Oceanic upwelling and productivity in the eastern tropical Pacific

International Nuclear Information System (INIS)

Fiedler, P.C.; Philbrick, V.; Chavez, F.P.

1991-01-01

An oceanographic survey of the eastern tropical Pacific Ocean in August-November 1990 found a productive, nutrient-rich, moderately high-chlorophyll surface layer in two oceanic upwelling regions: the equatorial divergence, especially east of the Galapagos, and the countercurrent divergence out to 105 degree W, > 1,000 km west of the Costa Rica Dome. Although NO 3 is not depleted in upwelling regions, relationships among nutrient concentrations and temperature in 1986-1988 data from the same area show that NO 3 is the first macronutrient to be depleted in adjacent, less-productive regions. A three-dimensional, two-layer box model of NO 3 flux within and into the euphotic zone gives estimated rates of new production that are ∼29% of measured rates of 14 C phytoplankton production. Persistence of excess NO 3 in the euphotic zone exceeds 1 yr under high-nutrient, low-chlorophyll conditions off the equator where weak upwelling, or downwelling, occurs. These results indicate substantial control or limitation of NO 3 utilization and productivity in nutrient-rich oceanic regions of the eastern tropical Pacific

Diversity and abundance of ammonia oxidizing archaea in tropical compost systems.

Science.gov (United States)

de Gannes, Vidya; Eudoxie, Gaius; Dyer, David H; Hickey, William J

2012-01-01

Composting is widely used to transform waste materials into valuable agricultural products. In the tropics, large quantities of agricultural wastes could be potentially useful in agriculture after composting. However, while microbiological processes of composts in general are well established, relatively little is known about microbial communities that may be unique to these in tropical systems, particularly nitrifiers. The recent discovery of ammonia oxidizing archaea (AOA) has changed the paradigm of nitrification being initiated solely by ammonia oxidizing bacteria. In the present study, AOA abundance and diversity was examined in composts produced from combinations of plant waste materials common in tropical agriculture (rice straw, sugar cane bagasse, and coffee hulls), which were mixed with either cow- or sheep-manure. The objective was to determine how AOA abundance and diversity varied as a function of compost system and time, the latter being a contrast between the start of the compost process (mesophilic phase) and the finished product (mature phase). The results showed that AOA were relatively abundant in composts of tropical agricultural wastes, and significantly more so than were the ammonia-oxidizing bacteria. Furthermore, while the AOA communities in the composts were predominatly group I.1b, the communities were diverse and exhibited structures that diverged between compost types and phases. These patterns could be taken as indicators of the ecophysiological diversity in the soil AOA (group I.1b), in that significantly different AOA communties developed when exposed to varying physico-chemical environments. Nitrification patterns and levels differed in the composts which, for the mature material, could have significant effects on its performance as a plant growth medium. Thus, it will also be important to determine the association of AOA (and diversity in their communities) with nitrification in these systems.

Productive vegetation: relationships between net primary productivity, vegetation types and climate change in the Wet Tropics bioregion

International Nuclear Information System (INIS)

Ramirez, Vanessa Valdez; Williams, Stephen E.; VanDerWal, Jeremy

2007-01-01

Full text: Full text: There is now ample evidence demonstrating the impacts of climate change on biodiversity and human society (Walther ef a/. 2002). Numerous studies have shown climate change is one of the most significant threats to tropical forests, such as the Wet Tropics Heritage Area, due to their high biodiversity and endemism (Pounds ef al. 1999; Hughes 2000; Parmesan and Yohe 2003). Williams ef al. (2003) suggested that small shifts in net primary productivity (NPP) as a result of climate change could lead to potentially massive follow-on effects for the extremely diverse and vulnerable rainforest flora and fauna. It is therefore crucial to explore the relationships between NPP and local biodiversity, especially to create models for different climate change scenarios. Nevertheless, NPP in the Wet Tropics has yet to be estimated. This is the first study to provide a general NPP estimate for the Wet Tropics bioregion using climate surrogates (Schuur 2003). This technique estimates NPP in an accurate, repeatable, and cost-effective way. NPP values were linked to vegetation types and examined under various climatic and environmental conditions. Results show a significant difference in productivity according to vegetation types and climatic variables, with temperature and rainfall seasonality as the most important determining variables. Additionally, lowland and upland vegetations showed a significant difference in productivity patterns throughout the year. Vegetation types located above 1000 metres in altitude had the lowest values of mean annual productivity due to their high rainfall and low temperatures; vegetation types located below 600 metres showed increased productivity values during the wet season (December-March). Net primary productivity will certainly be impacted by changes in temperature and rainfall, due to climate change. Although an increase in NPP values can be predicted for upland areas, the more widely distributed lowlands will drastically

Minimizing Risks of Invasive Alien Plant Species in Tropical Production Forest Management

Directory of Open Access Journals (Sweden)

Michael Padmanaba

2014-08-01

Full Text Available Timber production is the most pervasive human impact on tropical forests, but studies of logging impacts have largely focused on timber species and vertebrates. This review focuses on the risk from invasive alien plant species, which has been frequently neglected in production forest management in the tropics. Our literature search resulted in 114 publications with relevant information, including books, book chapters, reports and papers. Examples of both invasions by aliens into tropical production forests and plantation forests as sources of invasions are presented. We discuss species traits and processes affecting spread and invasion, and silvicultural practices that favor invasions. We also highlight potential impacts of invasive plant species and discuss options for managing them in production forests. We suggest that future forestry practices need to reduce the risks of plant invasions by conducting surveillance for invasive species; minimizing canopy opening during harvesting; encouraging rapid canopy closure in plantations; minimizing the width of access roads; and ensuring that vehicles and other equipment are not transporting seeds of invasive species. Potential invasive species should not be planted within dispersal range of production forests. In invasive species management, forewarned is forearmed.

Phenology and biomass production of adapted and non-adapted tropical corn populations in Central Iowa

Science.gov (United States)

Biofuel production in the Midwestern United States has largely focused on corn (Zea mays L.) grain for ethanol production and more recently, corn stover for lignocellulosic ethanol. As an alternative to conventional corn, tropical corn populations have been evaluated. Tropical corn is the term used ...

JPL Tropical Cyclone Information System

Data.gov (United States)

National Aeronautics and Space Administration — The JPL Tropical Cyclone Information System (TCIS) brings together satellite and in situ data sets from various sources to help you find information for a particular...

Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

Science.gov (United States)

Fabien H. Wagner; Bruno Herault; Damien Bonal; Clement Stahl; Liana O. Anderson; Timothy R. Baker; Gabriel Sebastian Becker; Hans Beeckman; Danilo Boanerges Souza; Paulo Cesar Botosso; David M. J. S. Bowman; Achim Brauning; Benjamin Brede; Foster Irving Brown; Jesus Julio Camarero; Plinio Barbosa Camargo; Fernanda C. G. Cardoso; Fabricio Alvim Carvalho; Wendeson Castro; Rubens Koloski Chagas; Jerome Chave; Emmanuel N. Chidumayo; Deborah A. Clark; Flavia Regina Capellotto Costa; Camille Couralet; Paulo Henrique da Silva Mauricio; Helmut Dalitz; Vinicius Resende de Castro; Jacanan Eloisa de Freitas Milani; Edilson Consuelo de Oliveira; Luciano de Souza Arruda; Jean-Louis Devineau; David M. Drew; Oliver Dunisch; Giselda Durigan; Elisha Elifuraha; Marcio Fedele; Ligia Ferreira Fedele; Afonso Figueiredo Filho; Cesar Augusto Guimaraes Finger; Augusto Cesar Franco; Joao Lima Freitas Junior; Franklin Galvao; Aster Gebrekirstos; Robert Gliniars; Paulo Mauricio Lima de Alencastro Graca; Anthony D. Griffiths; James Grogan; Kaiyu Guan; Jurgen Homeier; Maria Raquel Kanieski; Lip Khoon Kho; Jennifer Koenig; Sintia Valerio Kohler; Julia Krepkowski; Jose Pires Lemos-Filho; Diana Lieberman; Milton Eugene Lieberman; Claudio Sergio Lisi; Tomaz Longhi Santos; Jose Luis Lopez Ayala; Eduardo Eijji Maeda; Yadvinder Malhi; Vivian R. B. Maria; Marcia C. M. Marques; Renato Marques; Hector Maza Chamba; Lawrence Mbwambo; Karina Liana Lisboa Melgaco; Hooz Angela Mendivelso; Brett P. Murphy; Joseph O' Brien; Steven F. Oberbauer; Naoki Okada; Raphael Pelissier; Lynda D. Prior; Fidel Alejandro Roig; Michael Ross; Davi Rodrigo Rossatto; Vivien Rossi; Lucy Rowland; Ervan Rutishauser; Hellen Santana; Mark Schulze; Diogo Selhorst; Williamar Rodrigues Silva; Marcos Silveira; Susanne Spannl; Michael D. Swaine; Jose Julio Toledo; Marcos Miranda Toledo; Marisol Toledo; Takeshi Toma; Mario Tomazello Filho; Juan Ignacio Valdez Hernandez; Jan Verbesselt; Simone Aparecida Vieira; Gregoire Vincent; Carolina Volkmer de Castilho; Franziska Volland; Martin Worbes; Magda Lea Bolzan Zanon; Luiz E. O. C. Aragao

2016-01-01

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter...

Why do forest products become less available? A pan-tropical comparison of drivers of forest-resource degradation

OpenAIRE

Hermans, Kathleen; Gerstner, Katharina; Geijzendorffer, Ilse R.; Herold, Martin; Seppelt, Ralf; Wunder, Sven

2016-01-01

Forest products provide an important source of income and wellbeing for rural smallholder communities across the tropics. Although tropical forest products frequently become over-exploited, only few studies explicitly address the dynamics of degradation in response to socio-economic drivers. Our study addresses this gap by analyzing the factors driving changes in tropical forest products in the perception of rural smallholder communities. Using the poverty and environment network global datas...

NOAA JPSS Advanced Technology Microwave Sounder (ATMS)-based Tropical Cyclone (TC) Products from NDE

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The JPSS Microwave Sounder-based Tropical Cyclone (TC) Products provide estimates of tropical cyclone maximum wind speed, minimum sea level pressure, radii of 34,...

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

Science.gov (United States)

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

2010-12-01

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

Tropical Cyclone Information System

Science.gov (United States)

Li, P. Peggy; Knosp, Brian W.; Vu, Quoc A.; Yi, Chao; Hristova-Veleva, Svetla M.

2009-01-01

The JPL Tropical Cyclone Infor ma tion System (TCIS) is a Web portal (http://tropicalcyclone.jpl.nasa.gov) that provides researchers with an extensive set of observed hurricane parameters together with large-scale and convection resolving model outputs. It provides a comprehensive set of high-resolution satellite (see figure), airborne, and in-situ observations in both image and data formats. Large-scale datasets depict the surrounding environmental parameters such as SST (Sea Surface Temperature) and aerosol loading. Model outputs and analysis tools are provided to evaluate model performance and compare observations from different platforms. The system pertains to the thermodynamic and microphysical structure of the storm, the air-sea interaction processes, and the larger-scale environment as depicted by ocean heat content and the aerosol loading of the environment. Currently, the TCIS is populated with satellite observations of all tropical cyclones observed globally during 2005. There is a plan to extend the database both forward in time till present as well as backward to 1998. The portal is powered by a MySQL database and an Apache/Tomcat Web server on a Linux system. The interactive graphic user interface is provided by Google Map.

Why do forest products become less available? A pan-tropical comparison of drivers of forest-resource degradation

NARCIS (Netherlands)

Hermans, Kathleen; Gerstner, Katharina; Geijzendorffer, Ilse R.; Herold, Martin; Seppelt, Ralf; Wunder, Sven

2016-01-01

Forest products provide an important source of income and wellbeing for rural smallholder communities across the tropics. Although tropical forest products frequently become over-exploited, only few studies explicitly address the dynamics of degradation in response to socio-economic drivers. Our

Soil phosphorus dynamics in a humid tropical silvopastoral system

Energy Technology Data Exchange (ETDEWEB)

Cooperband, L.R.

1992-01-01

In developing countries of the humid tropics, timber exploitation and agricultural expansion frequently result in deforestation. Extensive land management, coupled with inherently low soil fertility invariably produce declines in agricultural/livestock productivity which eventually lead to land abandonment and further deforestation. Phosphorus is often the major nutrient limiting plant growth in tropical soils. Agroforestry systems have been considered as viable alternatives to current land use practices. Several hypotheses suggest that combining trees with crops or pasture, especially leguminous species will improve soil nutrient cycling, soil structure and soil organic matter. In this experiment Erythrina berteroana (an arboreous legume) was grown in native grass pastures in Costa Rica to determine the effects of tree pruning and cattle grazing on soil P availability. I measured soil P fluxes as well as changes in pasture biomass over an 18-month period. In a separate field experiment, I determined decomposition rates and P release characteristics of Erythrina leaves, pasture grass clippings and cattle dung. Erythrina leaves decomposed faster than both pasture grass and cattle dung. Erythrina and pasture residues released 4-5 times less P than dung. Phosphorus fluxes after tree pruning and grazing were highly dynamic for all treatments. Tree pruning increased labile soil P over time when coupled with grazing. Pasture biomass production was greatest in the grazed tree treatment. Pasture biomass P production and concentration was greatest in the non-grazed treatment. Trees and grazing together tended to increase nutrient (P) turnover which stimulated biomass production. In contrast, trees without grazing promoted nutrient (P) accumulation in pasture biomass.

Soil phosphorus dynamics in a humid tropical silvopastoral system

International Nuclear Information System (INIS)

Cooperband, L.R.

1992-01-01

In developing countries of the humid tropics, timber exploitation and agricultural expansion frequently result in deforestation. Extensive land management, coupled with inherently low soil fertility invariably produce declines in agricultural/livestock productivity which eventually lead to land abandonment and further deforestation. Phosphorus is often the major nutrient limiting plant growth in tropical soils. Agroforestry systems have been considered as viable alternatives to current land use practices. Several hypotheses suggest that combining trees with crops or pasture, especially leguminous species will improve soil nutrient cycling, soil structure and soil organic matter. In this experiment Erythrina berteroana (an arboreous legume) was grown in native grass pastures in Costa Rica to determine the effects of tree pruning and cattle grazing on soil P availability. I measured soil P fluxes as well as changes in pasture biomass over an 18-month period. In a separate field experiment, I determined decomposition rates and P release characteristics of Erythrina leaves, pasture grass clippings and cattle dung. Erythrina leaves decomposed faster than both pasture grass and cattle dung. Erythrina and pasture residues released 4-5 times less P than dung. Phosphorus fluxes after tree pruning and grazing were highly dynamic for all treatments. Tree pruning increased labile soil P over time when coupled with grazing. Pasture biomass production was greatest in the grazed tree treatment. Pasture biomass P production and concentration was greatest in the non-grazed treatment. Trees and grazing together tended to increase nutrient (P) turnover which stimulated biomass production. In contrast, trees without grazing promoted nutrient (P) accumulation in pasture biomass

Cost-benefit analysis of a green electricity system in Japan considering the indirect economic impacts of tropical cyclones

International Nuclear Information System (INIS)

Esteban, Miguel; Zhang, Qi; Longarte-Galnares, Gorka

2012-01-01

Global warming is likely to profoundly influence future weather patterns, and one consequence of this is the likelihood of an increase in tropical cyclone intensity. The present paper presents a cost-benefit analysis of introducing significant amounts of green energy in the electricity system in Japan in the light of the economic damage that an increase in tropical cyclone intensity could have on GDP growth between 2010 and 2085. Essentially the passage of a tropical cyclone will result not only in physical damage but also on a decrease in economic productivity due to precautionary cessation of the economic activity, which has an effect on GDP growth. By comparing the economic performance of different electricity system scenarios with the indirect economic damage of tropical cyclones from 2010 to 2085, based on the yearly economic data of green electricity, fossil fuel, GDP and population, it can be seen that the green scenarios are generally a cost-effective way of mitigating the effects of these weather systems, despite the large amount of initial investments necessary. - Highlights: ► Climate change is likely to increase the future strength of tropical cyclones. ► An increase in tropical cyclone strength would reduce GDP growth in Japan. ► Reducing green-house gas emissions is a cost-effective mitigation strategy.

Nitrogenous nutrients and primary production in a tropical oceanic environment

Digital Repository Service at National Institute of Oceanography (India)

Wafar, M.V.M.; Wafar, S.; Devassy, V.P.

Measurements of the concentrations of nitrogenous nutrients and primary production were made at 10 stations along 8 degrees N and 10 degrees N in the tropical oceanic Lakshadweep waters Inorganic nitrogen (NO3, NO2 and NH4) accounted for less than...

Macauba: a promising tropical palm for the production of vegetable oil

Directory of Open Access Journals (Sweden)

Colombo Carlos Augusto

2018-01-01

Full Text Available The growing global demand for vegetable oils for food and for replacing fossil fuels leads to increased oilseeds production. Almost 122 of the current 187 million tons of vegetable oils produced in the world correspond to palm and soybean oils. The oil palm is cultivated in the tropical zone, in areas formerly occupied by forests, and soybean oil is a by-product of protein meal production. The diversification of raw materials for the vegetable oil market is thus strategic for both food and non-food sectors. Sources for vegetable oil should be economically competitive and provide sustainability indexes higher than that provided by oil palm and soybean. In this context, we describe the potential of Acrocomia aculeata, popularly known as macauba. Macauba is an American palm from the tropical zones which presents oil productivity and quality similar to that of the oil palm. It grows spontaneously in a wide range of environments and it is not very water demanding. Macauba palm has a high potential for oil production and for diversification of co-products with some potential of value aggregation. Such a perennial and sustainable species will probably fulfill the requirements to become an important new commercial oilseed crop.

Biomass production and composition of temperate and tropical maize in central Iowa

Science.gov (United States)

Bioethanol production in the Midwestern U.S. has largely focused on corn (Zea mays L.) grain for starch-based ethanol production. There has been growing interest in lignocellulosic biomass as a feedstock for biofuels. Because corn adapted to the tropics does not initiate senescence as early as ada...

An Analysis of the U.S. Wood Products Import Sector: Prospects for Tropical Wood Products Exporters

Directory of Open Access Journals (Sweden)

W.A.R.T.W. Bandara

2012-10-01

Full Text Available The U.S. has dramatically altered its wood product imports and exports during the past few years,and at present, it is the second largest wood product importer in the world. Hence, an understanding ofmarket structures, factors in selecting foreign suppliers, and the emphasis placed on environmentalissues/certification are critical to understand from the perspective of wood products importers in the U.S.This study provides an analysis of the U.S. wood products import sector with special emphasis on currentand future opportunities for tropical wood products exporters to the U.S. market.In this study, 158 wood products importers in the U.S. were surveyed using a mailingquestionnaire. The adjusted response rate was 40.6 percent. Results indicated that most of the respondentswere small to medium scale firms, but major importers of wood products. According to respondents,wood products to the U.S. mainly come from Brazil, Chile, and China. From the importers’ perspective,Brazilian wood products ranked first for its quality followed by wood products from Chile and Finland.Product quality, long term customer relationships, on-time delivery of orders, fair prices, and supplierreputation were the factors deemed important in selecting overseas suppliers. Majority of respondentswere importing certified wood products. FSC, SFI, and ISO 14000 were the mostly accepted certificationprograms. However, certification was not a major factor in foreign supplier selection criteria. Whenconsidered the U.S. wood products importers’ tendency to diversify their products and species imported,attractive opportunities exist for wood products suppliers from tropical countries.

Primary production in a tropical large lake: The role of phytoplankton composition

International Nuclear Information System (INIS)

Darchambeau, F.; Sarmento, H.; Descy, J.-P.

2014-01-01

Phytoplankton biomass and primary production in tropical large lakes vary at different time scales, from seasons to centuries. We provide a dataset made of 7 consecutive years of phytoplankton biomass and production in Lake Kivu (Eastern Africa). From 2002 to 2008, bi-weekly samplings were performed in a pelagic site in order to quantify phytoplankton composition and biomass, using marker pigments determined by HPLC. Primary production rates were estimated by 96 in situ 14 C incubations. A principal component analysis showed that the main environmental gradient was linked to a seasonal variation of the phytoplankton assemblage, with a clear separation between diatoms during the dry season and cyanobacteria during the rainy season. A rather wide range of the maximum specific photosynthetic rate (P Bm ) was found, ranging between 1.15 and 7.21 g carbon g −1 chlorophyll a h −1 , and was best predicted by a regression model using phytoplankton composition as an explanatory variable. The irradiance at the onset of light saturation (I k ) ranged between 91 and 752 μE m −2 s −1 and was linearly correlated with the mean irradiance in the mixed layer. The inter-annual variability of phytoplankton biomass and production was high, ranging from 53 to 100 mg chlorophyll a m −2 (annual mean) and from 143 to 278 g carbon m −2 y −1 , respectively. The degree of seasonal mixing determined annual production, demonstrating the sensitivity of tropical lakes to climate variability. A review of primary production of other African great lakes allows situating Lake Kivu productivity in the same range as that of lakes Tanganyika and Malawi, even if mean phytoplankton biomass was higher in Lake Kivu. - Highlights: • We provide a 7-year dataset of primary production in a tropical great lake. • Specific photosynthetic rate was determined by community composition. • Annual primary production varied between 143 and 278 mg C m −2 y −1 . • Pelagic production was highly

Forests to fields. Restoring tropical lands to agriculture.

Science.gov (United States)

Wood, D

1993-04-01

In discussing land use in tropical forest regions, there is an emphasis on the following topics: the need for the expansion of cropping areas, the precedent for use of the tropical forest for cropping based on past use patterns, the pressure from conservationists against cropping, debunking the mythology that forests are "natural" and refuting the claims that forest clearance is not reversible, the archeological evidence of past forest use for agricultural purposes, abandonment of tropical land to forest, and rotation of forest and field. The assumption is that the way to stop food importation is to increase crop production in the tropics. Crop production can be increased through 1) land intensification or clearing new land, 2) output per unit of land increases, or 3) reallocation to agriculture land previously cleared and overgrown with tropical forest. "Temporary" reuse of land, which reverted back to tropical forest, is recommended. This reuse would ease population pressure, and benefit bioconservation, while populations stabilize and further progress is made in international plant breeding. The land would eventually be returned to a forest state. Conservation of tropical forest areas should be accomplished, after an assessment has been made of its former uses. Primary forests need to identified and conversion to farming ceased. Research needs to be directed to understanding the process of past forest regeneration, and to devising cropping systems with longterm viability. The green revolution is unsuitable for traditional cropping systems, is contrary to demands of international funding agencies for sustainability, and is not affordable by most poor farmers. Only .48 million sq. km of closed forest loss was in tropical rainforests; 6.53 million sq. km was lost from temperate forests cleared for intensive small-scale peasant farming. The use of tropical forest land for farming has some benefits; crops in the wetter tropics are perennial, which would "reduce

Eutrophication effects on phytoplankton size-fractioned biomass and production at a tropical estuary.

Science.gov (United States)

Guenther, Mariana; Araújo, Moacyr; Flores-Montes, Manuel; Gonzalez-Rodriguez, Eliane; Neumann-Leitão, Sigrid

2015-02-28

Size-fractioned phytoplankton (pico, nano and microplankton) biomass and production were estimated throughout a year at Recife harbor (NE Brazil), a shallow well mixed tropical hypereutrophic estuary with short residence times but restricted water renewal. Intense loads of P-PO4 (maximum 14 μM) resulted in low N:P ratios (around 2:1), high phytoplankton biomass (B=7.1-72 μg chl-a L(-1)), production (PP=10-2657 μg C L(-1) h(-1)) and photosynthetic efficiency (P(B)=0.5-45 μg C μg chl-a(-1)), but no oxygen depletion (average O2 saturation: 109.6%). Nanoplankton dominated phytoplankton biomass (66%) but micro- and nanoplankton performed equivalent primary production rates (47% each). Production-biomass models indicate an export of the exceeding microplankton biomass during most of the year, possibly through grazing. The intense and constant nutrient and organic matter loading at Recife harbor is thus supporting the high microplankton productivity that is not accumulating on the system nor contributing to oxygen depletion, but supporting the whole system's trophic web. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nursery function of tropical back-reef systems

NARCIS (Netherlands)

Adams, A.J.; Dahlgren, C.P.; Kellison, G.T.; Kendall, M.S.; Layman, C.A.; Ley, J.A.; Nagelkerken, I.; Serafy, J.E.

2006-01-01

Similar to nearshore systems in temperate latitudes, the nursery paradigm for tropical back-reef systems is that they provide a habitat for juveniles of species that subsequently make ontogenetic shifts to adult populations on coral reefs (we refer to this as the nursery function of back-reef

Management of organic matter in the tropics: Translating theory into practice

NARCIS (Netherlands)

Palm, C.A.; Giller, K.E.; Mafongoya, P.L.; Swift, M.J.

2001-01-01

Inputs of organic materials play a central role in the productivity of many tropical farming systems by providing nutrients through decomposition and substrate for synthesis of soil organic matter (SOM). The organic inputs in many tropical farming systems such as crop residues, manures, and natural

LivestockPlus — The sustainable intensification of forage-based agricultural systems to improve livelihoods and ecosystem services in the tropics

Directory of Open Access Journals (Sweden)

I. Rao

2015-05-01

Full Text Available As global demand for livestock products (such as meat, milk and eggs is expected to double by 2050, necessary increases to future production must be reconciled with negative environmental impacts that livestock cause. This paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the sustainable intensification of mixed crop-forage-livestock-tree systems in the tropics by producing multiple social, economic and environmental benefits. Sustainable intensification not only improves the productivity of tropical forage-based systems but also reduces the ecological footprint of livestock production and generates a diversity of ecosystem services (ES such as improved soil quality and reduced erosion, sedimentation and greenhouse gas (GHG emissions. Integrating improved grass and legume forages into mixed production systems (crop-livestock, tree-livestock, crop-tree-livestock can restore degraded lands and enhance system resilience to drought and waterlogging associated with climate change. When properly managed tropical forages accumulate large amounts of carbon in soil, fix atmospheric nitrogen (legumes, inhibit nitrification in soil and reduce nitrous oxide emissions (grasses, and reduce GHG emissions per unit livestock product. The LivestockPlus concept is defined as the sustainable intensification of forage-based systems, which is based on 3 interrelated intensification processes: genetic intensification - the development and use of superior grass and legume cultivars for increased livestock productivity; ecological intensification - the development and application of improved farm and natural resource management practices; and socio-economic intensification - the improvement of local and national institutions and policies, which enable refinements of technologies and support their enduring use. Increases in livestock productivity will require coordinated efforts to develop supportive government, non

Cloud Cover Assessment for Operational Crop Monitoring Systems in Tropical Areas

Directory of Open Access Journals (Sweden)

Isaque Daniel Rocha Eberhardt

2016-03-01

Full Text Available The potential of optical remote sensing data to identify, map and monitor croplands is well recognized. However, clouds strongly limit the usefulness of optical imagery for these applications. This paper aims at assessing cloud cover conditions over four states in the tropical and sub-tropical Center-South region of Brazil to guide the development of an appropriate agricultural monitoring system based on Landsat-like imagery. Cloudiness was assessed during overlapping four months periods to match the typical length of crop cycles in the study area. The percentage of clear sky occurrence was computed from the 1 km resolution MODIS Cloud Mask product (MOD35 considering 14 years of data between July 2000 and June 2014. Results showed high seasonality of cloud occurrence within the crop year with strong variations across the study area. The maximum seasonality was observed for the two states in the northern part of the study area (i.e., the ones closer to the Equator line, which also presented the lowest averaged values (15% of clear sky occurrence during the main (summer cropping period (November to February. In these locations, optical data faces severe constraints for mapping summer crops. On the other hand, relatively favorable conditions were found in the southern part of the study region. In the South, clear sky values of around 45% were found and no significant clear sky seasonality was observed. Results underpin the challenges to implement an operational crop monitoring system based solely on optical remote sensing imagery in tropical and sub-tropical regions, in particular if short-cycle crops have to be monitored during the cloudy summer months. To cope with cloudiness issues, we recommend the use of new systems with higher repetition rates such as Sentinel-2. For local studies, Unmanned Aircraft Vehicles (UAVs might be used to augment the observing capability. Multi-sensor approaches combining optical and microwave data can be another

Infrared heater system for warming tropical forest understory plants and soils

Science.gov (United States)

Bruce A. Kimball; Aura M. Alonso-Rodríguez; Molly A. Cavaleri; Sasha C. Reed; Grizelle González; Tana E. Wood

2018-01-01

The response of tropical forests to global warming is one of the largest uncertainties in predicting the future carbon balance of Earth. To determine the likely effects of elevated temperatures on tropical forest understory plants and soils, as well as other ecosystems, an infrared (IR) heater system was developed to provide in situ warming for the Tropical Responses...

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake.

Science.gov (United States)

Reis, P C J; Barbosa, F A R

2014-08-01

It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO2 because they receive allochthonous carbon inputs. However, autotrophy and CO2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO2 and CO2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO2 and CO2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO2 dynamics in tropical lakes. Net heterotrophy and CO2 outgassing from the lake were registered only at night, while significant CO2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO2 emissions from tropical lakes.

Microorganisms in Soils of Bovine Production Systems in Tropical Lowlands and Tropical Highlands in the Department of Antioquia, Colombia

Directory of Open Access Journals (Sweden)

Licet Paola Molina-Guzmán

2018-01-01

Full Text Available Studies on the physical and chemical effects of extensive grazing on soils have been performed in Colombia, but the effects of dairy cattle rearing on the biological properties of soils are not well known. The objective of this study was to evaluate microorganisms in 48 soils from livestock farms in the highland and lowland tropics in the Northern and Magdalena Medio subregions of the Department of Antioquia (Colombia. Principal component analysis demonstrated differences in the edaphic compositions of the soils, with increased percentages of root colonization by arbuscular mycorrhizal fungi and the density of microorganisms in farms that have soils with moderate phosphorus and nitrogen contents, low potassium content, and a moderately acidic pH. Agglomerative cluster analysis showed two groups for the highland tropic soils and six groups for the lowland tropic soils based on their population densities and interactions with the studied parameters. These results represent a first attempt to describe the density of microorganisms and the effect of soil physicochemical parameters on colonization by arbuscular mycorrhizal fungi in areas with determinant agroecological conditions, microbial functional diversity, and the presence of mycorrhizal fungi in livestock farm soils in Colombia.

Estimating productivity of tropical forest plantations by climatic factors

Energy Technology Data Exchange (ETDEWEB)

Pandey, D.

1996-12-31

This study presents an alternative method of estimating wood production at regional/global levels from tropical plantations based on climatic variables. A generic model for estimating potential yield in tropical plantations was formulated. The model was developed for teak (Tectona grandis L. F.) as a case study. Available data of teak sample plots from India, Myanmar, Indonesia, Nigeria and Ivory Coast, consisting of 153 plots distributed over 38 meteorological stations were used. A new base age invariant site index function was developed and the site index of each plot was estimated. The mean annual volume increment (MAI) of each plot from existing yield tables was then interpolated. Treating MAI at 50 years (rotation age) as potential yield of teak, a model was constructed which could explain about 59% variance of the potential yield. Models constructed for estimating the maximum MAI and the site index of teak explained the variability up to 61% and 57% respectively. The models underestimated the productivity of teak in Indonesia, Nigeria and Ivory Coast. The rainfall and the relative humidity have been identified as the most important climatic variables influencing the growth of teak. The length of the growing season and the temperature of the warmest month of the growing season were found significant in the models. The temperature and the day length (sunshine) have not been found to be the limiting factors for the growth of teak. However, the maximum temperature beyond a certain upper limit has a negative effect on growth. The study indicates that this upper limit is around 33 deg C for teak. The models could be used to forecast the potential yield of the existing as well as planned teak plantations in the tropical region. 109 refs, 15 figs, 11 tabs

Tropical Wetlands as Carbon Sinks

Science.gov (United States)

Jones, M. B.; Saunders, M.

2007-12-01

This presentation focuses on the tropical wetlands of sub-Saharan Africa. These are an understudied ecosystem in which large emergent grasses and sedges normally dominate and which have the potential to sequester significant amounts of carbon. Measurements of Net Primary Production of these wetlands show that they are some of the highest values recorded for any ecosystem. We have used eddy covariance to measure Net Ecosystem Exchange of pristine and disturbed wetlands and show that pristine systems can have sink strengths as strong as tropical forests while disturbed systems that have been reclaimed for agricultural purposes have a very much reduced carbon sink activity and may be net carbon sources. The management issues surrounding the use of these wetlands illustrate a direct conflict between the production of food crops for the local population and the maintenance of carbon sequestration as an ecosystem service.

