on the Nutrient Mineralization Dynamics in Hyperseasonal Tropical Savannas of the Brazilian Pantanal

    Science.gov (United States)

    Hentz, C. S.; Pinto-Jr, O. B.; Vourlitis, G. L.

    2015-12-01

    The tropical savanna of Brazil (cerrado) is extremely species diverse and it encompasses many different physiognomic features, which are influenced by rainfall, fire, and soil nutrient availability. Plant litter decomposition recycles nutrients to the soil, and in turn, assists plant growth. However the rate at which these nutrients become available to the soil is poorly understood. Thus, a six month field experiment that encompassed the wet and dry seasons was conducted to assess how different quantities of litter inputs affect nutrient (P, N, C, K, Ca, and Mg) availability. It was hypothesized that nutrient mineralization would be significantly influenced by manipulation of the surface litter and that there would be a positive correlation between soil moisture and nutrient mineralization. Initial results indicate that there were significant differences in mineralization over time for all nutrients, except P, supporting our hypothesis of changes in mineralization with soil moisture. However, there were no significant differences between litter treatments and net mineralization rates for all the nutrients tested. Our results indicate that litterpool size has little effect on short-term nutrient mineralization dynamics.

  20. Arborealities: The Tactile Ecology of Hardy’s Woodlanders

    Directory of Open Access Journals (Sweden)

    William A. Cohen

    2014-10-01

    Full Text Available This article asks what consequences two recent movements in scholarship - affect theory and environmental studies - might have for understanding the Victorian tactile imagination. Thomas Hardy's 1887 novel 'The Woodlanders' provides a means of addressing this question, for it shares with posthumanist critics a view that people are material things in a world of things, and that the world is itself a collection of vital agencies and networked actors. Hardy shows how a tactile modality provides a point of entry into discussions of both affect and ecology, situating the human in a proximate, contiguous relation to both bodily and environmental materialities. 'The Woodlanders' offers a world in which trees, in particular, work on - and are in turn worked on by - human objects; a world in which, one might say, the trees are people and the people are trees. This arboreality is far from a sentimental oneness with nature, nor is it an exercise in anthropomorphization. Instead, it provides a recognition of the inhuman, material, and sensate aspects of the human; or, perhaps better, of the human as rooted, budding, leafy, and abloom. Like some recent theoretical accounts, 'The Woodlanders' disperses agency among human and non-human elements alike, employing a tactile mode of representation to break down distinctions between them. Normal 0 false false false EN-US X-NONE X-NONE

  1. Predicting Polylepis distribution: vulnerable and increasingly important Andean woodlands

    Directory of Open Access Journals (Sweden)

    Brian R. Zutta

    2012-11-01

    Full Text Available Polylepis woodlands are a vital resource for preserving biodiversity and hydrological functions, which will be altered by climate change and challenge the sustainability of local human communities. However, these highaltitude Andean ecosystems are becoming increasingly vulnerable due to anthropogenic pressure including fragmentation, deforestation and the increase in livestock. Predicting the distribution of native woodlands has become increasingly important to counteract the negative effects of climate change through reforestation and conservation. The objective of this study was to develop and analyze the distribution models of two species that form extensive woodlands along the Andes, namely Polylepis sericea and P. weberbaueri. This study utilized the program Maxent, climate and remotely sensed environmental layers at 1 km resolution. The predicted distribution model for P. sericea indicated that the species could be located in a variety of habitats along the Andean Cordillera, while P. weberbaueri was restricted to the high elevations of southern Peru and Bolivia. For both species, elevation and temperature metrics were the most significant factors for predicted distribution. Further model refinement of Polylepis and other Andean species using increasingly available satellite data demonstrate the potential to help define areas of diversity and improve conservation strategies for the Andes.

  2. Woodland Extraction from High-Resolution CASMSAR Data Based on Dempster-Shafer Evidence Theory Fusion

    OpenAIRE

    Lijun Lu; Wenjun Xie; Jixian Zhang; Guoman Huang; Qiwei Li; Zheng Zhao

    2015-01-01

    Mapping and monitoring of woodland resources is necessary, since woodland is vital for the natural environment and human survival. The intent of this paper is to propose a fusion scheme for woodland extraction with different frequency (P- and X-band) polarimetric synthetic aperture radar (PolSAR) and interferometric SAR (InSAR) data. In the study area of Hanjietou, China, a supervised complex Wishart classifier based on the initial polarimetric feature analysis was first applied to the PolSAR...

  3. Plant species as a therapeutic resource in areas of the savanna in the state of Pernambuco, Northeast Brazil.

    Science.gov (United States)

    Saraiva, Manuele Eufrasio; Ulisses, Ana Vartan Ribeiro de Alencar; Ribeiro, Daiany Alves; de Oliveira, Liana Geraldo Souza; de Macêdo, Delmácia Gonçalves; de Sousa, Francisca de Fátima Silva; de Menezes, Irwin Rose Alencar; Sampaio, Everardo Valadares de Sá Barretto; Souza, Marta Maria de Almeida

    2015-08-02

    Ethnobotanical studies have contributed significantly in research of plants with therapeutic potential. The aim of the present study was to learn about the use of native medicinal plants cited by the traditional population in "cerradão" (savanna woodland) areas in Northeast Brazil, providing data on therapeutic indications of the species used and their versatility. Semi-structured interviews were conducted on the basis of a standardized questionnaire designed for key informants selected using the "snowball" technique. The selection of plants species with therapeutic potential was performed on the basis of the relative importance (RI) and informant consensus fator (ICF). A total of 78 species were indicated for 87 therapeutic purposes. Of these, 11 species presented great versatility of use (RI>1), as e.g.including Copaifera langsdorffii Desf., Hybanthus calceolaria (Mart.) Plumel., Heliotropium cf. indicum L., Croton zehntneri, Croton heliotropiifolius, Myracrodruon urundeuva, Stryphnodendro rotundifolium. Medicinal uses could be generalized Pax & K. Hoffm and Hymenaea courbaril L. The therapeutic indications were grouped into 14 use 15 categories with 594 species-category combinations. The largest number of medicinal species was indicated for illnesses or undefined pain, followed by diseases associated with respiratory, digestive and genitourinaryof body systems. The factor informant consensus highlighted the agreement in the use of plants and showed that the, of which Diseases of the Nervous System and, Diseases of the Circulatory System had the greatest agreement 1.0 and 0.87 repectively, Disorders of the Visual Sensory System - Eyes and Respiratory System Disorder showed the highest agreement of use. Most of the species cited by the key informants are well known scientifically, but it is interesting that some have been studied little or not all with regard to confirming their purported medicinal properties and can contribute substantially to pharmacological

  4. Validation of Global Evapotranspiration Product (MOD16 using Flux Tower Data in the African Savanna, South Africa

    Directory of Open Access Journals (Sweden)

    Abel Ramoelo

    2014-08-01

    Full Text Available Globally, water is an important resource required for the survival of human beings. Water is a scarce resource in the semi-arid environments, including South Africa. In South Africa, several studies have quantified evapotranspiration (ET in different ecosystems at a local scale. Accurate spatially explicit information on ET is rare in the country mainly due to lack of appropriate tools. In recent years, a remote sensing ET product from the MODerate Resolution Imaging Spectrometer (MOD16 has been developed. However, its accuracy is not known in South African ecosystems. The objective of this study was to validate the MOD16 ET product using data from two eddy covariance flux towers, namely; Skukuza and Malopeni installed in a savanna and woodland ecosystem within the Kruger National Park, South Africa. Eight day cumulative ET data from the flux towers was calculated to coincide with the eight day MOD16 products over a period of 10 years from 2000 to 2010. The Skukuza flux tower results showed inconsistent comparisons with MOD16 ET. The Malopeni site achieved a poorer comparison with MOD16 ET compared to the Skukuza, and due to a shorter measurement period, data validation was performed for 2009 only. The inconsistent comparison of MOD16 and flux tower-based ET can be attributed to, among other things, the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs. MODIS pixel. MOD16 is important for global inference of ET, but for use in South Africa's integrated water management, a locally parameterized and improved product should be developed.

  5. Status of woodland caribou in western north America

    Directory of Open Access Journals (Sweden)

    E. Janet Edmonds

    1991-10-01

    Full Text Available A review of current population size and trends of woodland caribou (Rangifer tarandus caribou in seven jurisdictions in western North America shows a wide range of situations. A total maximum population estimate of woodland caribou west of the Ontario/Manitoba border is 61 090. Of 44 herds or populations described in this review: 14 are stable; two are stable to slightly decreasing; four are decreasing; four are increasing; and 22 are of unknown status. Caribou are classified as a threatened species in Alberta and as an endangered species in Washington/Idaho. The decline of caribou in North America following settlement (Bergerud, 1974 has continued along the southern edge of woodland caribou distribution. Direct loss of habitat to logging, mines and dams continued throughout the I960s, 1970s and 1980s. The secondary effects of these habitat changes, (i.e. increased roads leading to increased hunting and poaching, and increased early succession habitat leading to increased alternate prey/predator densities has led in some cases to the total loss or decreased size of local herds. Three ecotypes of woodland caribou are described and their relative distribution delineated. These ecotypes live under different environmental conditions and require different inventory and management approaches. Woodland caribou herds in northern B.C., Yukon and N.W.T. generally are of good numbers and viable (stable or increasing, and management primarily is directed at regulating human harvest and natural predation to prevent, herd declines. Land use activities such as logging or energy development are not extensive. Managers in southern caribou ranges stress the need for a better understanding of caribou population stability within mixed prey/predator regimes; how habitat changes (eg. through logging affect these regimes; and how to develop effective land use guidelines for resource extraction that can sustian caribou populations and maintain resource industries

  6. 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 ...

  7. Woodland caribou management in Alberta: historical perspectives and future opportunities

    Directory of Open Access Journals (Sweden)

    Elston H. Dzus

    2007-04-01

    Full Text Available Woodland caribou conservation has been the topic of much debate for the past few decades. By the late 1970s there was growing concern about declining woodland caribou populations and the interaction between industrial activities and woodland caribou. Initial concerns led to the closure of the licensed hunting season in 1981. Early confrontation between government and industry in the late 1980s transformed into a series of evolving collaborative ventures. Improving our understanding of the basic ecology of woodland caribou in Alberta was at the center of early research efforts; more recent studies have examined the effects of industrial activities on caribou and effectiveness of various mitigation factors. Despite having amassed an impressive body of information from a research and monitoring perspective, progress on implementing effective management actions has been less dramatic. Industry has endured significant costs implementing a variety of perceived conservation initiatives, but caribou populations continued to decline through the last few decades. While some parties feel more research is needed, there is growing consensus that changes to habitat as induced by human activities are important factors influencing current caribou declines. Predation is a proximate cause of most caribou mortality. Climate change mediated alterations to habitat and predator-prey interactions remain a key source of uncertainty relative to future caribou population trends. Management actions will need to deal with long term habitat changes associated with human land use and short term implications of increased predation. In 2005, the provincial minister responsible for caribou conservation responded to the draft 2004 recovery plan and created the Alberta Caribou Committee (ACC. The goal of the ACC is to maintain and recover woodland caribou in Alberta’s forest ecosystems while providing opportunities for resource development, following guidance provided by the

  8. Influence of stocking rate, range condition and rainfall on seasonal beef production patterns in the semi-arid savanna of KwaZulu-Natal

    CSIR Research Space (South Africa)

    Hatch, GP

    1997-06-01

    Full Text Available of the Swartland form with Clovelly, Hutton, Mispah, Glenrosa and Bonheim forms, occurred at the sites (Soil Classification Working Group, 1991). Three treatments at each site were stocked at the start of each season (October) with 250 kg Brahman-cross cattle... rate. Derivation of the relation from the results of grazing trials. J. Agric. Sci. 83. 335-342. MCDONALD, I.A.W. 1982. The influence of short-term climatic fluctuations on the distribution of savanna organisms in southern Africa. M.Sc. thesis...

  9. Impacts of hydraulic redistribution on overstory-understory interactions in a semiarid savanna

    Science.gov (United States)

    Barron-Gafford, G.; Minor, R. L.; Hendryx, S.; Lee, E.; Sutter, L., Jr.; Colella, A.; Murphy, P.; Sanchez-Canete, E. P.; Hamerlynck, E. P.; Kumar, P.; Scott, R. L.