Primary production in a tropical large lake: The role of phytoplankton composition

Energy Technology Data Exchange (ETDEWEB)

Darchambeau, F., E-mail: francois.darchambeau@ulg.ac.be [Chemical Oceanography Unit, University of Liège, Liège (Belgium); Sarmento, H., E-mail: hugo.sarmento@gmail.com [Department of Hydrobiology, Federal University of São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Descy, J.-P., E-mail: jean-pierre.descy@unamur.be [Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur (Belgium)

2014-03-01

Phytoplankton biomass and primary production in tropical large lakes vary at different time scales, from seasons to centuries. We provide a dataset made of 7 consecutive years of phytoplankton biomass and production in Lake Kivu (Eastern Africa). From 2002 to 2008, bi-weekly samplings were performed in a pelagic site in order to quantify phytoplankton composition and biomass, using marker pigments determined by HPLC. Primary production rates were estimated by 96 in situ {sup 14}C incubations. A principal component analysis showed that the main environmental gradient was linked to a seasonal variation of the phytoplankton assemblage, with a clear separation between diatoms during the dry season and cyanobacteria during the rainy season. A rather wide range of the maximum specific photosynthetic rate (P{sub Bm}) was found, ranging between 1.15 and 7.21 g carbon g{sup −1} chlorophyll a h{sup −1}, and was best predicted by a regression model using phytoplankton composition as an explanatory variable. The irradiance at the onset of light saturation (I{sub k}) ranged between 91 and 752 μE m{sup −2} s{sup −1} and was linearly correlated with the mean irradiance in the mixed layer. The inter-annual variability of phytoplankton biomass and production was high, ranging from 53 to 100 mg chlorophyll a m{sup −2} (annual mean) and from 143 to 278 g carbon m{sup −2} y{sup −1}, respectively. The degree of seasonal mixing determined annual production, demonstrating the sensitivity of tropical lakes to climate variability. A review of primary production of other African great lakes allows situating Lake Kivu productivity in the same range as that of lakes Tanganyika and Malawi, even if mean phytoplankton biomass was higher in Lake Kivu. - Highlights: • We provide a 7-year dataset of primary production in a tropical great lake. • Specific photosynthetic rate was determined by community composition. • Annual primary production varied between 143 and 278 mg C m

Ecological and socio-economic functions across tropical land use systems after rainforest conversion.

Science.gov (United States)

Drescher, Jochen; Rembold, Katja; Allen, Kara; Beckschäfer, Philip; Buchori, Damayanti; Clough, Yann; Faust, Heiko; Fauzi, Anas M; Gunawan, Dodo; Hertel, Dietrich; Irawan, Bambang; Jaya, I Nengah S; Klarner, Bernhard; Kleinn, Christoph; Knohl, Alexander; Kotowska, Martyna M; Krashevska, Valentyna; Krishna, Vijesh; Leuschner, Christoph; Lorenz, Wolfram; Meijide, Ana; Melati, Dian; Nomura, Miki; Pérez-Cruzado, César; Qaim, Matin; Siregar, Iskandar Z; Steinebach, Stefanie; Tjoa, Aiyen; Tscharntke, Teja; Wick, Barbara; Wiegand, Kerstin; Kreft, Holger; Scheu, Stefan

2016-05-19

Tropical lowland rainforests are increasingly threatened by the expansion of agriculture and the extraction of natural resources. In Jambi Province, Indonesia, the interdisciplinary EFForTS project focuses on the ecological and socio-economic dimensions of rainforest conversion to jungle rubber agroforests and monoculture plantations of rubber and oil palm. Our data confirm that rainforest transformation and land use intensification lead to substantial losses in biodiversity and related ecosystem functions, such as decreased above- and below-ground carbon stocks. Owing to rapid step-wise transformation from forests to agroforests to monoculture plantations and renewal of each plantation type every few decades, the converted land use systems are continuously dynamic, thus hampering the adaptation of animal and plant communities. On the other hand, agricultural rainforest transformation systems provide increased income and access to education, especially for migrant smallholders. Jungle rubber and rubber monocultures are associated with higher financial land productivity but lower financial labour productivity compared to oil palm, which influences crop choice: smallholders that are labour-scarce would prefer oil palm while land-scarce smallholders would prefer rubber. Collecting long-term data in an interdisciplinary context enables us to provide decision-makers and stakeholders with scientific insights to facilitate the reconciliation between economic interests and ecological sustainability in tropical agricultural landscapes. © 2016 The Authors.

Maize, tropical (Zea mays L.).

Science.gov (United States)

Assem, Shireen K

2015-01-01

Maize (Zea mays L.) is the third most important food crop globally after wheat and rice. In sub-Saharan Africa, tropical maize has traditionally been the main staple of the diet; 95 % of the maize grown is consumed directly as human food and as an important source of income for the resource-poor rural population. The biotechnological approach to engineer biotic and abiotic traits implies the availability of an efficient plant transformation method. The production of genetically transformed plants depends both on the ability to integrate foreign genes into target cells and the efficiency with which plants are regenerated. Maize transformation and regeneration through immature embryo culture is the most efficient system to regenerate normal transgenic plants. However, this system is highly genotype dependent. Genotypes adapted to tropic areas are difficult to regenerate. Therefore, transformation methods used with model genotypes adapted to temperate areas are not necessarily efficient with tropical lines. Agrobacterium-mediated transformation is the method of choice since it has been first achieved in 1996. In this report, we describe a transformation method used successfully with several tropical maize lines. All the steps of transformation and regeneration are described in details. This protocol can be used with a wide variety of tropical lines. However, some modifications may be needed with recalcitrant lines.

Tropical radioecology

CERN Document Server

Baxter, M

2012-01-01

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

Effects of liana load, tree diameter and distances between conspecifics on seed production in tropical timber trees

NARCIS (Netherlands)

Nabe-Nielsen, J.; Kollmann, J.; Peña-Claros, M.

2009-01-01

Seed production in tropical timber trees is limited by abiotic resources, pollination and pre-dispersal seed predation. Resource availability is influenced by the number of competing trees and by lianas that often reach high densities in disturbed parts of tropical forests. The distance between

Trophic interactions and productivity of copepods as live feed from tropical Taiwanese outdoor aquaculture ponds

DEFF Research Database (Denmark)

Blanda, Elisa; Drillet, Guillaume; Huang, Cheng-Chien

2015-01-01

The present study describes three outdoor ponds for mass rearing of copepods in tropical southern Taiwan. The systems are designed for culturing and harvesting of copepods, which are used as live feed in the production of groupers in the region. However, the production of the most common copepod...... to enable a correct description of the copepods ecology and a preliminary evaluation of the status of the pond management; and (III) provide advices for improved management leading towards a higher and more stable output of P. annandalei. Copepods were experiencing prey ad libitum since the quantity...... during high season. This harvest, in terms of biomass, corresponded to 20–40% of the copepod standing stock, which indicates a sustainable management when compared to the secondary productivity of the copepods. To further increase the copepod production of the ponds, better water quality must be achieved...

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T

2006-01-01

... of tropical cyclones The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved...

Tropical Soil Chemistry

DEFF Research Database (Denmark)

Borggaard, Ole K.

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

Current status of tropical fruit breeding and genetics for three tropical fruit species cultivated in Japan: pineapple, mango, and papaya

Science.gov (United States)

Ogata, Tatsushi; Yamanaka, Shinsuke; Shoda, Moriyuki; Urasaki, Naoya; Yamamoto, Toshiya

2016-01-01

Tropical fruit crops are predominantly produced in tropical and subtropical developing countries, but some are now grown in southern Japan. Pineapple (Ananas comosus), mango (Mangifera indica) and papaya (Carica papaya) are major tropical fruits cultivated in Japan. Modern, well-organized breeding systems have not yet been developed for most tropical fruit species. Most parts of Japan are in the temperate climate zone, but some southern areas such as the Ryukyu Islands, which stretch from Kyushu to Taiwan, are at the northern limits for tropical fruit production without artificial heating. In this review, we describe the current status of tropical fruit breeding, genetics, genomics, and biotechnology of three main tropical fruits (pineapple, mango, and papaya) that are cultivated and consumed in Japan. More than ten new elite cultivars of pineapple have been released with improved fruit quality and suitability for consumption as fresh fruit. New challenges and perspectives for obtaining high fruit quality are discussed in the context of breeding programs for pineapple. PMID:27069392

Insight into the product film formed on Ni-advanced weathering steel in a tropical marine atmosphere

Science.gov (United States)

Wu, Wei; Cheng, Xuequn; Hou, Huaxing; Liu, Bo; Li, Xiaogang

2018-04-01

The product film formed on Ni-advanced weathering steel in a tropical marine environment was investigated in detail through outdoor exposure by using diverse surface analysis techniques combined with electrochemical impedance spectroscopy and scanning kelvin probe measurements. The results showed that the product film was mainly composed of nanophasic goethite in the inner layer and maghemite, akaganeite, and hematite in the outer layer. Moreover, the resistance to atmospheric corrosion gradually increased from the outermost product film to the innermost film. Ni was significantly enriched in the inner layer in the form of the spinel phase NiFe2O4, which transformed lepidocrocite to fine-grained goethite, withstood the invasion of chloridion, and improved the corrosion potential of the product film in a tropical marine atmosphere.

Benthic macrofaunal structure and secondary production in tropical estuaries on the Eastern Marine Ecoregion of Brazil.

Science.gov (United States)

Bissoli, Lorena B; Bernardino, Angelo F

2018-01-01

Tropical estuaries are highly productive and support diverse benthic assemblages within mangroves and tidal flats habitats. Determining differences and similarities of benthic assemblages within estuarine habitats and between regional ecosystems may provide scientific support for management of those ecosystems. Here we studied three tropical estuaries in the Eastern Marine Ecoregion of Brazil to assess the spatial variability of benthic assemblages from vegetated (mangroves) and unvegetated (tidal flats) habitats. A nested sampling design was used to determine spatial scales of variability in benthic macrofaunal density, biomass and secondary production. Habitat differences in benthic assemblage composition were evident, with mangrove forests being dominated by annelids (Oligochaeta and Capitellidae) whereas peracarid crustaceans were also abundant on tidal flats. Macrofaunal biomass, density and secondary production also differed between habitats and among estuaries. Those differences were related both to the composition of benthic assemblages and to random spatial variability, underscoring the importance of hierarchical sampling in estuarine ecological studies. Given variable levels of human impacts and predicted climate change effects on tropical estuarine assemblages in Eastern Brazil, our data support the use of benthic secondary production to address long-term changes and improved management of estuaries in Eastern Brazil.

Soil and water pollution in a banana production region in tropical Mexico

NARCIS (Netherlands)

Geissen, V.; Que Ramos, F.; Bastidas-Bastidas, de P.J.; Díaz-González, G.; Bello-Mendoza, R.; Huerta-Lwanga, E.; Ruiz-Suárez, L.E.

2010-01-01

The effects of abundant Mancozeb (Mn, Zn— bisdithiocarbamate) applications (2.5 kg ha-1week-1 for 10 years) on soil and surface-, subsurface- and groundwater pollution were monitored in a banana production region of tropical Mexico. In soils, severe manganese accumulation was observed, wheras the

Identifying N fertilizer regime and vegetable production system in tropical Brazil using (15) N natural abundance.

Science.gov (United States)

Inácio, Caio T; Urquiaga, Segundo; Chalk, Phillip M; Mata, Maria Gabriela F; Souza, Paulo O

2015-12-01

This study was conducted in areas of vegetable production in tropical Brazil, with the objectives of (i) measuring the variation in δ(15)  N in soils, organic N fertilizer sources and lettuce (Lactuca sativa L.) from different farming systems, (ii) measuring whether plant δ(15)  N can differentiate organic versus conventional lettuce and (iii) identifying the factors affecting lettuce δ(15)  N. Samples of soil, lettuce and organic inputs were taken from two organic, one conventional and one hydroponic farm. The two organic farms had different N-sources with δ(15)  N values ranging from 0.0 to +14.9‰ (e.g. leguminous green manure and animal manure compost, respectively), and differed significantly (P hydroponic lettuce δ(15)  N (+4.5 ± 0.2‰) due to manure inputs. The N from leguminous green manure made a small contribution to the N nutrition of lettuce in the multi-N-source organic farm. To differentiate organic versus conventional farms using δ(15)  N the several subsets of mode of fertilization should be considered. Comparisons of δ(15)  N of soil, organic inputs and lettuce allowed a qualitative analysis of the relative importance of different N inputs. © 2015 Society of Chemical Industry.

Conversion of tropical lowland forest reduces nutrient return through litterfall, and alters nutrient use efficiency and seasonality of net primary production.

Science.gov (United States)

Kotowska, Martyna M; Leuschner, Christoph; Triadiati, Triadiati; Hertel, Dietrich

2016-02-01

Tropical landscapes are not only rapidly transformed by ongoing land-use change, but are additionally confronted by increasing seasonal climate variation. There is an increasing demand for studies analyzing the effects and feedbacks on ecosystem functioning of large-scale conversions of tropical natural forest into intensively managed cash crop agriculture. We analyzed the seasonality of aboveground litterfall, fine root litter production, and aboveground woody biomass production (ANPP(woody)) in natural lowland forests, rubber agroforests under natural tree cover ("jungle rubber"), rubber and oil palm monocultures along a forest-to-agriculture transformation gradient in Sumatra. We hypothesized that the temporal fluctuation of litter production increases with increasing land-use intensity, while the associated nutrient fluxes and nutrient use efficiency (NUE) decrease. Indeed, the seasonal variation of aboveground litter production and ANPP(woody) increased from the natural forest to the plantations, while aboveground litterfall generally decreased. Nutrient return through aboveground litter was mostly highest in the natural forest; however, it was significantly lower only in rubber plantations. NUE of N, P and K was lowest in the oil palm plantations, with natural forest and the rubber systems showing comparably high values. Root litter production was generally lower than leaf litter production in all systems, while the root-to-leaf ratio of litter C flux increased along the land-use intensity gradient. Our results suggest that nutrient and C cycles are more directly affected by climate seasonality in species-poor agricultural systems than in species-rich forests, and therefore might be more susceptible to inter-annual climate fluctuation and climate change.

Strategic grazing management towards sustainable intensification at tropical pasture-based dairy systems.

Science.gov (United States)

Congio, Guilhermo F S; Batalha, Camila D A; Chiavegato, Marília B; Berndt, Alexandre; Oliveira, Patrícia P A; Frighetto, Rosa T S; Maxwell, Thomas M R; Gregorini, Pablo; Da Silva, Sila C

2018-05-01

Agricultural systems are responsible for environmental impacts that can be mitigated through the adoption of more sustainable principles. Our objective was to investigate the influence of two pre-grazing targets (95% and maximum canopy light interception during pasture regrowth; LI 95% and LI Max , respectively) on sward structure and herbage nutritive value of elephant grass cv. Cameroon, and dry matter intake (DMI), milk yield, stocking rate, enteric methane (CH 4 ) emissions by Holstein × Jersey dairy cows. We hypothesized that grazing strategies modifying the sward structure of elephant grass (Pennisetum purpureum Schum.) improves nutritive value of herbage, increasing DMI and reducing intensity of enteric CH 4 emissions, providing environmental and productivity benefits to tropical pasture-based dairy systems. Results indicated that pre-sward surface height was greater for LI Max (≈135 cm) than LI 95% (≈100 cm) and can be used as a reliable field guide for monitoring sward structure. Grazing management based on LI 95% criteria improved herbage nutritive value and grazing efficiency, allowing greater DMI, milk yield and stocking rate by dairy cows. Daily enteric CH 4 emission was not affected; however, cows grazing elephant grass at LI 95% were more efficient and emitted 21% less CH 4 /kg of milk yield and 18% less CH 4 /kg of DMI. The 51% increase in milk yield per hectare overcame the 29% increase in enteric CH 4 emissions per hectare in LI 95% grazing management. Thereby the same resource allocation resulted in a 16% mitigation of the main greenhouse gas from pasture-based dairy systems. Overall, strategic grazing management is an environmental friendly practice that improves use efficiency of allocated resources through optimization of processes evolving plant, ruminant and their interface, and enhances milk production efficiency of tropical pasture-based systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Tropical Veterinarian: Submissions

African Journals Online (AJOL)

Author Guidelines. 2012 Author Guidelines: Instructions to Authors: TROPICAL VETERINARIAN welcomes original work on all aspects of veterinary science as practiced in the Tropics, including livestock production and management, animal disease (domestic and wild), various aspects of preventive medicine and public ...

Spatial patterns of primary productivity derived from the Dynamic Habitat Indices predict patterns of species richness and distributions in the tropics

Science.gov (United States)

Suttidate, Naparat

Humans are changing the Earth's ecosystems, which has profound consequences for biodiversity. To understand how species respond to these changes, biodiversity science requires accurate assessments of biodiversity. However, biodiversity assessments are still limited in tropical regions. The Dynamic Habitat Indices (DHIs), derived from satellite data, summarize dynamic patterns of annual primary productivity: (a) cumulative annual productivity, (b) minimum annual productivity, and (c) seasonal variation in productivity. The DHIs have been successfully used in temperate regions, but not yet in the tropics. My goal was to evaluate the importance of primary productivity measured via the DHIs for assessing patterns of species richness and distributions in Thailand. First, I assessed the relationships between the DHIs and tropical bird species richness. I also evaluated the complementarity of the DHIs and topography, climate, latitudinal gradients, habitat heterogeneity, and habitat area in explaining bird species richness. I found that among three DHIs, cumulative annual productivity was the most important factor in explaining bird species richness and that the DHIs outperformed other environmental variables. Second, I developed texture measures derive from DHI cumulative annual productivity, and compared them to habitat composition and fragmentation as predictors of tropical forest bird distributions. I found that adding texture measures to habitat composition and fragmentation models improved the prediction of tropical bird distributions, especially area- and edge-sensitive tropical forest bird species. Third, I predicted the effects of trophic interactions between primary productivity, prey, and predators in relation to habitat connectivity for Indochinese tigers (Panthera tigris). I found that including trophic interactions improved habitat suitability models for tigers. However, tiger habitat is highly fragmented with few dispersal corridors. I also identified

The Role of Natural Products in Drug Discovery and Development against Neglected Tropical Diseases

Directory of Open Access Journals (Sweden)

Peter Mubanga Cheuka

2016-12-01

Full Text Available Endemic in 149 tropical and subtropical countries, neglected tropical diseases (NTDs affect more than 1 billion people annually, including 875 million children in developing economies. These diseases are also responsible for over 500,000 deaths per year and are characterized by long-term disability and severe pain. The impact of the combined NTDs closely rivals that of malaria and tuberculosis. Current treatment options are associated with various limitations including widespread drug resistance, severe adverse effects, lengthy treatment duration, unfavorable toxicity profiles, and complicated drug administration procedures. Natural products have been a valuable source of drug regimens that form the cornerstone of modern pharmaceutical care. In this review, we highlight the potential that remains untapped in natural products as drug leads for NTDs. We cover natural products from plant, marine, and microbial sources including natural-product-inspired semi-synthetic derivatives which have been evaluated against the various causative agents of NTDs. Our coverage is limited to four major NTDs which include human African trypanosomiasis (sleeping sickness, leishmaniasis, schistosomiasis and lymphatic filariasis.

Warming affects growth rates and microcystin production in tropical bloom-forming microcystis strains

NARCIS (Netherlands)

Bui, Trung; Dao, Thanh Son; Vo, Truong Giang; Lürling, Miquel

2018-01-01

Warming climate is predicted to promote cyanobacterial blooms but the toxicity of cyanobacteria under global warming is less well studied. We tested the hypothesis that raising temperature may lead to increased growth rates but to decreased microcystin (MC) production in tropical Microcystis

Trace Gas Emissions From the Production and Use of Biofuels in the African Tropics

Science.gov (United States)

Bertschi, I.; Yokelson, R. J.; Ward, D. E.; Christian, T. J.; Hao, W. M.

2001-12-01

Biomass burning is an important source of many atmospheric trace gases and particles that play a significant role in regional-global, tropospheric and stratospheric chemical processes, and in the global climate. About 80% of biomass burning is thought to occur in the tropics in association with traditional land management practices and domestic biofuel use. More than 220 Tg (1 Tg = 1 x 1012 g) of fuel-wood and 11 Tg of charcoal are consumed annually for domestic heating and cooking in tropical Africa alone. Approximately 90% of the fuel-wood is consumed in open fires in rural areas. Previously, the emissions for fuel-wood fires and charcoal use and production in the tropics were known for only a limited number of chemical species. During SAFARI-2000 we conducted field experiments in remote Zambian villages and observed most of the major trace gases emitted from the production and use of biofuels using open-path Fourier transform infrared (OP-FTIR) spectroscopy, which provides an artifact-free overview of the trace gases present above several ppbv. Our OP-FTIR was deployed for several spot measurements over the course of an earthen kiln charcoal-making process and of several open wood and charcoal fires, all of which were built and tended by local inhabitants. We quantified the emissions of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), nitrogen oxides (NOx), ammonia (NH3), non-methane hydrocarbons (NMHC), and oxygenated volatile organic compounds (OVOC). Our results also show much higher emission factors for methanol (CH3OH), acetic acid (CH3COOH), and formaldehyde (CH2O) from domestic biofuel production and use than from savanna fires in southern Africa. Thus, these year-round OVOC emissions will play an important role in the photochemistry of the troposphere and in the acidity of aerosols and precipitation especially in tropical regions.

Long-term Increases in Flower Production by Growth Forms in Response to Anthropogenic Change in a Tropical Forest

Science.gov (United States)

Pau, S.; Wright, S. J.

2016-12-01

There is mounting evidence that anthropogenic global change is altering the ecology of tropical forests. A limited number of studies have focused on long-term trends in tropical reproductive activity, yet differences in reproductive activity should have consequences for demography and ultimately forest carbon, water, and energy balance. Here we analyze a 28-year record of tropical flower production in response to anthropogenic climate change. We show that a multi-decadal increase in flower production is most strongly driven by rising atmospheric CO2, which had approximately 8x the effect of the Multivariate ENSO Index and approximately 13x the effect of rainfall or solar radiation. Interannual peaks in flower production were associated with greater solar radiation and low rainfall during El Niño years. Observed changes in solar radiation explained flower production better than rainfall (models including solar radiation accounted for 94% of cumulative AICc weight compared to 87% for rainfall). All growth forms (lianas, canopy trees, midstory trees, and shrubs) produced more flowers with increasing CO2 except for understory treelets. The increase in flower production was matched by a lengthening of flowering duration for canopy trees and midstory trees; duration was also longer for understory treelets. Given that anthropogenic CO2 emissions will continue to climb over the next century, the long-term increase in flower production may persist unless offset by increasing cloudiness in the tropics, or until rising CO2 and/or warming temperatures associated with the greenhouse effect pass critical thresholds for plant reproduction.

Economic and Biological Values for Pasture-Based Dairy Cattle Porduction Systems and their Application in Genetic Improvement in the Tropics

DEFF Research Database (Denmark)

Wahinya, P K; Otieno, Tobias Okeno; Kosgey, I S

2015-01-01

estimated under fixed herd (FH) and pasture (FP) production circumstances assuming milk marketing based on volume, and volume and butter fat. Further, economic values were estimated involving risk using the Arrow Pratt coefficients at two levels. For the former economic values for the traits ranged from KSh...... during the estimation of economic values. Genetic improvements targeting MY and growth traits would be recommended to production system with unlimited feed supply for profit maximization. However, since dairy production systems in the tropics are characterised by feed scarcity, fixing the herd...

Long-Range Lightning Products for Short Term Forecasting of Tropical Cyclogenesis

Science.gov (United States)

Businger, S.; Pessi, A.; Robinson, T.; Stolz, D.

2010-12-01

This paper will describe innovative graphical products derived in real time from long-range lightning data. The products have been designed to aid in short-term forecasting of tropical cyclone development for the Tropical Cyclone Structure Experiment 2010 (TCS10) held over the western Pacific Ocean from 17 August to 17 October 2010 and are available online at http://www.soest.hawaii.edu/cgi-bin/pacnet/tcs10.pl. The long-range lightning data are from Vaisala’s Global Lightning Data 360 (GLD360) network and include time, location, current strength, polarity, and data quality indication. The products currently provided in real time include i. Infrared satellite imagery overlaid with lighting flash locations, with color indication of current strength and polarity (shades of blue for negative to ground and red for positive to ground). ii. A 15x15 degree storm-centered tile of IR imagery overlaid with lightning data as in i). iii. A pseudo reflectivity product showing estimates of radar reflectivity based on lightning rate - rain rate conversion derived from TRMM and PacNet data. iv. A lightning history product that plots each hour of lightning flash locations in a different color for a 12-hour period. v. Graphs of lightning counts within 50 or 300 km radius, respectively, of the storm center vs storm central sea-level pressure. vi. A 2-D graphic showing storm core lightning density along the storm track. The first three products above can be looped to gain a better understanding of the evolution of the lightning and storm structure. Examples of the graphics and their utility will be demonstrated and discussed. Histogram of lightning counts within 50 km of the storm center and graph of storm central pressure as a function of time.

Sustainable forest management of tropical forests can reduce carbon emissions and stabilize timber production

Science.gov (United States)

N. Sasaki; G.P. Asner; Yude Pan; W. Knorr; P.B. Durst; H.O. Ma; I. Abe; A.J. Lowe; L.P. Koh

2016-01-01

The REDD+ scheme of the United Nations Framework Conventionon Climate Change has provided opportunities to manage tropical forests for timber production and carbon emission reductions. To determine the appropriate loggingtechniques, we analyzed potential timber production and carbon emission reductions under two logging techniques over a 40-year period of selective...

Predictors of death and production performance of layer chickens in opened and sealed pens in a tropical savannah environment.

Science.gov (United States)

Shittu, Aminu; Raji, Abdullahi Abdullahi; Madugu, Shuaibu A; Hassan, Akinola Waheed; Fasina, Folorunso Oludayo

2014-09-12

Layer chickens are exposed to high risks of production losses and mortality with impact on farm profitability. The harsh tropical climate and severe disease outbreaks, poor biosecurity, sub-minimal vaccination and treatment protocols, poor management practices, poor chick quality, feed-associated causes, and unintended accidents oftentimes aggravate mortality and negatively affect egg production. The objectives of this study were to estimate the probability of survival and evaluate risk factors for death under different intensive housing conditions in a tropical climate, and to assess the production performance in the housing systems. Daily mean mortality percentages and egg production figures were significantly lower and higher in the sealed pens and open houses (P ratio for mortality of layers raised in sealed pens was 0.568 (56.8%). Reasons for spiked mortality in layer chickens may not always be associated with disease. Hot-dry climatic environment is associated with heat stress, waning immunity and inefficient feed usage and increase probability of death with reduced egg production; usage of environmentally controlled building in conditions where environmental temperature may rise significantly above 25°C will reduce this impact. Since younger birds (19-38 weeks) are at higher risk of death due to stress of coming into production, management changes and diseases, critical implementation of protocols that will reduce death at this precarious period becomes mandatory. Whether older chickens' better protection from death is associated with many prophylactic and metaphylactic regimen of medications/vaccination will need further investigation.

Tropical Fruit Pulps: Processing, Product Standardization and Main Control Parameters for Quality Assurance

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Carlos Eduardo de Farias Silva

2017-05-01

Full Text Available ABSTRACT Fruit pulp is the most basic food product obtained from fresh fruit processing. Fruit pulps can be cold stored for long periods of time, but they also can be used to fabricate juices, ice creams, sweets, jellies and yogurts. The exploitation of tropical fruits has leveraged the entire Brazilian fruit pulp sector due mainly to the high acceptance of their organoleptic properties and remarkable nutritional facts. However, several works published in the last decades have pointed out unfavorable conditions regarding the consumption of tropical fruit pulps. This negative scenario has been associated with unsatisfactory physico-chemical and microbiological parameters of fruits pulps as outcomes of little knowledge and improper management within the fruit pulp industry. There are protocols for delineating specific identity and quality standards (IQSs and standardized good manufacturing practices (GMP for fruit pulps, which also embrace standard operating procedures (SOPs and hazard analysis and critical control points (HACCP, although this latter is not considered mandatory by the Brazilian legislation. Unfortunately, the lack of skilled labor, along with failures in complying established protocols have impaired quality of fruit pulps. It has been necessary to collect all information available with the aim to identify the most important hazards within fruit pulp processing lines. Standardizing methods and practices within the Brazilian fruit pulp industry would assurance high quality status to tropical fruit pulps and the commercial growth of this vegetal product towards international markets.

Agroforestry techniques in tropical countries: potential and limitations

Energy Technology Data Exchange (ETDEWEB)

Combe, J.

1982-01-01

A detailed scheme is proposed for classifying agroforestry systems on the basis of: the kinds of associated agricultural products (agrisilvicultural, silvopastoral and agrosilvopastoral systems); the major function of the forest component (productive or protective); the spatial distribution of the trees (regular or irregular); and the duration of the combination (temporary or permanent). Eight important tropical agroforestry systems are described and classified according to the scheme. The potential social, economic and ecological advantages of agroforestry systems are discussed and priorities for future research suggested. (Refs. 12).

Changes in the Diversity of Soil Arbuscular Mycorrhizal Fungi after Cultivation for Biofuel Production in a Guantanamo (Cuba) Tropical System

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Alguacil, Maria del Mar; Torrecillas, Emma; Hernández, Guillermina; Roldán, Antonio

2012-01-01

The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems. PMID:22536339

Changes in the diversity of soil arbuscular mycorrhizal fungi after cultivation for biofuel production in a Guantanamo (Cuba tropical system.

Directory of Open Access Journals (Sweden)

Maria del Mar Alguacil

Full Text Available The arbuscular mycorrhizal fungi (AMF are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba, in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems.

Birds as predators in tropical agroforestry systems.

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Van Bael, Sunshine A; Philpott, Stacy M; Greenberg, Russell; Bichier, Peter; Barber, Nicholas A; Mooney, Kailen A; Gruner, Daniel S

2008-04-01

Insectivorous birds reduce arthropod abundances and their damage to plants in some, but not all, studies where predation by birds has been assessed. The variation in bird effects may be due to characteristics such as plant productivity or quality, habitat complexity, and/or species diversity of predator and prey assemblages. Since agroforestry systems vary in such characteristics, these systems provide a good starting point for understanding when and where we can expect predation by birds to be important. We analyze data from bird exclosure studies in forests and agroforestry systems to ask whether birds consistently reduce their arthropod prey base and whether bird predation differs between forests and agroforestry systems. Further, we focus on agroforestry systems to ask whether the magnitude of bird predation (1) differs between canopy trees and understory plants, (2) differs when migratory birds are present or absent, and (3) correlates with bird abundance and diversity. We found that, across all studies, birds reduce all arthropods, herbivores, carnivores, and plant damage. We observed no difference in the magnitude of bird effects between agroforestry systems and forests despite simplified habitat structure and plant diversity in agroforests. Within agroforestry systems, bird reduction of arthropods was greater in the canopy than the crop layer. Top-down effects of bird predation were especially strong during censuses when migratory birds were present in agroforestry systems. Importantly, the diversity of the predator assemblage correlated with the magnitude of predator effects; where the diversity of birds, especially migratory birds, was greater, birds reduced arthropod densities to a greater extent. We outline potential mechanisms for relationships between bird predator, insect prey, and habitat characteristics, and we suggest future studies using tropical agroforests as a model system to further test these areas of ecological theory.

Organic carbon and nitrogen export from a tropical dam-impacted floodplain system

Science.gov (United States)

Zurbrügg, R.; Suter, S.; Lehmann, M. F.; Wehrli, B.; Senn, D. B.

2013-01-01

Tropical floodplains play an important role in organic matter transport, storage, and transformation between headwaters and oceans. However, the fluxes and quality of organic carbon (OC) and organic nitrogen (ON) in tropical river-floodplain systems are not well constrained. We explored the quantity and characteristics of dissolved and particulate organic matter (DOM and POM, respectively) in the Kafue River flowing through the Kafue Flats (Zambia), a tropical river-floodplain system in the Zambezi River basin. During the flooding season, > 80% of the Kafue River water passed through the floodplain, mobilizing large quantities of OC and ON, which resulted in a net export of 69-119 kg OC km-2 d-1 and 3.8-4.7 kg ON km-2 d-1, 80% of which was in the dissolved form. The elemental C : N ratio of ~ 20, the comparatively high δ13C values of -25‰ to -21‰, and its spectroscopic properties (excitation-emission matrices) showed that DOM in the river was mainly of terrestrial origin. Despite a threefold increase in OC loads due to inputs from the floodplain, the characteristics of the riverine DOM remained relatively constant along the sampled 410-km river reach. This suggests that floodplain DOM displayed properties similar to those of DOM leaving the upstream reservoir and implied that the DOM produced in the reservoir was relatively short-lived. In contrast, the particulate fraction was 13C-depleted (-29‰) and had a C : N ratio of ~ 8, which indicated that POM originated from phytoplankton production in the reservoir and in the floodplain, rather than from plant debris or resuspended sediments. While the upstream dam had little effect on the DOM pool, terrestrial particles were retained, and POM from algal and microbial sources was released to the river. A nitrogen mass balance over the 2200 km2 flooded area revealed an annual deficit of 15 500-22 100 t N in the Kafue Flats. The N isotope budget suggests that these N losses are balanced by intense N-fixation. Our

Magnitude and variability of methane production and concentration in tropical coastal lagoons sediments

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Antonella Petruzzella

Full Text Available AIM: Coastal wetlands are potential zones for methane (CH4 production. The present study aims to evaluate the spatial variation of CH4 production and concentration in ten tropical coastal lagoons, the influence of aquatic macrophytes on the sediment CH4 concentration and how the magnitude of these potential CH4 production rates compare to those in other ecosystems. METHODS: Sediments were sampled in ten coastal lagoons, with one site in the limnetic region and another site in aquatic macrophyte stands when they were present in the littoral region. We measured the CH4 production as a potential rate, and CH4 concentration was directly measured from sediment samples. RESULTS: The highest potential CH4 production (PMP rates were found in alkaline and hypersaline lagoons. However, Cabiúnas, which is a freshwater lagoon densely colonized by aquatic macrophytes, also exhibited a high PMP rate. We also observed that the sediment CH4 concentration in the littoral region was higher than in the limnetic region in all of the investigated lagoons except Paulista, which presented the opposite pattern. The PMP rates observed in the studied lagoons were low compared to other aquatic ecosystems. CONCLUSION: Our results suggest that the sediments of saline lagoons are important CH4 production sites, and in general, aquatic macrophytes have a positive influence on methanogenesis, which was evident based on the CH4 concentrations present in the sediments of these lagoons. Further studies should focus on the processes underlying the CH4 patterns observed in the tropical coastal lagoons, especially concerning the coupling between CH4 production and concentration.

Volatile sulfur compounds in tropical fruits

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Robert J. Cannon

2018-04-01

Full Text Available Global production and demand for tropical fruits continues to grow each year as consumers are enticed by the exotic flavors and potential health benefits that these fruits possess. Volatile sulfur compounds (VSCs are often responsible for the juicy, fresh aroma of tropical fruits. This poses a challenge for analytical chemists to identify these compounds as most often VSCs are found at low concentrations in most tropical fruits. The aim of this review is to discuss the extraction methods, enrichment techniques, and instrumentation utilized to identify and quantify VSCs in natural products. This will be followed by a discussion of the VSCs reported in tropical and subtropical fruits, with particular attention to the odor and taste attributes of each compound. Finally, the biogenesis and enzymatic formation of specific VSCs in tropical fruits will be highlighted along with the contribution each possesses to the aroma of their respective fruit. Keywords: Tropical fruits, Volatile sulfur compounds, Extraction methods

Methyl Mercury Production In Tropical Hydromorphic Soils: Impact Of Gold Mining.

Science.gov (United States)

Guedron, S.; Charlet, L.; Harris, J.; Grimaldi, M.; Cossa, D.

2007-12-01

Artisanal alluvial gold mining is important in many tropical developing countries and several million people are involved worldwide. The dominant use of mercury for gold amalgamation in this activity leads to mercury accumulation in soils, to sediment contamination and to methyl mercury (MMHg) bioaccumulation along the food chain. In this presentation we will present recent data on methyl mercury production in hydromorphic soils and tailing ponds from a former gold mining area located in French Guiana (South America). Comparison of specific fluxes between a pristine sub watershed and the contaminated watershed shows that former mining activities lead to a large enhancement of dissolved and particulate MMHg emissions at least by a factor of 4 and 6, respectively. MMHg production was identified in sediments from tailing ponds and in surrounding hydromorphic soils. Moreover, interstitial soil water and tailing pond water profiles sampled in an experimental tailing pond demonstrate the presence of a large MMHg production in the suboxic areas. Both tailing ponds and hydromorphic soils present geochemical conditions that are favorable to bacterial mercury methylation (high soil Hg content, high aqueous ferric iron and dissolved organic carbon concentrations). Although sulfate-reducing bacteria have been described as being the principal mercury methylating bacteria, the positive correlation between dissolved MMHg and ferrous iron concentrations argue for a significant role of iron-reducing bacteria. Identifications by sequencing fragments of 16S rRNA from total soil DNA support these interpretations. This study demonstrates that current and past artisanal gold mining in the tropics lead to methyl mercury production in contaminated areas. As artisanal activities are increasing with increasing gold prices, the bio- magnification of methyl mercury in fish presents an increasing threat to local populations whose diet relies on fish consumption.

Model for product development of vaccines against neglected tropical diseases: a vaccine against human hookworm.

Science.gov (United States)

Bottazzi, Maria Elena; Brown, Ami Shah

2008-12-01

This article provides an overview of the advances in product development and technology transfer of the vaccine against human hookworm, with particular emphasis on the lessons learned and the challenges of developing a vaccine in the nonprofit sector. The comprehensive approach to vaccine development established by the Human Hookworm Vaccine Initiative (HHVI) identifies key operational and technical aspects that are essential for a successful partnership with a developing country vaccine manufacturer. This article also highlights the importance of a global access roadmap to guide the vaccine development program. The advancement of new products for the control of neglected tropical diseases portends great challenges for global access, including aspects related to vaccine design, product development and manufacture, vaccine introduction and distribution, financing, knowledge dissemination and intellectual property management. With only three vaccines for neglected tropical diseases in clinical trials - hookworm, leishmaniasis and schistosomiasis - we are at the nascent stages of developing vaccines for neglected populations. Product development public-private partnerships, such as the HHVI, continue to show great promise on this front and will eventually provide significant control tools for achieving millennium development goals related to poverty reduction, as well as child and maternal health.

Logging disturbance shifts net primary productivity and its allocation in Bornean tropical forests.

Science.gov (United States)

Riutta, Terhi; Malhi, Yadvinder; Kho, Lip Khoon; Marthews, Toby R; Huaraca Huasco, Walter; Khoo, MinSheng; Tan, Sylvester; Turner, Edgar; Reynolds, Glen; Both, Sabine; Burslem, David F R P; Teh, Yit Arn; Vairappan, Charles S; Majalap, Noreen; Ewers, Robert M

2018-01-24

Tropical forests play a major role in the carbon cycle of the terrestrial biosphere. Recent field studies have provided detailed descriptions of the carbon cycle of mature tropical forests, but logged or secondary forests have received much less attention. Here, we report the first measures of total net primary productivity (NPP) and its allocation along a disturbance gradient from old-growth forests to moderately and heavily logged forests in Malaysian Borneo. We measured the main NPP components (woody, fine root and canopy NPP) in old-growth (n = 6) and logged (n = 5) 1 ha forest plots. Overall, the total NPP did not differ between old-growth and logged forest (13.5 ± 0.5 and 15.7 ± 1.5 Mg C ha -1  year -1 respectively). However, logged forests allocated significantly higher fraction into woody NPP at the expense of the canopy NPP (42% and 48% into woody and canopy NPP, respectively, in old-growth forest vs 66% and 23% in logged forest). When controlling for local stand structure, NPP in logged forest stands was 41% higher, and woody NPP was 150% higher than in old-growth stands with similar basal area, but this was offset by structure effects (higher gap frequency and absence of large trees in logged forest). This pattern was not driven by species turnover: the average woody NPP of all species groups within logged forest (pioneers, nonpioneers, species unique to logged plots and species shared with old-growth plots) was similar. Hence, below a threshold of very heavy disturbance, logged forests can exhibit higher NPP and higher allocation to wood; such shifts in carbon cycling persist for decades after the logging event. Given that the majority of tropical forest biome has experienced some degree of logging, our results demonstrate that logging can cause substantial shifts in carbon production and allocation in tropical forests. © 2018 John Wiley & Sons Ltd.

Biohydrogen Production from Hydrolysates of Selected Tropical Biomass Wastes with Clostridium Butyricum

Science.gov (United States)

Dan Jiang; Fang, Zhen; Chin, Siew-Xian; Tian, Xiao-Fei; Su, Tong-Chao

2016-06-01

Biohydrogen production has received widespread attention from researchers in industry and academic fields. Response surface methodology (RSM) was applied to evaluate the effects of several key variables in anaerobic fermentation of glucose with Clostridium butyrium, and achieved the highest production rate and yield of hydrogen. Highest H2 yield of 2.02 mol H2/mol-glucose was achieved from 24 h bottle fermentation of glucose at 35 °C, while the composition of medium was (g/L): 15.66 glucose, 6.04 yeast extract, 4 tryptone, 3 K2HPO4, 3 KH2PO4, 0.05 L-cysteine, 0.05 MgSO4·7H2O, 0.1 MnSO4·H2O and 0.3 FeSO4·7H2O, which was very different from that for cell growth. Sugarcane bagasse and Jatropha hulls were selected as typical tropical biomass wastes to produce sugars via a two-step acid hydrolysis for hydrogen production. Under the optimized fermentation conditions, H2 yield (mol H2/mol-total reducing sugar) was 2.15 for glucose, 2.06 for bagasse hydrolysate and 1.95 for Jatropha hull hydrolysate in a 3L fermenter for 24 h at 35 °C, with H2 purity of 49.7-64.34%. The results provide useful information and basic data for practical use of tropical plant wastes to produce hydrogen.

Growth, biomass production and photosynthesis of Cenchrus ciliaris L. under Acacia tortilis (Forssk.) Hayne based silvopastoral systems in semi arid tropics.

Science.gov (United States)

Mishra, A K; Tiwari, H S; Bhatt, R K

2010-11-01

The growth, biomass production and photosynthesis of Cenchrus ciliaris was studied under the canopies of 17 yr old Acacia tortilis trees in semi arid tropical environment. On an average the full grown canopy of A. tortilis at the spacing of 4 x 4 m allowed 55% of total Photosynthetically Active Radiation (PAR) which in turn increased Relative Humidity (RH) and reduced under canopy temperature to -1.75 degrees C over the open air temperature. C. ciliaris attained higher height under the shade of A. tortilis. The tiller production and leaf area index decreased marginally under the shade of tree canopies as compared to the open grown grasses. C. ciliaris accumulated higher chlorophyll a and b under the shade of tree canopies indicating its shade adaptation potential. The assimilatory functions such as rate of photosynthesis, transpiration, stomatal conductance, photosynthetic water use efficiency (PN/TR) and carboxylation efficiency (PN/CINT) decreased under the tree canopies due to low availability of PAR. The total biomass production in term of fresh and dry weight decreased under the tree canopies. On average of 2 yr C. ciliaris had produced 12.78 t ha(-1) green and 3.72 -t ha(-1) dry biomass under the tree canopies of A. tortilis. The dry matter yield reduced to 38% under the tree canopies over the open grown grasses. The A. tortilis + C. ciliaris maintained higher soil moisture, organic carbon content and available N P K for sustainable biomass production for the longer period. The higher accumulation of crude protein, starch, sugar and nitrogen in leaves and stem of C. ciliaris indicates that this grass species also maintained its quality under A. tortilis based silvopastoral system. The photosynthesis and dry matter accumulation are closely associated with available PAR indicating that for sustainable production of this grass species in the silvopasture systems for longer period about 55% or more PAR is required.

Tropical Peatland Geomorphology and Hydrology

Science.gov (United States)

Cobb, A.; Harvey, C. F.

2017-12-01

Tropical peatlands cover many low-lying areas in the tropics. In tropical peatlands, a feedback between hydrology, landscape morphology, and carbon storage causes waterlogged organic matter to accumulate into gently mounded land forms called peat domes over thousands of years. Peat domes have a stable morphology in which peat production is balanced by loss and net precipitation is balanced by lateral flow, creating a link between peatland morphology, rainfall patterns and drainage networks. We show how landscape morphology can be used to make inferences about hydrologic processes in tropical peatlands. In particular, we show that approaches using simple storage-discharge relationships for catchments are especially well suited to tropical peatlands, allowing river forecasting based on peatland morphology in catchments with tropical peatland subcatchments.

Challenges and opportunities for improving eco-efficiency of tropical forage-based systems to mitigate greenhouse gas emissions

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Michael Peters

2013-12-01

Full Text Available Forage-based livestock production plays a key role in national and regional economies, for food security and poverty alleviation, but is considered a major contributor to agricultural GHG emissions. While demand for livestock products is predicted to increase, there is political and societal pressure both to reduce environmental impacts and to convert some of the pasture area to alternative uses, such as crop production and environmental conservation. Thus, it is essential to develop approaches for sustainable intensification of livestock systems to mitigate GHG emissions, addressing biophysical, socio-economic and policy challenges. This paper highlights the potential of improved tropical forages, linked with policy incentives, to enhance livestock production, while reducing its environmental footprint. Emphasis is on crop-livestock systems. We give examples for sustainable intensification to mitigate GHG emissions, based on improved forages in Brazil and Colombia, and suggest future perspectives.

Mycorrhizas and tropical soil fertility

NARCIS (Netherlands)

Cardoso, I.M.; Kuyper, T.W.

2006-01-01

Major factors that constrain tropical soil fertility and sustainable agriculture are low nutrient capital, moisture stress, erosion, high P fixation, high acidity with aluminium toxicity, and low soil biodiversity. The fragility of many tropical soils limits food production in annual cropping

High primary production contrasts with intense carbon emission in a eutrophic tropical reservoir

NARCIS (Netherlands)

Almeida, Rafael M.; Nóbrega, Gabriel N.; Junger, Pedro C.; Figueiredo, Aline V.; Andrade, Anízio S.; Moura, de Caroline G.B.; Tonetta, Denise; Oliveira, Ernandes S.; Araújo, Fabiana; Rust, Felipe; Piñeiro-Guerra, Juan M.; Mendonça, Jurandir R.; Medeiros, Leonardo R.; Pinheiro, Lorena; Miranda, Marcela; Costa, Mariana R.A.; Melo, Michaela L.; Nobre, Regina L.G.; Benevides, Thiago; Roland, Fábio; Klein, de Jeroen; Barros, Nathan O.; Mendonça, Raquel; Becker, Vanessa; Huszar, Vera L.M.; Kosten, Sarian

2016-01-01

Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (CO₂) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO₂ sinks in some cases. However, the scarcity of data from tropical systems is critical for a

Microorganisms in Soils of Bovine Production Systems in Tropical Lowlands and Tropical Highlands in the Department of Antioquia, Colombia

OpenAIRE

Molina-Guzmán, Licet Paola; Henao-Jaramillo, Paula Andrea; Gutiérrez-Builes, Lina Andrea; Ríos-Osorio, Leonardo Alberto

2018-01-01

Studies on the physical and chemical effects of extensive grazing on soils have been performed in Colombia, but the effects of dairy cattle rearing on the biological properties of soils are not well known. The objective of this study was to evaluate microorganisms in 48 soils from livestock farms in the highland and lowland tropics in the Northern and Magdalena Medio subregions of the Department of Antioquia (Colombia). Principal component analysis demonstrated differences in the edaphic comp...

Production of tropical forage grasses under different shading levels

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Francisco Eduardo Torres

2017-12-01

Full Text Available This study aimed to evaluate the forage production of three tropical forage grasses under different shading levels. The experiment was conducted in a greenhouse at Universidade Estadual de Mato Grosso do Sul, University Unit of Aquidauana (UEMS/UUA, in a soil classified as Ultisol sandy loam texture. The treatments consisted of three grasses species combinations (B. brizantha cv. Marandu, B. decumbens cv. Basilisck and Panicum maximum cv. Tanzania, submitted to four shading levels (0, 30, 50 and 75%, arranged in a completely randomized blocks design in a factorial 3 x 4, with eight replications. After harvest, the plants were separated into shoot and roots for determination of shoot fresh mass (SFM, shoot dry mass (SDM and roots dry mass production. After analysis of variance, the qualitative factor was subjected to comparison of averages by Tukey’s test, and the quantitative factor to analysis of polynomial regression, being interactions appropriately unfolded. It was verified that B. decumbens, by its linearly increasing production of forage and less decrease of root formation, is the most recommended for shading conditions compared to grasses Tanzania and Marandu.

Soil carbon sequestration in rainfed production systems in the semiarid tropics of India.

Science.gov (United States)

Srinivasarao, Ch; Lal, Rattan; Kundu, Sumanta; Babu, M B B Prasad; Venkateswarlu, B; Singh, Anil Kumar

2014-07-15

Severe soil organic carbon (SOC) depletion is a major constraint in rainfed agroecosystems in India because it directly influences soil quality, crop productivity and sustainability. The magnitude of soil organic, inorganic and total carbon stocks in the semi-arid bioclimate is estimated at 2.9, 1.9 and 4.8 Pg respectively. Sorghum, finger millet, pearl millet, maize, rice, groundnut, soybean, cotton, food legumes etc. are predominant crop production systems with a little, if any, recycling of organic matter. Data from the long term experiments on major rainfed production systems in India show that higher amount of crop residue C input (Mg/ha/y) return back to soil in soybean-safflower (3.37) system practiced in Vertisol region of central India. Long term addition of chemical fertilizer and organic amendments improved the SOC stock. For every Mg/ha increase in SOC stock in the root zone, there occurs an increase in grain yield (kg/ha) of 13, 101, 90, 170, 145, 18 and 160 for groundnut, finger millet, sorghum, pearl millet, soybean and rice, respectively. Long-term cropping without using any organic amendment and/or mineral fertilizers can severely deplete the SOC stock which is the highest in groundnut-finger millet system (0.92 Mg C/ha/y) in Alfisols. Some agroforestry systems also have a huge potential of C sequestration to the extent of 10Mg/ha/y in short rotation eucalyptus and Leucaena plantations. The critical level of C input requirements for maintaining SOC at the antecedent level ranges from 1.1 to 3.5 Mg C/ha/y and differs among soil type and production systems. National level policy interventions needed to promote sustainable use of soil and water resources include prohibiting residue burning, reducing deforestation, promoting integrated farming systems and facilitating payments for ecosystem services. A wide spread adoption of these measures can improve soil quality through increase in SOC sequestration and improvement in agronomic productivity of

Seagrasses in tropical Australia, productive and abundant for decades decimated overnight.

Science.gov (United States)

Pollard, Peter C; Greenway, Margaret

2013-03-01

Seagrass ecosystems provide unique coastal habitats critical to the life cycle of many species. Seagrasses are a major store of organic carbon. While seagrasses are globally threatened and in decline, in Cairns Harbour, Queensland, on the tropical east coast of Australia, they have flourished. We assessed seagrass distribution in Cairns Harbour between 1953 and 2012 from historical aerial photographs, Google map satellite images, existing reports and our own surveys of their distribution. Seasonal seagrass physiology was assessed through gross primary production, respiration and photosynthetic characteristics of three seagrass species, Cymodocea serrulata, Thalassia hemprichii and Zostera muelleri. At the higher water temperatures of summer, respiration rates increased in all three species, as did their maximum rates of photosynthesis. All three seagrasses achieved maximum rates of photosynthesis at low tide and when they were exposed. For nearly six decades there was little change in seagrass distribution in Cairns Harbour. This was most likely because the seagrasses were able to achieve sufficient light for growth during intertidal and low tide periods. With historical data of seagrass distribution and measures of species production and respiration, could seagrass survival in a changing climate be predicted? Based on physiology, our results predicted the continued maintenance of the Cairns Harbour seagrasses, although one species was more susceptible to thermal disturbance. However, in 2011 an unforeseen episodic disturbance - Tropical Cyclone Yasi - and associated floods lead to the complete and catastrophic loss of all the seagrasses in Cairns Harbour.

Optimum Temperatures for Net Primary Productivity of Three Tropical Seagrass Species

Directory of Open Access Journals (Sweden)

Catherine J. Collier

2017-08-01

Full Text Available Rising sea water temperature will play a significant role in responses of the world's seagrass meadows to climate change. In this study, we investigated seasonal and latitudinal variation (spanning more than 1,500 km in seagrass productivity, and the optimum temperatures at which maximum photosynthesis and net productivity (for the leaf and the whole plant occurs, for three seagrass species (Cymodocea serrulata, Halodule uninervis, and Zostera muelleri. To obtain whole plant net production, photosynthesis, and respiration rates of leaves and the root/rhizome complex were measured using oxygen-sensitive optodes in closed incubation chambers at temperatures ranging from 15 to 43°C. The temperature-dependence of photosynthesis and respiration was fitted to empirical models to obtain maximum metabolic rates and thermal optima. The thermal optimum (Topt for gross photosynthesis of Z. muelleri, which is more commonly distributed in sub-tropical to temperate regions, was 31°C. The Topt for photosynthesis of the tropical species, H. uninervis and C. serrulata, was considerably higher (35°C on average. This suggests that seagrass species are adapted to water temperature within their distributional range; however, when comparing among latitudes and seasons, thermal optima within a species showed limited acclimation to ambient water temperature (Topt varied by 1°C in C. serrulata and 2°C in H. uninervis, and the variation did not follow changes in ambient water temperature. The Topt for gross photosynthesis were higher than Topt calculated from plant net productivity, which includes above- and below-ground respiration for Z. muelleri (24°C and H. uninervis (33°C, but remained unchanged at 35°C in C. serrulata. Both estimated plant net productivity and Topt are sensitive to the proportion of below-ground biomass, highlighting the need for consideration of below- to above-ground biomass ratios when applying thermal optima to other meadows. The

Evaluation of tropical Pacific observing systems using NCEP and GFDL ocean data assimilation systems

Science.gov (United States)

Xue, Yan; Wen, Caihong; Yang, Xiaosong; Behringer, David; Kumar, Arun; Vecchi, Gabriel; Rosati, Anthony; Gudgel, Rich

2017-08-01

The TAO/TRITON array is the cornerstone of the tropical Pacific and ENSO observing system. Motivated by the recent rapid decline of the TAO/TRITON array, the potential utility of TAO/TRITON was assessed for ENSO monitoring and prediction. The analysis focused on the period when observations from Argo floats were also available. We coordinated observing system experiments (OSEs) using the global ocean data assimilation system (GODAS) from the National Centers for Environmental Prediction and the ensemble coupled data assimilation (ECDA) from the Geophysical Fluid Dynamics Laboratory for the period 2004-2011. Four OSE simulations were conducted with inclusion of different subsets of in situ profiles: all profiles (XBT, moorings, Argo), all except the moorings, all except the Argo and no profiles. For evaluation of the OSE simulations, we examined the mean bias, standard deviation difference, root-mean-square difference (RMSD) and anomaly correlation against observations and objective analyses. Without assimilation of in situ observations, both GODAS and ECDA had large mean biases and RMSD in all variables. Assimilation of all in situ data significantly reduced mean biases and RMSD in all variables except zonal current at the equator. For GODAS, the mooring data is critical in constraining temperature in the eastern and northwestern tropical Pacific, while for ECDA both the mooring and Argo data is needed in constraining temperature in the western tropical Pacific. The Argo data is critical in constraining temperature in off-equatorial regions for both GODAS and ECDA. For constraining salinity, sea surface height and surface current analysis, the influence of Argo data was more pronounced. In addition, the salinity data from the TRITON buoys played an important role in constraining salinity in the western Pacific. GODAS was more sensitive to withholding Argo data in off-equatorial regions than ECDA because it relied on local observations to correct model biases and

Hydrological structure and biological productivity of the tropical Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Muraleedharan, U.D.; Muraleedharan, P.M.

Hydrological structure analyses of regions in the tropical Atlantic Ocean have consistently revealed the existence of a typical tropical structure characterized by a nitrate-depleted mixed layer above the thermocline. The important biological...

Catastrophic shifts in the aquatic primary production revealed by a small low-flow section of tropical downstream after dredging.

Science.gov (United States)

Marotta, H; Enrich-Prast, A

2015-11-01

Dredging is a catastrophic disturbance that directly affects key biological processes in aquatic ecosystems, especially in those small and shallow. In the tropics, metabolic responses could still be enhanced by the high temperatures and solar incidence. Here, we assessed changes in the aquatic primary production along a small section of low-flow tropical downstream (Imboassica Stream, Brazil) after dredging. Our results suggested that these ecosystems may show catastrophic shifts between net heterotrophy and autotrophy in waters based on three short-term stages following the dredging: (I) a strongly heterotrophic net primary production -NPP- coupled to an intense respiration -R- likely supported by high resuspended organic sediments and nutrients from the bottom; (II) a strongly autotrophic NPP coupled to an intense gross primary production -GPP- favored by the high nutrient levels and low solar light attenuation from suspended solids or aquatic macrophytes; and (III) a NPP near to the equilibrium coupled to low GPP and R rates following, respectively, the shading by aquatic macrophytes and high particulate sedimentation. In conclusion, changes in aquatic primary production could be an important threshold for controlling drastic shifts in the organic matter cycling and the subsequent silting up of small tropical streams after dredging events.

Cutover tropical forest productivity potential merits assessment, Puerto Rico

Science.gov (United States)

Frank H. Wadsworth; Brynne Bryan; Julio Figueroa-Colón

2010-01-01

Timber extraction continues to add to vast cutover tropical forests. They are unattractive economically because of the loss of merchantable timber and the long delay foreseen for recovery. Despite this, wood in cutover tropical forests is in line to become more marketable as demand continues and old-growth forests become less accessible. In a cutover forest in Puerto...

Tropical forage legumes for environmental benefits: An overview

Directory of Open Access Journals (Sweden)

Rainer Schultze-Kraft

2018-01-01

Full Text Available Ruminant livestock production in the tropics, particularly when based on pastures, is frequently blamed for being detrimental to the environment, allegedly contributing to: (1 degradation and destruction of ecosystems, including degradation and loss of soil, water and biodiversity; and (2 climate change (global warming. In this paper we argue that, rather than being detrimental, tropical forage legumes can have a positive impact on the environment, mainly due to key attributes that characterize the Leguminosae (Fabaceae family: (1 symbiotic nitrogen fixation; (2 high nutritive value; (3 deep-reaching tap-root system; (4 wide taxonomic and genetic diversity; and (5 presence of particular secondary metabolites. Although there are also potential negative aspects, such as soil acidification and the risks of introduced legumes becoming invasive weeds, we submit that legumes have potential to contribute significantly to sustainable intensification of livestock production in the tropics, along with the provision of ecosystem services. To further assess, document and realize this potential, research for development needs in a range of areas are indicated.

Soil and water pollution in a banana production region in tropical Mexico

OpenAIRE

Geissen, V.; Que Ramos, F.; Bastidas-Bastidas, de, P.J.; Díaz-González, G.; Bello-Mendoza, R.; Huerta-Lwanga, E.; Ruiz-Suárez, L.E.

2010-01-01

The effects of abundant Mancozeb (Mn, Zn— bisdithiocarbamate) applications (2.5 kg ha-1week-1 for 10 years) on soil and surface-, subsurface- and groundwater pollution were monitored in a banana production region of tropical Mexico. In soils, severe manganese accumulation was observed, wheras the main metabolite ethylenethiourea was near the detection limit. Surface and subsurface water was highly polluted with ethylenethiourea, the main metabolite of Mancozeb (22.5 and 4.3 lg L-1, respective...

High hydrostatic pressure processing of tropical fruits.

Science.gov (United States)

Lopes, Maria Lúcia M; Valente Mesquita, Vera L; Chiaradia, Ana Cristina N; Fernandes, Antônio Alberto R; Fernandes, Patricia M B

2010-02-01

Interest in the nonthermal method of high hydrostatic pressure (HHP) for food preservation has increased recently due to the possibility of inactivating microorganisms and enzymes while maintaining product sensorial and nutritional properties. This work deals with HHP use for the preservation of tropical fruit products. HHP is shown to be a practical approach to obtaining high-quality tropical fruit products that are both nutritive and safe.

Organic carbon and nitrogen export from a tropical dam-impacted floodplain system

Directory of Open Access Journals (Sweden)

R. Zurbrügg

2013-01-01

Full Text Available Tropical floodplains play an important role in organic matter transport, storage, and transformation between headwaters and oceans. However, the fluxes and quality of organic carbon (OC and organic nitrogen (ON in tropical river-floodplain systems are not well constrained. We explored the quantity and characteristics of dissolved and particulate organic matter (DOM and POM, respectively in the Kafue River flowing through the Kafue Flats (Zambia, a tropical river-floodplain system in the Zambezi River basin. During the flooding season, > 80% of the Kafue River water passed through the floodplain, mobilizing large quantities of OC and ON, which resulted in a net export of 69–119 kg OC km⁻² d⁻¹ and 3.8–4.7 kg ON km⁻² d⁻¹, 80% of which was in the dissolved form. The elemental C : N ratio of ~ 20, the comparatively high δ¹³C values of −25‰ to −21‰, and its spectroscopic properties (excitation-emission matrices showed that DOM in the river was mainly of terrestrial origin. Despite a threefold increase in OC loads due to inputs from the floodplain, the characteristics of the riverine DOM remained relatively constant along the sampled 410-km river reach. This suggests that floodplain DOM displayed properties similar to those of DOM leaving the upstream reservoir and implied that the DOM produced in the reservoir was relatively short-lived. In contrast, the particulate fraction was ¹³C-depleted (−29‰ and had a C : N ratio of ~ 8, which indicated that POM originated from phytoplankton production in the reservoir and in the floodplain, rather than from plant debris or resuspended sediments. While the upstream dam had little effect on the DOM pool, terrestrial particles were retained, and POM from algal and microbial sources was released to the river. A nitrogen mass balance over the 2200 km² flooded area revealed an annual deficit of 15 500–22 100 t N in

Tropical rainforest response to marine sky brightening climate engineering

Science.gov (United States)

Muri, Helene; Niemeier, Ulrike; Kristjánsson, Jón Egill

2015-04-01

Tropical forests represent a major atmospheric carbon dioxide sink. Here the gross primary productivity (GPP) response of tropical rainforests to climate engineering via marine sky brightening under a future scenario is investigated in three Earth system models. The model response is diverse, and in two of the three models, the tropical GPP shows a decrease from the marine sky brightening climate engineering. Partial correlation analysis indicates precipitation to be important in one of those models, while precipitation and temperature are limiting factors in the other. One model experiences a reversal of its Amazon dieback under marine sky brightening. There, the strongest partial correlation of GPP is to temperature and incoming solar radiation at the surface. Carbon fertilization provides a higher future tropical rainforest GPP overall, both with and without climate engineering. Salt damage to plants and soils could be an important aspect of marine sky brightening.

Tropical Agroecosystems: These habitats are misunderstood by the temperate zones, mismanaged by the tropics.

Science.gov (United States)

Janzen, D H

1973-12-21

structured around a single export crop such as coffee, sugar, rubber, cotton, cacao, or tea. A major portion of their budgets comes directly or indirectly from the industry concerned. This industry can hardly be expected to wish to see its production integrated with a sustained-yield system that charges real costs for its materials. When an experiment station is centered around a major food crop, such as rice or maize, the goal becomes one of maximizing production per acre rather than per unit of resource spent; this goal may often be translated into one of generating more people. More general experiment stations tend to be established in the most productive regions of the country and, therefore, receive the most funding. Such regions (islands, intermediate elevations, areas with severe dry seasons) need experiment stations the least because they can often be successfully farmed with only slightly modified temperate zone technologies and philosophies. The administrators of tropical experiment stations often regard their job as a hardship post and tend to orient their research toward the hand that feeds them, which is certainly not the farming communities in which they have been placed. The tropics do not need more hard cash for tractors; they need a program that will show when, where, and how hand care should be replaced with draft animals, and draft animals with tractors. The tropics do not need more randomly gathered, esoteric or applied agricultural research: they need a means to integrate what is already known into the process of developing SYTA's. The tropics do not need more food as much as a means of evaluating the resources they have and generating social systems that will maximize the standard of living possible with those resources, whatever the size. The tropics need a realistic set of expectations.

Effects of liana load, tree diameter and distances between conspecifics on seed production in tropical timber trees

DEFF Research Database (Denmark)

Nabe-Nielsen, Jacob; Kollmann, Johannes Christian; Peña-Claros, Marielos

2009-01-01

Seed production in tropical timber trees is limited by abiotic resources, pollination and pre-dispersal seed predation. Resource availability is influenced by the number of competing trees and by lianas that often reach high densities in disturbed parts of tropical forests. The distance between...... conspecific trees affects pollination efficiency and seed predation intensity, and may therefore indirectly affect the long-term sustainability of selective logging. Here we investigate how reproductive status and the number of seeds dispersed per tree are affected by liana load, distance to the nearest...... and positively with tree diameter. In C. ianeirensis the most liana-infested trees dispersed fewer seeds. In T. oblonga the intensity of pre-dispersal seed predation decreased with distance to the nearest conspecifics. There was no evidence that seed viability or seed production decreased with distance...