    2016-12-01

    Hydraulic redistribution (HR) is an important ecohydrological process in dryland environments by which plants preferentially move water from wet to dry soil layers. How does this water movement by the overstory influence physiological activity in the understory? Are there periods of facilitation when the tree is lifting water and periods of competition when the water is being moved deeper in the profile? We combined trunk, lateral root, and taproot sap flow data, and linked these measures with shallow and deep soil moisture data to show that soil moisture gradients control hydraulic redistribution in overstory mesquite trees. During prolonged inter-rain periods of drought and in response to periods of high vapor pressure deficits, mesquites drew upon this deeper, stored water to meet biological demands. We created plots under mesquite that experienced HR and plots where HR was physically prohibited to quantify the impacts of HR on understory performance. We measured carbon and water exchange at the leaf-level on mesquite and understory grass and for entire understory ecosystem using a large, portable chamber. We found that HR provided a drought-buffering capacity for the overstory mesquite and a significant decrease in mesquite photosynthesis in trees where the capacity for HR was reduced. While we had hypothesized that water lifted by the mesquite in periods of drought would facilitate understory grass function, we found no evidence for this. In fact, we found that grasses actually conducted higher rates of photosynthesis in plots where HR was eliminated. Ultimately, we found that HR in upland savannas, where there is little to no access to deep water, yields a competitive interaction between overstory mesquites and understory grasses at the scale of individual precipitation pulse events and across entire growing seasons.

  10. Effect of tillage and fertilizer on soil chemical properties, leaf nutrient ...

    African Journals Online (AJOL)

    Effect of tillage and fertilizer on soil chemical properties, leaf nutrient content and yield of soyabean in the Guinea Savanna zone of Nigeria. A Ali, SA Ayuba, SO Ojeniyi. Abstract. No Abstract. Nigerian Journal of Soil Science Vol. 16 (1) 2006: pp. 126-130. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL ...

  11. Effects of Charcoal Production on Soil in Kiln Sites in Ibarapa Area ...

    African Journals Online (AJOL)

    In Nigeria, charcoal is a major source of energy, especially among the urban poor. However, the effects of charcoal production on the environment, especially the soil, have not been adequately documented. This study examines the effects of charcoal production in kiln sites on soil properties in the derived savanna zone of ...

  12. Mean residence time of soil organic matter associated with kaolinite and smectite

    NARCIS (Netherlands)

    Wattel-Koekkoek, E.J.W.; Buurman, P.; Plicht, J. van der; Wattel, E.; Breemen, N. van

    To gain insight into the effect of clay mineralogy on the turnover of organic matter, we analysed the C-14 activity of soil organic matter associated with clay in soils dominated by kaolinite and smectite in natural savanna systems in seven countries. Assuming that carbon inputs and outputs are in

  13. Profile distribution of clay, Ca, Mg and K in some soils of the ...

    African Journals Online (AJOL)

    The objective of this study was to establish a relationship between the distribution of clay, Mg, Ca, K and their ratios in some Nigerian soils. A total of 72 profile pits were prepared in 7 locations distributed in Niger, Edo, Oyo, Ogun and Osun States in the savanna region of Nigeria. The soils (comprising 49 Alfisols, 16 Entisols ...

  14. [Impact of land use type on stability and organic carbon of soil aggregates in Jinyun Mountain].

    Science.gov (United States)

    Li, Jian-Lin; Jiang, Chang-Sheng; Hao, Qing-Ju

    2014-12-01

    Soil aggregates have the important effect on soil fertility, soil quality and the sustainable utilization of soil, and they are the mass bases of water and fertilizer retention ability of soil and the supply or release of soil nutrients. In this paper, in order to study the impact of land use type on stability and organic carbon of soil aggregates in Jinyun Mountain, we separated four land use types of soil, which are woodland, abandoned land, orchard and sloping farmland by wet sieving method, then we got the proportion of large macroaggregates (> 2 mm), small macroaggregates (0.25-2 mm), microaggregates (53 μm-0.25 mm) and silt + clay (aggregate fraction in soil depth of 0-60 cm and calculated the total content of organic carbon of all aggregates fraction in each soil. The results showed that reclamation of woodland will lead to fragmentation of macroaggregates and deterioration of soil structure, and the proportion of macroaggrgates (> 0.25 mm) were 44.62% and 32.28% respectively in the soils of orchard and sloping farmland, which reduced 38.58% (P soil fraction from silt + clay to large macroaggregates and small macroaggregates, so it will improve the soil structure. MWD (mean weight diameter) and GMD (geometric mean diameter) are important indicators of evaluating the stability of soil aggregates. We found the MWD and GWD in soil depth of 0-60 cm in orchards and sloping farmland were significantly lower than those in woodland (P stability of soil aggregates, and they will be separated more easily by water. However, after changing the sloping farmland to abandoned land will enhance the stability of soil aggregates, and improve the ability of soil to resist external damage. The organic carbon content in each soil aggregate of four land use types decreased with the increase of soil depth. In soil depth of 0-60 cm, the storage of organic carbon of large macroaggregates in each soil are in orders of woodland (14.98 Mg x hm(-2)) > abandoned land (8.71 Mg x hm(-2

  15. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  16. Detecting animals in African Savanna with UAVs and the crowds

    Science.gov (United States)

    Rey, Nicolas; Volpi, Michele; Joost, Stéphane; Tuia, Devis

    2017-10-01

    Unmanned aerial vehicles (UAVs) offer new opportunities for wildlife monitoring, with several advantages over traditional field-based methods. They have readily been used to count birds, marine mammals and large herbivores in different environments, tasks which are routinely performed through manual counting in large collections of images. In this paper, we propose a semi-automatic system able to detect large mammals in semi-arid Savanna. It relies on an animal-detection system based on machine learning, trained with crowd-sourced annotations provided by volunteers who manually interpreted sub-decimeter resolution color images. The system achieves a high recall rate and a human operator can then eliminate false detections with limited effort. Our system provides good perspectives for the development of data-driven management practices in wildlife conservation. It shows that the detection of large mammals in semi-arid Savanna can be approached by processing data provided by standard RGB cameras mounted on affordable fixed wings UAVs.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Ipomea asarifolia (Desr), A Potential Cover Crop for Soil Fertility ...

    African Journals Online (AJOL)

    Ipomea asarifolia (Desr), A Potential Cover Crop for Soil Fertility Improvement in The Sudan Savanna Region, Nigeria. ... University main Campus; VC complex area, University stadium area, Behind new library area and opposite IBB centre area and four distances from the plant (control, plant base, 0.5 m and 1 m from the ...

  19. Herbage Dynamics and Soils of two Different Sites of Calotropis ...

    African Journals Online (AJOL)

    The relative abundance of Calotropis procera (Ait) R. Br. (Asclepiadaeceae), types and relative abundance of herb species in association with it and the soil types in two different sites, Tudun Sarki (ABU) and Basawa in the Northern Guinea Savanna zone of Nigeria were assessed. To determine herbage dynamics, herbs in ...

  20. Forage yield and soil improvement potential of some annual and ...

    African Journals Online (AJOL)

    Six annual and semi-perennial legumes were evaluated for forage production and their effect on soil properties at two sites, Pokoase (transition zone) and Nyankpala (Guinea savanna zone). The common legumes evaluated at the two sites were Lablab purpureus, Desmodium distortum, Crotalaria ochroleuca, and ...

  1. Climate change and long-term fire management impacts on Australian savannas.

    Science.gov (United States)

    Scheiter, Simon; Higgins, Steven I; Beringer, Jason; Hutley, Lindsay B

    2015-02-01

    Tropical savannas cover a large proportion of the Earth's land surface and many people are dependent on the ecosystem services that savannas supply. Their sustainable management is crucial. Owing to the complexity of savanna vegetation dynamics, climate change and land use impacts on savannas are highly uncertain. We used a dynamic vegetation model, the adaptive dynamic global vegetation model (aDGVM), to project how climate change and fire management might influence future vegetation in northern Australian savannas. Under future climate conditions, vegetation can store more carbon than under ambient conditions. Changes in rainfall seasonality influence future carbon storage but do not turn vegetation into a carbon source, suggesting that CO₂ fertilization is the main driver of vegetation change. The application of prescribed fires with varying return intervals and burning season influences vegetation and fire impacts. Carbon sequestration is maximized with early dry season fires and long fire return intervals, while grass productivity is maximized with late dry season fires and intermediate fire return intervals. The study has implications for management policy across Australian savannas because it identifies how fire management strategies may influence grazing yield, carbon sequestration and greenhouse gas emissions. This knowledge is crucial to maintaining important ecosystem services of Australian savannas. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  2. 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.

  3. Quantitative analysis of savanna wood species, in Teixeira, state of Paraiba, Brazil

    Directory of Open Access Journals (Sweden)

    José Adelmo Nunes Leite

    2015-06-01

    Full Text Available Savanna is the vegetation of semi-arid northeastern region of Brazil, which is largely determined by climate and topography. The municipality of Teixeira in the state of Paraiba presents hyperxerophilous shrub-arboreal caatinga land cover, which differs in size and density from those found in Sertaneja Depression, due to higher humidity. The objective of this work was to quantify forest remnant in the municipality of Teixeira, using geographic information system and forest inventory techniques. Native vegetation was mapped using satellite images, from November, 2008. Forest inventory was carried out in 40 sample plots (20 m × 20 m that were selected systematically. Height and diameter at 1.30 m from soil level (DBH were measured in every tree with DBH ≥ 10 cm. Each tree was identified by common and scientific names. A total of 4,911 trees were sampled, representing 46 species and 24 families that corresponds to 3,069 trees ha-1. The species with highest importance value (IV were: Croton sonderianus, Mimosa tenuiflora and Piptadenia stipulacea and the more important families were Euphorbiaceae, Mimosaceae and Caesalpinaceae. The municipality of Teixeira has its best preserved areas in mountainous regions with difficult access.

  4. Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference

    Directory of Open Access Journals (Sweden)

    Alla eShvaleva

    2015-10-01

    Full Text Available Cork oak woodlands (montado are agroforestry systems distributed all over the Mediterranean basin with a very important social, economic and ecological value. A generalized cork oak decline has been occurring in the last decades jeopardizing its future sustainability. It is unknown how loss of tree cover affects microbial processes that are consuming greenhouse gas fluxes in the montado ecosystem. The study was conducted under two different conditions in the natural understory of a cork oak woodland in center Portugal: under tree canopy (UC and open areas without trees (OA. Fluxes of methane and nitrous oxide were measured with a static chamber technique. In order to quantify methanotrophs and bacteria capable of nitrous oxide consumption, we used quantitative real-time PCR targeting the pmoA and nosZ gene encoding the subunit of particulate methane mono-oxygenase and catalytic subunit of the nitrous oxide reductase, respectively. A significant seasonal effect was found on CH4 and N2O fluxes and pmoA and nosZ gene abundance. Tree cover had no effect on methane fluxes; conversely, whereas the UC plots were net emitters of nitrous oxide, the loss of tree cover resulted in a shift in the emission pattern such that the OA plots were a net sink for nitrous oxide. In a seasonal time scale, the UC had higher gene abundance of Type I methanotrophs. Methane flux correlated negatively with abundance of Type I methanotrophs in the UC plots. Nitrous oxide flux correlated negatively with nosZ gene abundance at the OA plots in contrast to that at the UC plots. In the UC soil, SOM had a positive effect on soil extracellular enzyme activities (EEA, which correlated positively with the N2O flux. Our results demonstrated that tree cover affects soil properties, key enzyme activities and abundance of microorganisms and, consequently net CH4 and N2O exchange.

  5. Effects of thinning, burning, seeding, and slash arrangements on understory communities in pinyon-juniper woodlands of northern Arizona

    Directory of Open Access Journals (Sweden)

    Maria R. Irwin

    2011-06-01

    Full Text Available Pinyon-juniper woodlands are a dominant ecosystem in the American Southwest that have been increasing in density over the last century, generating concerns about the effects on wildlife habitat, livestock forage, and wildfire risk. We tested 16 treatment combinations designed to restore stands to historic conditions by examining the impact on understory plant richness and abundance. We thinned three sites comprised of different parent soil materials: limestone, sandstone, and basalt. Each site had one of four slash arrangements: piled, broadcast, clustered, or no thinning. Each of these arrangements received a different burning/seeding treatment: prescribed fire, seeding, prescribed fire and seeding, or none. This study corresponded with the driest period in the last 55 years, and plant species richness decreased by an average of 40% from the previous year in the control plots. Richness was significantly different due to slash arrangement at the basalt site only. Burning or seeding did not affect richness at any of the sites. Plant species abundance was generally low and not influenced by treatment or site. This study demonstrates that extensive ecosystem manipulation in the pinyon-juniper woodlands of northern Arizona did not affect understory richness or abundance the first year after treatment during a drought.

  6. Will elevated CO2 alter fuel characteristics and flammability of eucalypt woodlands?

    Science.gov (United States)

    Collins, Luke; Resco, Victor; Boer, Matthias; Bradstock, Ross; Sawyer, Robert

    2016-04-01

    Rising atmospheric CO2 may enhance forest productivity via CO2 fertilisation and increased soil moisture associated with water savings, potentially resulting in increased woody plant abundance i.e. woody thickening. Changes to vegetation structure via woody thickening, as well as changes to vegetation properties (e.g. leaf characteristics and moisture content), may have important implications for ecosystem flammability and fire regimes. Understanding how elevated CO2 alters flammability and fire regimes will have implications for ecosystem dynamics, particularly carbon sequestration and emissions. We present data from Free Air CO2 Enrichment (EucFACE) and whole tree growth chamber (WTC) experiments to assess the effect of elevated CO2 on fuel properties and flammability of eucalypt woodlands. Experiments involved ambient (˜400 ppm) and elevated CO2treatments, with elevated treatments being +150 ppm and +240 ppm at EucFACE and the WTCs respectively. We examined the response of vegetation parameters known to influence ecosystem flammability, namely (i) understorey vegetation characteristics (ii) understorey fuel moisture and (iii) leaf flammability. Understorey growth experiments at EucFACE using seedlings of two common woody species (Hakea sericia, Eucalyptus tereticornis) indicate that elevated CO2 did not influence stem and leaf biomass, height or crown dimensions of seedlings after 12 months exposure to experimental treatments. Temporal changes to understorey live fuel moisture were assessed at EucFACE over an 18 month period using time lapse cameras. Understorey vegetation greenness was measured daily from digital photos using the green chromatic coordinate (GCC), an index that is highly correlated with live fuel moisture (R2 = 0.90). GCC and rates of greening and browning were not affected by elevated CO2, though they were highly responsive to soil moisture availability and temperature. This suggests that there is limited potential for elevated CO2 to alter

  7. Variations in wood production and C storage of tropical savanna trees along an edaphic gradient in Mato Grosso, Brazil

    Science.gov (United States)

    Vourlitis, G. L.; Lobo, F. D. A., Sr.; Borges Pinto, O.; Dalmagro, H. J.; Zappia, A. J.; Nogueira, J. D. S.

    2016-12-01

    Brazilian savanna (cerrado) is composed of vegetation and soil types that are spatially variable. To understand how woody growth and carbon (C) storage vary as a function of soil physical and chemical properties we installed plastic, spring-loaded dendrometers on over 500 trees in nine cerrado stands that varied in physiognomy, soil physical and chemical properties, and hydrology and measured changes in trunk diameter over a period of one year. Rates of trunk C storage ranged between -0.20 MgC ha-1 y-1 for upland grass-dominated cerrado (campo sujo) to 1.36 MgC ha-1 y-1 for hyperseasonal (seasonally flooded) gallery forest (cerradão). Using ANCOVA to factor out potential differences in site hydrology (flooded vs. upland), which are known to affect tree growth, we found that rates of trunk growth and C storage were significantly related to total soil N, extractable Ca, Mg, Al, and cation exchange capacity (CEC), and soil texture (sand and clay content and bulk density). Linear correlation indicated that both trunk growth and C storage were positively related to N, Ca, Mg, Al, CEC, and clay content and negatively related to sand content and bulk density. These results suggest that tree growth and C storage in our cerrado stands are nutrient limited; however, links between growth and soil texture may also indicate the potential for water limitation during the dry season. These data suggest that variations in soil fertility are important controls on ecosystem C storage in Brazilian cerrado. These results are qualitatively similar to those reported for tropical forests across regional fertility gradients in the Amazon Basin, and have implications for the maintenance of cerrado ecosystem C storage.

  8. Patterns of Woody Growth for Brazilian Savanna (Cerrado) Trees in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil

    Science.gov (United States)

    Zappia, A. J.; Vourlitis, G. L.; Pinto-Jr, O. B.

    2015-12-01

    The Brazilian savanna, locally known as cerrado, is a major ecosystem that covers a vast majority of central Brazil. Little is known about how woody growth within the cerrado is affected by soil properties such as texture and/or nutrient availability. Thus, in this study we assessed the relationship between woody growth and soil properties in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil. We sampled 4-5 vegetation stands in each site that varied in hydrology, soil type, and vegetation composition and structure, and measured diameter at breast height, wood density, and soil nutrient concentration and physical properties every 5-10 m along a 100 m long transect. We hypothesized that as tree diameter at breast height increases, annual tree growth rate will decrease and that woody carbon (C) storage will increase as a function of soil nutrient availability. Our preliminary data support our hypotheses. Tree growth rates declined with tree size in both the Cuiaba Basin and the Pantanal. Rates of woody C storage, both on a per tree basis (kgC tree-1 year-1) and on a per unit ground area basis (kgC m-2 year-1) were significantly positively correlated with soil extractable phosphorus (P), calcium (Ca), and clay content, while only woody C storage on a per tree basis was positively correlated with potassium (K), magnesium (Mg), and cation exchange capacity (CEC). These data suggest that rates of woody C storage in cerrado are nutrient limited, while correspondence between C storage and soil physical properties could indicate both nutrient and water limitations to C storage.

  9. Understanding the ecological complexity of semi-arid savannas using remote sensing

    Science.gov (United States)

    Huang, Cho-Ying

    Savannas are ecosystems with a background herbaceous layer and intermittently distributed woody plants. A large body of literature has revealed that the ecological processes within savannas are complex and the spatial pattern and abundance of woody and herbaceous plants through time may be influenced by various factors. This dissertation research consists of three studies demonstrating the feasibility of utilizing remote sensing techniques to better understand the ecological complexity of semisavannas in southern Arizona, USA. The first study investigated the impacts of recent fire disturbance on structural changes of woody plants at varying scales. Results indicated that while field canopy cover and remote sensing woody cover fraction were strong predictors of woody biomass at local and landscape scales, respectively, fire history can significantly alter the nature of these relationships. This work suggested that simple predictions of woody biomass from field and remote sensing cover measures without considering disturbance will underestimate biomass in mature undisturbed settings, and overestimate biomass in recently disturbed locations in most cases. The second study investigated the ecological stability by implementing a top-down approach to analyze 21 years (1984--2005) of Landsat satellite data. This work suggested that a stable system needed to receive sufficient precipitation for basic plant growth, to be on coarse-textured and shallow soils that can efficiently store precipitation but inhibit the proliferation of woody plants, and to be on east facing slopes which can support clement microclimate. The perspectives gained from this study will enable us to target fine-scale field studies seeking to address circumstances conferring ecosystem stability; and improve predictions of potential carbon stocks in drylands. The third study derived the unique temporal and spatial signatures of vegetation [the Normalized Difference Vegetation Index (NDVI)] and

  10. Evaporation over a Heterogeneous Mixed Savanna-Agricultural Catchment using a Distributed Wireless Sensor Network

    Science.gov (United States)

    Ceperley, N. C.; Mande, T.; Barrenetxea, G.; Vetterli, M.; Yacouba, H.; Repetti, A.; Parlange, M. B.

    2010-12-01

    Small scale rain fed agriculture is the primary livelihood for a large part of the population of Burkina Faso. Regional climate change means that this population is becoming increasingly vulnerable. Additionally, as natural savanna is converted for agriculture, hydrological systems are observed to become less stable as infiltration is decreased and rapid runoff is increased to the detriment of crop productivity, downstream populations and local water sources. The majority of the Singou River Basin, located in South East Burkina Faso is managed by hunting reserves, geared to maintaining high populations of wild game; however, residents surrounding the protected areas have been forced to intensify agriculture that has resulted in soil degradation as well as increases in the frequency and severity of flooding and droughts. Agroforestry, or planting trees in cultivated fields, has been proposed as a solution to help buffer these negative consequences, however the specific hydrologic behavior of the watershed land cover is unknown. We have installed a distributed sensor network of 17 Sensorscope wireless meteorological stations. These stations are dispersed across cultivated rice and millet fields, natural savanna, fallow fields, and around agroforestry fields. Sensorscope routes data through the network of stations to be delivered by a GPRS connection to a main server. This multi hop network allows data to be gathered over a large area and quickly adapts to changes in station performance. Data are available in real time via a website that can be accessed by a mobile phone. The stations are powered autonomously by small photovoltaic panels. This deployment is the first time that these meteorological stations have been used on the African continent. Initial calibration with measures from 2 eddy covariance stations allows us to calculate the energy balance at each of the Sensorscope stations. Thus, we can observe variation in evaporation over the various land cover in the

  11. Causes and consequences of tree mortality in Piñon-Juniper woodlands. Introducing an ecosystem scale rainfall manipulation.

    Science.gov (United States)

    Yepez, E. A.; Elliot, J.; White, S. A.; Plaut, J. A.; McDowell, N. G.; Pockman, W. T.

    2007-05-01

    Tree mortality as a consequence of drought is widespread worldwide. In Piñon-Juniper woodlands of the semiarid North American Southwest this phenomenon is patent but the consequences for the functioning of these ecosystems remain largely unknown. Although several factors have been proposed to explain tree mortality following drought (e.g. plant desiccation, bark beetle attack), no substantial experimental evidence has been produced to give mechanistic explanations for the occurrence of these events, nor for the potential effects on the ecosystem carbon and water cycles following this rapid landscape transformation. In this work, we introduce a plant-to-ecosystem rainfall manipulation experiment in Piñon-Juniper woodlands at the Sevilleta LTER in central New Mexico, USA. The goal of our study is to understand the causes (plant-level) and consequences (ecosystem-level) of tree mortality and/or survival following experimental drought in these woodlands. Framed in hydraulic concepts involving the soil-plant-atmosphere continuum, we are investigating how Pinus edulis and Juniperus monosperma would respond to treatments of rainfall diversion and addition in replicated (n=3) 1600 m2 plots. Within this experimental framework, we are first describing the hydraulic architecture of both species to predict plant allocation patterns (e.g. root vs. leaf area) and assess tree-level water transport capacity and/or failure. We believe that a thorough understanding of the tree hydraulic characteristics controlling transpiration will allow us to make robust predictions about the likelihood of plant death or survival during drought episodes and concomitant effects on the ecosystem rain use efficiency. Pre-treatment results (summer-fall 2006) indicate that transpiration rates per unit of leaf area were highly sensitive to variation in hydraulic conductance in the soil and plants and varied according to the contrasting vulnerabilities to xylem cavitation between P. edulis and J

  12. Eddy flux and leaf level measurements of biogeni VOC emissions from Mopane woodland of Botswana

    NARCIS (Netherlands)

    Greenberg, J.P.; Guenter, A.; Harley, P.; Otter, L.; Veenendaal, E.M.; Hewwit, C.N.; James, A.E.; Owen, S.M.

    2003-01-01

    Biogenic volatile organic compound (BVOC) emissions were measured in a mopane woodland near Maun, Botswana in January–February 2001 as part of SAFARI 2000. This landscape is comprised of more than 95% of one woody plant species, Colophospermum mopane (Caesalpinaceae). Mopane woodlands extend over a

  13. Facilitation of Quercus ilex recruitment by shrubs in Mediterranean open woodlands

    NARCIS (Netherlands)

    Smit, C.; Ouden, den J.; Diaz, M.

    2008-01-01

    Question: Insufficient tree regeneration threatens the long-term persistence of biodiverse Mediterranean open oak woodlands. Could shrubs, scarce due to decades of management (clearing and ploughing), facilitate holm oak recruitment at both acorn and seedling stages? Location: Open oak woodlands in

  14. Small mammals in successional prairie woodlands of the northern Great Plains

    Science.gov (United States)

    Mark A. Rumble; John E. Gobeille

    2001-01-01

    Prairie woodlands comprise about 1 percent of the landscape in the northern Great Plains. However, prairie woodlands provide habitat for far more than 1 percent of the wildlife species that occur in the prairie region. With increasing pressures on natural resources, managers need methods for managing wildlife habitat and biodiversity that are based on ecological...

  15. Effects of short-rotation controlled burning on amphibians and reptiles in pine woodlands

    Science.gov (United States)

    Roger W. Perry; D. Craig Rudolph; Ronald E. Thill

    2012-01-01

    Fire is being used increasingly as a forest management tool throughout North America, but its effects on reptiles and amphibians in many ecosystems are unclear. Open woodlands with understories dominated by herbaceous vegetation benefit many wildlife species, but maintaining these woodlands requires frequent burning. Although many studies have compared herpetofaunal...