On the Tropical Rainfall Measuring Mission (TRMM): Bringing NASA's Earth System Science Program to the Classroom

Science.gov (United States)

Shepherd, J. Marshall

1998-01-01

The Tropical Rainfall Measuring Mission is the first mission dedicated to measuring tropical and subtropical rainfall using a variety of remote sensing instrumentation, including the first spaceborne rain-measuring radar. Since the energy released when tropical rainfall occurs is a primary "fuel" supply for the weather and climate "engine"; improvements in computer models which predict future weather and climate states may depend on better measurements of global tropical rainfall and its energy. In support of the STANYS conference theme of Education and Space, this presentation focuses on one aspect of NASA's Earth Systems Science Program. We seek to present an overview of the TRMM mission. This overview will discuss the scientific motivation for TRMM, the TRMM instrument package, and recent images from tropical rainfall systems and hurricanes. The presentation also targets educational components of the TRMM mission in the areas of weather, mathematics, technology, and geography that can be used by secondary school/high school educators in the classroom.

Evaluating zootechnical and environmental inefficiency for ecological intensification of tropical livestock systems. Case study of Reunion Island

Directory of Open Access Journals (Sweden)

J. Vayssières

2011-01-01

Full Text Available According to FAO, animal production would contribute up to 18% to global anthropogenic green house gas (GHG emissions. In the face of an increasing world population and demand in food products, more productive and more environmentally- friendly livestock systems have to be conceived. With that aim, non-renewable energy uses and GHG emissions of main animal productions (dairy cattle, beef cattle, pig, poultry and rabbit were assessed in Reunion tropical island. Based on a method developed in mainland France, energy coefficients and emission factors were redefined to include specificities of the local context and livestock systems. The studied sample comprised 195 farms, i.e. more than 25% of farms overseen by local cooperatives. The study highlights the positive correlation between environmental inefficiency (non renewable energy uses, and GHG emissions per kilogram of animal product and zootechnical inefficiency (quantity of concentrate feed consumed per kilogram of animal product. It is thus possible to intensify ecologically animal productions. Similar studies are rare in countries of the South. Their development supposes even more drastic methodological adaptations than those conducted in Reunion so as to evaluate little- mechanized low-input mixed systems, where livestock activities are multifunctional and use various energy types.

Cooling performance assessment of horizontal earth tube system and effect on planting in tropical greenhouse

International Nuclear Information System (INIS)

Mongkon, S.; Thepa, S.; Namprakai, P.; Pratinthong, N.

2014-01-01

Graphical abstract: - Highlights: • The cooling ability of HETS is studied for planting in tropical greenhouse. • The effective of system was moderate with COP more than 2.0. • Increasing diameter and air velocity increase COP more than other parameters. • The plant growth with HETS was significantly better than no-HETS plant. - Abstract: The benefit of geothermal energy is used by the horizontal earth tube system (HETS); which is not prevalent in tropical climate. This study evaluated geothermal cooling ability and parameters studied in Thailand by mathematical model. The measurement of the effect on plant cultivation was carried out in two identical greenhouses with 30 m 2 of greenhouse volume. The HETS supplied cooled air to the model greenhouse (MGH), and the plant growth results were compared to the growth results of a conventional greenhouse (CGH). The prediction demonstrated that the coefficient of performance (COP) in clear sky day would be more than 2.0 while in the experiment it was found to be moderately lower. The parameters study could be useful for implementation of a system for maximum performance. Two plants Dahlias and head lettuce were grown satisfactory. The qualities of the plants with the HETS were better than the non-cooled plants. In addition, the quality of production was affected by variations of microclimate in the greenhouses and solar intensity throughout the cultivation period

Symbiotic Performance of Herbaceous Legumes in Tropical Cover Cropping Systems

Directory of Open Access Journals (Sweden)

Basil Ibewiro

2001-01-01

Full Text Available Increasing use of herbaceous legumes such as mucuna (Mucuna pruriens var. utilis [Wright] Bruck and lablab (Lablab purpureus [L.] Sweet in the derived savannas of West Africa can be attributed to their potential to fix atmospheric nitrogen (N2. The effects of management practices on N2 fixation in mucuna and lablab were examined using 15N isotope dilution technique. Dry matter yield of both legumes at 12 weeks was two to five times more in in situ mulch (IM than live mulch (LM systems. Land Equivalent Ratios, however, showed 8 to 30% more efficient utilization of resources required for biomass production under LM than IM systems. Live mulching reduced nodule numbers in the legumes by one third compared to values in the IM systems. Similarly, nodule mass was reduced by 34 to 58% under LM compared to the IM systems. The proportion of fixed N2 in the legumes was 18% higher in LM than IM systems. Except for inoculated mucuna, the amounts of N fixed by both legumes were greater in IM than LM systems. Rhizobia inoculation of the legumes did not significantly increase N2 fixation compared to uninoculated plots. Application of N fertilizer reduced N2 fixed in the legumes by 36 to 51% compared to inoculated or uninoculated systems. The implications of cover cropping, N fertilization, and rhizobia inoculation on N contributions of legumes into tropical low-input systems were discussed.

Biogas energy production from tropical biomass wastes by anaerobic digestion

Science.gov (United States)

Anaerobic digestion (AD) is an attractive technology in tropical regions for converting locally abundant biomass wastes into biogas which can be used to produce heat, electricity, and transportation fuels. However, investigations on AD of tropical forestry wastes, such as albizia biomass, and food w...

Introduction to tropical geometry

CERN Document Server

Maclagan, Diane

2015-01-01

Tropical geometry is a combinatorial shadow of algebraic geometry, offering new polyhedral tools to compute invariants of algebraic varieties. It is based on tropical algebra, where the sum of two numbers is their minimum and the product is their sum. This turns polynomials into piecewise-linear functions, and their zero sets into polyhedral complexes. These tropical varieties retain a surprising amount of information about their classical counterparts. Tropical geometry is a young subject that has undergone a rapid development since the beginning of the 21st century. While establishing itself as an area in its own right, deep connections have been made to many branches of pure and applied mathematics. This book offers a self-contained introduction to tropical geometry, suitable as a course text for beginning graduate students. Proofs are provided for the main results, such as the Fundamental Theorem and the Structure Theorem. Numerous examples and explicit computations illustrate the main concepts. Each of t...

Diurnal variations in depth profiles of UV-induced DNA damage and inhibition of bacterioplankton production in tropical coastal waters

NARCIS (Netherlands)

Visser, PM; Poos, JJ; Scheper, BB; Boelen, P; van Duyl, FC

2002-01-01

In this study, diurnal changes in bacterial production and DNA damage in bacterio-plankton (measured as cyclobutane pyrimidine dimers, CPDs) incubated in bags at different depths in tropical coastal waters were investigated. The DNA damage and inhibition of the bacterial production was highest at

Identifying and Analyzing Uncertainty Structures in the TRMM Microwave Imager Precipitation Product over Tropical Ocean Basins

Science.gov (United States)

Liu, Jianbo; Kummerow, Christian D.; Elsaesser, Gregory S.

2016-01-01

Despite continuous improvements in microwave sensors and retrieval algorithms, our understanding of precipitation uncertainty is quite limited, due primarily to inconsistent findings in studies that compare satellite estimates to in situ observations over different parts of the world. This study seeks to characterize the temporal and spatial properties of uncertainty in the Tropical Rainfall Measuring Mission Microwave Imager surface rainfall product over tropical ocean basins. Two uncertainty analysis frameworks are introduced to qualitatively evaluate the properties of uncertainty under a hierarchy of spatiotemporal data resolutions. The first framework (i.e. 'climate method') demonstrates that, apart from random errors and regionally dependent biases, a large component of the overall precipitation uncertainty is manifested in cyclical patterns that are closely related to large-scale atmospheric modes of variability. By estimating the magnitudes of major uncertainty sources independently, the climate method is able to explain 45-88% of the monthly uncertainty variability. The percentage is largely resolution dependent (with the lowest percentage explained associated with a 1 deg x 1 deg spatial/1 month temporal resolution, and highest associated with a 3 deg x 3 deg spatial/3 month temporal resolution). The second framework (i.e. 'weather method') explains regional mean precipitation uncertainty as a summation of uncertainties associated with individual precipitation systems. By further assuming that self-similar recurring precipitation systems yield qualitatively comparable precipitation uncertainties, the weather method can consistently resolve about 50 % of the daily uncertainty variability, with only limited dependence on the regions of interest.

Determinants of scientific output: an in-depth view of the productivity of tropical botanist and conservationist, Luis Diego Gómez Pignataro

Directory of Open Access Journals (Sweden)

Julián Monge-Nájera

2010-12-01

Full Text Available Bibliometric studies have found that male researchers have their greatest productivity around the age of 40, that female researchers produce less than their male colleagues, that incentives for collaboration are slow to affect productivity and that, just like humans, research institutes become larger, less productive, more expensive to maintain and less able to raise money as they grow old. Almost invariably, these conclusions come from statistical studies of large numbers of European and American scientists, and there are practically no studies about tropical researchers. We present an in-depth analysis of the productivity of an internationally recognized tropical botanist and conservationist, Luis Diego Gómez Pignataro, based on the totality of his published work and on our own knowledge, as co-workers and friends, of the life frame in which that scientific output was produced. His life output departs from the expected pattern in that he had the highest productivity before reaching the expected peak productivity age, and that when he reached it his productivity fell and never recovered. Furthermore, marriage did not produce the expected fall in productivity. A close analysis of his life indicates that in the middle of his career he switched to intense teaching and conservation activities, and this better explains why his output of scientific research articles was low afterwards. This switch may occur in other tropical scientists. Rev. Biol. Trop. 58 (4: 1093-1114. Epub 2010 December 01.

Optimum Temperatures for Net Primary Productivity of Three Tropical Seagrass Species.

Science.gov (United States)

Collier, Catherine J; Ow, Yan X; Langlois, Lucas; Uthicke, Sven; Johansson, Charlotte L; O'Brien, Katherine R; Hrebien, Victoria; Adams, Matthew P

2017-01-01

Rising sea water temperature will play a significant role in responses of the world's seagrass meadows to climate change. In this study, we investigated seasonal and latitudinal variation (spanning more than 1,500 km) in seagrass productivity, and the optimum temperatures at which maximum photosynthesis and net productivity (for the leaf and the whole plant) occurs, for three seagrass species ( Cymodocea serrulata, Halodule uninervis , and Zostera muelleri ). To obtain whole plant net production, photosynthesis, and respiration rates of leaves and the root/rhizome complex were measured using oxygen-sensitive optodes in closed incubation chambers at temperatures ranging from 15 to 43°C. The temperature-dependence of photosynthesis and respiration was fitted to empirical models to obtain maximum metabolic rates and thermal optima. The thermal optimum ( T opt ) for gross photosynthesis of Z. muelleri , which is more commonly distributed in sub-tropical to temperate regions, was 31°C. The T opt for photosynthesis of the tropical species, H. uninervis and C. serrulata , was considerably higher (35°C on average). This suggests that seagrass species are adapted to water temperature within their distributional range; however, when comparing among latitudes and seasons, thermal optima within a species showed limited acclimation to ambient water temperature ( T opt varied by 1°C in C. serrulata and 2°C in H. uninervis , and the variation did not follow changes in ambient water temperature). The T opt for gross photosynthesis were higher than T opt calculated from plant net productivity, which includes above- and below-ground respiration for Z. muelleri (24°C) and H. uninervis ( 33°C), but remained unchanged at 35°C in C. serrulata . Both estimated plant net productivity and T opt are sensitive to the proportion of below-ground biomass, highlighting the need for consideration of below- to above-ground biomass ratios when applying thermal optima to other meadows. The

Agricultural expansion and its impacts on tropical nature.

Science.gov (United States)

Laurance, William F; Sayer, Jeffrey; Cassman, Kenneth G

2014-02-01

The human population is projected to reach 11 billion this century, with the greatest increases in tropical developing nations. This growth, in concert with rising per-capita consumption, will require large increases in food and biofuel production. How will these megatrends affect tropical terrestrial and aquatic ecosystems and biodiversity? We foresee (i) major expansion and intensification of tropical agriculture, especially in Sub-Saharan Africa and South America; (ii) continuing rapid loss and alteration of tropical old-growth forests, woodlands, and semi-arid environments; (iii) a pivotal role for new roadways in determining the spatial extent of agriculture; and (iv) intensified conflicts between food production and nature conservation. Key priorities are to improve technologies and policies that promote more ecologically efficient food production while optimizing the allocation of lands to conservation and agriculture. Copyright © 2013 Elsevier Ltd. All rights reserved.

Tropical wetlands: A missing link in the global carbon cycle?

Science.gov (United States)

Sjögersten, Sofie; Black, Colin R; Evers, Stephanie; Hoyos-Santillan, Jorge; Wright, Emma L; Turner, Benjamin L

2014-01-01

Tropical wetlands are not included in Earth system models, despite being an important source of methane (CH4) and contributing a large fraction of carbon dioxide (CO2) emissions from land use, land use change, and forestry in the tropics. This review identifies a remarkable lack of data on the carbon balance and gas fluxes from undisturbed tropical wetlands, which limits the ability of global change models to make accurate predictions about future climate. We show that the available data on in situ carbon gas fluxes in undisturbed forested tropical wetlands indicate marked spatial and temporal variability in CO2 and CH4 emissions, with exceptionally large fluxes in Southeast Asia and the Neotropics. By upscaling short-term measurements, we calculate that approximately 90 ± 77 Tg CH4 year−1 and 4540 ± 1480 Tg CO2 year−1 are released from tropical wetlands globally. CH4 fluxes are greater from mineral than organic soils, whereas CO2 fluxes do not differ between soil types. The high CO2 and CH4 emissions are mirrored by high rates of net primary productivity and litter decay. Net ecosystem productivity was estimated to be greater in peat-forming wetlands than on mineral soils, but the available data are insufficient to construct reliable carbon balances or estimate gas fluxes at regional scales. We conclude that there is an urgent need for systematic data on carbon dynamics in tropical wetlands to provide a robust understanding of how they differ from well-studied northern wetlands and allow incorporation of tropical wetlands into global climate change models. PMID:26074666

A model for the identification of tropical weather systems over South ...

African Journals Online (AJOL)

drinie

2002-07-03

Jul 3, 2002 ... with, these two high-pressure systems, controls to a large extent, the weather of ... researchers provided general rules to differentiate between tropical- ..... inclusion of this graph therefore does not serve as a verification of.

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

2004-01-01

.... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T; Augustus, Ellsworth H; Colonnese, Christopher P

2003-01-01

.... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

2005-01-01

.... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

Making Agricultural Innovation Systems (AIS Work for Development in Tropical Countries

Directory of Open Access Journals (Sweden)

Philipp Aerni

2015-01-01

Full Text Available Agricultural innovation in low-income tropical countries contributes to a more effective and sustainable use of natural resources and reduces hunger and poverty through economic development in rural areas. Yet, despite numerous recent public and private initiatives to develop capacities for agricultural innovation, such initiatives are often not well aligned with national efforts to revive existing Agricultural Innovation Systems (AIS. In an effort to improve coordination and responsiveness of Capacity Development (CD initiatives, the G20 Agriculture Ministers requested the Food and Agriculture Organization of the United Nations (FAO to lead the development of a Tropical Agricultural Platform (TAP, which is designed to improve coherence and coordination of CD for agricultural innovation in the tropics. This paper presents a summary of the results obtained from three regional needs assessments undertaken by TAP and its partners. The surveyed tropical regions were Southeast Asia, Sub-Saharan Africa and Central America. The findings reveal a mismatch in all three regions between the external supply of primarily individual CD and the actual demand for institutional CD. The misalignment might be addressed by strengthening south-south and triangular collaboration and by improving the institutional capacities that would render national AIS more demand-oriented and responsive to the needs of smallholders in domestic agriculture.

Utilization of tropical crop residues and agroindustrial by-products in animal nutrition. Constraints and perspectives

International Nuclear Information System (INIS)

Preston, T.R.; Parra, R.

1983-01-01

The importance of by-products and crop residues as animal feeds is increasing steadily. This is a consequence of the increasing demand for cereal grains as both human and animal (chiefly poultry) food, and the increasing demand for energy coupled with decreasing availability of fossil fuels. The effects of these two trends are that primary use of land for livestock production (usually grazing systems) will steadily diminish; at the same time, sources of biomass will increase in importance as renewable energy sources, and greater emphasis will be placed on draught animal power. Most by-products and crop residues are fibrous and therefore of only low to moderate nutritive value, or have special physical and chemical characteristics making them difficult to incorporate in conventional ''balanced'' rations. Such feed raw materials may need special processing and/or special forms of supplementation if they are to be used efficiently. It is hypothesized that industrial by-products and crop residues will be more efficiently utilized if they are incorporated in diversified and integrated production systems, i.e. (a) livestock production is integrated with production of cash crops both for food and fuel; (b) different livestock species are utilized in the same enterprise in a complementary way; (c) livestock feeding is based on crop residues (energy) supplemented with protein-rich forages and aquatic plants; and (d) animal wastes are recycled and used for food, fertilizer and fuel. This strategy is particularly suitable for the conditions in (i) tropical countries, whose climate favours high crop/biomass yields per unit area and ease of fermentation of organic wastes, and (ii) family farms, for which diversification means greater opportunity for self-sufficiency and increased possibilities for use of family resources. (author)

Actual performance and characteristic of a grid connected photovoltaic power system in the tropics: A short term evaluation

International Nuclear Information System (INIS)

Khatib, Tamer; Sopian, Kamaruzzaman; Kazem, Hussein A.

2013-01-01

Highlights: • We analyzed an actual performance of grid connected PV system. • We derived accurate models for the system based on the actual performance. • We assist the electricity productively of the proposed system. - Abstract: This paper presents a field operation experience for a grid connected PV system under tropical climate. The system is consisted of a 5 kWp photovoltaic (PV) array and a 6 kW DC/AC inverter. The operation performance data are recorded in order to develop accurate mathematical models for the system as well as to evaluate the productivity of the system. The experiment results show that, the average PV performance (the ratio of the theoretical performance to the actual performance) is 73.12% while the average inverter performance (the ratio of the theoretical inverter efficiency to the actual inverter efficiency) is 98.56%. Moreover, it is found that the daily yield factor of the PV system is 2.51 kW h/kWp day while, the capacity factor is 10.47%. However, it is concluded that the productivity of the system is below the prospected rate and thus, an inspection of the system must be done in order to diagnose the problem of the system’s low productivity. This paper presents worthwhile information for those who are interested in PV system installation in Malaysia and nearby country

Sustainable production of cultivations, using biological and conservationists techniques; an applicable model to the Colombian warm tropic

International Nuclear Information System (INIS)

Castro F, Hugo E

1995-01-01

The hot Colombian tropics represent nearly 82% of the national territory. The intensive and wrongly use of the soil has been subjected for years in agricultural areas of the inter-Andean valleys, Caribbean region, the eastern plains and others sectors of the commercial agriculture in the hot climate it is promoting a progressive physical, chemical and biological degradation of the soil. The physical losses of soil and organic matter due to erosion, excessive mechanization, flooding rice as single crop, burning of crop residues, unsuitable systems of irrigation and drainage, alkalinization an compaction in cropping areas, and the problems with more incidence in the deployment of land productivity in the areas. The methods to overcome these limitations agree with the application of modem and sustainable technologies focusing production systems. The management of production systems, selecting tillage systems according to the physical development of the soil, planting species in continuous rotation cycles, planting and incorporation of green manure, between two agricultural semesters, the appropriate management of water in non-irrigated crops an modem irrigation and the utilization of crop residues, to return to the soil, part of the nutrients extracted constitute some of the factors management dependent that could affect favorably the land productivity, for the benefit of future generations. Based on these concepts, it is presented in this article some of the experimental results obtained by national of Agriculture Colombian Institute (ICA) in the Regional Soil Program Center of Agricultural Research (Nataima), located in El Espinal, Tolima State, Colombia

Mixed grazing systems of goats with cattle in tropical conditions: an alternative to improving animal production in the pasture.

Science.gov (United States)

d'Alexis, S; Periacarpin, F; Jackson, F; Boval, M

2014-08-01

Mixed grazing systems combining sheep and cattle have shown better growth performance for one or both species. This observation has been attributed to their complementary feeding behaviour and the reduced host infection by gastrointestinal nematodes. Less attention has been paid to mixed grazing systems combining goats and cattle. Here, continuously grazing goats mixed with cattle (M) were compared with control goats reared alone (C) under tropical conditions. The comparison was conducted with gastrointestinal nematode-infected (I) and non-infected (nI) goats. Thus, the four treatments were cattle with gastrointestinal nematode-infected goats (MI), gastrointestinal nematode-infected goats alone (CI), cattle with non-infected goats (MnI) and non-infected goats (CnI). Average daily gain (ADG, g/day) and grass production were measured for the four groups of animals (six goats and two heifers treated with MI or MnI) grazing for 3 months on 4 subplots. Monthly measurements were performed over 5-day periods. This pattern was replicated in space for a second set of four subplots and in time for six successive cohorts of animals (bands 1 to 6). The ADG of goats in mixed grazing conditions was higher than controls irrespective of the infection status (32.6 v. 18.4 g/day for MI v. CI; 44.2 v. 33.5 g/day for MnI v. CnI). Concomitantly, the average biomass was lower for mixed grazing animals compared with controls (174 v. 170 for MI and MnI; 235 v. 208 for CI and CnI, respectively), suggesting better use of the sward. For daily BW gain (g/kg DM), mixed grazing also yielded better results than the control (1.88 v. 0.52 g BW/kg DM per day for MI v. CI; 2.08 v. 1.47 g BW/kg DM per day for MnI and CnI). Mixed grazing of goats and heifers offers a promising alternative for increasing goat and overall animal production as well as improving the management of pastures.

Emission of carbon dioxide from a tropical estuarine system, Goa, India

Digital Repository Service at National Institute of Oceanography (India)

Sarma, V.V.S.S.; DileepKumar, M.; Manerikar, M.

Carbon dioxide species were studied in Mandovi-Zuari system, a tropical estuarine complex influenced by strong monsoonal run-off, with implications to build up and air-water exchange of CO sub(2) . Total carbon dioxide (TOC sub(2)) behaved...

Studies on saponin production in tropical medicinal plants Maesa argentea and Maesa lanceolata

Science.gov (United States)

Faizal, Ahmad; Geelen, Danny

2015-09-01

The continuous need for new compounds with important medicinal activities has lead to the identification and characterization of various plant-derived natural products. As a part of this program, we studied the saponin production from two tropical medicinal plants Maesa argentea and M. lanceolata and evaluated several treatments to enhance their saponin production. In this experiment, we present the analyses of saponin production from greenhouse grown plants by means of TLC and HPLC-MS. We observed that the content of saponin from these plants varied depending on organ and physiological age of the plants. In addition, the impact of elicitors on saponin accumulation on in vitro grown plants was analyzed using TLC. The production of saponin was very stable and not affected by treatment with methyl jasmonate, and salicylic acid. In conclusion, Maesa saponins are constitutively produced in plants and the level of these compounds in plants is mainly affected by the developmental or physiological stage.

Jatropha curcas and Ricinus communis differentially affect arbuscular mycorrhizal fungi diversity in soil when cultivated for biofuel production in a Guantanamo (Cuba) tropical system.

Science.gov (United States)

Alguacil, M. M.; Torrecillas, E.; Hernández, G.; Torres, P.; Roldán, A.

2012-04-01

The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a control soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) disappeared in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were improved by the cultivation of the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the control soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable in long-term conservation and sustainable management of these tropical ecosystems.

Urgent need for warming experiments in tropical forests

Science.gov (United States)

Calaveri, Molly A.; Reed, Sasha C.; Smith, W. Kolby; Wood, Tana E.

2015-01-01

Although tropical forests account for only a fraction of the planet's terrestrial surface, they exchange more carbon dioxide with the atmosphere than any other biome on Earth, and thus play a disproportionate role in the global climate. In the next 20 years, the tropics will experience unprecedented warming, yet there is exceedingly high uncertainty about their potential responses to this imminent climatic change. Here, we prioritize research approaches given both funding and logistical constraints in order to resolve major uncertainties about how tropical forests function and also to improve predictive capacity of earth system models. We investigate overall model uncertainty of tropical latitudes and explore the scientific benefits and inevitable trade-offs inherent in large-scale manipulative field experiments. With a Coupled Model Intercomparison Project Phase 5 analysis, we found that model variability in projected net ecosystem production was nearly 3 times greater in the tropics than for any other latitude. Through a review of the most current literature, we concluded that manipulative warming experiments are vital to accurately predict future tropical forest carbon balance, and we further recommend the establishment of a network of comparable studies spanning gradients of precipitation, edaphic qualities, plant types, and/or land use change. We provide arguments for long-term, single-factor warming experiments that incorporate warming of the most biogeochemically active ecosystem components (i.e. leaves, roots, soil microbes). Hypothesis testing of underlying mechanisms should be a priority, along with improving model parameterization and constraints. No single tropical forest is representative of all tropical forests; therefore logistical feasibility should be the most important consideration for locating large-scale manipulative experiments. Above all, we advocate for multi-faceted research programs, and we offer arguments for what we consider the most

Tropical forests and the changing earth system.

Science.gov (United States)

Lewis, Simon L

2006-01-29

Tropical forests are global epicentres of biodiversity and important modulators of the rate of climate change. Recent research on deforestation rates and ecological changes within intact forests, both areas of recent research and debate, are reviewed, and the implications for biodiversity (species loss) and climate change (via the global carbon cycle) addressed. Recent impacts have most likely been: (i) a large source of carbon to the atmosphere, and major loss of species, from deforestation and (ii) a large carbon sink within remaining intact forest, accompanied by accelerating forest dynamism and widespread biodiversity changes. Finally, I look to the future, suggesting that the current carbon sink in intact forests is unlikely to continue, and that the tropical forest biome may even become a large net source of carbon, via one or more of four plausible routes: changing photosynthesis and respiration rates, biodiversity changes in intact forest, widespread forest collapse via drought, and widespread forest collapse via fire. Each of these scenarios risks potentially dangerous positive feedbacks with the climate system that could dramatically accelerate and intensify climate change. Given that continued land-use change alone is already thought to be causing the sixth mass extinction event in Earth's history, should such feedbacks occur, the resulting biodiversity and societal consequences would be even more severe.

Sustainable landscapes in a world of change: tropical forests, land use and implementation of REDD+: Part I

Science.gov (United States)

Richard Birdsey; Yude Pan; Richard Houghton

2013-01-01

Tropical forests play a critical role in the Earth system; however, tropical landscapes have changed greatly in recent decades because of increasing demand for land to support agriculture and timber production, fuel wood, and other pressures of population and human economics. The observable results are a legacy of persistent deforestation, forest degradation, increased...

Evolution of the Tropical Cyclone Integrated Data Exchange And Analysis System (TC-IDEAS)

Science.gov (United States)

Turk, J.; Chao, Y.; Haddad, Z.; Hristova-Veleva, S.; Knosp, B.; Lambrigtsen, B.; Li, P.; Licata, S.; Poulsen, W.; Su, H.;

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

2005-01-01

The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

2004-01-01

The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

National Research Council Canada - National Science Library

Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T; Augustus, Ellsworth H; Colonnese, Christopher P

2003-01-01

The long-term goal of this partnership is to establish an operational forecasting system of the wind field and resulting waves and surge impacting the coastline during the approach and landfall of tropical cyclones...

Modeling methane emissions by cattle production systems in Mexico

Science.gov (United States)

Castelan-Ortega, O. A.; Ku Vera, J.; Molina, L. T.

2013-12-01

Methane emissions from livestock is one of the largest sources of methane in Mexico. The purpose of the present paper is to provide a realistic estimate of the national inventory of methane produced by the enteric fermentation of cattle, based on an integrated simulation model, and to provide estimates of CH4 produced by cattle fed typical diets from the tropical and temperate climates of Mexico. The Mexican cattle population of 23.3 million heads was divided in two groups. The first group (7.8 million heads), represents cattle of the tropical climate regions. The second group (15.5 million heads), are the cattle in the temperate climate regions. This approach allows incorporating the effect of diet on CH4 production into the analysis because the quality of forages is lower in the tropics than in temperate regions. Cattle population in every group was subdivided into two categories: cows (COW) and other type of cattle (OTHE), which included calves, heifers, steers and bulls. The daily CH4 production by each category of animal along an average production cycle of 365 days was simulated, instead of using a default emission factor as in Tier 1 approach. Daily milk yield, live weight changes associated with the lactation, and dry matter intake, were simulated for the entire production cycle. The Moe and Tyrrell (1979) model was used to simulate CH4 production for the COW category, the linear model of Mills et al. (2003) for the OTHE category in temperate regions and the Kurihara et al. (1999) model for the OTHE category in the tropical regions as it has been developed for cattle fed tropical diets. All models were integrated with a cow submodel to form an Integrated Simulation Model (ISM). The AFRC (1993) equations and the lactation curve model of Morant and Gnanasakthy (1989) were used to construct the cow submodel. The ISM simulates on a daily basis the CH4 production, milk yield, live weight changes associated with lactation and dry matter intake. The total daily CH

Electrical conductivity of the nutrient solution and plant density in aeroponic production of seed potato under tropical conditions (winter/spring

Directory of Open Access Journals (Sweden)

Alex Humberto Calori

Full Text Available ABSTRACT The recent introduction in Brazil of production of quality seed potatoes in hydroponic systems, such as aeroponics, demands studies on the nutritional and crop management. Thus, this study evaluated the influence of electrical conductivity of the nutrient solution and plant density on the seed potato minitubers production in aeroponics system. The Agata and Asterix cultivars were produced in a greenhouse under tropical conditions (winter/spring. The experimental design was a randomized block in a split-split plot design. The plot consisted of 4 electrical conductivities of the nutrient solution (1.0; 2.0; 3.0; and 4.0 dS∙m−1; the subplot, of 4 plant densities (25; 44; 66; and 100 plants∙m−2; and the subsubplot, of the 2 potato cultivars (Ágata and Asterix, totaling 4 blocks. The 2.2 and 2.1 dS∙m−1 electrical conductivities yielded the highest productivity of seed potato minitubers, for Ágata and Asterix cultivars, respectively, regardless of plant density. For both cultivars, the highest yield was observed for the 100 plants∙m−2 density.

Evaluation of the productivity decrease risk due to a future increase in tropical cyclone intensity in Japan.

Science.gov (United States)

Esteban, Miguel; Longarte-Galnares, Gorka

2010-12-01

A number of scientists have recently conducted research that shows that tropical cyclone intensity is likely to increase in the future. This would result in an increase in the damage along with a decrease in economic productivity due to precautionary cessation of the economic activity of the affected areas during the passage of the cyclone. The economic effect of this stop in economic activity is a phenomenon that has not received much attention in the past, and the cumulative effect that it can have on the Japanese economy over the next 75 years has never been evaluated. The starting point for the evaluation of the economic risks is the change in the patterns of tropical cyclone intensity suggested by Knutson and Tuleya. The results obtained show how a significant decrease in the overall productivity of the country could be expected, which could lower GDP by between 6% and 13% by 2085. © 2010 Society for Risk Analysis.

Amino acid composition reveals functional diversity of zooplankton in tropical lakes related to geography, taxonomy and productivity.

Science.gov (United States)

Aranguren-Riaño, Nelson J; Guisande, Cástor; Shurin, Jonathan B; Jones, Natalie T; Barreiro, Aldo; Duque, Santiago R

2018-04-16

Variation in resource use among species determines their potential for competition and co-existence, as well as their impact on ecosystem processes. Planktonic crustaceans consume a range of micro-organisms that vary among habitats and species, but these differences in resource consumption are difficult to characterize due to the small size of the organisms. Consumers acquire amino acids from their diet, and the composition of tissues reflects both the use of different resources and their assimilation in proteins. We examined the amino acid composition of common crustacean zooplankton from 14 tropical lakes in Colombia in three regions (the Amazon floodplain, the eastern range of the Andes, and the Caribbean coast). Amino acid composition varied significantly among taxonomic groups and the three regions. Functional richness in amino acid space was greatest in the Amazon, the most productive region, and tended to be positively related to lake trophic status, suggesting the niche breadth of the community could increase with ecosystem productivity. Functional evenness increased with lake trophic status, indicating that species were more regularly distributed within community-wide niche space in more productive lakes. These results show that zooplankton resource use in tropical lakes varies with both habitat and taxonomy, and that lake productivity may affect community functional diversity and the distribution of species within niche space.