  16. Drought induced tree mortality and ensuing bark beetle outbreaks in southwestern pinyon-juniper woodlands

    Science.gov (United States)

    Michael J. Clifford; Monique E. Rocca; Robert Delph; Paulette L. Ford; Neil S. Cobb

    2008-01-01

    The current drought and ensuing bark beetle outbreaks during 2002 to 2004 in the Southwest have greatly increased tree mortality in pinyon-juniper woodlands. We studied causes and consequences of the drought-induced mortality. First, we tested the paradigm that high stand densities in pinyon-juniper woodlands would increase tree mortality. Stand densities did not...

  17. Diversity of woodlands in the groundnut basin of Kaffrine region in ...

    African Journals Online (AJOL)

    SARAH

    2013-03-30

    Mar 30, 2013 ... ABSTRACT. Objective: This work has examined the current state of woodlands in the groundnut basin to determine its importance. Methodology and results: The floristic diversity of woodlands in the Groundnut Basin of was studied through ecological parameters. The woody flora contained 75 species with ...

  18. Working woodlands: public demand, owner management, and government intervention in conserving mediterranean ranches and dehesas

    Science.gov (United States)

    Pablo Campos-Palacín; Lynn Huntsinger; Richard Standiford; David Martin-Barroso; Pedro Mariscal-Lorente; Paul F. Starrs

    2002-01-01

    The contributions of California and Spanish oak woodlands to owners, neighbors, and society are undervalued. Recent Spanish studies have begun to identify the components of value provided by traditional oak woodland agro-sylvo-pastoral systems, including environmental and self-consumption values. Work in California has revealed that self-consumption by owners, benefits...

  19. Facilitation of Quercus ilex recruitment by shrubs in Mediterranean open woodlands

    NARCIS (Netherlands)

    Smit, Christian; den Ouden, Jan; Diaz, Mario

    Question: Insufficient tree regeneration threatens the long-term persistence of biodiverse Mediterranean open oak woodlands. Could shrubs, scarce due to decades of management ( clearing and ploughing), facilitate holm oak recruitment at both acorn and seedling stages? Location: Open oak woodlands in

  20. USDA Forest Service National Woodland Owner Survey, 2011-2013: design, implementation, and estimation methods

    Science.gov (United States)

    Brett J. Butler; Brenton J. Dickinson; Jaketon H. Hewes; Sarah M. Butler; Kyle Andrejczyk; Marla. Markowski-Lindsay

    2016-01-01

    The National Woodland Owner Survey (NWOS) is conducted by the U.S. Forest Service, Forest Inventory and Analysis program to increase the understanding of the attitudes, behaviors, and demographics of private forest and woodland ownerships across the United States. The information is intended to help policy makers, resource managers, educators, service providers, and...

  1. Hydrologic vulnerability of western US rangelands in the wake of woodland encroachment and increasing wildfire activity

    Science.gov (United States)

    Pinyon and juniper woodlands have dramatically increased their range in the past 150 years and currently occupy more than 30 million ha of the western US. Range expansion has primarily occurred through encroachment into sagebrush rangelands. Woodland expansion and infill on western rangelands have a...

  2. Evaporation, sensible heat and canopy conductance of fallow savannah and patterned woodland in the Sahel

    NARCIS (Netherlands)

    Kabat, P.; Dolman, A.J.; Elbers, J.A.

    1997-01-01

    The behaviour of evaporation, sensible heat and canopy conductance of fallow savannah and patterned woodland in the Sahel is studied for the HAPEX-Sahel Intensive Observation Period. Both fallow savannah and patterned woodland reach evaporation rates of 4–5 mm day−1 during the rainy part of the IOP

  3. Energy-conserving site design: case study, The Woodlands, Texas

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, M

    1980-03-01

    The Woodlands is a HUD Title VII New Town located north of Houston. It includes 22,000 acres and the plan for the new town consists of 6 residential villages, a town center called the Metro Center and several additional tracts, such as the Trade Center for larger-scale industrial use. Each village is to be structured around one large and several supporting neighborhood centers. Ultimate population is planned to be 150,000. Included in this report are sections on background, team structure and organization, methodological considerations, the conventional and energy-conserving plan, constraints to implementation, and general conclusions and next phases.

  4. The Adolescent Condition in Thomas Hardy's The Woodlanders.

    Science.gov (United States)

    Nunan, Rosanna

    In The Woodlanders, Hardy examines the intersections between adolescence as scientific fact and adolescence as utilitarian economic construction. Hardy posits that the emergence of adolescence as a social category provides an opportunity for further, excessive control of young women in a patriarchal society when science is taken at its word, but, paradoxically, also opens up a space for a new kind of freedom and rebellion when the adolescent condition of nineteenth-century scientific theorists is seized for the very subversive qualities which the Victorians oppose.

  5. Are There Consistent Grazing Indicators in Drylands? Testing Plant Functional Types of Various Complexity in South Africa’s Grassland and Savanna Biomes

    Science.gov (United States)

    Linstädter, Anja; Schellberg, Jürgen; Brüser, Katharina; Moreno García, Cristian A.; Oomen, Roelof J.; du Preez, Chris C.; Ruppert, Jan C.; Ewert, Frank

    2014-01-01

    Despite our growing knowledge on plants’ functional responses to grazing, there is no consensus if an optimum level of functional aggregation exists for detecting grazing effects in drylands. With a comparative approach we searched for plant functional types (PFTs) with a consistent response to grazing across two areas differing in climatic aridity, situated in South Africa’s grassland and savanna biomes. We aggregated herbaceous species into PFTs, using hierarchical combinations of traits (from single- to three-trait PFTs). Traits relate to life history, growth form and leaf width. We first confirmed that soil and grazing gradients were largely independent from each other, and then searched in each biome for PFTs with a sensitive response to grazing, avoiding confounding with soil conditions. We found no response consistency, but biome-specific optimum aggregation levels. Three-trait PFTs (e.g. broad-leaved perennial grasses) and two-trait PFTs (e.g. perennial grasses) performed best as indicators of grazing effects in the semi-arid grassland and in the arid savanna biome, respectively. Some PFTs increased with grazing pressure in the grassland, but decreased in the savanna. We applied biome-specific grazing indicators to evaluate if differences in grazing management related to land tenure (communal versus freehold) had effects on vegetation. Tenure effects were small, which we mainly attributed to large variability in grazing pressure across farms. We conclude that the striking lack of generalizable PFT responses to grazing is due to a convergence of aridity and grazing effects, and unlikely to be overcome by more refined classification approaches. Hence, PFTs with an opposite response to grazing in the two biomes rather have a unimodal response along a gradient of additive forces of aridity and grazing. The study advocates for hierarchical trait combinations to identify localized indicator sets for grazing effects. Its methodological approach may also be

  6. Soil characteristics and landcover relationships on soil hydraulic conductivity at a hillslope scale: A view towards local flood management

    Science.gov (United States)

    Archer, N. A. L.; Bonell, M.; Coles, N.; MacDonald, A. M.; Auton, C. A.; Stevenson, R.

    2013-08-01

    There are surprisingly few studies in humid temperate forests which provide reliable evidence that soil permeability is enhanced under forests. This work addresses this research gap through a detailed investigation of permeability on a hillslope in the Eddleston Catchment, Scottish Borders UK, to evaluate the impact of land cover, superficial geology and soil types on permeability using measurements of field saturated hydraulic conductivity (Kfs) supported by detailed topsoil profile descriptions and counting of roots with diameters >2 mm. Kfs was measured at depth 0.04-0.15 m using a constant head well permeameter across four paired landcover sites of adjacent tree and intensely grazed grassland. The measured tree types were: 500-year-old mixed woodland; 180-year-old mixed woodland; 45-year-old Pinus sylvestris plantation; and 180-year-old Salix caprea woodland. The respective paired grids of trees and grassland were compared on similar soil texture and topography. This study highlights the significant impact of broadleaf woodland at a hillslope scale on Kfs in comparison to grassland areas: median Kfs values under 180-year-old S. caprea woodland (8 mm h-1), 180-year-old mixed woodland (119 mm h-1) and 500-year-old broadleaf woodland (174 mm h-1) were found to be respectively 8, 6 and 5 times higher than neighbouring grazed grassland areas on the same superficial geology. Further statistical analysis indicates that such Kfs enhancement is associated with the presence of coarse roots (>2 mm diameter) creating conduits for preferential flow and a deeper organic layer in the topsoil profile under woodlands. By contrast the P. sylvestris forest had only slightly higher (42 mm h-1), but not statistically different Kfs values, when compared to adjacent pasture (35 mm h-1). In the grassland areas, in the absence of course roots, the superficial geology was dominant in accounting for differences in Kfs, with the alluvium floodplain having a significantly lower median Kfs

  7. Ecohydrological and Socioeconomic Relationships in Disturbed Woodland Ecosystems of the Western U.S.

    Science.gov (United States)

    Ochoa, C. G.; Guldan, S. J.; Tidwell, V. C.; Deboodt, T.

    2016-12-01

    In many areas of the western U.S., the significant encroachment of juniper (Juniperus spp.) into grassland and sage steppe ecosystems has disrupted important ecological and hydrological functions. Striking landscape changes attributed to high levels of encroachment have raised considerable concerns about the negative impacts of juniper expansion on multiple ecosystem functions and services. Juniper encroachment can limit the growth of understory vegetation, reduce biodiversity, modify hydrologic processes, and alter soil nutrient cycling. Many producers, agency staff, and scientists have indicated the need for an integrated approach to manage juniper woodlands for multiple ecosystem benefits (e.g., water, forage, and wildlife habitat). Using a systems approach, we are investigating biophysical and socioeconomic linkages in very dense juniper-dominated landscapes of Oregon and New Mexico. Ongoing study results in the biophysical component in Oregon show that increases in perennial grass cover are positively correlated with soil moisture, whereas increases in juniper cover are negatively correlated. Winter precipitation infiltrates relatively rapidly through the soil profile and into the aquifer. Greater springflow and runoff rates are observed in a watershed where juniper was removed (90%). Shallow groundwater response observed in watershed and valley monitoring wells show there are temporary hydrologic connections between upland and lowland locations during the winter precipitation season. Study findings indicate that in similar, highly encroached landscapes, reducing juniper tree density may improve overall watershed function and enhance ecosystems services such as forage and water provisioning. In the socioeconomic component, we are in constant communication with different stakeholders to enhance our understanding of current management practices and perceptions related to juniper control. Also, we are gathering economic data from secondary sources that will

  8. Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia

    Directory of Open Access Journals (Sweden)

    M. M. Mukelabai

    2011-01-01

    Full Text Available Carbon dioxide efflux from the soil surface was measured over a period of several weeks within a heterogeneous Brachystegia spp. dominated miombo woodland in Western Zambia. The objectives were to examine spatial and temporal variation of soil respiration along a disturbance gradient from a protected forest reserve to a cut, burned, and grazed area outside, and to relate the flux to various abiotic and biotic drivers. The highest daily mean fluxes (around 12 μmol CO2 m−2 s−1 were measured in the protected forest in the wet season and lowest daily mean fluxes (around 1 μmol CO2 m−2 s−1 in the most disturbed area during the dry season. Diurnal variation of soil respiration was closely correlated with soil temperature. The combination of soil water content and soil temperature was found to be the main driving factor at seasonal time scale. There was a 75% decrease in soil CO2 efflux during the dry season and a 20% difference in peak soil respiratory flux measured in 2008 and 2009. Spatial variation of CO2 efflux was positively related to total soil carbon content in the undisturbed area but not at the disturbed site. Coefficients of variation of efflux rates between plots decreased towards the core zone of the protected forest reserve. Normalized soil respiration values did not vary significantly along the disturbance gradient. Spatial variation of respiration did not show a clear distinction between the disturbed and undisturbed sites and could not be explained by variables such as leaf area index. In contrast, within plot variability of soil respiration was explained by soil organic carbon content. Three different approaches to calculate total ecosystem respiration (Reco from eddy covariance measurements were compared to two bottom-up estimates of Reco obtained from chambers measurements of soil- and leaf respiration which differed in the consideration of spatial heterogeneity. The consideration of spatial variability resulted only in

  9. Woodland caribou population decline in Alberta: fact or fiction?

    Directory of Open Access Journals (Sweden)

    Corey J.A. Bradshaw

    1996-01-01

    Full Text Available We re-assessed the view of a major woodland caribou (Rangifer tarandus caribou population decline in Alberta. Several historical publications and provincial documents refer to this drastic decline as the major premise for the designation of Alberta's woodland caribou an endangered species. In the past, wildlife management and inventory techniques were speculative and limited by a lack of technology, access and funding. The accepted trend of the decline is based on many speculations, opinions and misinterpretation of data and is unsubstantiated. Many aerial surveys failed to reduce variance and did not estimate sightability. Most surveys have underestimated numbers and contributed unreliable data to support a decline. Through forest fire protection and the presence of extensive wetlands, the majority of potential caribou habitat still exists. Recreational and aboriginal subsistence hunting does not appear to have contributed greatly to mortality, although data are insufficient for reliable conclusions. Wolf (Canis lupus, population fluctuations are inconclusive and do not provide adequate information on which to base prey population trends. The incidence of documented infection by parasites in Alberta is low and likely unimportant as a cause of the proposed decline.