Productivity, utilization efficiency and sward targets for mixed pastures of marandugrass, forage peanut and tropical kudzu

Directory of Open Access Journals (Sweden)

Carlos Mauricio Soares de Andrade

2012-03-01

Full Text Available This study was carried out to evaluate the productivity and utilization efficiency of a mixed marandugrass (Brachiaria brizantha cv. Marandu, forage peanut (Arachis pintoi cv. Mandobi and tropical kudzu (Pueraria phaseoloides pasture, rotationally stocked at four daily forage allowance levels (6.6, 10.3, 14.3 and 17.9% of live weight, in order to define sward management targets for these mixtures. In each stocking cycle, dry matter (DM accumulation rates, defoliation intensity (%, grazing depth (% and grazed horizon (cm were evaluated. Sward targets were defined according to the sward condition that best conciliated the grass-legume balance and the equilibrium between forage production and utilization. Pastures submitted to higher forage allowance levels showed higher productivity, but were less efficiently utilized. It was not possible to establish sward management targets for marandugrass-tropical kudzu pastures. For marandugrass-forage peanut pastures the best sward state was set with forage allowance of 10.3% of live weight. Under rotational stocking, the following sward targets were suggested for these pastures in the Western Amazon: pre-grazing height of 30-35 cm (June to September or 45-50 cm (October to May and post-grazing sward height of 20-25 cm (June to September or 25-30 cm (October to May.

Rapid wave and storm surge warning system for tropical cyclones in Mexico

Science.gov (United States)

Appendini, C. M.; Rosengaus, M.; Meza, R.; Camacho, V.

2015-12-01

The National Hurricane Center (NHC) in Miami, is responsible for the forecast of tropical cyclones in the North Atlantic and Eastern North Pacific basins. As such, Mexico, Central America and Caribbean countries depend on the information issued by the NHC related to the characteristics of a particular tropical cyclone and associated watch and warning areas. Despite waves and storm surge are important hazards for marine operations and coastal dwellings, their forecast is not part of the NHC responsibilities. This work presents a rapid wave and storm surge warning system based on 3100 synthetic tropical cyclones doing landfall in Mexico. Hydrodynamic and wave models were driven by the synthetic events to create a robust database composed of maximum envelops of wind speed, significant wave height and storm surge for each event. The results were incorporated into a forecast system that uses the NHC advisory to locate the synthetic events passing inside specified radiuses for the present and forecast position of the real event. Using limited computer resources, the system displays the information meeting the search criteria, and the forecaster can select specific events to generate the desired hazard map (i.e. wind, waves, and storm surge) based on the maximum envelop maps. This system was developed in a limited time frame to be operational in 2015 by the National Hurricane and Severe Storms Unit of the Mexican National Weather Service, and represents a pilot project for other countries in the region not covered by detailed storm surge and waves forecasts.

Enhancing agricultural productivity and rural incomes through sustainable use of natural resources in the semi arid tropics.

Science.gov (United States)

Wani, Suhas P; Dixin, Yin; Li, Zhong; Dar, William D; Chander, Girish

2012-03-30

A participatory watershed management approach is one of the tested, sustainable and eco-friendly options to upgrade rain-fed agriculture to meet growing food demand along with additional multiple benefits in terms of improving livelihoods, addressing equity issues and biodiversity concerns. Watershed interventions at study sites in Thailand (Tad Fa and Wang Chai) and India (Kothapally) effectively reduced runoff and the associated soil loss. Such interventions at Xiaoxincun (China) and Wang Chai improved groundwater recharging and availability. Enhanced productive transpiration increased rainwater use efficiency for crop production by 13-29% at Xiaoxincun; 13-160% at Lucheba (China), 32-37% at Tad Fa and 23-46% at Wang Chai and by two to five times at Kothapally. Watershed interventions increased significantly the additional net returns from crop production as compared with the pre-watershed intervention period. Increased water availability opened up options for crop diversification with high-value crops, including increased forage production and boosted livestock-based livelihoods. In dryland tropics, integrated watershed management approach enabled farmers to diversify the systems along with increasing agricultural productivity through increased water availability, while conserving the natural resource base. Household incomes increased substantially, leading to improved living and building the resilience of the community and natural resources. Copyright © 2011 Society of Chemical Industry.

Pan-tropical monitoring of deforestation

International Nuclear Information System (INIS)

Achard, F; DeFries, R; Eva, H; Hansen, M; Mayaux, P; Stibig, H-J

2007-01-01

This paper reviews the technical capabilities for monitoring deforestation from a pan-tropical perspective in response to the United Nations Framework Convention on Climate Change (UNFCCC) process, which is studying the technical issues surrounding the ability to reduce greenhouse gas emissions from deforestation in developing countries. The successful implementation of such policies requires effective forest monitoring systems that are reproducible, provide consistent results, meet standards for mapping accuracy, and can be implemented from national to pan-tropical levels. Remotely sensed data, supported by ground observations, are crucial to such efforts. Recent developments in global to regional monitoring of forests can contribute to reducing the uncertainties in estimates of emissions from deforestation. Monitoring systems at national levels in developing countries can also benefit from pan-tropical and regional observations, mainly by identifying hot spots of change and prioritizing areas for monitoring at finer spatial scales. A pan-tropical perspective is also required to ensure consistency between different national monitoring systems. Data sources already exist to determine baseline periods in the 1990s as historical reference points. Key requirements for implementing such monitoring programs, both at pan-tropical and at national scales, are international commitment of resources to increase capacity, coordination of observations to ensure pan-tropical coverage, access to free or low-cost data, and standardized, consensus protocols for data interpretation and analysis

Phosphorus, carbon- and nitrogen interactions in productive and degraded tropical pastures

Science.gov (United States)

Oberson, A.; Hegglin, D. D.; Nesper, M.; Rao, I.; Fonte, S.; Ramirez, B.; Velasquez, J.; Tamburini, F.; Bünemann, E. K.; Frossard, E.

2011-12-01

Pastures are the main land use in deforested areas of tropical South America. The highly weathered soils of these regions usually have low total and available phosphorus (P) contents. Low P availability can strongly limit plant and animal productivity and other soil ecosystem functions. Most introduced pastures of Brachiaria spp. are grass-alone (GA) while some are grass-legume (GL) pastures. The majority of the introduced pastures, particularly the grass-alone are at some state of degradation (GD). Pasture degradation induces severe loss of plant biomass production, with drastic ecological and economic implications. Although the importance of P deficiency in pasture degradation has been recognized, the knowledge generated on stoichiometry of carbon (C), nitrogen (N) and P along pathways of the nutrient cycles of pastures, with different botanical composition and productivity, has been very limited. We will present results of a case study realized during 2010 to 2011 in the forest margins agro-ecosystem of the department of Caquetá, Colombia. Our objectives were to determine: i) whether P availability is lower in degraded compared to productive pastures, and ii) whether the introduction of legumes in the pasture increases P availability through enhanced biological P cycling through plant growth, plant litter decomposition and the soil microbial biomass; and iii) whether pasture types (GA vs GL) and the state of pasture degradation affect the C:N:P ratios in nutrient pools of the soil-plant system. An on-farm study was conducted on nine farms in the department of Caquetá, Colombia. On every farm three different pasture types were studied: degraded grass alone pastures (GD), productive grass-alone pastures (GA) and productive grass-legume pastures (GL). Basic soil characteristics and indicators on soil P status, microbial P cycling, plant biomass production, plant litter deposition and nutrient concentrations in plant tissue were determined. Analysis of P, C and N

Drivers of aboveground wood production in a lowland tropical forest of West Africa: teasing apart the roles of tree density, tree diversity, soil phosphorus, and historical logging.

Science.gov (United States)

Jucker, Tommaso; Sanchez, Aida Cuni; Lindsell, Jeremy A; Allen, Harriet D; Amable, Gabriel S; Coomes, David A

2016-06-01

Tropical forests currently play a key role in regulating the terrestrial carbon cycle and abating climate change by storing carbon in wood. However, there remains considerable uncertainty as to whether tropical forests will continue to act as carbon sinks in the face of increased pressure from expanding human activities. Consequently, understanding what drives productivity in tropical forests is critical. We used permanent forest plot data from the Gola Rainforest National Park (Sierra Leone) - one of the largest tracts of intact tropical moist forest in West Africa - to explore how (1) stand basal area and tree diversity, (2) past disturbance associated with past logging, and (3) underlying soil nutrient gradients interact to determine rates of aboveground wood production (AWP). We started by statistically modeling the diameter growth of individual trees and used these models to estimate AWP for 142 permanent forest plots. We then used structural equation modeling to explore the direct and indirect pathways which shape rates of AWP. Across the plot network, stand basal area emerged as the strongest determinant of AWP, with densely packed stands exhibiting the fastest rates of AWP. In addition to stand packing density, both tree diversity and soil phosphorus content were also positively related to productivity. By contrast, historical logging activities negatively impacted AWP through the removal of large trees, which contributed disproportionately to productivity. Understanding what determines variation in wood production across tropical forest landscapes requires accounting for multiple interacting drivers - with stand structure, tree diversity, and soil nutrients all playing a key role. Importantly, our results also indicate that logging activities can have a long-lasting impact on a forest's ability to sequester and store carbon, emphasizing the importance of safeguarding old-growth tropical forests.

Bacterial domination over Archaea in ammonia oxidation in a monsoon-driven tropical estuary

Digital Repository Service at National Institute of Oceanography (India)

Vipindas, P.V.; Anas, A.; Jasmin, C.; Lallu, K.R.; Fausia, K.H.; Balachandran, K.K.; Muraleedharan, K.R.; Nair, S.

Autotrophic ammonia oxidizing microorganisms,which are responsible for the rate-limiting step of nitrification in most aquatic systems, have not been studied in tropical estuaries. Cochin estuary (CE) is one of the largest, productive, and monsoon...

Photovoltaic Systems with and without Radiation Concentrators for Temperate and Tropical Regions

Directory of Open Access Journals (Sweden)

Vania Reis de Souza Sant’Anna

2015-11-01

Full Text Available The industrial development of solar photovoltaic technology has attracted investors and influenced governments to establish public policies for the sector. The present research consisted of studying, building and testing low concentration solar radiation systems for photovoltaic energy conversion. The study used optical nonimaging parameters for the V-trough type radiation concentrator constructed of anodized aluminum, to reflect and to cool. Designed to concentrate radiation by about two times and consisting of a set of photovoltaic modules connected in parallel, they were modeled in the Laboratory of Energy Area in the Department of Agricultural Engineering of the Federal University of Vicosa, Brazil, at the coordinates 20°45′14′′ S latitude, 42°52′53′′ W longitude and altitude 648.74 m. They were installed to the geographic North, with the same slope as the local latitude. For comparative analysis, it was determined the electrical characteristics for evaluation of the prototype’s performance with and without radiation concentration, the final productivity for cities in tropical and temperate regions and economic analysis for the system. It was concluded that the prototypes allowed for a gain of energy with concentration, about 31.3% more, and therefore a productivity gain for the analyzed cities in, kWh·kWp−1.

Comprehensive overview of FPL field testing conducted in the tropics (1945-2005)

Science.gov (United States)

Grant T. Kirker; Stan L. Lebow; Mark E. Mankowski

2016-01-01

Tropical exposure often represents a more severe environment for treated wood and wood based products. Accelerated tropical decay rates are typically attributed to higher mean rainfall and temperatures. The Forest Products Laboratory (FPL) in Madison, WI has been conducting tropical field tests in a variety of locations since the early 1940’s. This paper summarizes FPL...

Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

Science.gov (United States)

Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

2014-05-01

It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

[Development of APSIM (agricultural production systems simulator) and its application].

Science.gov (United States)

Shen, Yuying; Nan, Zhibiao; Bellotti, Bill; Robertson, Michael; Chen, Wen; Shao, Xinqing

2002-08-01

Soil-crop simulator model is an effective tool for providing decision on agricultural management. APSIM (Agricultural Production Systems Simulator) was developed to simulate the biophysical process in farming system, and particularly in the economic and ecological features of the systems under climatic risk. The current literatures revealed that APSIM could be applied in wide zone, including temperate continental, temperate maritime, sub-tropic and arid climate, and Mediterranean climates, with the soil type of clay, duplex soil, vertisol, silt sandy, silt loam and silt clay loam. More than 20 crops have been simulated well. APSIM is powerful on describing crop structure, crop sequence, yield prediction, and quality control as well as erosion estimation under different planting pattern.

Interactions between tropical cyclones and mid-latitude systems in the Northeastern Pacific

Science.gov (United States)

Lugo, A.; Abarca, S. F.; Raga, G. B.; Vargas, D. C.

2014-12-01

Major challenges in tropical meteorology include the short-term forecast of tropical cyclone (TC) intensity, which is defined as the maximum tangential wind. Several efforts have been made in order to reach this goal over the last decade: Among these efforts, the study of lightning in the TC inner core (the region inside a disc of 100 km radius from the center) as a proxy to deep convection, has the potential to be used as a predictor to forecast intensity (DeMaria et al, 2012, Mon. Wea. Rev., 140, 1828-1842).While most studies focus their objectives in studying the lightning flash density in the inner core, we study the probability of flash occurrence for intensifying and weakening cyclones. We have analyzed the trajectories of the observed 62 tropical cyclones that developed in the basin from 2006 to 2009, and classified them into separate clusters according to their trajectories. These clusters can broadly be described as having trajectories mostly oriented: East-West, towards the central Pacific, NW far from the Mexican coast, parallel to the Mexican coast and recurving towards the Mexican coast.We estimate that probability of inner core lightning occurrence increases as cyclones intensify but the probability rapidly decrease as the systems weaken. This is valid for cyclones in most of the clusters. However, the cyclones that exhibit trajectories that recurve towards the Mexican coast, do not present the same relationship between intensity and inner-core lightning probability, these cyclones show little or no decrease in the lightning occurrence probability as they weaken.We hypothesize that one of the reasons for this anomalous behavior is likely the fact that these cyclones interact with mid-latitude systems. Mid-latitude systems are important in determining the recurving trajectory but they may also influence the TC by advecting mid-level moisture towards the TC inner core. This additional supply of moisture as the system is approaching land may enhance deep

Soil and water pollution in a banana production region in tropical Mexico.

Science.gov (United States)

Geissen, Violette; Ramos, Franzisco Que; de J Bastidas-Bastidas, Pedro; Díaz-González, Gilberto; Bello-Mendoza, Ricardo; Huerta-Lwanga, Esperanza; Ruiz-Suárez, Luz E

2010-10-01

The effects of abundant Mancozeb (Mn, Zn-bisdithiocarbamate) applications (2.5 kg ha⁻¹week⁻¹ for 10 years) on soil and surface-, subsurface- and groundwater pollution were monitored in a banana production region of tropical Mexico. In soils, severe manganese accumulation was observed, wheras the main metabolite ethylenethiourea was near the detection limit. Surface and subsurface water was highly polluted with ethylenethiourea, the main metabolite of Mancozeb (22.5 and 4.3 μg L⁻¹, respectively), but not with manganese. In deep ground water, no ethylenethiourea was detected. The level of pollution in the region presents a worrisome risk for aquatic life and for human health.

Introduction of energy-production systems from plant resources. The question of transferring to agricultural-production systems in tropical Africa

Energy Technology Data Exchange (ETDEWEB)

Forest, F.

1981-01-01

The current economic and food situations of the African countries located in the semi-arid zones are introduced. The case of the region north of Maradi, Niger, is taken as an example of the ecological use of a rural environment. The results of the experimental unit at Thysse Kaynor Sonkorong, Senegambia, are examined with regard to the energy balance of the rural eco-system. The use of technologies for biomass production to develop small irrigated fields is examined.

Tropical Agro-Sciences

International Nuclear Information System (INIS)

Anon.

1977-01-01

The Tropical Agro-Sciences Division has two functions: conduct research on the impact of air pollution on tropical agricultural and to provide training to UPR graduate students and visiting scientists. Since the reorientation of the Center's interests under ERDA, the Division has directed its research activities, with particular emphasis on the effects of atmospheric pollution on tropical agriculture in the Guayanilla-Penuelas region, which has a fossil-fuel power plant, petroleum refineries, and associated industries. This new area of research is important to ERDA because the knowledge gained regarding the effects of air pollution related to energy technology on the agricultural environment and productivity will be useful in planning future energy developments. Information about the potential harm of air pollutants to man through the food chain and about ways of alleviating their impact on agriculture are of practical importance. Studies of the mechanisms involved in pollution injury, protection, and tolerance are of basic significance

Landsat Pathfinder tropical forest information management system

Science.gov (United States)

Salas, W.; Chomentowski, W.; Harville, J.; Skole, D.; Vellekamp, K.

1994-01-01

A Tropical Forest Information Management System_(TFIMS) has been designed to fulfill the needs of HTFIP in such a way that it tracks all aspects of the generation and analysis of the raw satellite data and the derived deforestation dataset. The system is broken down into four components: satellite image selection, processing, data management and archive management. However, as we began to think of how the TFIMS could also be used to make the data readily accessible to all user communities we realized that the initial system was too project oriented and could only be accessed locally. The new system needed development in the areas of data ingest and storage, while at the same time being implemented on a server environment with a network interface accessible via Internet. This paper summarizes the overall design of the existing prototype (version 0) information management system and then presents the design of the new system (version 1). The development of version 1 of the TFIMS is ongoing. There are no current plans for a gradual transition from version 0 to version 1 because the significant changes are in how the data within the HTFIP will be made accessible to the extended community of scientists, policy makers, educators, and students and not in the functionality of the basic system.

Neutron activation analysis of zinc in forages used in intensive dairy cattle production systems

International Nuclear Information System (INIS)

Armelin, M.J.A.; Piasentin, R.M.; Primavesi, O.

2002-01-01

Instrumental neutron activation analysis (INAA) was applied for the determination of Zn concentration in the main tropical grass forages used in intensive dairy cattle production systems, in Brazil. Smaller Zn concentration could be verified in the rainy period. Comparison of results obtained in these analyses of forages dry matter with daily requirements pointed towards deficiency of Zn in the forages. (author)

[Nutrition value of tropical and subtropical fruits].

Science.gov (United States)

Dubtsov, G G; Bessonov, V V; Baĭkov, V G; Makhova, N N; Sheviakova, L V; Bogachuk, M N; Baĭgarin, E K; Iao Bru, Lazar

2013-01-01

The article is devoted to the study of the chemical composition of tropical and subtropical fruit (avocado, papaya and mango), which are now in great numbers are on the appeared on the Russian market. Due to use technology tropical and subtropical fruits can be implemented in almost all areas and regions of the country. Relatively low cost makes these products quite popular among the people. In domestic scientific literature there are no systematic data describing the chemical composition of these tropical and subtropical fruits sold in the domestic market, while the information needed to calculate food and energy value of diets and culinary products derived from tropical and subtropical fruit. Avocado fruits are sources of insoluble dietary fiber content of which was equal to 12.2%, as well as minerals. The study of the fatty acid composition of lipids avocados showed high content of oleic acid fruit, which accounts for 53.2% of total fatty acids in these fruits. Which makes them a valuable source of unsaturated fatty acids.

Persea schiedeana: A High Oil “Cinderella Species” Fruit with Potential for Tropical Agroforestry Systems

Directory of Open Access Journals (Sweden)

Jay Bost

2013-12-01

Full Text Available Persea schiedeana, a close relative of avocado (Persea americana, is an important part of agroforestry systems and diets in parts of Mesoamerica, particularly in the coffee growing areas of southeastern Mexico and Guatemala, where it is known as chinene, coyo, and yas. Little research attention has been given to this species, other than as a rootstock for avocado. Research carried out in six villages composing the Comité de Recursos Naturales de la Chinantla Alta (CORENCHI in Oaxaca, Mexico shows that Persea schiedeana has potential as a supplement to avocado production in subsistence systems and as a potential oil crop in more market oriented agroforestry systems. This survey of Persea schiedeana in the Chinantla area reports on the ethnoecology and management of chinene, as well as on the morphological diversity of the fruit in the area. High morphological diversity for fruit characters was noted and it is suggested that artificial selection has occurred and been modestly successful for desired fruit characters. Superior fruiting trees, identified during village level “chinene fairs” were targeted for vegetative propagation as part of a participatory domestication project. Such superior genotypes hold potential for addressing food security and creating marketable products in tropical areas around the globe.

BubbleZERO—Design, Construction and Operation of a Transportable Research Laboratory for Low Exergy Building System Evaluation in the Tropics

Directory of Open Access Journals (Sweden)

Arno Schlueter

2013-09-01

Full Text Available We present the design, construction and operation of a novel building systems laboratory, the BubbleZERO—Zero Emission Research Operation. Our objective was to design a space to evaluate the performance of Swiss-developed low exergy building systems in the tropical climate of Singapore using an integrated design approach. The method we employed for evaluation in the tropics was to design and build a test bed out of the shipping containers that transported the prototype low exergy systems from Switzerland to Singapore. This approach resulted in a novel laboratory environment containing radiant cooling panels and decentralized air supply, along with a self-shading, inflated “bubble” skin, experimental low emissivity (LowE glazing, LED lighting, wireless sensors and distributed control. The laboratory evaluates and demonstrates for the first time in Singapore an integrated high-temperature cooling system with separate demand-controlled ventilation adapted for the tropics. It is a functional lab testing system in real tropical conditions. As such, the results showing the ability to mitigate the risk of condensation by maintaining a dew point below 18 °C by the separate decentralized ventilation are significant and necessary for potential future implementation in buildings. In addition, the control system provides new proof of concept for distributed wireless sensors and control for reliable automation of the systems. These key results are presented along with the integrated design process and real-life tropical operation of the laboratory.

Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests

NARCIS (Netherlands)

Wagner, Fabien H.; Hérault, Bruno; Bonal, Damien; Stahl, Clément; Anderson, Liana O.; Baker, Timothy R.; Becker, Gabriel Sebastian; Beeckman, Hans; Boanerges Souza, Danilo; Botosso, Paulo Cesar; Bowman, David M.J.S.; Bräuning, Achim; Brede, Benjamin; Brown, Foster Irving; Camarero, Jesus Julio; Camargo, Plínio Barbosa; Cardoso, Fernanda C.G.; Carvalho, Fabrício Alvim; Castro, Wendeson; Chagas, Rubens Koloski; Chave, Jérome; Chidumayo, Emmanuel N.; Clark, Deborah A.; Costa, Flavia Regina Capellotto; Couralet, Camille; Silva Mauricio, Da Paulo Henrique; Dalitz, Helmut; Castro, De Vinicius Resende; Freitas Milani, De Jaçanan Eloisa; Oliveira, De Edilson Consuelo; Souza Arruda, De Luciano; Devineau, Jean-Louis; Drew, David M.; Dünisch, Oliver; Durigan, Giselda; Elifuraha, Elisha; Fedele, Marcio; Ferreira Fedele, Ligia; Figueiredo Filho, Afonso; Finger, César Augusto Guimarães; Franco, Augusto César; Freitas Júnior, João Lima; Galvão, Franklin; Gebrekirstos, Aster; Gliniars, Robert; Lima De Alencastro Graça, Paulo Maurício; Griffiths, Anthony D.; Grogan, James; Guan, Kaiyu; Homeier, Jürgen; Kanieski, Maria Raquel; Kho, Lip Khoon; Koenig, Jennifer; Kohler, Sintia Valerio; Krepkowski, Julia; Lemos-filho, José Pires; Lieberman, Diana; Lieberman, Milton Eugene; Lisi, Claudio Sergio; Longhi Santos, Tomaz; López Ayala, José Luis; Maeda, Eduardo Eijji; Malhi, Yadvinder; Maria, Vivian R.B.; Marques, Marcia C.M.; Marques, Renato; Maza Chamba, Hector; Mbwambo, Lawrence; Melgaço, Karina Liana Lisboa; Mendivelso, Hooz Angela; Murphy, Brett P.; O'Brien, Joseph J.; Oberbauer, Steven F.; Okada, Naoki; Pélissier, Raphaël; Prior, Lynda D.; Roig, Fidel Alejandro; Ross, Michael; Rossatto, Davi Rodrigo; Rossi, Vivien; Rowland, Lucy; Rutishauser, Ervan; Santana, Hellen; Schulze, Mark; Selhorst, Diogo; Silva, Williamar Rodrigues; Silveira, Marcos; Spannl, Susanne; Swaine, Michael D.; Toledo, José Julio; Toledo, Marcos Miranda; Toledo, Marisol; Toma, Takeshi; Tomazello Filho, Mario; Valdez Hernández, Juan Ignacio; Verbesselt, Jan; Vieira, Simone Aparecida; Vincent, Grégoire; Volkmer De Castilho, Carolina; Volland, Franziska; Worbes, Martin; Zanon, Magda Lea Bolzan; Aragão, Luiz E.O.C.

2016-01-01

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68

Energy and cost associated with ventilating office buildings in a tropical climate.

Science.gov (United States)

Rim, Donghyun; Schiavon, Stefano; Nazaroff, William W

2015-01-01

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This study evaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the following factors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor air temperature and humidity, air conditioning system coefficient of performance (COP), and cost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore's tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment. Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore's. This result implies that the benefits of increasing outdoor air ventilation rate up to 25 L/s per person--which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave--can be much larger than the incremental cost of ventilation.

Carbon budget of leaves of the tropical intertidal seagrass Thalassia hemprichii

Science.gov (United States)

Chiu, Shih-Han; Huang, Yen-Hsun; Lin, Hsing-Juh

2013-07-01

The question of whether seagrass beds are effective carbon sinks has recently attracted much attention. Leaf production and consumption, and detrital export and decomposition were determined to quantify the carbon budget of leaf production in a southern Taiwan seagrass bed composed of the tropical intertidal seagrass Thalassia hemprichii, which is widely distributed in intertidal zones of the western Pacific. The influence of elevation in the intertidal zone on these processes was also investigated. Leaf production and consumption, and export of leaf detritus showed seasonal variations, with higher rates in the wet season (summer and autumn) and lower rates in the dry season (winter and spring). At the high-elevation site, leaf consumption by fish was significantly higher than that by sea urchins. At the low-elevation site, however, the proportion of leaves consumed by sea urchins was equivalent to that by fish. Leaf detritus decomposed rapidly within the first 9 days, then gradually slowed down, and stabilised after 212 days, at which only 8.7% of dry weight remained in the litterbags. The carbon budget of seagrass leaves demonstrated that 20% of leaf production was grazed by fish and sea urchins and 80% flowed to detritus. This suggests that seagrass leaves are important food sources for inhabiting herbivores. Most of the detritus decomposed (44% of leaf production) or was exported (32% of leaf production), and only 4% of leaf production or 22 g C m-2 yr-1 was stored in this tropical intertidal seagrass bed. Mass balance calculations support this tropical seagrass bed acting as a carbon sink and an outwelling system which exports organic detritus to neighboring coral reefs.

Contribution of landfalling tropical system rainfall to the hydroclimate of the eastern U.S. Corn Belt 1981–2012

Directory of Open Access Journals (Sweden)

Olivia Kellner

2016-09-01

Landfalling tropical system rainfall accounts for approximately 20% of the observed monthly rainfall during the tropical storm season (June–November across the eastern U.S. Corn Belt (1981–2012. Correlation between the annual number of landfalling tropical systems and annual yield by state results in no relationship, but correlation of August monthly observed rainfall by climate division to crop reporting district annual yields has a weak to moderate, statistically significant correlation in Ohio districts 30–60 and Indiana CRD 90. ANOVA analysis suggests that landfalling tropical rainfall may actually reduce yields in some state's climate divisions/crop reporting districts while increasing yield in others. Results suggest that there is a balance between landfalling tropical storms providing sufficient rainfall or too much rainfall to be of benefit to crops. Findings aim to provide information to producers, crop advisers, risk managers and commodity groups so that seasonal hurricane forecasts can potentially be utilized in planning for above or below normal precipitation during phenologically important portions of the growing season.

Relationships between the Tropical Pacific and the Southern California Current productivity at different timescales

Science.gov (United States)

Abella-Gutiérrez, J. L.; Herguera, J. C.

2016-02-01

The influence of Tropical Pacific in climate during the Common Era has been largely debated due to the lack of agreement between proxies. Some records suggest a La Niña-like conditions during the Medieval Climate Anomaly (MCA) and El Niño-like conditions during the Little Ice Age (LIA) (i.e. Graham et al., 2007), but other records suggest the contrary (i.e. Conroy et al., 2008). Here we present a 2.3Ky biogenic based record from San Lázaro Basin that, in its different modes of variability, contains both visions. Furthermore, these proxies share a centennial mode of variability that dominates the last millennium and connects the Indo-Pacific Warm Pool (IPWP) with the Western North America Drought Area Index (WNA-DAI) through variations in the thermocline.San Lázaro Basin (SLB) is a suboxic basin located in the southern dynamic boundary of the California Current System (CCS). During La Niña-like conditions, the intensification of the trade winds increase the Ekman transport and the invasion of subartic waters, with the result of a shoaled thermocline and enhanced ecosystem productivity. When the winds relax, El Niño-like conditions became, and the intrusion of warm stratified water from the tropical and subtropical regions plummeted the productivity and a coccolitophorid based ecosystem dominates. The opposite relation between Carbonates and Total Organic Carbon (TOC) in SLB sediments confirms this observations. A significant positive correlation between XRF measurements of Br/Si with TOC and Ca counts with Carbonates, allows us to study SCC variability from interannual to centennial resolution.The Spectral Analysis of Br/Si and Carbonates show a common 110y cycle that is also present in the IPWP and WNA-DAI with a ENSO-like pattern. This centennial mode is excited by warm Equatorial Pacific conditions as its variance is correlated with Galapagos precipitation record. Although Galapagos precipitation record has been related with ENSO intensity, the Br

Expounding the Value of Grain Legumes in the Semi- and Arid Tropics

Directory of Open Access Journals (Sweden)

Tendai P. Chibarabada

2017-01-01

Full Text Available Approximately 70% of the population in the semi- and arid tropics reside in rural areas and depend on agriculture for their livelihood. Crop production is primarily focused on a few starchy staple crops. While this can ensure adequate calories, it inadvertently neglects the need for dietary diversity. Consequently, food and nutritional insecurity remains prevalent in the semi- and arid tropics. We reviewed the legume value chain with the aim to identify opportunities and challenges to unlocking their value and promoting them in the tropics. Several grain legumes are rich in proteins and micronutrients. They also possess adaptability to marginal environmental conditions such as drought and low input systems which typify rural landscapes. Adaptability to abiotic stresses such as drought makes them key to agriculture in areas that will receive less rainfall in the future. However, this potential was currently not being realized due to a range of challenges. Aspects related to their seed systems, production, post-harvest handling and marketing remain relatively under-researched. This was especially true for minor legumes. There is a need for trans-disciplinary research which will address the entire value chain, as has been done for major starchy crops. This could also unlock significant economic opportunities for marginalized groups such as women. This will unlock their value and allow them to contribute meaningfully to food and nutrition security as well as sustainable and resilient cropping systems.

Dairy goat production systems: status quo, perspectives and challenges.

Science.gov (United States)

Escareño, Luis; Salinas-Gonzalez, Homero; Wurzinger, Maria; Iñiguez, Luiz; Sölkner, Johann; Meza-Herrera, Cesar

2013-01-01

Goat production concentrated in developing countries (tropics, dry areas), contributes largely to the livelihoods of low and medium income farmers. Farming systems in these areas have evolved to cope with the formidable constraints imposed by harsh natural and economic conditions by adapting integrated crop/livestock production strategies. In Asia, Africa and Latin America, due to its almost exclusive extensive nature, goat production relies mainly on grazing on communal lands that hardly provide the minimum nutrient requirements due to overstocking and degradation. While some of these production systems are becoming semi-intensive, appropriate breeding strategies should be designed to promote conservation and improvement of their unique attributes, such as adaptability, water use efficiency and suitability under harsh climatic conditions. In Europe, dairy goat production is more common around the Mediterranean basin, where it is important from an economic, environmental and sociological perspective to the Mediterranean countries: Spain, France, Italy and Greece. Europe owns only 5.1 % of the world's dairy goat herds, but produces 15.6 % of the world's goat milk; this is the only continent where goat milk has such an economic importance and organization. In developing countries the dairy goat sector requires a systemic approach, whereby nutrition, animal health, breeding, know-how, inputs and technologies must be assembled. This would allow the optimization of natural and local resources and would promote the transition from a risk reduction strategy towards an increased productivity strategy. Such an increase would privilege production efficiency based on clean, green and ethical practices for responsible innovation.

Sensitivity of tropical climate to low-level clouds in the NCEP climate forecast system

Energy Technology Data Exchange (ETDEWEB)

Hu, Zeng-Zhen [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); NCEP/NWS/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Huang, Bohua; Schneider, Edwin K. [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); George Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Hou, Yu-Tai; Yang, Fanglin [NCEP/NWS/NOAA, Environmental Modeling Center, Camp Springs, MD (United States); Wang, Wanqiu [NCEP/NWS/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Stan, Cristiana [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States)

2011-05-15

In this work, we examine the sensitivity of tropical mean climate and seasonal cycle to low clouds and cloud liquid water path (CLWP) by prescribing them in the NCEP climate forecast system (CFS). It is found that the change of low cloud cover alone has a minor influence on the amount of net shortwave radiation reaching the surface and on the warm biases in the southeastern Atlantic. In experiments where CLWP is prescribed using observations, the mean climate in the tropics is improved significantly, implying that shortwave radiation absorption by CLWP is mainly responsible for reducing the excessive surface net shortwave radiation over the southern oceans in the CFS. Corresponding to large CLWP values in the southeastern oceans, the model generates large low cloud amounts. That results in a reduction of net shortwave radiation at the ocean surface and the warm biases in the sea surface temperature in the southeastern oceans. Meanwhile, the cold tongue and associated surface wind stress in the eastern oceans become stronger and more realistic. As a consequence of the overall improvement of the tropical mean climate, the seasonal cycle in the tropical Atlantic is also improved. Based on the results from these sensitivity experiments, we propose a model bias correction approach, in which CLWP is prescribed only in the southeastern Atlantic by using observed annual mean climatology of CLWP. It is shown that the warm biases in the southeastern Atlantic are largely eliminated, and the seasonal cycle in the tropical Atlantic Ocean is significantly improved. Prescribing CLWP in the CFS is then an effective interim technique to reduce model biases and to improve the simulation of seasonal cycle in the tropics. (orig.)

Performance of a 34 kWp grid-connected PV system in Indonesia - A comparison of tropical and European PV systems

NARCIS (Netherlands)

Veldhuis, A.J.; Reinders, Angelina H.M.E.

2014-01-01

We analysed a monitored grid-connected PV system of 34 kWp in Indonesia to investigate the performance of PV systems in tropical climates. The PV system has been installed in Jayapura, the capital of the Province of Papua, Indonesia, by the beginning of 2012. Due to the aged gensets and frequent

Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

Directory of Open Access Journals (Sweden)

Maxine A.D. Mowe

2014-12-01

Full Text Available Toxic cyanobacterial blooms are a major issue in freshwater systems in many countries. The potentially toxic species and their ecological causes are likely to be different in tropical zones from those in temperate water bodies; however, studies on tropical toxic cyanobacterial blooms are sporadic and currently there is no global synthesis. In this review, we examined published information on tropical cyanobacterial bloom occurrence and toxin production to investigate patterns in their growth and distribution. Microcystis was the most frequently occurring bloom genus throughout tropical Asia, Africa and Central America, while Cylindrospermopsis and Anabaena blooms occurred in various locations in tropical Australia, America and Africa. Microcystis blooms were more prevalent during the wet season while Cylindrospermopsis blooms were more prevalent during the dry period. Microcystin was the most encountered toxin throughout the tropics. A meta-analysis of tropical cyanobacterial blooms showed that Microcystis blooms were more associated with higher total nitrogen concentrations, while Cylindrospermopsis blooms were more associated with higher maximum temperatures. Meta-analysis also showed a positive linear relationship between levels of microcystin and N:P (nitrate:phosphate ratio. Tropical African Microcystis blooms were found to have the lowest microcystin levels in relation to biomass and N:P (nitrate:phosphate compared to tropical Asian, Australian and American blooms. There was also no significant correlation between microcystin concentration and cell concentration for tropical African blooms as opposed to tropical Asian and American blooms. Our review illustrates that some cyanobacteria and toxins are more prevalent in tropical areas. While some tropical countries have considerable information regarding toxic blooms, others have few or no reported studies. 

Improving yield and nitrogen fixation of grain legumes in the tropics and sub-tropics of Asia. Results of a co-ordinated research programme

International Nuclear Information System (INIS)

1998-07-01

The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture initiated a Co-ordinated Research Project on The Use of Isotopes in Studies to Improve Yield and N 2 Fixation of Grain Legumes with the Aim of Increasing Food Production and Saving N-fertilizer in the Tropics and Sub-Tropics of Asia that was operational from 1990 to 1995. This Project was underpinned by extensive experience in the use of 15 N-labelled fertilizer in quantifying N 2 fixation by food and pasture legumes; the isotope-dilution technique, recognized as the most accurate mode of quantifying fixation, was developed at the IAEA and has been used profitably for over 20 years in co-ordinated research projects that were focused on aspects relevant to the sustainability of agriculture in developing countries in which food security is most under threat. This effort to improve N 2 fixation by food legumes in Asia, and in so doing to increase productivity of cereal-based farming systems as a whole, was timely in terms of regional needs. It was complemented by an overlapping Co-ordinated Research Project entitled ''The Use of Nuclear and Related Techniques in Management of Nitrogen Fixation by trees for Enhancing Soil Fertility and Soil Conservation in Fragile Tropical Soils''. The project involved scientists from Australia, Bangladesh, China, India, Malaysia, Pakistan the Philippines, Sri Lanka, Thailand and Viet Nam

Tropical Pacific Observing for the Next Decade

Science.gov (United States)

Legler, David M.; Hill, Katherine

2014-06-01

More than 60 scientists and program officials from 13 countries met at the Scripps Institution of Oceanography for the Tropical Pacific Observing System (TPOS) 2020 Workshop. The workshop, although motivated in part by the dramatic decline of NOAA's Tropical Atmosphere Ocean (TAO) buoy reporting from mid-2012 to early 2014 (see http://www.bloomberg.com/news/2014-03-07/aging-el-nino-buoys-getting-fixed-as-weather-forecasts-at-risk.html), evaluated the needs for tropical Pacific observing and initiated efforts to develop a more resilient and integrative observing system for the future.

Estimates of Crossbreeding Parameters for Defining Optimal Crossbreeding Systems for the Coastal Lowland Tropics

International Nuclear Information System (INIS)

Kahi, A.K.; Thorpe, W.

1999-01-01

An individual animal model was fitted to data from crossbred herd in the lowland coastal tropics of Kenya to estimate breed cross means for a total of 25 genotypes having different proportions of Ayrshire (A), Brown swiss (B), Friesian (F) and Sahiwal (S) genes. These means were then regressed on gene proportion of breeds and on the coefficients of heterosis and recombination loss. Per lactation, the S contributed 1802 kg and 18.4 kg less milk and milk per unit of metabolic weight (MW), respectively, than the F. The performance of A and B were intermediate. The contribution of the F breed for most traits was superior to that of the other Bos taurus breeds. the heterosis effect between B and S was large for lactation milk yield (MY) (296 kg) and calving interval (CL) (-36 days). The heterosis between A and B for most traits was small, which is consistent with other studies in the literature. The estimates of recombination loss were negative in crosses A * B and B * S for MY,daily milk yield (DMY) and MY expressed per unit MW. Modelling of alternative crossbreeding strategy should be considered in relation to the ecological and socio-economic characteristics of the target production systems, which vary markedly. Therefore, the generalisation that the first cross (F 1 ) is best suited for dairying in the tropics could be misleading, and there is the need to evaluate the potential of synthetic breeds

Management of whitefly-transmitted viruses in open-field production systems

Science.gov (United States)

Whiteflies are a key pest of crops in open field production throughout the tropics and subtropics. This is due in large part to the long and diverse list of devastating plant viruses transmitted by these vectors. Open field production provides many challenges to manage these viruses and in many case...

Climate Prediction Center(CPC)Global Tropics Hazards and Benefits Assessment

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Global Tropics Hazards and Benefits Assessment (GTH) is an outlook product for the areas in the Tropics. Forecasts for the Week-1 and Week-2 period are given for...

Unprecedented drought over tropical South America in 2016: significantly under-predicted by tropical SST.

Science.gov (United States)

Erfanian, Amir; Wang, Guiling; Fomenko, Lori

2017-07-19

Tropical and sub-tropical South America are highly susceptible to extreme droughts. Recent events include two droughts (2005 and 2010) exceeding the 100-year return value in the Amazon and recurrent extreme droughts in the Nordeste region, with profound eco-hydrological and socioeconomic impacts. In 2015-2016, both regions were hit by another drought. Here, we show that the severity of the 2015-2016 drought ("2016 drought" hereafter) is unprecedented based on multiple precipitation products (since 1900), satellite-derived data on terrestrial water storage (since 2002) and two vegetation indices (since 2004). The ecohydrological consequences from the 2016 drought are more severe and extensive than the 2005 and 2010 droughts. Empirical relationships between rainfall and sea surface temperatures (SSTs) over the tropical Pacific and Atlantic are used to assess the role of tropical oceanic variability in the observed precipitation anomalies. Our results indicate that warmer-than-usual SSTs in the Tropical Pacific (including El Niño events) and Atlantic were the main drivers of extreme droughts in South America, but are unable to explain the severity of the 2016 observed rainfall deficits for a substantial portion of the Amazonia and Nordeste regions. This strongly suggests potential contribution of non-oceanic factors (e.g., land cover change and CO2-induced warming) to the 2016 drought.

Design of Tropical Flowers Environmental Parameters Wireless Monitoring System Based on MSP430

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Huang Jian-Qing

2016-01-01

Full Text Available Considering the importance of real-time monitoring tropical flower environment parameters, the paper designs a wireless monitoring system based on MSP430F149 for tropical flower growing parameters. The proposed system uses sensor nodes to obtain data of temperature, humidity and light intensity, sink node to collect data from sensor nodes through wireless sensor network, and monitoring center to process data downloaded from the sink node through RS232 serial port. The node hardware platform is composed of a MSP430F149 processor, AM2306 and NHZD10AI sensors used to adopt temperature, humidity and light intensity data, and an nRF905 RF chip used to receive and send data. The node software, operated in IAR Embedded Workbench, adopts C Language to do node data collection and process, wireless transmission and serial port communication. The software of monitoring center develops in VB6.0, which can provide vivid and explicit real-time monitoring platform for flower farmers.

Nitrous oxide production by nitrification and denitrification in the Eastern Tropical South Pacific oxygen minimum zone

Science.gov (United States)

Ji, Qixing; Babbin, Andrew R.; Jayakumar, Amal; Oleynik, Sergey; Ward, Bess B.

2015-12-01

The Eastern Tropical South Pacific oxygen minimum zone (ETSP-OMZ) is a site of intense nitrous oxide (N2O) flux to the atmosphere. This flux results from production of N2O by nitrification and denitrification, but the contribution of the two processes is unknown. The rates of these pathways and their distributions were measured directly using 15N tracers. The highest N2O production rates occurred at the depth of peak N2O concentrations at the oxic-anoxic interface above the oxygen deficient zone (ODZ) because slightly oxygenated waters allowed (1) N2O production from both nitrification and denitrification and (2) higher nitrous oxide production yields from nitrification. Within the ODZ proper (i.e., anoxia), the only source of N2O was denitrification (i.e., nitrite and nitrate reduction), the rates of which were reflected in the abundance of nirS genes (encoding nitrite reductase). Overall, denitrification was the dominant pathway contributing the N2O production in the ETSP-OMZ.

An Ocean Biology-induced Negative Feedback on ENSO in the Tropical Pacific Climate System

Science.gov (United States)

Zhang, R. H.

2016-02-01

Biological conditions in the tropical Pacific Ocean (e.g., phytoplankton biomass) are strongly regulated by physical changes associated with the El Niño-Southern Oscillation (ENSO). The existence and variation of phytoplankton biomass, in turn, act to modulate the vertical penetration of the incoming sunlight in the upper ocean, presenting an ocean biology-induced heating (OBH) effect on the climate system. Previously, a penetration depth of solar radiation in the upper ocean (Hp) is defined to describe the related bio-climate connections. Parameterized in terms of its relationship with the sea surface temperature (SST) in the tropical Pacific, an empirical model for interannual Hp variability has been derived from remotely sensed ocean color data, which is incorporated into a hybrid coupled model (HCM) to represent OBH effects. In this paper, various HCM experiments are performed to demonstrate the bio-feedback onto ENSO, including a climatological Hp run (in which Hp is prescribed as seasonally varying only), interannual Hp runs (with different intensities of interannually varying OBH effects), and a run in which the sign of the OBH effect is artificially reversed. Significant modulating impacts on interannual variability are found in the HCM, characterized by a negative feedback between ocean biology and the climate system in the tropical Pacific: the stronger the OBH feedback, the weaker the interannual variability. Processes involved in the feedback are analyzed; it is illustrated that the SST is modulated indirectly by ocean dynamical processes induced by OBH. The significance and implication of the OBH effects are discussed for their roles in ENSO variability and model biases in the tropical Pacific.

Tropical Glaciers

Science.gov (United States)

Fountain, Andrew

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

Mediterranean climate and some tropical teleconnections

International Nuclear Information System (INIS)

Alpert, P.; Price, C.; Krichak, S.; Saaroni, H.; Osetinsky, I.; Barkan, J.; Kishcha, P.; Ziv, B.

2006-01-01

Some strong natural fluctuations of climate in the Eastern Mediterranean (EM) region are shown to be connected to the major tropical systems, e.g., El Ni no Southern Oscillation, South Asian Monsoon and hurricanes. Modelling of the severe floods suggests a relation to tropical hurricanes. For a specific event, high-resolution modelling of the severe flood on December 3-5, 2001 in Israel suggests a relation to hurricane Olga. In order to understand the factors governing the Eastern Mediterranean climate variability in the summer season, the relationship between extreme summer temperatures and the South Asian Monsoon was examined. Other tropical factors, like the Red Sea Trough system and the Saharan dust, also contribute to the Mediterranean climate variability

Ozone phytotoxicity evaluation and prediction of crops production in tropical regions

Science.gov (United States)

Mohammed, Nurul Izma; Ramli, Nor Azam; Yahya, Ahmad Shukri

2013-04-01

Increasing ozone concentration in the atmosphere can threaten food security due to its effects on crop production. Since the 1980s, ozone has been believed to be the most damaging air pollutant to crops. In Malaysia, there is no index to indicate the reduction of crops due to the exposure of ozone. Therefore, this study aimed to identify the accumulated exposure over a threshold of X ppb (AOTX) indexes in assessing crop reduction in Malaysia. In European countries, crop response to ozone exposure is mostly expressed as AOT40. This study was designed to evaluate and predict crop reduction in tropical regions and in particular, the Malaysian climate, by adopting the AOT40 index method and modifying it based on Malaysian air quality and crop data. Nine AOTX indexes (AOT0, AOT5, AOT10, AOT15, AOT20, AOT25, AOT30, AOT40, and AOT50) were analyzed, crop responses tested and reduction in crops predicted. The results showed that the AOT50 resulted in the highest reduction in crops and the highest R2 value between the AOT50 and the crops reduction from the linear regression analysis. Hence, this study suggests that the AOT50 index is the most suitable index to estimate the potential ozone impact on crops in tropical regions. The result showed that the critical level for AOT50 index if the estimated crop reduction is 5% was 1336 ppb h. Additionally, the results indicated that the AOT40 index in Malaysia gave a minimum percentage of 6% crop reduction; as contrasted with the European guideline of 5% (due to differences in the climate e.g., average amount of sunshine).

Life Cycle and Secondary Production of Four Species from Functional Feeding Groups in a Tropical Stream of South India

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Sankarappan Anbalagan

2014-01-01

Full Text Available This study focused on life strategies of species from functional feeding groups (FFGs found in a tropical stream of the Sirumalai hills, South India. We examined the life cycle and secondary production of species of shredders (Lepidostoma nuburagangai, scrapers (Baetis sp., collectors (Choroterpes alagarensis, and predators (Neoperla biseriata. In addition, we studied the assemblage structure of functional feeding groups. We found the collectors occupied the highest percentage, followed in turn by scrapers, predators, and shredders. The diversity of FFGs was higher at riffle areas and assemblage with stream substrates differing in each functional group. An asynchronous life cycle was observed for Baetis, C. alagarensis, and N. biseriata, while L. nuburagangai was found in four to five generations per year. We acquired data on secondary production of scraper species of Baetis, which reached the highest values among all investigated species. This observation stresses the importance of scrapers as playing a key role in converting coarse particulate organic matter to fine particulate organic matter with low or high abundances of shredder population and maintaining the food chain in tropical streams.

The Next-Generation Goddard Convective-Stratiform Heating Algorithm: New Retrievals for Tropical and Extra-tropical Environments

Science.gov (United States)

Lang, S. E.; Tao, W. K.; Iguchi, T.

2017-12-01

The Goddard Convective-Stratiform Heating (or CSH) algorithm has been used to estimate cloud heating over the global Tropics using TRMM rainfall data and a set of look-up-tables (LUTs) derived from a series of multi-week cloud-resolving model (CRM) simulations using the Goddard Cumulus Ensemble model (GCE). These simulations link satellite observables (i.e., surface rainfall and stratiform fraction) with cloud heating profiles, which are not directly observable. However, with the launch of GPM in 2014, the range over which such algorithms can be applied has been extended from the Tropics into higher latitudes, including cold season and synoptic weather systems. In response, the CSH algorithm and its LUTs have been revised both to improve the retrievals in the Tropics as well as expand retrievals to higher latitudes. For the Tropics, the GCE simulations used to build the LUTs were upgraded using larger 2D model domains (512 vs 256 km) and a new, improved Goddard 4-ice scheme as well as expanded with additional cases (4 land and 6 ocean in total). The new tropical LUTs are also re-built using additional metrics. Besides surface type, conditional rain intensity and stratiform fraction, the new LUTs incorporate echo top heights and low-level (0-2 km) vertical reflectivity gradients. CSH retrievals in the Tropics based on the new LUTs show significant differences from previous iterations using TRMM data or the old LUT metrics. For the Extra-tropics, 6 NU-WRF simulations of synoptic events (3 East Coast and 3 West Coast), including snow, were used to build new extra-tropical CSH LUTs. The LUT metrics for the extra-tropics are based on radar characteristics and freezing level height. The extra-tropical retrievals are evaluated with a self-consistency check approach using the model heating as `truth,' and freezing level height is used to transition CSH retrievals from the Tropics to Extra-tropics. Retrieved zonal average heating structures in the Extra-tropics are

Female fruit production depends on female flower production and crown size rather than male density in a continuous population of a tropical dioecious tree (Virola surinamensis).

Science.gov (United States)

Riba-Hernández, Pablo; Segura, Jorge Lobo; Muñoz-Valverde, Jenny

2016-11-01

Factors related to pollen and resource limitation were evaluated to predict female fruit production in a tropical dioecious tree. Pollen limitation via variation in the male density at local scales is expected to limit female reproduction success in dioecious plants. We modeled the roles of local male density, female crown size, crown illumination, and female flower production on female fruit initiation and mature fruit production in a continuous population (62 ha plot) of a tropical dioecious tree (Virola surinamensis). In addition, we used microsatellites to describe the scale of effective pollen flow, the male effective population size, and the spatial genetic structure within/between progenies and males. The local male density was not related to female fruit initiation or mature fruit production. Female floral production had a positive effect on fruit initiation. The female crown size was positively related to fruit maturation. Seeds from the same female and seeds from different but spatially proximal females were generally half-siblings; however, proximal females showed greater variation. Proximal male-female adult pairs were not significantly more genetically related than distant pairs. The probability of paternity was negatively affected by the distance between seeds and males; most effective pollen dispersal events (∼85%) occurred from males located less than 150 m from females. The number of males siring progenies was greater than the number of males found at local scales. Female fecundity in this continuous population of Virola surinamensis is not limited by the availability of pollen from proximal males. Rather, resource allocation to floral production may ultimately determine female reproductive success. © 2016 Botanical Society of America.

Indirect quantification of fine root production in a near tropical wet mountainous region

Science.gov (United States)

Lu, X.; Zhang, J.; Huang, C.

2016-12-01

The main functions of fine root (defined as diameter floristic) and external (environmental) factors into account, including litter production, canopy density (leaf area index), leaf nutrients (N, K, Ca, Mg, P), weather and/or soil physical conditions (air temperature, humidity, precipitation, solar radiation and soil moisture). The study was conducted in near tropical broadleaf (700 m asl) and conifer (1700 m asl) forests in northeastern Taiwan, generally receiving more than 4000 mm of precipitation per year. For each site, 16 50-cm long minirhizotron tubes were installed. Fine root images were acquired every three weeks. Growth and decline, newly presence and absence of fine roots were delineated by image processing algorithms to derive fine-root productivity through time. Aforementioned internal and external attributes were simultaneously collected as well. Some of these variables were highly correlated and were detrended using principal component analysis. We found that these transformed variables (mainly associated with litter production, precipitation and solar radiation) can delineate the spatiotemporal dynamics of root production well (r2 = 0.87, p = 0.443). In conclusion, this study demonstrated the feasibility of utilized aboveground variables to indirectly assess fine root growth, which could be further developed for the regional scale mapping with aid of remote sensing.

Bibliometry of Costa Rica biodiversity studies published in the Revista de Biología Tropical/International Journal of Tropical Biology and Conservation (2000-2010): the content and importance of a leading tropical biology journal in its 60th anniversary.

Science.gov (United States)

Nielsen-Muñoz, Vanessa; Azofeifa-Mora, Ana Beatriz; Monge-Nájera, Julián

2012-12-01

Central America is recognized as a mega diverse "hot-spot" and one of its smaller countries, Costa Rica, as one of the world's leaders in the study and conservation of tropical biodiversity. For this study, inspired by the 60th anniversary of the journal Revista de Biología Tropical, we tabulated all the scientific production on Costa Rican biodiversity published in Revista de Biología Tropical between 2000 and 2010. Most articles are zoological (62%) and 67% of authors had only one publication in the jounal within that period. A 54% of articles were published in English and 46% in Spanish. A 41% of articles were written in collaboration among Costa Rican institutions and 36% in collaboration with foreign institutions. The Collaboration Index was 2.53 signatures per article. Visibility in American sources was 56% in Google Scholar and 42.66% in the Web of Science, but the real visibility and impact are unknown because these sources exclude the majority of tropical journals. Revista de Biología Tropical is the main output channel for Costa Rican biology and despite its small size, Costa Rica occupies the 10th. place in productivity among Latin American countries, with productivity and impact levels that compare favorably with larger countries such as Brazil, Mexico, Argentina and Chile.

Warming Affects Growth Rates and Microcystin Production in Tropical Bloom-Forming Microcystis Strains

Directory of Open Access Journals (Sweden)

Trung Bui

2018-03-01

Full Text Available Warming climate is predicted to promote cyanobacterial blooms but the toxicity of cyanobacteria under global warming is less well studied. We tested the hypothesis that raising temperature may lead to increased growth rates but to decreased microcystin (MC production in tropical Microcystis strains. To this end, six Microcystis strains were isolated from different water bodies in Southern Vietnam. They were grown in triplicate at 27 °C (low, 31 °C (medium, 35 °C (high and 37 °C (extreme. Chlorophyll-a-, particle- and MC concentrations as well as dry-weights were determined. All strains yielded higher biomass in terms of chlorophyll-a concentration and dry-weight at 31 °C compared to 27 °C and then either stabilised, slightly increased or declined with higher temperature. Five strains easily grew at 37 °C but one could not survive at 37 °C. When temperature was increased from 27 °C to 37 °C total MC concentration decreased by 35% in strains with MC-LR as the dominant variant and by 94% in strains with MC-RR. MC quota expressed per particle, per unit chlorophyll-a and per unit dry-weight significantly declined with higher temperatures. This study shows that warming can prompt the growth of some tropical Microcystis strains but that these strains become less toxic.

Comparison of TOPEX/Poseidon Sea Level and Linear Model Results forced by Various Wind Products for the Tropical Pacific

Science.gov (United States)

Hackert, Eric C.; Busalacchi, Antonio J.

1997-01-01

The goal of this paper is to compare TOPEX/Posaidon (T/P) sea level with sea level results from linear ocean model experiments forced by several different wind products for the tropical Pacific. During the period of this study (October 1992 - October 1995), available wind products include satellite winds from the ERS-1 scatterometer product of [HALP 97] and the passive microwave analysis of SSMI winds produced using the variational analysis method (VAM) of [ATLA 91]. In addition, atmospheric GCM winds from the NCEP reanalysis [KALN 96], ECMWF analysis [ECMW94], and the Goddard EOS-1 (GEOS-1) reanalysis experiment [SCHU 93] are available for comparison. The observed ship wind analysis of FSU [STRI 92] is also included in this study. The linear model of [CANE 84] is used as a transfer function to test the quality of each of these wind products for the tropical Pacific. The various wind products are judged by comparing the wind-forced model sea level results against the T/P sea level anomalies. Correlation and RMS difference maps show how well each wind product does in reproducing the T/P sea level signal. These results are summarized in a table showing area average correlations and RMS differences. The large-scale low-frequency temporal signal is reproduced by all of the wind products, However, significant differences exist in both amplitude and phase on regional scales. In general, the model results forced by satellite winds do a better job reproducing the T/P signal (i.e. have a higher average correlation and lower RMS difference) than the results forced by atmospheric model winds.

The limited contribution of large trees to annual biomass production in an old-growth tropical forest.

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Ligot, Gauthier; Gourlet-Fleury, Sylvie; Ouédraogo, Dakis-Yaoba; Morin, Xavier; Bauwens, Sébastien; Baya, Fidele; Brostaux, Yves; Doucet, Jean-Louis; Fayolle, Adeline

2018-04-16

Although the importance of large trees regarding biodiversity and carbon stock in old-growth forests is undeniable, their annual contribution to biomass production and carbon uptake remains poorly studied at the stand level. To clarify the role of large trees in biomass production, we used data of tree growth, mortality, and recruitment monitored during 20 yr in 10 4-ha plots in a species-rich tropical forest (Central African Republic). Using a random block design, three different silvicultural treatments, control, logged, and logged + thinned, were applied in the 10 plots. Annual biomass gains and losses were analyzed in relation to the relative biomass abundance of large trees and by tree size classes using a spatial bootstrap procedure. Although large trees had high individual growth rates and constituted a substantial amount of biomass, stand-level biomass production decreased with the abundance of large trees in all treatments and plots. The contribution of large trees to annual stand-level biomass production appeared limited in comparison to that of small trees. This pattern did not only originate from differences in abundance of small vs. large trees or differences in initial biomass stocks among tree size classes, but also from a reduced relative growth rate of large trees and a relatively constant mortality rate among tree size classes. In a context in which large trees are increasingly gaining attention as being a valuable and a key structural characteristic of natural forests, the present study brought key insights to better gauge the relatively limited role of large trees in annual stand-level biomass production. In terms of carbon uptake, these results suggest, as already demonstrated, a low net carbon uptake of old-growth forests in comparison to that of logged forests. Tropical forests that reach a successional stage with relatively high density of large trees progressively cease to be carbon sinks as large trees contribute sparsely or even

Assessing the impact of rumen microbial communities on methane emissions and production traits in Holstein cows in a tropical climate.

Science.gov (United States)

Cunha, Camila S; Veloso, Cristina M; Marcondes, Marcos I; Mantovani, Hilario C; Tomich, Thierry R; Pereira, Luiz Gustavo R; Ferreira, Matheus F L; Dill-McFarland, Kimberly A; Suen, Garret

2017-12-01

The evaluation of how the gut microbiota affects both methane emissions and animal production is necessary in order to achieve methane mitigation without production losses. Toward this goal, the aim of this study was to correlate the rumen microbial communities (bacteria, archaea, and fungi) of high (HP), medium (MP), and low milk producing (LP), as well as dry (DC), Holstein dairy cows in an actual tropical production system with methane emissions and animal production traits. Overall, DC cows emitted more methane, followed by MP, HP and LP cows, although HP and LP cow emissions were similar. Using next-generation sequencing, it was found that bacteria affiliated with Christensenellaceae, Mogibacteriaceae, S24-7, Butyrivibrio, Schwartzia, and Treponema were negatively correlated with methane emissions and showed positive correlations with digestible dry matter intake (dDMI) and digestible organic matter intake (dOMI). Similar findings were observed for archaea in the genus Methanosphaera. The bacterial groups Coriobacteriaceae, RFP12, and Clostridium were negatively correlated with methane, but did not correlate with dDMI and dOMI. For anaerobic fungal communities, no significant correlations with methane or animal production traits were found. Based on these findings, it is suggested that manipulation of the abundances of these microbial taxa may be useful for modulating methane emissions without negatively affecting animal production. Copyright © 2017 Elsevier GmbH. All rights reserved.

An eddy-permitting, dynamically consistent adjoint-based assimilation system for the tropical Pacific: Hindcast experiments in 2000

KAUST Repository

Hoteit, Ibrahim; Cornuelle, B.; Heimbach, P.

2010-01-01

An eddy-permitting adjoint-based assimilation system has been implemented to estimate the state of the tropical Pacific Ocean. The system uses the Massachusetts Institute of Technology's general circulation model and its adjoint. The adjoint method

A comprehensive survey of fruit grading systems for tropical fruits of Maharashtra.

Science.gov (United States)

Khoje, Suchitra A; Bodhe, S K

2015-01-01

It is said that the backbone of Indian economy is agriculture. The contribution of the agriculture sector to the national GDP (Gross Domestic Products) was 14.6% in the year 2010. To attain a growth rate equivalent to that of industry (viz., about 9%), it is highly mandatory for Indian agriculture to modernize and use automation at various stages of cultivation and post-harvesting techniques. The use of computers in assessing the quality of fruits is one of the major activities in post-harvesting technology. As of now, this assessment is majorly done manually, except for a few fruits. Currently, the fruit quality assessment by machine vision in India is still at research level. Major research has been carried out in countries like China, Malaysia, UK, and Netherlands. To suit the Indian market and psychology of Indian farmers, it is necessary to develop indigenous technology. This paper is the first step toward evaluating the research carried out by the research community all over world for tropical fruits. For the purpose of survey, we have concentrated on the tropical fruits of the state of Maharashtra, while keeping in focus of the review image processing algorithms.

Emissions of biogenic volatile organic compounds and subsequent photochemical production of secondary organic aerosol in mesocosm studies of temperate and tropical plant species

Science.gov (United States)

Wyche, K. P.; Ryan, A. C.; Hewitt, C. N.; Alfarra, M. R.; McFiggans, G.; Carr, T.; Monks, P. S.; Smallbone, K. L.; Capes, G.; Hamilton, J. F.; Pugh, T. A. M.; MacKenzie, A. R.

2014-12-01

Silver birch (Betula pendula) and three Southeast Asian tropical plant species (Ficus cyathistipula, Ficus benjamina and Caryota millis) from the pantropical fig and palm genera were grown in a purpose-built and environment-controlled whole-tree chamber. The volatile organic compounds emitted from these trees were characterised and fed into a linked photochemical reaction chamber where they underwent photo-oxidation under a range of controlled conditions (relative humidity or RH ~65-89%, volatile organic compound-to-NOx or VOC / NOx ~3-9 and NOx ~2 ppbV). Both the gas phase and the aerosol phase of the reaction chamber were monitored in detail using a comprehensive suite of on-line and off-line chemical and physical measurement techniques. Silver birch was found to be a high monoterpene and sesquiterpene but low isoprene emitter, and its emissions were observed to produce measurable amounts of secondary organic aerosol (SOA) via both nucleation and condensation onto pre-existing seed aerosol (YSOA 26-39%). In contrast, all three tropical species were found to be high isoprene emitters with trace emissions of monoterpenes and sesquiterpenes. In tropical plant experiments without seed aerosol there was no measurable SOA nucleation, but aerosol mass was shown to increase when seed aerosol was present. Although principally isoprene emitting, the aerosol mass produced from tropical fig was mostly consistent (i.e. in 78 out of 120 aerosol mass calculations using plausible parameter sets of various precursor specific yields) with condensation of photo-oxidation products of the minor volatile organic compounds (VOCs) co-emitted; no significant aerosol yield from condensation of isoprene oxidation products was required in the interpretations of the experimental results. This finding is in line with previous reports of organic aerosol loadings consistent with production from minor biogenic VOCs co-emitted with isoprene in principally isoprene-emitting landscapes in Southeast

Strategies and perspectives of influential environmental organizations toward tropical deforestation

International Nuclear Information System (INIS)

Ozanne, L.K.; Smith, P.M.

1993-01-01

In recent years, environmental nongovernment organizations (NGOs) have been active in alerting the public and governments to tropical forest issues. Many feel that these efforts have begun to affect the trade in tropical timber and influence the perceptions of logging in the tropics. However, the influence of environmental organizations is not restricted to tropical timber trade but has the potential to impact the global wood products industry. The wood products industry has an opportunity to address these pressures by understanding the strategies and perceptions of the environmental community on this issue and developing proactive strategies to deal with the situation. This study included a phase 1 prestudy, which reported the results of interview with over 39 environmental NGOs in both the US and Europe to develop an overview of this complex industry. A phase 2 followup fax questionnaire was administered to the most relevant US environmental NGOs in order to classify them on two important criteria: (1) their level of specialization; and (2) their organizational strategy. This paper provides an overview of the complex issues in the environmental debate regarding tropical deforestation and how environmental organizations are attempting to address these issues

Lightning and 85-GHz MCSs in the Global Tropics

Science.gov (United States)

Toracinta, E. Richard; Zipser, E. J.