  10. Monitoring of Savanna degradation in Namibia using landsat TM/ETM+ data

    CSIR Research Space (South Africa)

    Lück-Vogel, Melanie

    2009-07-01

    Full Text Available . However, the accurate assessment of savanna degradation using remote sensing techniques has turned out difficult, as the described processes are frequently overlaid by ecosystem-inherent variability in response to the usually highly variable rain falls...

  11. Upper Mississippi River National Wildlife and Fish Refuge : Savanna District : Annual Narrative Report : Fiscal Year 2007

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for the Savanna District of the Upper Mississippi River National Wildlife and Fish Refuge summarizes Refuge activities during the 2007...

  12. The bulldozer herbivore: how animals benefit from elephant modifying an African savanna

    NARCIS (Netherlands)

    Kohi, E.

    2013-01-01

    Herbivore-vegetation interactions are important structuring forces in savanna that modify the availability and quality of forage resources. Elephant for example, are known for their ability to change the vegetation structure through toppling trees, uprooting, snapping, debarking and breaking

  13. Upper Mississippi River National Wildlife and Fish Refuge : Savanna District : Annual Narrative Report : Fiscal Year 2004

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for the Savanna District of the Upper Mississippi River National Wildlife and Fish Refuge summarizes Refuge activities during the 2004...

  14. Upper Mississippi River National Wildlife and Fish Refuge : Savanna District : Annual Narrative Report : Fiscal Year 2006

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for the Savanna District of the Upper Mississippi River National Wildlife and Fish Refuge summarizes Refuge activities during the 2006...

  15. 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 savanna patch dynamics. They generally are considered as prominent keystone structures associated with a stable ecological stage. A variety of anthropogenic land use and management activities are however putting increasing pressure on the big tree...

  16. 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...

  17. 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 savanna grass species (Digitariaeriantha). Spectral measurements were made using a spectrometer. The D. eriantha was cut, dried and chemically analyzed for foliar N and P concentrations. WR spectra were determined by calculating the residual from...

  18. Spatial variation of the stable nitrogen isotope ratio of woody plants along a topoedaphic gradient in a subtropical savanna.

    Science.gov (United States)

    Bai, Edith; Boutton, Thomas W; Liu, Feng; Wu, X Ben; Archer, Steven R; Hallmark, C Thomas

    2009-03-01

    Variation in the stable N isotope ratio (delta15N) of plants and soils often reflects the influence of environment on the N cycle. We measured leaf delta15N and N concentration ([N]) on all individuals of Prosopis glandulosa (deciduous tree legume), Condalia hookeri (evergreen shrub), and Zanthoxylum fagara (evergreen shrub) present within a belt transect 308 m long x 12 m wide in a subtropical savanna ecosystem in southern Texas, USA in April and August 2005. Soil texture, gravimetric water content (GWC), total N and delta15N were also measured along the transect. At the landscape scale, leaf delta15N was negatively related to elevation for all the three species along this topoedaphic sequence. Changes in soil delta15N, total N, and GWC appeared to contribute to this spatial pattern of leaf delta15N. In lower portions of the landscape, greater soil N availability and GWC are associated with relatively high rates of both N mineralization and nitrification. Both soil delta15N and leaf [N] were positively correlated with leaf delta15N of non-N2 fixing plants. Leaf delta15N of P. glandulosa, an N2-fixing legume, did not correlate with leaf [N]; the delta15N of P. glandulosa's leaves were closer to atmospheric N2 and significantly lower than those of C. hookeri and Z. fagara. Additionally, at smaller spatial scales, a proximity index (which reflected the density and distance of surrounding P. glandulosa trees) was negatively correlated with leaf delta15N of C. hookeri and Z. fagara, indicating the N2-fixing P. glandulosa may be important to the N nutrition of nearby non-N2-fixing species. Our results indicate plant 15N natural abundance can reflect the extent of N retention and help us better understand N dynamics and plant-soil interactions at ecosystem and landscape scales.

  19. Combined Spatial and Temporal Effects of Environmental Controls on Long-Term Monthly NDVI in the Southern Africa Savanna

    Directory of Open Access Journals (Sweden)

    Miguel A. Campo-Bescós

    2013-12-01

    Full Text Available Deconstructing the drivers of large-scale vegetation change is critical to predicting and managing projected climate and land use changes that will affect regional vegetation cover in degraded or threated ecosystems. We investigate the shared dynamics of spatially variable vegetation across three large watersheds in the southern Africa savanna. Dynamic Factor Analysis (DFA, a multivariate time-series dimension reduction technique, was used to identify the most important physical drivers of regional vegetation change. We first evaluated the Advanced Very High Resolution Radiometer (AVHRR- vs. the Moderate Resolution Imaging Spectroradiometer (MODIS-based Normalized Difference Vegetation Index (NDVI datasets across their overlapping period (2001–2010. NDVI follows a general pattern of cyclic seasonal variation, with distinct spatio-temporal patterns across physio-geographic regions. Both NDVI products produced similar DFA models, although MODIS was simulated better. Soil moisture and precipitation controlled NDVI for mean annual precipitation (MAP < 750 mm, and above this, evaporation and mean temperature dominated. A second DFA with the full AVHRR (1982–2010 data found that for MAP < 750 mm, soil moisture and actual evapotranspiration control NDVI dynamics, followed by mean and maximum temperatures. Above 950 mm, actual evapotranspiration and precipitation dominate. The quantification of the combined spatio-temporal environmental drivers of NDVI expands our ability to understand landscape level changes in vegetation evaluated through remote sensing and improves the basis for the management of vulnerable regions, like the southern Africa savannas.

  20. Amazonian forest-savanna bistability and human impact

    Science.gov (United States)

    Wuyts, Bert; Champneys, Alan R.; House, Joanna I.

    2017-05-01

    A bimodal distribution of tropical tree cover at intermediate precipitation levels has been presented as evidence of fire-induced bistability. Here we subdivide satellite vegetation data into those from human-unaffected areas and those from regions close to human-cultivated zones. Bimodality is found to be almost absent in the unaffected regions, whereas it is significantly enhanced close to cultivated zones. Assuming higher logging rates closer to cultivated zones and spatial diffusion of fire, our spatiotemporal mathematical model reproduces these patterns. Given a gradient of climatic and edaphic factors, rather than bistability there is a predictable spatial boundary, a Maxwell point, that separates regions where forest and savanna states are naturally selected. While bimodality can hence be explained by anthropogenic edge effects and natural spatial heterogeneity, a narrow range of bimodality remaining in the human-unaffected data indicates that there is still bistability, although on smaller scales than claimed previously.

  1. Antimicrobial activity of six plant extracts from the brazilian savanna on periodontal pathogens

    OpenAIRE

    Gaetti-Jardim Júnior, Elerson [UNESP; Landucci, Luís Fernando; Arafat, Omar Khalil Kidudsi; Ranieri, Robson Varlei [UNESP; Ramos, Marcelle Marie Buso [UNESP; Ciesielski, Francisco Isaak Nícolas [UNESP; Schweitzer, Chrisitane Marie [UNESP; Okamoto, Ana Cláudia [UNESP

    2011-01-01

    The extracts of plants from Brazilian savanna are currently used in popular medicine. This study evaluated the inhibitory activity of the alcoholic and aqueous extracts from savanna plants on periodontal bacteria. The minimal inhibitory concentrations were evaluated by the agar dilution method, using Wilkins-Chalgren agar. Antimicrobial activity of plants extracts on microbial biofilms was determined in microplates. Psidium cattleianum and Myracrodruon urundeuva extracts demonstrated signific...

  2. Savanna burning methodology for fire management and emissions reduction: a critical review of influencing factors

    Directory of Open Access Journals (Sweden)

    Tek Narayan Maraseni

    2016-11-01

    Full Text Available Abstract Savanna fire is a major source of global greenhouse gas (GHG emissions. In Australia, savanna fire contributes about 3% of annual GHG emissions reportable to the Kyoto Protocol. In order to reduce GHG emissions from savanna burning, the Australian government has developed and approved a Kyoto compliant savanna controlled burning methodology—the first legal instrument of this kind at a global level—under its Emission Reduction Fund. However, this approved methodology is currently only applicable to nine vegetation fuel types across northern parts of Australia in areas which receive on average over 600 mm rainfall annually, covering only 15.4% of the total land area in Australia. Savanna ecosystems extend across a large proportion of mainland Australia. This paper provides a critical review of ten key factors that need to be considered in developing a savanna burning methodology applicable to the other parts of Australia. It will also inform discussion in other countries intent on developing similar emissions reduction strategies.

  3. Effects of past climate variability on fire and vegetation in the cerrãdo savanna of the Huanchaca Mesetta, NE Bolivia

    Science.gov (United States)

    Maezumi, S. Y.; Power, M. J.; Mayle, F. E.; McLauchlan, K. K.; Iriarte, J.

    2015-06-01

    Cerrãdo savannas have the greatest fire activity of all major global land-cover types and play a significant role in the global carbon cycle. During the 21st century, temperatures are projected to increase by ~ 3 °C coupled with a precipitation decrease of ~ 20%. Although these conditions could potentially intensify drought stress, it is unknown how that might alter vegetation composition and fire regimes. To assess how Neotropical savannas responded to past climate changes, a 14 500-year, high-resolution, sedimentary record from Huanchaca Mesetta, a palm swamp located in the cerrãdo savanna in northeastern Bolivia, was analyzed with phytoliths, stable isotopes, and charcoal. A non-analogue, cold-adapted vegetation community dominated the Lateglacial-early Holocene period (14 500-9000 cal yr BP, which included trees and C3 Pooideae and C4 Panicoideae grasses. The Lateglacial vegetation was fire-sensitive and fire activity during this period was low, likely responding to fuel availability and limitation. Although similar vegetation characterized the early Holocene, the warming conditions associated with the onset of the Holocene led to an initial increase in fire activity. Huanchaca Mesetta became increasingly fire-dependent during the middle Holocene with the expansion of C4 fire-adapted grasses. However, as warm, dry conditions, characterized by increased length and severity of the dry season, continued, fuel availability decreased. The establishment of the modern palm swamp vegetation occurred at 5000 cal yr BP. Edaphic factors are the first-order control on vegetation on the rocky quartzite mesetta. Where soils are sufficiently thick, climate is the second-order control of vegetation on the mesetta. The presence of the modern palm swamp is attributed to two factors: (1) increased precipitation that increased water table levels and (2) decreased frequency and duration of surazos (cold wind incursions from Patagonia) leading to increased temperature minima

  4. Five-year dynamics and carbon stock of vegetation in miombo woodlands of Niassa National Reserve, northern Mozambique

    Science.gov (United States)

    Ribeiro, N. S.; Matos, C. N.