1999-01-01

Numerous observations of tropical convection show that tropical continental mesoscale convective systems (MCSs) are much more prolific lightning producers than their oceanic counterparts. Satellite-based climatologies using 85-GHz passive microwave ice-scattering signatures from the Special Sensor Microwave/Imager (SSM/I) indicate that MCSs of various size and intensity are found throughout the global tropics. In contrast, global lightning distributions show a strong land bias with an order of magnitude difference between land and ocean lightning. This is somewhat puzzling, since 85-GHz ice-scattering and the charge separation processes that lead to lightning are both thought to depend upon the existence of large graupel particles. The fact that low 85-GHz brightness temperatures are observed in tropical oceanic MCSs containing virtually no lightning leads to the postulate that tropical oceanic and tropical continental MCSs have fundamentally different hydrometeor profiles through the mixed phase region of the cloud (0 C Lightning Imaging Sensor (LIS), and the first space-borne radar, facilitates high-resolution case studies of MCS structure throughout the global tropics. An important precursor, however, is to better understand the distribution of MCSs and lightning in the tropics. With that objective in mind, this research undertakes a systematic comparison of 85-GHz-defined MCSs and lightning over the global tropics for a full year, as an initial step toward quantifying differences between land and ocean convective systems.

Physiological and production response of dairy goats bred in a tropical climate

Science.gov (United States)

de Souza, Priscila Teixeira; Salles, Maria Gorete Flores; da Costa, Antônio Nélson Lima; Carneiro, Hilton Alexandre Vidal; de Souza, Leonardo Peres; Rondina, Davide; de Araújo, Airton Alencar

2014-09-01

The aim of this work was to determine the adaptability of Saanen and ½Saanen × ½Anglo-Nubian (½S½AN) goats bred in tropical climates. The study included 30 goats, 15 Saanen and 15 ½S½AN. The data was collected during the rainy and dry seasons. During the whole experimental period, the environment variables were recorded, as well as rectal temperature (RT), superficial temperature (ST), respiratory rate (RR) and heart rate (HR) and milk production (MP). The adaptability coefficient (AC) was calculated for both genotypes. The averages were evaluated by ANOVA at 5 % probability. There was a genotype and period of year effect, as well as the interaction genotype × period of year. Pearson's simple correlation analysis was then carried out between milk production and physiological and environment variables. There was a statistical difference ( p goats, regardless of the season. MP was greater in the dry season ( p goats. Under the conditions of the present study, it is concluded that the goats were influenced by climatic factors, where the rainy period was more likely to cause thermal stress in the animals.

Tropical food chains: Governance regimes for quality management

NARCIS (Netherlands)

Ruben, R.; Boekel, van M.A.J.S.; Tilburg, van A.; Trienekens, J.H.

2007-01-01

International supply chains of vulnerable tropical food products face major problems in the fields of quality performance and coordination between supply chain partners. Degradation and variability of quality, segmentation of supply networks and scattered production by smallholder producers could

Long term hydrogen production potential of concentrated photovoltaic (CPV) system in tropical weather of Singapore

KAUST Repository

Burhan, Muhammad; Chua, Kian Jon Ernest; Ng, Kim Choon

2016-01-01

far, only conventional flat plate PV systems are being used for almost all of the commercial applications. However, most of the studies have only shown the maximum efficiency of hydrogen production using CPV. In actual field conditions, the performance

Determinants of scientific output: an in-depth view of the productivity of tropical botanist and conservationist, Luis Diego Gómez Pignataro

Directory of Open Access Journals (Sweden)

Julián Monge-Nájera

2010-12-01

Full Text Available Bibliometric studies have found that male researchers have their greatest productivity around the age of 40, that female researchers produce less than their male colleagues, that incentives for collaboration are slow to affect productivity and that, just like humans, research institutes become larger, less productive, more expensive to maintain and less able to raise money as they grow old. Almost invariably, these conclusions come from statistical studies of large numbers of European and American scientists, and there are practically no studies about tropical researchers. We present an in-depth analysis of the productivity of an internationally recognized tropical botanist and conservationist, Luis Diego Gómez Pignataro, based on the totality of his published work and on our own knowledge, as co-workers and friends, of the life frame in which that scientific output was produced. His life output departs from the expected pattern in that he had the highest productivity before reaching the expected peak productivity age, and that when he reached it his productivity fell and never recovered. Furthermore, marriage did not produce the expected fall in productivity. A close analysis of his life indicates that in the middle of his career he switched to intense teaching and conservation activities, and this better explains why his output of scientific research articles was low afterwards. This switch may occur in other tropical scientists. Rev. Biol. Trop. 58 (4: 1093-1114. Epub 2010 December 01.Los estudios bibliométricos han encontrado que los investigadores de sexo masculino tienen su mayor productividad aproximadamente a los 40 años; que las investigadoras producen menos que sus colegas masculinos, que los incentivos para la colaboración tardan en aumentar la productividad y que, al igual que los seres humanos, los institutos de investigación se hacen más grandes, menos productivos, más costosos y menos capaces de recaudar dinero a medida que

Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM rainfall products from December 1997 to November 2001

Science.gov (United States)

Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

2002-01-01

NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2001. Rainfall, latent heating and radar reflectivity structures between El Nino (DE 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs. west Pacific, Africa vs. S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in strtaiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

The Multiple Use of Tropical Forests by Indigenous Peoples in Mexico: a Case of Adaptive Management

Directory of Open Access Journals (Sweden)

Víctor M. Toledo

2003-12-01

Full Text Available The quest for an appropriate system of management for tropical ecosystems necessitates that ecologists consider the accumulated experiences of indigenous peoples in their long-term management of local resources, a subject of current ethnoecology. This paper provides data and empirical evidence of an indigenous multiple-use strategy (MUS of tropical forest management existing in Mexico, that can be considered a case of adaptive management. This conclusion is based on the observation that some indigenous communities avoid common modernization routes toward specialized, unsustainable, and ecologically disruptive systems of production, and yet probably achieve the most successful tropical forest utilization design, in terms of biodiversity conservation, resilience, and sustainability. This analysis relies on an exhaustive review of the literature and the authors' field research. Apparently, this MUS represents an endogenous reaction of indigenous communities to the intensification of natural resource use, responding to technological, demographic, cultural, and economic changes in the contemporary world. This transforms traditional shifting cultivators into multiple-use strategists. Based on a case study, three main features (biodiversity, resilience, and permanence considered relevant to achieving adaptive and sustainable management of tropical ecosystems are discussed.

CDOM fluorescence as a proxy of DOC concentration in natural waters : a comparison of four contrasting tropical systems

OpenAIRE

Rochelle Newall, Emma; Hulot, F. D.; Janeau, Jean-Louis; Merroune, A.

2014-01-01

Chromophoric dissolved organic matter (CDOM) fluorescence or absorption is often proposed as a rapid alternative to chemical methods for the estimation of bulk dissolved organic carbon (DOC) concentration in natural waters. However, the robustness of this method across a wide range of systems remains to be shown. We measured CDOM fluorescence and DOC concentration in four tropical freshwater and coastal environments (estuary and coastal, tropical shallow lakes, water from the freshwater lens ...

Utilizing GNSS Reflectometry to Assess Surface Inundation Dynamics in Tropical Wetlands

Science.gov (United States)

Jensen, K.; McDonald, K. C.; Podest, E.; Chew, C. C.

2017-12-01

Tropical wetlands play a significant role in global atmospheric methane and terrestrial water storage. Despite the growing number of remote sensing products from satellite sensors, both spatial distribution and temporal variability of wetlands remain highly uncertain. An emerging innovative approach to mapping wetlands is offered by GNSS reflectometry (GNSS-R), a bistatic radar concept that takes advantage of GNSS transmitting satellites to yield observations with global coverage and rapid revisit time. This technology offers the potential to capture dynamic inundation changes in wetlands at higher temporal fidelity and sensitivity under the canopy than presently possible. We present an integrative analysis of radiometric modeling, ground measurements, and several microwave remote sensing datasets traditionally used for wetland observations. From a theoretical standpoint, GNSS-R sensitivities for vegetation and wetlands are investigated with a bistatic radar model in order to understand the interactions of the signal with various land surface components. GNSS reflections from the TechDemoSat-1 (TDS-1), Soil Moisture Active Passive (SMAP), and Cyclone GNSS (CYGNSS) missions are tested experimentally with contemporaneous (1) field measurements collected from the Pacaya Samiria National Reserve in the Peruvian Amazon, (2) imaging radar from Sentinel-1 and PALSAR-2 observed over a variety of tropical wetland systems, and (3) pan-tropical coarse-resolution (25km) microwave datasets (Surface Water Microwave Product Series). We find that GNSS-R data provide the potential to extend capabilities of current remote sensing techniques to characterize surface inundation extent, and we explore how to maximize synergism between different satellite sensors to produce an enhanced wetland monitoring product.

Initialization shock in decadal hindcasts due to errors in wind stress over the tropical Pacific

Science.gov (United States)

Pohlmann, Holger; Kröger, Jürgen; Greatbatch, Richard J.; Müller, Wolfgang A.

2017-10-01

Low prediction skill in the tropical Pacific is a common problem in decadal prediction systems, especially for lead years 2-5 which, in many systems, is lower than in uninitialized experiments. On the other hand, the tropical Pacific is of almost worldwide climate relevance through its teleconnections with other tropical and extratropical regions and also of importance for global mean temperature. Understanding the causes of the reduced prediction skill is thus of major interest for decadal climate predictions. We look into the problem of reduced prediction skill by analyzing the Max Planck Institute Earth System Model (MPI-ESM) decadal hindcasts for the fifth phase of the Climate Model Intercomparison Project and performing a sensitivity experiment in which hindcasts are initialized from a model run forced only by surface wind stress. In both systems, sea surface temperature variability in the tropical Pacific is successfully initialized, but most skill is lost at lead years 2-5. Utilizing the sensitivity experiment enables us to pin down the reason for the reduced prediction skill in MPI-ESM to errors in wind stress used for the initialization. A spurious trend in the wind stress forcing displaces the equatorial thermocline in MPI-ESM unrealistically. When the climate model is then switched into its forecast mode, the recovery process triggers artificial El Niño and La Niña events at the surface. Our results demonstrate the importance of realistic wind stress products for the initialization of decadal predictions.

Biomass expansion factors of Olea ferruginea (Royle) in sub tropical ...

African Journals Online (AJOL)

Wood biomass gives information about total productivity of the forest as well as individual tree. Olea ferruginea (Royle) which is small and evergreen is widely distributed in native sub tropical forests of Pakistan and extensively used as fuelwood domestically. This study was carried out in the sub tropical forests of Pakistan at ...

First direct landscape-scale measurement of tropical rain forest Leaf Area Index, a key driver of global primary productivity

Science.gov (United States)

David B. Clark; Paulo C. Olivas; Steven F. Oberbauer; Deborah A. Clark; Michael G. Ryan

2008-01-01

Leaf Area Index (leaf area per unit ground area, LAI) is a key driver of forest productivity but has never previously been measured directly at the landscape scale in tropical rain forest (TRF). We used a modular tower and stratified random sampling to harvest all foliage from forest floor to canopy top in 55 vertical transects (4.6 m2) across 500 ha of old growth in...

Variations of net ecosystem production due to seasonal precipitation differences in a tropical dry forest of northwest Mexico

Science.gov (United States)

Verduzco, Vivian S.; Garatuza-Payán, Jaime; Yépez, Enrico A.; Watts, Christopher J.; Rodríguez, Julio C.; Robles-Morua, Agustin; Vivoni, Enrique R.

2015-10-01

Due to their large extent and high primary productivity, tropical dry forests (TDF) are important contributors to atmospheric carbon exchanges in subtropical and tropical regions. In northwest Mexico, a bimodal precipitation regime that includes winter precipitation derived from Pacific storms and summer precipitation from the North American monsoon (NAM) couples water availability with ecosystem processes. We investigated the net ecosystem production of a TDF ecosystem using a 4.5 year record of water and carbon fluxes obtained from the eddy covariance method complemented with remotely sensed data. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer that respiration is mainly due to decomposition of soil organic matter accumulated from the prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production but can be overwhelmed by the strength of the primary productivity during the NAM. Precipitation characteristics during NAM have significant controls on sustaining carbon fixation in the TDF into the fall season. We identified that a threshold of ~350 to 400 mm of monsoon precipitation leads to a switch in the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This monsoonal precipitation threshold is typically exceeded one out of every 2 years. The close coupling of winter and summer periods with respect to carbon fluxes suggests that the annual carbon balance is dependent on precipitation amounts in both seasons in TDF ecosystems.

Absorption of gamma-emitting fission products and activation products by rice under flooded and unflooded conditions from two tropical soils

International Nuclear Information System (INIS)

D'Souza, T.J.; Mistry, K.B.

1980-01-01

The absorption of gamma-emitting fission products 106 Ru, 125 Sb, 137 Cs and 144 Ce and activation products 59 Fe, 58 Co, 54 Mn and 65 Zn by rice plants grown on two contrasting tropical soils, namely, a blak soil (pellustert) and a laterite (oxisol), and the effects of flooding were studied under controlled conditions. Results indicated greater uptake of 106 Ru and 125 Sb from the black soil than from the laterite. In contrast, the uptake of 144 Ce and 137 Cs was greater in the laterite than in the black soil. Flooding treatment enhanced the uptake of all these fission products by rice plants in the laterite soil whereas this effect was observed only for 125 Sb and 137 Cs in the black soil. The plant uptake of activation products from the two soil types showed maximum accumulation of 65 Zn followed by 54 Mn, 59 Fe and 58 Co in both soil types. Besides, uptake of these nuclides was greater from the laterite soil than from the black soil. Flooding treatment for rice while showing a reduction of 59 Fe uptake showed an increase in plant uptake of 58 Co, 54 Mn and 65 Zn in both soil types. (orig.)

Tropical crops as a basic source of food

Energy Technology Data Exchange (ETDEWEB)

Araujo, J.E.G.

1979-01-01

A study is made of the potential that exists for food production in the Latin American tropics, and ways in which this could improve and diversify nutritional patterns in other ecological regions. Crops which could become more important include roots and tubers, varieties of beans, fruits, nuts and vegetables. Tropical crops such as sugar cane and cassava could also be used as renewable sources of energy, to replace conventional non-renewable fuels.

Maintenance of Austral Summertime Upper-Tropospheric Circulation over Tropical South America: The Bolivian High-Nordeste Low System.

Science.gov (United States)

Chen, Tsing-Chang; Weng, Shu-Ping; Schubert, Siegfried

1999-07-01

Using the NASA/GEOS reanalysis data for 1980-95, the austral-summer stationary eddies in the tropical-subtropical Southern Hemisphere are examined in two wave regimes: long and short wave (wave 1 and waves 2-6, respectively). The basic structure of the Bolivian high-Nordeste low (BH-NL) system is formed by a short-wave train across South America but modulated by the long-wave regime. The short-wave train exhibits a monsoonlike vertical phase reversal in the midtroposphere and a quarter-wave phase shift relative to the divergent circulation. As inferred from (a) the spatial relationship between the streamfunction and velocity potential and (b) the structure of the divergent circulation, the short-wave train forming the BH-NL system is maintained by South American local heating and remote African heating, while the long-wave regime is maintained by western tropical Pacific heating.The maintenance of the stationary waves in the two wave regimes is further illustrated by a simple diagnostic scheme that includes the velocity-potential maintenance equation (which links velocity potential and diabatic heating) and the streamfunction budget (which is the inverse Laplacian transform of the vorticity equation). Some simple relationships between streamfunction and velocity potential for both wave regimes are established to substantiate the links between diabatic heating and streamfunction; of particular interest is a Sverdrup balance in the short-wave regime. This simplified vorticity equation explains the vertical structure of the short-wave train associated with the BH-NL system and its spatial relationship with the divergent circulation.Based upon the diagnostic analysis of its maintenance a simple forced barotropic model is adopted to simulate the BH-NL system with idealized forcings, which imitates the real 200-mb divergence centers over South America, Africa, and the tropical Pacific. Numerical simulations demonstrate that the formation of the BH-NL system is affected

End-product quality of composts produced under tropical and temperate climates using different raw materials: A meta-analysis.

Science.gov (United States)

Faverial, Julie; Boval, Maryline; Sierra, Jorge; Sauvant, Daniel

2016-12-01

A meta-analysis on end-product quality of 442 composts was performed to assess the effects of climate and raw materials on compost quality. The analysis was performed using an ANOVA including a mixed model with nested factors (climate, raw material and publication effect). Tropical composts presented lower carbon, nitrogen, potassium and soluble-carbon contents, and higher electrical conductivity. The results suggest that compost quality in the tropics was affected by weather conditions during composting (e.g. high temperature and rainfall), which induced high losses of carbon and nutrients. For most properties, industrial, sewage sludge and manure-based composts displayed the highest quality under both climates, while the contrary was found for household and municipal solid waste-based composts. The publication effect represented >50% of total variance, which was mainly due to the heterogeneity of the composting procedures. The meta-analysis was found to be a helpful tool to analyse the imbalanced worldwide database on compost quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Near Real-time Decision Support System Improving Forest Management in the Tropics

Science.gov (United States)

Tabor, K.; Musinsky, J.; Ledezma, J.; Rasolohery, A.; Mendoza, E.; Kistler, H.; Steininger, M.; Morton, D. C.; Melton, F. S.; Manwell, J.; Koenig, K.

2013-12-01

Conservation International (CI) has a decade of experience developing near real-time fire and deforestation monitoring and forecasting systems that channel monitoring information from satellite observations directly to national and sub-national government agencies, Non-Government Organizations (NGOs), and local communities. These systems are used to strengthen forest surveillance and monitoring, fire management and prevention, protected areas management and sustainable land use planning. With support from a NASA Wildland Fires grant, in September 2013 CI will launch a brand new near real-time alert system (FIRECAST) to better meet the outstanding needs and challenges users face in addressing ecosystem degradation from wildland fire and illegal forest activities. Outreach efforts and user feedback have indicated the need for seasonal fire forecasts for effective land use planning, faster alert delivery to enhance response to illegal forest activities, and expanded forest monitoring capabilities that enable proactive responses and that strengthen forest conservation and sustainable development actions. The new FIRECAST system addresses these challenges by integrating the current fire alert and deforestation systems and adding improved ecological forecasting of fire risk; expanding data exchange capabilities with mobile technologies; and delivering a deforestation alert product that can inform policies related to land use management and Reduced Emissions from Deforestation and forest Degradation (REDD+). In addition to demonstrating the capabilities of this new real-time alert system, we also highlight how coordination with host-country institutions enhances the system's capacity to address the implementation needs of REDD+ forest carbon projects, improve tropical forest management, strengthen environmental law enforcement, and facilitate the uptake of near real-time satellite monitoring data into business practices of these national/sub-national institutions.

Bibliometry of the Revista de Biología Tropical / International Journal of Tropical Biology and Conservation: document types, languages, countries, institutions, citations and article lifespan.

Science.gov (United States)

Monge-Nájera, Julián; Ho, Yuh-Shan

2016-09-01

The Revista de Biología Tropical / International Journal of Tropical Biology and Conservation, founded in 1953, publishes feature articles about tropical nature and is considered one of the leading journals in Latin America. This article analyzes document type, language, countries, institutions, citations and for the first time article lifespan, from 1976 through 2014. We analyzed 3 978 documents from the Science Citation Index Expanded. Articles comprised 88 % of the total production and had 3.7 citations on average, lower than reviews. Spanish and English articles were nearly equal in numbers and citation for English articles was only slightly higher. Costa Rica, Mexico, and the USA are the countries with more articles, and the leading institutions were Universidad de Costa Rica, Universidad Nacional, Universidad Nacional Autónoma de Mexico and Universidad de Oriente (Venezuela). The citation lifespan of articles is long, around 37 years. It is not surprising that Costa Rica, Mexico, and Venezuela lead in productivity and cooperation, because they are mostly covered by tropical ecosystems and share a common culture and a tradition of scientific cooperation. The same applies to the leading institutions, which are among the largest Spanish language universities in the neotropical region. American output can be explained by the regional presence of the Smithsonian Tropical Research Institute and the Organization for Tropical Studies. Tropical research does not have the rapid change typical of medical research, and for this reason, the impact factor misses most of citations for the Revista, which are made after the two-year window used by the Web of Science. This issue is especially damaging for the Revista because most journals that deal with tropical biology are never checked when citations are counted for by the Science Citation Index.

Aboveground tree growth varies with belowground carbon allocation in a tropical rainforest environment

Science.gov (United States)

J.W. Raich; D.A. Clark; L. Schwendenmann; Tana Wood

2014-01-01

Young secondary forests and plantations in the moist tropics often have rapid rates of biomass accumulation and thus sequester large amounts of carbon. Here, we compare results from mature forest and nearby 15–20 year old tree plantations in lowland Costa Rica to evaluate differences in allocation of carbon to aboveground production and root systems. We found that the...

Tropical organic soils ecosystems in relation to regional water resources in southeast Asia

Energy Technology Data Exchange (ETDEWEB)

Armentano, T. V.

1982-01-01

Tropical organic soils have functioned as natural sinks for carbon, nitrogen, slfur and other nutrients for the past 4000 years or more. Topographic evolution in peat swamp forests towards greater oligotrophy has concentrated storage of the limited nutrient stock in surface soils and biota. Tropical peat systems thus share common ecosystem characteristics with northern peat bogs and certain tropical oligotrophic forests. Organic matter accumulation and high cation-exchange-capacity limit nutrient exports from undisturbed organic soils, although nutrient retention declines with increasing eutrophy and wetland productivity. Peat swamps are subject to irreversible degradation if severely altered because disturbance of vegetation, surface peats and detritus can disrupt nuttrient cycles and reduce forest recovery capacity. Drainage also greatly increases exports of nitrogen, phosphorus and other nutrients and leads to downstream eutrophication and water quality degradation. Regional planning for clean water supplies must recognize the benefits provided by natural peatlands in balancing water supplies and regulating water chemistry.

Genetic improvements to productivity of cattle in tropical Africa

International Nuclear Information System (INIS)

Frisch, J.E.; Vercoe, J.E.

1986-01-01

Improvement in productivity of cattle in some areas of tropical Africa is likely to be related mainly to improvement in environmental conditions, including the implementation of effective vaccination programmes and an increased availability of feed. In other areas, scope also exists to increase output by increasing the genetic potential of indigenous breeds and animals. The variation within indigenous breeds in resistance to environmental stresses and in genetic potentials could be exploited by within-breed selection but responses are likely to be slow. Initial attempts at genetic improvements should therefore concentrate on utilizing between-breed variation in these traits by identifying breeds with the required attributes and crossing them to the breed under improvement. Increases in milk yield and size are mainly dependent on the successful implementation of cross-breeding programmes aimed at maintaining high resistance to environmental stresses while also increasing genetic potentials up to the level that can be supported by the available nutrition. The most suitable combination of breeds to be used in these crosses is not known at present. However, in areas of high trypanosome challenge, crosses between trypanotolerant breeds from East and West Africa may be the best option. In areas of lower trypanosome challenge but where high levels of other environmental stresses exist, crosses between indigenous and Indian breeds may be the most appropriate. Only in those areas where parasite and disease challenge is low and the plane of nutrition is high will crosses to higher yielding European Bos taurus breeds be suitable. Improved standards of living of sections of society and increases in population have contributed to increased demand for cattle products. If this demand is to be met from African sources, output must be increased. Some of the ways in which this may be achieved are considered in the paper. (author)

Life Cycle of Tropical Convection and Anvil in Observations and Models

Science.gov (United States)

McFarlane, S. A.; Hagos, S. M.; Comstock, J. M.

2011-12-01

Tropical convective clouds are important elements of the hydrological cycle and produce extensive cirrus anvils that strongly affect the tropical radiative energy balance. To improve simulations of the global water and energy cycles and accurately predict both precipitation and cloud radiative feedbacks, models need to realistically simulate the lifecycle of tropical convection, including the formation and radiative properties of ice anvil clouds. By combining remote sensing datasets from precipitation and cloud radars at the Atmospheric Radiation Measurement (ARM) Darwin site with geostationary satellite data, we can develop observational understanding of the lifetime of convective systems and the links between the properties of convective systems and their associated anvil clouds. The relationships between convection and anvil in model simulations can then be compared to those seen in the observations to identify areas for improvement in the model simulations. We identify and track tropical convective systems in the Tropical Western Pacific using geostationary satellite observations. We present statistics of the tropical convective systems including size, age, and intensity and classify the lifecycle stage of each system as developing, mature, or dissipating. For systems that cross over the ARM Darwin site, information on convective intensity and anvil properties are obtained from the C-Pol precipitation radar and MMCR cloud radar, respectively, and are examined as a function of the system lifecycle. Initial results from applying the convective identification and tracking algorithm to a tropical simulation from the Weather Research and Forecasting (WRF) model run show that the model produces reasonable overall statistics of convective systems, but details of the life cycle (such as diurnal cycle, system tracks) differ from the observations. Further work will focus on the role of atmospheric temperature and moisture profiles in the model's convective life cycle.

Teleconnections of the tropical Atlantic to the tropical Indian and Pacific Oceans. A review of recent findings

Energy Technology Data Exchange (ETDEWEB)

Wang Chunzai [NOAA Atlantic Oceanographic and Meteorological Lab., Miami, FL (United States); Kucharski, Fred; Barimalala, Rondrotiana [The Abdus Salam International Centre for Theoretical Physics, Earth System Physics, Section Trieste (Italy); Bracco, Annalisa [School of Earth and Atmospheric Sciences Georgia, Inst. of Tech., Atlanta, GA (United States)

2009-08-15

Recent studies found that tropical Atlantic variability may affect the climate in both the tropical Pacific and Indian Ocean basins, possibly modulating the Indian summer monsoon and Pacific ENSO events. A warm tropical Atlantic Ocean forces a Gill-Matsuno-type quadrupole response with a low-level anticyclone located over India that weakens the Indian monsoon circulation, and vice versa for a cold tropical Atlantic Ocean. The tropical Atlantic Ocean can also induce changes in the Indian Ocean sea surface temperatures (SSTs). especially along the coast of Africa and in the western side of the Indian basin. Additionally, it can influence the tropical Pacific Ocean via an atmospheric teleconnection that is associated with the Atlantic Walker circulation. Although the Pacific El Nino does not contemporaneously correlate with the Atlantic Nino, anomalous warming or cooling of the two equatorial oceans can form an inter-basin SST gradient that induces surface zonal wind anomalies over equatorial South America and other regions in both ocean basins. The zonal wind anomalies act as a bridge linking the two ocean basins, and in turn reinforce the inter-basin SST gradient through the atmospheric Walker circulation and oceanic processes. Thus, a positive feedback seems to exist for climate variability of the tropical Pacific-Atlantic Oceans and atmospheric system, in which the inter-basin SST gradient is coupled to the overlying atmospheric wind. (orig.)

Climate-mediated nitrogen and carbon dynamics in a tropical watershed

Science.gov (United States)

Ballantyne, A. P.; Baker, P. A.; Fritz, S. C.; Poulter, B.

2011-06-01

Climate variability affects the capacity of the biosphere to assimilate and store important elements, such as nitrogen and carbon. Here we present biogeochemical evidence from the sediments of tropical Lake Titicaca indicating that large hydrologic changes in response to global glacial cycles during the Quaternary were accompanied by major shifts in ecosystem state. During prolonged glacial intervals, lake level was high and the lake was in a stable nitrogen-limited state. In contrast, during warm dry interglacials lake level fell and rates of nitrogen concentrations increased by a factor of 4-12, resulting in a fivefold to 24-fold increase in organic carbon concentrations in the sediments due to increased primary productivity. Observed periods of increased primary productivity were also associated with an apparent increase in denitrification. However, the net accumulation of nitrogen during interglacial intervals indicates that increased nitrogen supply exceeded nitrogen losses due to denitrification, thereby causing increases in primary productivity. Although primary productivity in tropical ecosystems, especially freshwater ecosystems, tends to be nitrogen limited, our results indicate that climate variability may lead to changes in nitrogen availability and thus changes in primary productivity. Therefore some tropical ecosystems may shift between a stable state of nitrogen limitation and a stable state of nitrogen saturation in response to varying climatic conditions.

Management of agroforestry systems for enhancing resource use efficiency and crop productivity

International Nuclear Information System (INIS)

2008-11-01

Agroforestry is a low-input system which combines trees with crops in various combinations or sequences. It is an alternative to intensive cropping systems, which rely on large inputs of manufactured fertilizers and other external inputs to sustain production. Agroforestry also has the potential to reduce risk through diversification of a variety of products, including food, fuelwood and animal fodder. Other perceived benefits include enhanced nutrient and water use efficiencies, reduced nutrient leaching to groundwater and improved soil physical and biological properties. The use of leguminous or actinorhizal trees may further enhance these benefits because of their capacity to fix atmospheric nitrogen. Depending on the type of agroforestry system and the management practices employed, a substantial portion of this fixed nitrogen can be transferred to companion crops and to the soil. In considering the overall productivity of agroforestry systems, it is essential to investigate the competition or complementarity in the capture and partitioning of resources between tree and crop components. This is especially true for nutrients and water, usually the two most limiting factors influencing crop growth. The focus of this coordinated research project (CRP) was to evaluate the efficacy of various agroforestry systems used in Member States in terms of crop productivity, resource use efficiency and improvements in soil properties. The use of isotopes and nuclear techniques was essential for understanding the dynamics of nutrients and water in agroforestry systems. The contribution of nitrogen from fertilizers and leguminous trees to soil and crops was studied using both direct and indirect 15 N labelling techniques. The cycling of carbon from trees or crops to soil was studied using natural variations in the 13 C signatures of the soils and the different species. The soil moisture neutron probe in conjunction with tensionics was used to monitor soil water status and

A real-time ocean reanalyses intercomparison project in the context of tropical pacific observing system and ENSO monitoring

Science.gov (United States)

Xue, Yan; Wen, C.; Kumar, A.; Balmaseda, M.; Fujii, Y.; Alves, O.; Martin, M.; Yang, X.; Vernieres, G.; Desportes, C.; Lee, T.; Ascione, I.; Gudgel, R.; Ishikawa, I.

2017-12-01

An ensemble of nine operational ocean reanalyses (ORAs) is now routinely collected, and is used to monitor the consistency across the tropical Pacific temperature analyses in real-time in support of ENSO monitoring, diagnostics, and prediction. The ensemble approach allows a more reliable estimate of the signal as well as an estimation of the noise among analyses. The real-time estimation of signal-to-noise ratio assists the prediction of ENSO. The ensemble approach also enables us to estimate the impact of the Tropical Pacific Observing System (TPOS) on the estimation of ENSO-related oceanic indicators. The ensemble mean is shown to have a better accuracy than individual ORAs, suggesting the ensemble approach is an effective tool to reduce uncertainties in temperature analysis for ENSO. The ensemble spread, as a measure of uncertainties in ORAs, is shown to be partially linked to the data counts of in situ observations. Despite the constraints by TPOS data, uncertainties in ORAs are still large in the northwestern tropical Pacific, in the SPCZ region, as well as in the central and northeastern tropical Pacific. The uncertainties in total temperature reduced significantly in 2015 due to the recovery of the TAO/TRITON array to approach the value before the TAO crisis in 2012. However, the uncertainties in anomalous temperature remained much higher than the pre-2012 value, probably due to uncertainties in the reference climatology. This highlights the importance of the long-term stability of the observing system for anomaly monitoring. The current data assimilation systems tend to constrain the solution very locally near the buoy sites, potentially damaging the larger-scale dynamical consistency. So there is an urgent need to improve data assimilation systems so that they can optimize the observation information from TPOS and contribute to improved ENSO prediction.

The future of tropical forests.

Science.gov (United States)

Wright, S Joseph

2010-05-01

Five anthropogenic drivers--land use change, wood extraction, hunting, atmospheric change, climate change--will largely determine the future of tropical forests. The geographic scope and intensity of these five drivers are in flux. Contemporary land use change includes deforestation (approximately 64,000 km(2) yr(-1) for the entire tropical forest biome) and natural forests regenerating on abandoned land (approximately 21,500 km(2) yr(-1) with just 29% of the biome evaluated). Commercial logging is shifting rapidly from Southeast Asia to Africa and South America, but local fuelwood consumption continues to constitute 71% of all wood production. Pantropical rates of net deforestation are declining even as secondary and logged forests increasingly replace old-growth forests. Hunters reduce frugivore, granivore and browser abundances in most forests. This alters seed dispersal, seed and seedling survival, and hence the species composition and spatial template of plant regeneration. Tropical governments have responded to these local threats by protecting 7% of all land for the strict conservation of nature--a commitment that is only matched poleward of 40 degrees S and 70 degrees N. Protected status often fails to stop hunters and is impotent against atmospheric and climate change. There are increasing reports of stark changes in the structure and dynamics of protected tropical forests. Four broad classes of mechanisms might contribute to these changes. Predictions are developed to distinguish among these mechanisms.

Radio Occultation Bending Angle Anomalies During Tropical Cyclones

DEFF Research Database (Denmark)

Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC), we show that the bending angle anomaly of a GPS radio occultation signal is typically larger...