    2011-12-01

    Niassa National Reserve (NNR) incorporates one of the most pristine miombo woodlands in southern Africa. It provides habitat to several plant and animal species and is home for ca. 40,000 people who depend on forest resources to sustain their livelihoods. Anthropogenic fires have been considered a major concern for the management of this large conservation area. This study investigates the dynamics of ecosystem vegetation and carbon stock across a fire-gradient in NNR. Fifty sampling plots established in 2004 were measured in 2005 and 2009 for growth of adult, ingrowth (individuals entering the 5 cm class of diameter at breast height), mortality and carbon stocks in woody, shrubby and grass vegetation and soils. We found 62 species for a total of 2172 individuals, which represents an increase in order of 5% from 2005. About 72% of the species had an increase in biomass during the five-year period, while 28% showed a decrease in biomass. The latter was a result of damage and mortality by fires and elephants. In general the ingrowth is low (between 0 and 3%) as well as the mortality which varied between -9.25% and 0.25%. The average carbon stock in the various compartments of the ecosystem are: soils (34.7 ± 17.93), Trees (62 MgC/ha ± 30.94), Dead trees (164 MgC/ha ± 259.95), grass (4.47 MgC/ha ± 3.51), Litter (0.12 MgC/ha ± 0.07), Shrubs (0.04 MgC/ha ± 0.03). This gives a total carbon stock of 127.6 mgC/ha ± 126.06. These results indicate that NNR is still a stable ecosystem in which the rates of mortality are low and mainly caused by fires and elephants. The ingrowth and growth seems to be enough to guarantee reposition of vegetation stocks in this ecosystem. The carbon stock is similar to other areas of miombo woodlands in the region. This is an indication that miombo in NNR is still function as a sink of carbon. This associated with the fact that NNR is one of the largest conservation areas of miombo in the world, makes the reserve an important area to

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

    Directory of Open Access Journals (Sweden)

    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. Numerical Simulation of Surface Energy and Water Balances over a Semiarid Grassland Ecosystem in the West African Savanna

    Directory of Open Access Journals (Sweden)

    Emmanuel Quansah

    2017-01-01

    Full Text Available To understand surface energy exchange processes over the semiarid regions in West Africa, numerical simulations of surface energy and water balances were carried out using a one-dimensional multilayer atmosphere-SOil-VEGetation (SOLVEG model for selected days of the dry and rainy seasons over a savanna grassland ecosystem in Sumbrungu in the Upper East region of Ghana. The measured Bowen ratio was used to partition the residual energy into the observed sensible heat flux (H and latent heat flux (LE in order to investigate the impact of the surface energy closure on model performance. The results showed that the model overall reproduced the diurnal changes in the observed energy fluxes, especially the net radiation (Rn, compared to half-hourly eddy covariance flux measurements, for the study periods. The performance measure in terms of the correlation coefficient (R, centred root mean square error (RMSE, and normalized standard deviation (σ between the simulated H and LE and their corresponding uncorrected observed values ranged between R = 0.63–0.99 and 0.83–0.94, RMSE = 0.88–1.25 and 0.88–1.92, and σ = 0.95–2.23 and 0.13–2.82 for the dry and rainy periods respectively, indicating a moderate to good model performance. The partitioning of H and LE by SOLVEG was generally in agreement with the observations during the dry period but showed clear discrepancies during the rainy period, particularly after rainfall events. Further sensitivity tests over longer simulation periods (e.g., 1 year are required to improve model performance and to investigate seasonal exchanges of surface energy fluxes over the West African Savanna ecosystems in more details.

  7. Multi-objective reserve design using MARXAN analysis for protected area conservation in savanna ecosystems in Belize

    OpenAIRE

    Fingler, Theresa

    2012-01-01

    Belize has long been considered a leader in conservation within the Mesoamerican region with 36% of its terrestrial area under protection status. However, a gap analysis conducted in 2005 reveal savannas are under-represented by the existing network of protected areas. With the savannas under numerous threats which include climate change, infrastructure development, deforestation and species decline, it has become necessary to address the current protected area effectiveness for the savanna...

  8. Post-fire reproduction of herbs at a savanna-gallery forest boundary in Distrito Federal, Brazil

    OpenAIRE

    K. G. Massi; C. U. O. Eugênio; Franco, A.C.

    2017-01-01

    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-fores...

  9. Biodiversity and ecology of soil fungi in a primary succession of a temperate coastal dune system

    NARCIS (Netherlands)

    Prenafeta Boldú, F.X.; Summerbell, R.C.; de Boer, W.; Boschker, H.T.S.; Gamsformerly, W.

    2014-01-01

    Soil fungal communities were studied in an actively developing coastal dune system at Goeree Island, the Netherlands. A shore to inland sampling transect was laid out, extending from coastal brackish marshes to recently formed foredunes to older dune pastures to adjacent woodlands. Soil samples from

  10. Identification of metal-responsive oribatid mites in a comparative survey of polluted soils.

    NARCIS (Netherlands)

    Khalil, M.A.; Janssens, T.K.S.; Berg, M.P.; van Straalen, N.M.

    2009-01-01

    Responses of oribatid mites to anthropogenic soil pollution vary greatly according to the species. In this study we aimed to identify sensitive and resistant species with a consistent relationship to soil metal concentrations. A regional survey of nine woodlands polluted to various degrees, was

  11. Saproxylic beetles of the Po plain woodlands, Italy

    Science.gov (United States)

    Bogliani, Giuseppe

    2014-01-01

    Abstract Forest ecosystems play an important role for the conservation of biodiversity, and for the protection of ecological processes. The Po plain woodlands which once covered the whole Plain, today are reduced in isolated highly threatened remnants by modern intensive agriculture. These close to natural floodplain forests are one of the most scarce and endangered ecosystems in Europe. Saproxylic species represent a major part of biodiversity of woodlands. The saproxylic insects are considered one of the most reliable bio-indicators of high-quality mature woodlands and have a very important role in regard to the protection and monitoring of forest biodiversity due to their highly specific living environments. As a result of the dramatic reduction of mature forests and the decreased availability of deadwood most of the saproxylic communities are greatly diminishing. The study was conducted in the Ticino Valley Regional Park and the aim is to contribute to the expansion of knowledge on the saproxylic beetles of Lombardy. We investigated 6 sampling sites belonging to alluvial and riparian mixed forests. For each forest we selected 12 trees. For beetles’ collection we used two different traps: Eclector Traps and Trunk Window Traps (total of 72 traps and 864 samples collected). We determined 4.387 beetles from 87 saproxylic species belonging to 21 families. Of these species 51 were not included in the previous checklist of the Park. By comparing the two different techniques used for catching saproxylic beetles, we found a significantly high difference in species richness between Window Traps (WT) and Eclector Traps (ET) with a higher number of species captured in the Window Traps. However, the combined use of two different types of traps significantly expanded the spectrum of insects captured Among the species reported as Least Concern in the IUCN Red List, we found interesting species such as the Elateridae Calambus bipustulats, the Eucnemidae Melasis buprestoides

  12. Socialist and postsocialist land-use legacies determine farm woodland composition and structure

    DEFF Research Database (Denmark)

    Plieninger, Tobias; Schaich, H.

    2014-01-01

    European agroecosystems host a variety of farm woodlands that act as primary determinants of biodiversity and ecosystem services. While woodland areas have been in decline worldwide, they have regionally increased, for example, in Eastern Germany. This study performs a quantitative and spatially...... explicit assessment of differences in species richness, diversity, and evenness as well as forest physiognomy and structure among Eastern German farm woodlands established during (1) the presocialist era (until 1945), (2) the socialist era (1945-1990), and (3) the postsocialist era (after 1990). Aerial...

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

    CSIR Research Space (South Africa)

    Huntely, BJ

    1978-07-01

    Full Text Available of a bushveld community was aimed at developing a quantitative description of the Study Area, in particular its soils, climate, vegetation and fauna. Details are provided of the main soil types, climatic variables, plant and animal communities...

  14. UAV – a useful tool for monitoring woodlands

    Directory of Open Access Journals (Sweden)

    Zmarz Anna

    2014-06-01

    Full Text Available Unmanned aerial systems are in many countries one of the most dynamically developing branches of technology. They have also been recognized and are being utilized by scientists who find remote sensing indispensable in their work. Today, it is increasingly common to find research teams utilizing so-called drones in field research. Unmanned systems are becoming ever more important for environment monitoring by, on the one hand, providing data from inaccessible or remote areas, and, on the other hand, reducing the human costs required by traditional large field teams while also increasing the efficiency of the work. This paper presents the possibility of utilizing UAVs for image data collection in woodland areas.

  15. Surveying woodland raptors by broadcast of conspecific vocalizations

    Science.gov (United States)

    Mosher, J.A.; Fuller, M.R.; Kopeny, M.

    1990-01-01

    We surveyed for raptors in forests on study areas in five of the eastern United States. For Cooper's Hawks (Accipiter cooperi), Red-shouldered Hawks (Buteo lineatus), and Barred Owls (Strix varia) the contact rates obtained by broadcasting taped vocalizations of conspecifics along roads were significantly greater than contact rates obtained by only looking and listening from the roadside. Broad-winged Hawks (B. platypterus) were detected only after their calls were broadcast. Most raptors were detected within 10 min of the beginning of the broadcasts. Red-tailed Hawks (B. jamaicensis) and Goshawks (A. gentilis) nested infrequently on our study areas, and we were unable to increase detections of these species. Generally, point count transects along woodland roads, from which conspecific vocalizations were broadcast, resulted in higher species specific detection rates than when walking, driving continuously, or only looking and listening for raptors at roadside stops.

  16. Challenging the Woodfuel Crisis in West African Woodlands

    DEFF Research Database (Denmark)

    Hansfort, Sofie Louise; Mertz, Ole

    2011-01-01

    Fear of an upcoming woodfuel crisis caused by increasing woodfuel consumption in Bamako has had great influence on forestry policies aiming to reduce the impacts of urban woodfuel consumption. During the last 20 years, energy gap analyses—the relationship between supply and demand of woodfuels...... to evaluate its sustainability using a simple methodology such as the energy gap analysis. Trends over the last 20 years show a highly efficient woodfuel system that has adapted to changing circumstances, ensuring a continued affordable woodfuel supply for the urban residents. Better data on the productivity......—have been produced by the government of Mali to prove the impacts of woodfuel consumption in Bamako on surrounding woodlands. This study evaluates the methodology and data used to describe this woodfuel crisis through a comparison with regional and historical data. The results of the energy gap analyses...

  17. Stable oxygen isotope and flux partitioning demonstrates understory of an oak savanna contributes up to half of ecosystem carbon and water exchange

    Directory of Open Access Journals (Sweden)

    Maren eDubbert

    2014-10-01

    Full Text Available Semi-arid ecosystems contribute about 40% to global net primary production (GPP even though water is a major factor limiting carbon uptake. Evapotranspiration (ET accounts for up to 95% of the water loss and in addition, vegetation can also mitigate drought effects by altering soil water distribution. Hence, partitioning of carbon and water fluxes between the soil and vegetation components is crucial to gain mechanistic understanding of vegetation effects on carbon and water cycling. However, the possible impact of herbaceous vegetation in savanna type ecosystems is often overlooked. Therefore, we aimed at quantifying understory vegetation effects on the water balance and productivity of a Mediterranean oak savanna. ET and net ecosystem CO2 exchange (NEE were partitioned based on flux and stable oxygen isotope measurements and also rain infiltration was estimated.The understory vegetation contributed importantly to total ecosystem ET and GPP with a maximum of 43% and 51%, respectively. It reached water-use efficiencies (WUE; ratio of carbon gain by water loss similar to cork-oak trees. The understory vegetation inhibited soil evaporation (E and, although E was large during wet periods, it did not diminish WUE during water-limited times. The understory strongly increased soil water infiltration, specifically following major rain events. At the same time, the understory itself was vulnerable to drought, which led to an earlier senescence of the understory growing under trees as compared to open areas, due to competition for water. Thus, beneficial understory effects are dominant and contribute to the resilience of this ecosystem. At the same time the vulnerability of the understory to drought suggests that future climate change scenarios for the Mediterranean basin threaten understory development. This in turn will very likely diminish beneficial understory effects like infiltration and ground water recharge and therefore ecosystem resilience to

  18. Integrating in-situ, Landsat, and MODIS data for mapping in Southern African savannas: experiences of LCCS-based land-cover mapping in the Kalahari in Namibia.

    Science.gov (United States)

    Hüttich, Christian; Herold, Martin; Strohbach, Ben J; Dech, Stefan

    2011-05-01

    Integrated ecosystem assessment initiatives are important steps towards a global biodiversity observing system. Reliable earth observation data are key information for tracking biodiversity change on various scales. Regarding the establishment of standardized environmental observation systems, a key question is: What can be observed on each scale and how can land cover information be transferred? In this study, a land cover map from a dry semi-arid savanna ecosystem in Namibia was obtained based on the UN LCCS, in-situ data, and MODIS and Landsat satellite imagery. In situ botanical relevé samples were used as baseline data for the definition of a standardized LCCS legend. A standard LCCS code for savanna vegetation types is introduced. An object-oriented segmentation of Landsat imagery was used as intermediate stage for downscaling in-situ training data on a coarse MODIS resolution. MODIS time series metrics of the growing season 2004/2005 were used to classify Kalahari vegetation types using a tree-based ensemble classifier (Random Forest). The prevailing Kalahari vegetation types based on LCCS was open broadleaved deciduous shrubland with an herbaceous layer which differs from the class assignments of the global and regional land-cover maps. The separability analysis based on Bhattacharya distance measurements applied on two LCCS levels indicated a relationship of spectral mapping dependencies of annual MODIS time series features due to the thematic detail of the classification scheme. The analysis of LCCS classifiers showed an increased significance of life-form composition and soil conditions to the mapping accuracy. An overall accuracy of 92.48% was achieved. Woody plant associations proved to be most stable due to small omission and commission errors. The case study comprised a first suitability assessment of the LCCS classifier approach for a southern African savanna ecosystem.

  19. Phytoliths in woody plants from the Miombo woodlands of Mozambique.

    Science.gov (United States)

    Mercader, Julio; Bennett, Tim; Esselmont, Chris; Simpson, Steven; Walde, Dale

    2009-07-01

    There are no descriptions of phytoliths produced by plants from the 'Zambezian' zone, where Miombo woodlands are the dominant element of the largest single phytochorion in sub-Saharan Africa. The preservation of phytoliths in fossil records of Africa makes phytoliths a tool to study early plant communities. Paleo-ethnobotanical interpretation of phytoliths relies on the comparison of ancient types with morphotypes extracted from living reference collections. Phytoliths were extracted from plant samples representing 41 families, 77 genera and 90 species through sonic cleaning, dry ashing and acid treatment; and phytoliths thus extracted were quantified. For each species, an average of 216 phytoliths were counted. The percentage of each morphotype identified per species was calculated, and types were described according to the descriptors from the International Code for Phytolith Nomenclature. Phytolith assemblages were subject to discriminant analysis, cluster analysis and principal component analysis. Phytoliths were grouped into 57 morphotypes (two were articulated forms and 55 were discrete shapes), and provide a reference collection of phytolith assemblages produced by Miombo woody species. Common and unique morphotypes are described and taxonomic and grouping variables are looked into from a statistical perspective. The first quantitative taxonomy of phytoliths from Miombos is presented here, including new types and constituting the most extensive phytolith key for any African ecoregion. Evidence is presented that local woody species are hypervariable silica producers and their phytolith morphotypes are highly polymorphic. The taxonomic significance of these phytoliths is largely poor, but there are important exceptions that include the morphotypes produced by members from >10 families and orders. The typical phytolithic signal that would allow scientists to identify ancient woodlands of 'Zambezian' affiliation comprises only half of the original number of

  20. Carbon and nitrogen cycle dynamics during forest regrowth in the dry tropical Miombo Woodlands of western Tanzania

    Science.gov (United States)

    Mayes, Marc; Melillo, Jerry; Mustard, John; Neill, Christopher; Nyadzi, Gerson

    2015-04-01

    Extensive regions of dry tropical forests, such as the Miombo woodlands of sub-Saharan Africa, are experiencing high rates of both deforestation and forest regrowth on abandoned agricultural lands. Changes in the cycles of key elements such as carbon (C) and nitrogen (N) in the regrowing woodlands are not well understood. This study examines the plant and soil C and N dynamics along a chronosequence of regrowing Miombo woodland sites in western Tanzania following abandonment from cultivation. Our primary goals were to address two questions: (1) what are the timescales over which aboveground tree C stocks recover and soil mineral N stocks change during regrowth; (2) when, and/or to what degree, do tree C stocks and soil mineral N reach conditions of mature forests at decadal timescales? We established a chronosequence of 18 sites ranging in age from 3 to >40 years since abandonment. At each site, we conducted tree surveys and made measurements to quantify the aboveground tree C stocks using multiple sets of Miombo-specific allometric equations. In addition, we sampled soils at each site to a depth of 100 cm, and determined total and mineral N standing stocks. We also conducted short-term soil incubations to determine nitrogen mineralization potentials for the surface soils at each site. Aboveground tree C stocks ranged from 0.4 ± 0.1 Mg C ha-1 for 3-4 year sites (n = 3) to 27.2 ± 5.2 Mg C ha-1 (n = 3) for 30-40 year sites, and were 44.5 ± 7.4 Mg C ha-1 for mature forest sites (n = 6) . Annualized rates of aboveground tree C stock changes (0.68 - 0.89 Mg C ha-1 yr-1) were comparable to the few published for Miombo forests. However, tree C stocks of regrowth sites between 10 - 24 years (5.2 ± 1.1 Mg C ha -1 (n=3)) were much lower than those reported at similarly aged sites in other comparable studies. Across this study's chronosequence, only the regrowth sites older than three decades (30-40 year sites) had C stocks approaching those of mature forests. Further

  1. Hydrological changes due to land-use change from Brazilian savanna to managed Eucalyptus

    Science.gov (United States)

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

    2014-12-01

    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 have 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 were installed in each site. Data from the towers will be used to parameterized a Soil-Vegetation-Atmosphere (SVAT) model to simulate hydrological and atmospheric boundary layer (ABL) processes in order to understand how the two vegetation cover modulates the exchange of mass and energy between the biosphere and atmosphere. Simulations of 30-day dry down from saturation to complete water stress were performed and were analyzed on how ABL respond to soil moisture

  2. Variation in woody plant delta(13)C along a topoedaphic gradient in a subtropical savanna parkland.

    Science.gov (United States)

    Bai, Edith; Boutton, Thomas W; Liu, Feng; Wu, X Ben; Archer, Steven R

    2008-06-01

    delta(13)C values of C(3) plants are indicators of plant carbon-water relations that integrate plant responses to environmental conditions. However, few studies have quantified spatial variation in plant delta(13)C at the landscape scale. We determined variation in leaf delta(13)C, leaf nitrogen per leaf area (N(area)), and specific leaf area (SLA) in April and August 2005 for all individuals of three common woody species within a 308 x 12-m belt transect spanning an upland-lowland topoedaphic gradient in a subtropical savanna in southern Texas. Clay content, available soil moisture, and soil total N were all negatively correlated with elevation. The delta(13)C values of Prosopis glandulosa (deciduous N(2)-fixing tree legume), Condalia hookeri (evergreen shrub), and Zanthoxylum fagara (evergreen shrub) leaves increased 1-4 per thousand with decreasing elevation, with the delta(13)C value of P. glandulosa leaves being 1-3 per thousand higher than those of the two shrub species. Contrary to theory and results from previous studies, delta(13)C values were highest where soil water was most available, suggesting that some other variable was overriding or interacting with water availability. Leaf N(area) was positively correlated with leaf delta(13)C of all species (p < 0.01) and appeared to exert the strongest control over delta(13)C along this topoedaphic gradient. Since leaf N(area) is positively related to photosynthetic capacity, plants with high leaf N(area) are likely to have low p (I)/p (a) ratios and therefore higher delta(13)C values, assuming stomatal conductance is constant. Specific leaf area was not correlated significantly with leaf delta(13)C. Following a progressive growing season drought in July/August, leaf delta(13)C decreased. The lower delta(13)C in August may reflect the accumulation of (13)C-depleted epicuticular leaf wax. We suggest control of leaf delta(13)C along this topoedaphic gradient is mediated by leaf N(area) rather than by stomatal

  3. Valoración física comparativa del muestreador Uhland y el Proctor en un suelo franco arenoso de sabana del estado Monagas, Venezuela Comparative physical evaluation of Uhland and Proctor samplers on a sandy savanna soil in the state of Monagas in Venezuela

    Directory of Open Access Journals (Sweden)

    Américo J. Hossne García

    2013-09-01

    Full Text Available Es común la obtención de muestras de suelos agrícolas mediante el equipo Uhland. El ín­dice crítico de compactación del suelo se establece con la prueba Proctor. El objetivo fue la comparación física del muestreador Uhland, con caída libre y forzada del martillo, con el aparato Proctor para valorar la alteración mecánica de la muestra. Se utilizaron los Proctor estándar y modificado, el Uhland a caída libre y forzada del martillo, un diseño estadístico completamente aleatorizado con diez repeticiones y cuatro tratamientos, Análisis de Va­rianza, Mínima Diferencia Significativa y regresión polinómica. Se concluyó que el Uhland produjo resultados similares al Proctor. La energía penetrante del Uhland resultó superior a la compactante del Proctor. La humedad del suelo influyó sobre la densidad aparente seca. La relación de solidez y la porosidad aerífera identificaron mejor el proceso.It is common to obtain agricultural soil samples using the Uhland sampler. The critical index of soil compaction is obtained with the Proctor test. The objective of this work was to perform a physical comparison between the Uhland sampler, with free and forced fall of the hammer, and the Proctor apparatus to assess mechanical alterations of the sample. Standard and modified Proctor instruments were used, as well as the Uhland with free and forced hammer fall. A completely randomized statistical design with ten replicates and four treatments was performed along with the analysis of variance, Minimum Significant Differ­ence and polynomial regression. It was concluded that Uhland and Proctor instruments pro­duced similar results. The penetrating energy of the Uhland was higher than the compacting energy of the Proctor. Humidity in the soil had an influence of the apparent dry density. The solidity ratio of the soil and the air porosity were the parameters that best identified the compaction process for the Proctor and Uhland instruments.

  4. Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Jucai Li

    2017-01-01

    Full Text Available In contrast to herbaceous canopies and forests, savannas are grassland ecosystems with sparsely distributed individual trees, so the canopy is spatially heterogeneous and open, whereas the woody cover in savannas, e.g., tree cover, adversely affects ecosystem structures and functions. Studies have shown that the dynamics of canopy structure are related to available water, climate, and human activities in the form of porosity, leaf area index (LAI, and clumping index (CI. Therefore, it is important to identify the biophysical parameters of savanna ecosystems, and undertake practical actions for savanna conservation and management. The canopy openness presents a challenge for evaluating canopy LAI and other biophysical parameters, as most remotely sensed methods were developed for homogeneous and closed canopies. Clumping index is a key variable that can represent the clumping effect from spatial distribution patterns of components within a canopy. However, it is a difficult task to measure the clumping index of the moderate resolution savanna pixels directly using optical instruments, such as the Tracing Radiation and Architecture of Canopies, LAI-2000 Canopy Analyzer, or digital hemispherical photography. This paper proposed a new method using hemispherical photographs combined with high resolution remote sensing images to estimate the clumping index of savanna canopies. The effects of single tree LAI, crown density, and herbaceous layer on the clumping index of savanna pixels were also evaluated. The proposed method effectively calculated the clumping index of moderate resolution pixels. The clumping indices of two study regions located in Ejina Banner and Weichang were compared with the clumping index product over China’s landmass.

  5. Deriving Multiple Benefits from Carbon Market-Based Savanna Fire Management: An Australian Example.

    Directory of Open Access Journals (Sweden)

    Jeremy Russell-Smith

    Full Text Available Carbon markets afford potentially useful opportunities for supporting socially and environmentally sustainable land management programs but, to date, have been little applied in globally significant fire-prone savanna settings. While fire is intrinsic to regulating the composition, structure and dynamics of savanna systems, in north Australian savannas frequent and extensive late dry season wildfires incur significant environmental, production and social impacts. Here we assess the potential of market-based savanna burning greenhouse gas emissions abatement and allied carbon biosequestration projects to deliver compatible environmental and broader socio-economic benefits in a highly biodiverse north Australian setting. Drawing on extensive regional ecological knowledge of fire regime effects on fire-vulnerable taxa and communities, we compare three fire regime metrics (seasonal fire frequency, proportion of long-unburnt vegetation, fire patch-size distribution over a 15-year period for three national parks with an indigenously (Aboriginal owned and managed market-based emissions abatement enterprise. Our assessment indicates improved fire management outcomes under the emissions abatement program, and mostly little change or declining outcomes on the parks. We attribute improved outcomes and putative biodiversity benefits under the abatement program to enhanced strategic management made possible by the market-based mitigation arrangement. For these same sites we estimate quanta of carbon credits that could be delivered under realistic enhanced fire management practice, using currently available and developing accredited Australian savanna burning accounting methods. We conclude that, in appropriate situations, market-based savanna burning activities can provide transformative climate change mitigation, ecosystem health, and community benefits in northern Australia, and, despite significant challenges, potentially in other fire-prone savanna

  6. Spatial Patterns of Plant δ13C and δ15N Along a Topoedaphic Gradient in a Subtropical Savanna Landscape

    Science.gov (United States)

    Bai, E.; Boutton, T. W.; Liu, F.; Wu, B.; Archer, S. R.

    2005-12-01

    δ13C and δ15N values of plants are powerful tools in physiological ecology, ecosystem science, and global biogeochemistry, yet we know relatively little about their variation and controls at the landscape scale. In this study, we investigated landscape-scale spatial variations in the foliar isotopic composition of 3 woody plant species across a 308 m topoedaphic gradient, along which soil texture and plant resources (water and nitrogen availability) varied from upland (86 m) to lowland (84 m) portions of the landscape. The study was conducted in a subtropical savanna at the La Copita Research Area, approximately 60 km west of Corpus Christi, TX. Foliar δ13C, δ15N, leaf nitrogen concentration ([N]), and specific leaf area (SLA) were measured on all individuals of Prosopis glandulosa, Condalia hookeri, and Zanthoxylum fagara present within a belt transect 308 m long x 12 m wide. Soil texture, available soil moisture, and total N were measured at 1 m intervals along the center-line of the belt transect. Clay content, available soil moisture, and soil total N were all negatively correlated with elevation along the transect. Leaf δ13C and δ15N values for all 3 species increased by 1-4 o/oo with decreasing elevation along the transect. Contrary to theory and previous studies, δ13C values were highest where soil water was most available, suggesting that some other variable could be overriding or interacting with water availability. Foliar [N] appeared to exert the strongest control over landscape-level variation, and was positively correlated with δ13C of all species (R 2 = 0.58, pCondalia were positively correlated with leaf [N] and soil water availability; however, these relationships were absent for Prosopis, an N-fixing tree legume. We speculate that the relationship between δ15N and leaf [N] and soil water may reflect the fact that plants with high δ15N values occurred on lower-lying portions of the landscape with relatively high N-transformation rates

  7. 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.

  8. Continuous evapotranspiration monitoring and water stress at watershed scale in a Mediterranean oak savanna

    Science.gov (United States)

    Carpintero, E.; González Dugo, M. P.; Hain, C.; Nieto, H.; Gao, F.; Andreu, A.; Kustas, W. P.; Anderson, M. C.

    2016-10-01

    The regular monitoring of the evapotranspiration rates and their links with vegetation conditions and soil moisture may support management and hydrological planning leading to reduce the economic and environmental vulnerability of complex water-controlled Mediterranean ecosystems. In this work, the monitoring of water use over a basin with a predominant oak savanna (known in Spain as dehesa) was conducted for two years, 2013 and 2014, monitoring ET at both fine spatial and temporal resolution in different seasons. A global 5 km daily ET product, developed with the ALEXI model and MODIS day-night temperature difference, was used as starting point. Flux estimations with higher spatial resolutions were obtained with the associated flux disaggregation scheme, DisALEXI, using surface temperature data from the polar orbiting satellites MODIS (1 Km, daily) and Landsat 7/8 (60-120m and sharpened to 30m, 16 days) and the previously estimated coarse resolution fluxes. The results achieved supported the ability of this scheme to accurately estimate daytime-integrated energy fluxes over this system, using input data with different spatio-temporal resolution and without the need for ground observations. Daily ET series at 30 m spatial resolution, generated using STARFM fusion technique, has provided a significant improvement in spatial heterogeneity assessment of the ET series, with RMSE values of 0.56 and 0.68 mm/day for each year, representing an enhancement with respect to interpolated Landsat series. In summary, this approach was demostrated to be robust and operative to map ET at watershed scale with a suitable spatial and temporal resolution for applications over the dehesa ecosystem.

  9. The Woodlands Metro Center energy study. Case studies of project planning and design for energy conservation

    Energy Technology Data Exchange (ETDEWEB)

    1980-03-01

    Appendix II of The Woodlands Metro Center Energy Study near Houston consists of the following: Metro Center Program, Conventional Plan Building Prototypes and Detail Parcel Analysis, Energy Plan Building Prototypes, and Energy Plan Detail Parcel Analysis.

  10. Monitoring forest carbon in a Tanzanian woodland using interferometric SAR: a novel methodology for REDD

    National Research Council Canada - National Science Library

    Solberg, Svein; Gizachew, Belachew; Næsset, Erik; Gobakken, Terje; Bollandsås, Ole Martin; Mauya, Ernest William; Olsson, Håkan; Malimbwi, Rogers; Zahabu, Eliakimu

    2015-01-01

    ... as a basis for a reference emission level. Working in a miombo woodland in Tanzania, we here aim at demonstrating a novel 3D satellite approach based on interferometric processing of radar imagery (InSAR...

  11. The Role of Small Woodland Remnants on Ground Dwelling Insect Conservation in Chaco Serrano, Central Argentina

    National Research Council Canada - National Science Library

    María Laura Moreno; María Guadalupe Fernández; Silvia Itati Molina; Graciela Valladares

    2013-01-01

    .... In this study, the effects of patch size, isolation, and edge/interior localization on the ground dwelling insect communities in the Chaco Serrano woodland remnants in central Argentina were examined...

  12. Mapping forest stand complexity for woodland caribou habitat assessment using multispectral airborne imagery

    OpenAIRE

    Zhang, W.; Hu, B.; Woods, M.

    2014-01-01

    The decline of the woodland caribou population is a result of their habitat loss. To conserve the habitat of the woodland caribou and protect it from extinction, it is critical to accurately characterize and monitor its habitat. Conventionally, products derived from low to medium spatial resolution remote sensing data, such as land cover classification and vegetation indices are used for wildlife habitat assessment. These products fail to provide information on the structure complexi...

  13. Sensitivity of the grassland-forest ecotone in East African open woodland savannah to historical rainfall variation

    Science.gov (United States)

    Ssemmanda, I.; Gelorini, V.; Verschuren, D.

    2014-04-01

    Fossil pollen records provide key insight into the sensitivity of terrestrial ecosystems to climate change at longer time scales. However, tracing vegetation response to relatively modest historical climate fluctuations is often complicated by the overriding signature of anthropogenic landscape disturbance. Here we use high-resolution pollen data from a ~200 year lake-sediment record in open woodland savannah of Queen Elisabeth National Park (southwestern Uganda) to assess the sensitivity of the tropical lowland grassland-forest ecotone to historical fluctuations in annual rainfall on the order of 10% lasting several decades. Specifically we trace vegetation response to three episodes of increased regional rainfall dated to the 1820s-1830s, ca. 1865-1890 and from 1962 to around 2000. During inferred wetter episodes we find increases in the relative pollen abundance from trees and shrubs of moist semi-deciduous forest (Allophylus, Macaranga, Celtis, Alchornea), riparian forest (Phoenix reclinata) and savannah woodland (Myrica, Acalypha, Combretaceae/Melostomataceae) as well as local savannah taxa (Acacia, Rhus type vulgaris, Ficus), together creating strong temporary reductions in Poaceae pollen (to 45-55% of the terrestrial pollen sum). During intervening dry episodes, most notably the period ca. 1920-1962, Poaceae pollen attained values of 65-75%, and dryland herbs such as Commelina, Justicia type odora and Chenopodiaceae expanded at the expense of Asteraceae, Solanum-type, Swertia usumbarensis-type, and (modestly so) Urticaceae. Noting that the overall diversity of arboreal taxa remained high but their combined abundance low, we conclude that the landscape surrounding Lake Chibwera has been an open woodland savannah throughout the past 200 years, with historical rainfall variation exerting modest effects on local tree cover (mostly the abundance of Acacia and Ficus) and the prevalence of damp soil areas promoting Phoenix reclinata. The strong apparent expansion

  14. Potential for Ammonia Recapture by Farm Woodlands: Design and Application of a New Experimental Facility

    Directory of Open Access Journals (Sweden)

    Mark R. Theobald

    2001-01-01

    Full Text Available There has been increasing pressure on farmers in Europe to reduce the emissions of ammonia from their land. Due to the current financial climate in which farmers have to operate, it is important to identify ammonia control measures that can be adopted with minimum cost. The planting of trees around farmland and buildings has been identified as a potentially effective and low-cost measure to enhance ammonia recapture at a farm level and reduce long-range atmospheric transport. This work assesses experimentally what fraction of ammonia farm woodlands could potentially remove from the atmosphere. We constructed an experimental facility in southern Scotland to simulate a woodland shelterbelt planted in proximity to a small poultry unit. By measuring horizontal and vertical ammonia concentration profiles within the woodland, and comparing this to the concentration of an inert tracer (SF6 we estimate the depletion of ammonia due to dry deposition to the woodland canopy. Together with measurements of mean ammonia concentrations and throughfall fluxes of nitrogen, this information is used to provide a first estimate of the fraction of emitted ammonia that is recaptured by the woodland canopy. Analysis of these data give a lower limit of recapture of emitted ammonia, at the experimental facility, of 3%. By careful design of shelterbelt woodlands this figure could be significantly higher.

  15. Distinguishing forest and savanna African elephants using short nuclear DNA sequences.

    Science.gov (United States)

    Ishida, Yasuko; Demeke, Yirmed; van Coeverden de Groot, Peter J; Georgiadis, Nicholas J; Leggett, Keith E A; Fox, Virginia E; Roca, Alfred L

    2011-01-01

    A more complete description of African elephant phylogeography would require a method that distinguishes forest and savanna elephants using DNA from low-quality samples. Although mitochondrial DNA is often the marker of choice for species identification, the unusual cytonuclear patterns in African elephants make nuclear markers more reliable. We therefore designed and utilized genetic markers for short nuclear DNA regions that contain fixed nucleotide differences between forest and savanna elephants. We used M13 forward and reverse sequences to increase the total length of PCR amplicons and to improve the quality of sequences for the target DNA. We successfully sequenced fragments of nuclear genes from dung samples of known savanna and forest elephants in the Democratic Republic of Congo, Ethiopia, and Namibia. Elephants at previously unexamined locations were found to have nucleotide character states consistent with their status as savanna or forest elephants. Using these and results from previous studies, we estimated that the short-amplicon nuclear markers could distinguish forest from savanna African elephants with more than 99% accuracy. Nuclear genotyping of museum, dung, or ivory samples will provide better-informed conservation management of Africa's elephants.

  16. 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.

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

    Science.gov (United States)

    Ngomanda, A.; Chepstow-Lusty, A.; Makaya, M.; Favier, C.; Schevin, P.; Maley, J.; Fontugne, M.; Oslisly, R.; Jolly, D.

    2009-10-01

    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.

  18. 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.

  19. Ecosystem management can mitigate vegetation shifts induced by climate change in African savannas

    Science.gov (United States)

    Scheiter, Simon; Savadogo, Patrice

    2017-04-01

    The welfare of people in the tropics and sub-tropics strongly depends on goods and services that ecosystems supply. Flows of these ecosystem services are strongly influenced by interactions between climate change and land use. A prominent example are savannas, covering approximately 20% of the Earth's land surface. Key ecosystem services in these areas are fuel wood for cooking and heating, food production and livestock. Changes in the structure and dynamics of savanna vegetation may strongly influence local people's living conditions, as well as the climate system and biogeochemical cycles. We used a dynamic vegetation model to explore interactive effects of climate and land use on the vegetation structure, distribution and carbon cycling of African savannas under current and future conditions. More specifically, we simulate long term impacts of fire management, grazing and fuel wood harvesting. The model projects that under future climate without human land use impacts, large savanna areas would shift towards more wood dominated vegetation due to CO2 fertilization effects and changes in water use efficiency. However, land use activities can mitigate climate change impacts on vegetation to maintain desired ecosystem states that ensure fluxes of important ecosystem services. We then use optimization algorithms to identify sustainable land use strategies that maximize the utility of people managing savannas while preserving a stable vegetation state. Our results highlight that the development of land use policy for tropical and sub-tropical areas needs to account for climate change impacts on vegetation.

  20. Effects of anthropogenic fire history on savanna vegetation in northeastern Namibia.

    Science.gov (United States)

    Sheuyange, Asser; Oba, Gufu; Weladji, Robert B

    2005-05-01

    Anthropogenic fires in Africa are an ancient form of environmental disturbance, which probably have shaped the savanna vegetation more than any other human induced disturbance. Despite anthropogenic fires having played a significant role in savanna management by herders, previous ecological research did not incorporate the traditional knowledge of anthropogenic fire history. This paper integrates ecological data and anthropogenic fire history, as reconstructed by herders, to assess landscape and regional level vegetation change in northeastern Namibia. We investigated effects of fire frequency (i.e. 10 years) to understand changes in vegetation cover, life form species richness and savanna conditions (defined as a ratio of shrub cover to herbaceous cover). Additionally, we analysed trends in the vegetation variables between different fire histories at the landscape and regional scales. Shrub cover was negatively correlated to herbaceous cover and herbaceous species richness. The findings showed that bush cover homogenisation at landscape and regional scales may suggest that the problem of bush encroachment was widespread. Frequent fires reduced shrub cover temporarily and promoted herbaceous cover. The effects on tree cover were less dramatic. The response to fire history was scale-independent for shrub, herbaceous and tree cover, but scale-dependent for the richness of grass and tree life forms. Fire history, and not grazing pressure, improved savanna conditions. The findings emphasise the need to assess effects of anthropogenic fires on vegetation change before introducing new fire management policies in savanna ecosystems of northeastern Namibia.