Role of Biotechnology in Animal Production Systems in Hot Climates

Directory of Open Access Journals (Sweden)

P. J. Hansen

1996-01-01

Full Text Available Developments in the biological sciences in the last three decades have revolutionized mankind's ability to manipulate the genetics, cell biology and physiology of biological organisms. These techniques, collectively termed biotechnology, create the opportunity for modifying domestic animals in ways that markedly increase the efficiency of production. Among the procedures being developed for animal production systems are marker-assisted selection of specific alleles of a gene that are associated with high production, production of transgenic animals , super ovulation and embryo transfer, in vitro fertilization, embryo sexing and cloning, production of large amounts of previously-rare proteins through use of genetically -engineered bacteria or other cells, and identification of new biologically-active molecules as potential regulators of animal function. To date, most uses of biotechnology have concentrated on problems of general relevance to animal agriculture rather than specific problems related to livestock production in hot climates. However, it is likely that biotechnology will be used for this latter purpose also. Strategies to increase disease resistance using marker-assisted selection, production of transgenic animals expressing viral proteins, and recombinant cytokines to enhance immune function should prove useful to reducing the incidence and seventy of various tropical diseases. Additionally, there are methods to reduce effects of heat stress on oestrus detection and establishment of pregnancy. These include remote sensing of oestrus, ovulation synchronization systems and embryo transfer. More research regarding the physiological processes determining heat tolerance and of the pathways through which heat stress alters physiological function will be required before molecular biology techniques can be used to reduce the adverse effects of heat stress on animal production.

Criteria for evaluating the condition of a tropical cyclone warning system.

Science.gov (United States)

Parker, D

1999-09-01

This paper evaluates the condition (i.e. health) of a tropical cyclone warning system (TCWS) during a 'quiet period' between infrequent intense cyclones. Capacity to make pre-disaster evaluations is important--disaster warning systems need to be in sound condition before, not after, disaster. The research--part of the UK's International Decade of Natural Disaster Reduction Flagship Programme--focuses upon an evaluatory method first used on flood warning systems. The Criteria-development Matrix comprises social, organisational and institutional criteria by which a TCWS may be assessed using a five-stage development scale. This method is used to evaluate Mauritius's TCWS using in-depth interview data. Ways to enhance the method and apply it to other disaster warning systems are discussed. The TCWS in Mauritius is a relatively sound one from which others can learn. Weaknesses requiring attention for Mauritius's TCWS to progress to an advanced level of development are identified.

Tropical Cyclone Signatures in Atmospheric Convective Available Potential Energy

Science.gov (United States)

Studholme, Joshua; Gulev, Sergey

2016-04-01

Tropical cyclones play an important role in the climate system providing transports of energy and water vapor, forcing the ocean, and also affecting mid-latitude circulation phenomena. Tropical cyclone tracks experience strong interannual variability and in addition, longer term trend-like changes in all ocean basins. Analysis of recent historical data reveal a poleward shift in the locations of tropical cyclone tracks in both the Northern and Southern Hemispheres (Kossin et al. 2014, Nature, 509, 349-352). The physical consequences of these alterations are largely unconstrained. For example, the increasing encroachment of tropical cyclone activity into the extra-tropical environment presents a novel and still poorly understood paradigm for tropical-extratropical interactions. In this respect, the role that the atmospheric convective available potential energy (CAPE) plays in the dynamics of tropical cyclones is highly interesting. The two characteristic global-scale spatial patterns in CAPE are identified using EOF analysis. The first pattern shows an abundance of CAPE in the centre of the Pacific and corresponds to the El Nino Southern Oscillation. The second one is capturing positive CAPE anomalies in the oceanic tropics and negative anomalies over equatorial Africa. Associated with these buoyancy patterns, alterations in tropical cyclone activity occur in all basins forming both zonal and meridional patterns. Atmospheric buoyancy is the trigger for deep convection, and subsequently cyclone genesis. This is the mechanism of impact upon location at the start of cyclone tracks. It is found to have less impact upon where cyclones subsequently move, whether or not they undergo extratropical transition and when and where they experience lysis. It is shown that CAPE plays a critical role in the general circulation in the tropics which in turn is the larger steering context for embedded systems within the Walker and Hadley cells. So this lack of `latter life' impact

The Research of Dr. Joanne Simpson: Fifty Years Investigating Hurricanes, Tropical Clouds and Cloud Systems

Science.gov (United States)

Tao, W. -K.; Halverson, J.; Adler, R.; Garstang, M.; Houze, R., Jr.; LeMone, M.; Pielke, R., Sr.; Woodley, W.; O'C.Starr, David (Technical Monitor)

2001-01-01

This AMS Meteorological Monographs is dedicated to Dr. Joanne Simpson for her many pioneering research efforts in tropical meteorology during her fifty-year career. Dr. Simpson's major areas of scientific research involved the "hot tower" hypothesis and its role in hurricanes, structure and maintenance of trade winds, air-sea interaction, and observations and the mechanism for hurricanes and waterspouts. She was also a pioneer in cloud modeling with the first one-dimensional model and had the first cumulus model on a computer. She also played a major role in planning and leading observational experiments on convective cloud systems. The launch of the Tropical Rainfall Measuring Mission (TRMM) satellite, a joint U.S.-Japan project, in November of 1997 made it possible for quantitative measurements of tropical rainfall to be obtained on a continuous basis over the entire global tropics. Dr. Simpson was the TRAM Project Scientist from 1986 until its launch in 1997. Her efforts during this crucial period ensured that the mission was both well planned scientifically and well engineered as well as within budget. In this paper, Dr. J. Simpson's nine specific accomplishments during her fifty-year career: (1) hot tower hypothesis, (2) hurricanes, (3) airflow and clouds over heated islands, (4) cloud models, (5) trade winds and their role in cumulus development, (6) air-sea interaction, (7) cloud-cloud interactions and mergers, (8) waterspouts, and (9) TRMM science, will be described and discussed.

Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2002

Science.gov (United States)

Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

2003-01-01

NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs. S. America ) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model. Review of other latent heating algorithms will be discussed in the workshop.

Absorption of gamma-emitting fission products and activation products by rice under flooded and unflooded conditions from two tropical soils

Energy Technology Data Exchange (ETDEWEB)

D' Souza, T J; Mistry, K B [Bhabha Atomic Research Centre, Bombay (India). Biology and Agriculture Div.

1980-01-01

The absorption of gamma-emitting fission products /sup 106/Ru, /sup 125/Sb, /sup 137/Cs and /sup 144/Ce and activation products /sup 59/Fe, /sup 58/Co, /sup 54/Mn and /sup 65/Zn by rice plants grown on two contrasting tropical soils, namely, a blak soil (pellustert) and a laterite (oxisol), and the effects of flooding were studied under controlled conditions. Results indicated greater uptake of /sup 106/Ru and /sup 125/Sb from the black soil than from the laterite. In contrast, the uptake of /sup 144/Ce and /sup 137/Cs was greater in the laterite than in the black soil. Flooding treatment enhanced the uptake of all these fission products by rice plants in the laterite soil whereas this effect was observed only for /sup 125/Sb and /sup 137/Cs in the black soil. The plant uptake of activation products from the two soil types showed maximum accumulation of /sup 65/Zn followed by /sup 54/Mn, /sup 59/Fe and /sup 58/Co in both soil types. Besides, uptake of these nuclides was greater from the laterite soil than from the black soil. Flooding treatment for rice while showing a reduction of /sup 59/Fe uptake showed an increase in plant uptake of /sup 58/Co, /sup 54/Mn and /sup 65/Zn in both soil types.

Heterotrophic utilization of extracellular products of phytoplankton in a tropical estuary

Digital Repository Service at National Institute of Oceanography (India)

Gomes, H.; Pant, A; Goes, J.I.; Parulekar, A

Bacterial uptake of algal exudates has been estimated in a tropical estuary, Dona Paula, Goa, India, where the seasonal fluctuations in hydrographic and nutrient parameters as well as dissolved organic matter concentrations and phytoplankton species...

Product Service Systems

DEFF Research Database (Denmark)

Departing from Product Development models based on physical artefacts. Moving towards integrated Product Development and System Operations models suited Product/Service-systems......Departing from Product Development models based on physical artefacts. Moving towards integrated Product Development and System Operations models suited Product/Service-systems...

An innovative roofing system for tropical building interiors: Separating heat from useful visible light

Energy Technology Data Exchange (ETDEWEB)

Al-Obaidi, K.M.; Ismail, M.; Abdul Rahman, A.M. [School of Housing, Building and Planning, Universiti Sains Malaysia, 11800, Minden, Pulau Pinang (Malaysia)

2013-07-01

Generally it has been known that energy consumption costs are high in temperate countries. In buildings, room spaces are normally designed so as to consume less energy for thermal comfort especially in winter. Passive strategies such large double-glazing windows are to contain heat indoors and also for maximum daylight to reduce dependence on artificial lighting. Thus roof lights are popular building design elements in cold and temperate countries. Unlike in the tropics where it has high temperatures and humidity throughout the year, achieving indoor comfort is a challenge especially with plenty of sunshine and unpredictable wind conditions. This paper explores the possibility of roof light for indoor comfort to be considered as a tropical design element. Initial simulation was carried out before any attempt to do life-sized model for empirical data. By simulation, the hypothesis has been achieved but several factors have to be considered. The solution is not as simple as those achieved in the temperate countries. Comfort can be achieved but permutations of several design factors such as dimensions of room, glazing, reflective materials, blackbody concept and building materials need adjustment to meet the Malaysian Comfort Temperature. With this finding the Tropical Architecture would then be redefined with the introduction of this Innovative Roofing System (IRS) as named by the author.

Design method for photovoltaics-battery storage systems under tropical conditions

Energy Technology Data Exchange (ETDEWEB)

Salem, A I.E.; Bassyouni, A H; Al-Motawakel, M K

1989-01-01

A very limited number of the available design methods can be used with confidence in sizing and costing the stand-alone photovoltaic-battery storage systems operating under the weather conditions of the tropical countries located between 0 and 30/sup 0/N. For this reason we investigated the performance and economics of various photovoltaic-battery storage system configurations. The aim was to prepare a number of sizing and costing design diagrams which detail the effect of climatic, social, and economics parameters on the choice of the stand-alone photovoltaic-battery storage systems. Our strategy was to guide designers, particularly those trying to utilize the stand-alone photovoltaic-battery storage systems in Sana'a (15/sup 0/N) and Cairo (30/sup 0/N), to the logic for selecting a system that physically and economically matches the site potential and the user's electrical needs. Considered here are the relatively small stand-alone photovoltaic-battery storage systems that can be purchased by individuals or commercial and governmental firms to supply all or part of the electrical needs consumed in residence, farms, remote rural communities, or small factories.

International Journal of Tropical Agriculture and Food Systems ...

African Journals Online (AJOL)

Manuscript should be typed on white A4 paper, double-spaced with wide margin. ... Anyanwu, G. A., Esonu, B. O., Iwuala, F., Okorie, K. and Etuk, E. B. (2003). ... Books: Payne, W. J. A. (1990). An introduction to animal husbandry in the tropics.

An expert system model for mapping tropical wetlands and peatlands reveals South America as the largest contributor.

Science.gov (United States)

Gumbricht, Thomas; Roman-Cuesta, Rosa Maria; Verchot, Louis; Herold, Martin; Wittmann, Florian; Householder, Ethan; Herold, Nadine; Murdiyarso, Daniel

2017-09-01

Wetlands are important providers of ecosystem services and key regulators of climate change. They positively contribute to global warming through their greenhouse gas emissions, and negatively through the accumulation of organic material in histosols, particularly in peatlands. Our understanding of wetlands' services is currently constrained by limited knowledge on their distribution, extent, volume, interannual flood variability and disturbance levels. We present an expert system approach to estimate wetland and peatland areas, depths and volumes, which relies on three biophysical indices related to wetland and peat formation: (1) long-term water supply exceeding atmospheric water demand; (2) annually or seasonally water-logged soils; and (3) a geomorphological position where water is supplied and retained. Tropical and subtropical wetlands estimates reach 4.7 million km 2 (Mkm 2 ). In line with current understanding, the American continent is the major contributor (45%), and Brazil, with its Amazonian interfluvial region, contains the largest tropical wetland area (800,720 km 2 ). Our model suggests, however, unprecedented extents and volumes of peatland in the tropics (1.7 Mkm 2 and 7,268 (6,076-7,368) km 3 ), which more than threefold current estimates. Unlike current understanding, our estimates suggest that South America and not Asia contributes the most to tropical peatland area and volume (ca. 44% for both) partly related to some yet unaccounted extended deep deposits but mainly to extended but shallow peat in the Amazon Basin. Brazil leads the peatland area and volume contribution. Asia hosts 38% of both tropical peat area and volume with Indonesia as the main regional contributor and still the holder of the deepest and most extended peat areas in the tropics. Africa hosts more peat than previously reported but climatic and topographic contexts leave it as the least peat-forming continent. Our results suggest large biases in our current understanding of

The Genesis of Tropical Cyclone Bilis (2000) Associated with Cross-equatorial Surges

Institute of Scientific and Technical Information of China (English)

XU Yamei

2011-01-01

The purpose of this paper is to explore how a tropical cyclone forms from a pre-existing large-scale depression which has been observed and associated with cross-equatorial surges in the western North Pacific. Tropical cyclone Bilis (2000) was selected as the case to study. The research data used are from the results of the non-hydrostatic mesoscale model (MM5), which has successfully simulated the transformation of a pre-existing weak large-scale tropical depression into a strong tropical storm. The scale separation technique is used to separate the synoptic-scale and sub-synoptic-scale fields from the model output fields. The scale-separated fields show that the pre-existing synoptic-scale tropical depression and the subsynoptic scale tropical cyclone formed later were different scale systems from beginning to end. It is also shown that the pre-existing synoptic-scale tropical depression did not contract to become the tropical cyclone. A series of weak, sub-synoptic-scale low and high pressure systems appeared and disappeared in the synopticscale depression, with one of the low systems near the center of the synoptic-scale depression having deepened to become the tropical cyclone. The roles of the synoptic-scale flow and the sub-synoptic scale disturbances in the formation of the tropical cyclone are investigated by diagnoses of the scale-separated vertical vorticity equation. The results show that the early development of the sub-synoptic scale vortex was fundamentally dependent on the strengthening synoptic-scale environmental depression. The depression was strengthened by cross-equatorial surges, which increased the convergence of the synoptic-scale depression at low levels and triggered the formation of the tropical cyclone.

On the role of ice-nucleating aerosol in the formation of ice particles in tropical mesoscale convective systems

Science.gov (United States)

Ladino, Luis A.; Korolev, Alexei; Heckman, Ivan; Wolde, Mengistu; Fridlind, Ann M.; Ackerman, Andrew S.

2018-01-01

Over decades, the cloud physics community has debated the nature and role of aerosol particles in ice initiation. The present study shows that the measured concentration of ice crystals in tropical mesoscale convective systems exceeds the concentration of ice nucleating particles (INPs) by several orders of magnitude. The concentration of INPs was assessed from the measured aerosol particles concentration in the size range of 0.5 to 1 µm. The observations from this study suggest that primary ice crystals formed on INPs make only a minor contribution to the total concentration of ice crystals in tropical mesoscale convective systems. This is found by comparing the predicted INP number concentrations with in-situ ice particle number concentrations. The obtained measurements suggest that ice multiplication is the likely explanation for the observed high concentrations of ice crystals in this type of convective system. PMID:29551842

Tropical tele-connections to the Mediterranean climate and weather

Directory of Open Access Journals (Sweden)

P. Alpert

2005-01-01

Full Text Available Some strong natural fluctuations of climate in the Eastern Mediterranean (EM region are shown to be connected to the major tropical systems. Potential relations between EM rainfall extremes to tropical systems, e.g. El Niño, Indian Monsoon and hurricanes, are demonstrated. For a specific event, high resolution modelling of the severe flood on 3-5 December 2001 in Israel suggests a relation to hurricane Olga. In order to understand the factors governing the EM climate variability in the summer season, the relationship between extreme summer temperatures and the Indian Monsoon was examined. Other tropical factors like the Red-Sea Trough system and the Saharan dust are also likely to contribute to the EM climate variability.

Spatial distribution and secondary production of Copepoda in a tropical reservoir: Barra Bonita, SP, Brazil

Directory of Open Access Journals (Sweden)

MJ. Santos-Wisniewski

Full Text Available The present paper aims to describe the spatial distribution of zooplankton copepods, their biomass and instantaneous secondary production, in Barra Bonita, a large eutrophic, polymitic reservoir (22° 29' S and 48° 34' W on the Tietê River, of the Paraná basin. Sampling was carried out during two seasons: dry winter and rainy summer. Species composition, age structure and numerical density of each copepod species population were analyzed at 25 sampling stations. Secondary production was calculated for Copepoda, the dominant group in zooplankton communities, taking Calanoida and Cyclopoida separately. Copepoda represented the largest portion of the total zooplankton biomass, the dominant species being Notodiaptomus iheringi among the Calanoida and Mesocyclops ogunnus and Thermocyclops decipiens among the Cyclopoida. The production of Copepoda was higher during the rainy summer (23.61 mgDW.m-3.d-1 in January 1995 than during the dry winter season (14 mgDW.m-3.d-1 in August 1995, following the general pattern of abundance for the whole zooplankton community. Among the copepods, Cyclopoida production was higher than that of Calanoida, a pattern commonly observed for tropical lakes and reservoirs. Barra Bonita copepods are very productive, but there was a great degree of spatial heterogeneity, related to the physical and chemical conditions, particularly the level of nutrients and also to phytoplankton biomass.

Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

Science.gov (United States)

Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G; Efitre, Jackson; Nowlan, Tobias E; Taranu, Zofia E; Chapman, Lauren J

2014-01-01

African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2) adj  = 0.23, e.d.f. = 7, pdeterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions.

Regeneration in natural and logged tropical rain forest : modelling seed dispersal and regeneration

NARCIS (Netherlands)

Ulft, Lambertus Henricus van

2004-01-01

Regeneration and disturbance are thought to play key roles in the maintenance of the high tree species diversity in tropical rain forests. Nevertheless, the earliest stages in the regeneration of tropical rain forest trees, from seed production to established seedlings, have received little

Coupled nutrient cycling determines tropical forest trajectory under elevated CO2.

Science.gov (United States)

Bouskill, N.; Zhu, Q.; Riley, W. J.

2017-12-01

Tropical forests have a disproportionate capacity to affect Earth's climate relative to their areal extent. Despite covering just 12 % of land surface, tropical forests account for 35 % of global net primary productivity and are among the most significant of terrestrial carbon stores. As atmospheric CO2 concentrations increase over the next century, the capacity of tropical forests to assimilate and sequester anthropogenic CO2 depends on limitation by multiple factors, including the availability of soil nutrients. Phosphorus availability has been considered to be the primary factor limiting metabolic processes within tropical forests. However, recent evidence points towards strong spatial and temporal co-limitation of tropical forests by both nitrogen and phosphorus. Here, we use the Accelerated Climate Modeling for Energy (ACME) Land Model (ALMv1-ECA-CNP) to examine how nutrient cycles interact and affect the trajectory of the tropical forest carbon sink under, (i) external nutrient input, (ii) climate (iii) elevated CO2, and (iv) a combination of 1-3. ALMv1 includes recent theoretical advances in representing belowground competition between roots, microbes and minerals for N and P uptake, explicit interactions between the nitrogen and phosphorus cycles (e.g., phosphatase production and nitrogen fixation), the dynamic internal allocation of plant N and P resources, and the integration of global datasets of plant physiological traits. We report nutrient fertilization (N, P, N+P) predictions for four sites in the tropics (El Verde, Puerto Rico, Barro Colorado Island, Panama, Manaus, Brazil and the Osa Peninsula, Coast Rica) to short-term nutrient fertilization (N, P, N+P), and benchmarking of the model against a meta-analysis of forest fertilization experiments. Subsequent simulations focus on the interaction of the carbon, nitrogen, and phosphorus cycles across the tropics with a focus on the implications of coupled nutrient cycling and the fate of the tropical

Exclusion of soil macrofauna did not affect soil quality but increases crop yields in a sub-humid tropical maize-based system

NARCIS (Netherlands)

Paul, B.K.; Vanlauwe, B.; Hoogmoed, M.; Hurisso, T.T.; Ndabamenye, T.; Terano, Y.; Ayuke, F.O.; Pulleman, M.M.

2015-01-01

Soil macrofauna such as earthworms and termites are involved in key ecosystem functions and thus considered important for sustainable intensification of crop production. However, their contribution to tropical soil and crop performance, as well as relations with agricultural management (e.g.

Toward a whole-landscape approach for sustainable land use in the tropics.

Science.gov (United States)

DeFries, R; Rosenzweig, C

2010-11-16

Increasing food production and mitigating climate change are two primary but seemingly contradictory objectives for tropical landscapes. This special feature examines synergies and trade-offs among these objectives. Four themes emerge from the papers: the important roles of both forest and agriculture sectors for climate mitigation in tropical countries; the minor contribution from deforestation-related agricultural expansion to overall food production at global and continental scales; the opportunities for synergies between improved food production and reductions in greenhouse gas emissions through diversion of agricultural expansion to already-cleared lands, improved soil, crop, and livestock management, and agroforestry; and the need for targeted policy and management interventions to make these synergistic opportunities a reality. We conclude that agricultural intensification is a key factor to meet dual objectives of food production and climate mitigation, but there is no single panacea for balancing these objectives in all tropical landscapes. Place-specific strategies for sustainable land use emerge from assessments of current land use, demographics, and other biophysical and socioeconomic characteristics, using a whole-landscape, multisector perspective.

Vaccines to combat the neglected tropical diseases

Science.gov (United States)

Bethony, Jeffrey M.; Cole, Rhea N.; Guo, Xiaoti; Kamhawi, Shaden; Lightowlers, Marshall W.; Loukas, Alex; Petri, William; Reed, Steven; Valenzuela, Jesus G.; Hotez, Peter J.

2012-01-01

Summary The neglected tropical diseases (NTDs) represent a group of parasitic and related infectious diseases such as amebiasis, Chagas disease, cysticercosis, echinococcosis, hookworm, leishmaniasis, and schistosomiasis. Together, these conditions are considered the most common infections in low- and middle-income countries, where they produce a level of global disability and human suffering equivalent to better known conditions such as human immunodeficiency virus/acquired immunodeficiency syndrome and malaria. Despite their global public health importance, progress on developing vaccines for NTD pathogens has lagged because of some key technical hurdles and the fact that these infections occur almost exclusively in the world’s poorest people living below the World Bank poverty line. In the absence of financial incentives for new products, the multinational pharmaceutical companies have not embarked on substantive research and development programs for the neglected tropical disease vaccines. Here, we review the current status of scientific and technical progress in the development of new neglected tropical disease vaccines, highlighting the successes that have been achieved (cysticercosis and echinococcosis) and identifying the challenges and opportunities for development of new vaccines for NTDs. Also highlighted are the contributions being made by non-profit product development partnerships that are working to overcome some of the economic challenges in vaccine manufacture, clinical testing, and global access. PMID:21198676

Mercury in tropical and subtropical coastal environments

Science.gov (United States)

Costa, Monica F.; Landing, William M.; Kehrig, Helena A.; Barletta, Mário; Holmes, Christopher D.; Barrocas, Paulo R. G.; Evers, David C.; Buck, David G.; Vasconcellos, Ana Claudia; Hacon, Sandra S.; Moreira, Josino C.; Malm, Olaf

2012-01-01

Anthropogenic activities influence the biogeochemical cycles of mercury, both qualitatively and quantitatively, on a global scale from sources to sinks. Anthropogenic processes that alter the temporal and spatial patterns of sources and cycling processes are changing the impacts of mercury contamination on aquatic biota and humans. Human exposure to mercury is dominated by the consumption of fish and products from aquaculture operations. The risk to society and to ecosystems from mercury contamination is growing, and it is important to monitor these expanding risks. However, the extent and manner to which anthropogenic activities will alter mercury sources and biogeochemical cycling in tropical and sub-tropical coastal environments is poorly understood. Factors as (1) lack of reliable local/regional data; (2) rapidly changing environmental conditions; (3) governmental priorities and; (4) technical actions from supra-national institutions, are some of the obstacles to overcome in mercury cycling research and policy formulation. In the tropics and sub-tropics, research on mercury in the environment is moving from an exploratory “inventory” phase towards more process-oriented studies. Addressing biodiversity conservation and human health issues related to mercury contamination of river basins and tropical coastal environments are an integral part of paragraph 221 paragraph of the United Nations document “The Future We Want” issued in Rio de Janeiro in June 2012. PMID:22901765

Palm oil expansion in tropical forest margins or sustainability of production?

NARCIS (Netherlands)

Noordwijk, van M.; Pacheco, Pablo; Slingerland, M.A.; Dewi, S.; Khasanah, N.

2017-01-01

Palm oil expansion captures headlines, primarily out of concern that encroachment to tropical forest causes environmental problem and ignites social issues. Cascading ecological and social issues cause loss of trust, (threats of) consumer boycotts and multiple standards and certification responses.

Tropical Atlantic Hurricanes, Easterly Waves, and West African Mesoscale Convective Systems

Directory of Open Access Journals (Sweden)

Yves K. Kouadio

2010-01-01

Full Text Available The relationship between tropical Atlantic hurricanes (Hs, atmospheric easterly waves (AEWs, and West African mesoscale convective systems (MCSs is investigated. It points out atmospheric conditions over West Africa before hurricane formation. The analysis was performed for two periods, June–November in 2004 and 2005, during which 12 hurricanes (seven in 2004, five in 2005 were selected. Using the AEW signature in the 700 hPa vorticity, a backward trajectory was performed to the African coast, starting from the date and position of each hurricane, when and where it was catalogued as a tropical depression. At this step, using the Meteosat-7 satellite dataset, we selected all the MCSs around this time and region, and tracked them from their initiation until their dissipation. This procedure allowed us to relate each of the selected Hs with AEWs and a succession of MCSs that occurred a few times over West Africa before initiation of the hurricane. Finally, a dipole in sea surface temperature (SST was observed with a positive SST anomaly within the region of H generation and a negative SST anomaly within the Gulf of Guinea. This SST anomaly dipole could contribute to enhance the continental convergence associated with the monsoon that impacts on the West African MCSs formation.

Isotope aided studies on sheep and goat production in the Tropics

International Nuclear Information System (INIS)

1991-01-01

The fifteen papers in this volume have been indexed separately. The main focus of the coordinated research program was the use of radioisotopes to investigate ways of increasing the fertility and growth of sheep and goats in the Tropics. Refs, figs and tabs

Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific.

Science.gov (United States)

Ryan, John P; Green, Jonathan R; Espinoza, Eduardo; Hearn, Alex R

2017-01-01

Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100-350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in

Bioclimatic influence of extension of white and black coat color on Holstein cows production in a hot tropical climate

International Nuclear Information System (INIS)

Manrique P, Luis Phanor

1999-01-01

Was determined the influence of the white and black hair coat percentage in Holstein cows managed under hot climate condition at the San Jose del Hato farm, located in Palmira, Cauca Valley, Colombia. Three categories or classes of hair score were established, according to the white color distribution and with three observers it was determined the relative frequency of cows within each color category; the productive data were studied through an Anova using the least squares means method and Ducan test for means separation. The results were in agreement with the effect of color categories in the 305 days of milk production and in the total milk production (p < 0.05), being the best producer the cows group with 40 - 60 % white hair coats. These results showed the influence of the hair coat surface over the productive capability of Holstein cattle for selection programs in tropical conditions of hot climates

Are Mixed Tropical Tree Plantations More Resistant to Drought than Monocultures?

Directory of Open Access Journals (Sweden)

Norbert Kunert

2015-06-01

Full Text Available Tropical tree plantations usually consist of a single exotic fast growing species, but recent research describes positive effects on ecosystem functions from mixed tropical tree plantations. In this review, we present the current knowledge of drought resistance of tropical mixed species plantations and summarize preliminary evidence from a tree biodiversity experiment in Panama. Converting mono-specific stands into mixed ones may improve stand stability and might reduce increasing abiotic and biotic disturbances due to climate change. However, little is known about the extent to which tropical tree species or tropical tree communities can resist increasing disturbances in the short term, e.g., water limitations due to increasing dry season intensity or length, or about their resilience after such disturbances and their capacity to adapt to changing conditions in the long term. Studies relating drought resistance and resilience to community diversity are missing. Further, we highlight the urgent need for a multifactorial manipulative throughfall reduction experiment in tropical environments. The outcome of such studies would greatly assist the forestry sector in tropical regions to maintain highly productive and ecologically sound forest plantations in a changing climate.

Propagation of dry tropical forest trees in Mexico

Science.gov (United States)

Martha A. Cervantes Sanchez

2002-01-01

There is a distinct lack of technical information on the propagation of native tree species from the dry tropical forest ecosystem in Mexico. This ecosystem has come under heavy human pressures to obtain several products such as specialty woods for fuel, posts for fences and construction, forage, edible fruits, stakes for horticulture crops, and medicinal products. The...

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Simulation and Interpretation of the Genesis of Tropical Storm Gert (2005) as Part of the NASA Tropical Cloud Systems and Processes Experiment

Science.gov (United States)

Braun, Scott A.; Montgomery, Michael T.; Mallen, Kevin

2009-01-01

Several hypotheses have been put forward for the how tropical cyclones (tropical storms and hurricanes in the Atlantic) first develop circulation at the surface, a key event that needs to occur before a storm can begin to draw energy from the warm ocean. One hypothesis suggests that the surface circulation forms from a "top-down" approach in which a storm s rotating circulation begins at middle levels of the atmosphere and builds down to the surface through processes related to light "stratiform" (horizontally extensive) precipitation. Another hypothesis suggests a bottom-up approach in which deep thunderstorm towers (convection) play the major role in spinning up the flow at the surface. These "hot towers" form in the area of the mid-level circulation and strongly concentrate this rotation at low levels within their updrafts. Merger of several of these hot towers then intensifies the surface circulation to the point in which a storm forms. This paper examines computer simulations of Tropical Storm Gert (2005), which formed in the Gulf of Mexico during the National Aeronautics and Space Administration s (NASA) Tropical Cloud Systems and Processes (TCSP) Experiment, to investigate the development of low-level circulation and, in particular, whether stratiform or hot tower processes were responsible for the storm s formation. Data from NASA satellites and from aircraft were used to show that the model did a good job of reproducing the formation and evolution of Gert. The simulation shows that a mix of both stratiform and convective rainfall occurred within Gert. While the stratiform rainfall clearly acted to increase rotation at middle levels, the diverging outflow beneath the stratiform rain worked against spinning up the low-level winds. The hot towers appeared to dominate the low-level flow, producing intense rotation within their cores and often being associated with significant pressure falls at the surface. Over time, many of these hot towers merged, with each

Tropical forest soil microbial communities couple iron and carbon biogeochemistry

Energy Technology Data Exchange (ETDEWEB)

Dubinsky, E.A.; Silver, W.L.; Firestone, M.K.

2009-10-15

We report that iron-reducing bacteria are primary mediators of anaerobic carbon oxidation in upland tropical soils spanning a rainfall gradient (3500 - 5000 mm yr-1) in northeast Puerto Rico. The abundant rainfall and high net primary productivity of these tropical forests provide optimal soil habitat for iron-reducing and iron-oxidizing bacteria. Spatially and temporally dynamic redox conditions make iron-transforming microbial communities central to the belowground carbon cycle in these wet tropical forests. The exceedingly high abundance of iron-reducing bacteria (up to 1.2 x 10{sup 9} cells per gram soil) indicated that they possess extensive metabolic capacity to catalyze the reduction of iron minerals. In soils from the higher rainfall sites, measured rates of ferric iron reduction could account for up to 44 % of organic carbon oxidation. Iron reducers appeared to compete with methanogens when labile carbon availability was limited. We found large numbers of bacteria that oxidize reduced iron at sites with high rates of iron reduction and large numbers of iron-reducers. the coexistence of large populations of ironreducing and iron-oxidizing bacteria is evidence for rapid iron cycling between its reduced and oxidized states, and suggests that mutualistic interactions among these bacteria ultimately fuel organic carbon oxidation and inhibit CH4 production in these upland tropical forests.

CDOM fluorescence as a proxy of DOC concentration in natural waters: a comparison of four contrasting tropical systems.

Science.gov (United States)

Rochelle-Newall, E; Hulot, F D; Janeau, J L; Merroune, A

2014-01-01

Chromophoric dissolved organic matter (CDOM) fluorescence or absorption is often proposed as a rapid alternative to chemical methods for the estimation of bulk dissolved organic carbon (DOC) concentration in natural waters. However, the robustness of this method across a wide range of systems remains to be shown. We measured CDOM fluorescence and DOC concentration in four tropical freshwater and coastal environments (estuary and coastal, tropical shallow lakes, water from the freshwater lens of two small islands, and soil leachates). We found that although this method can provide an estimation of DOC concentration in sites with low variability in DOC and CDOM sources in systems where the variability of DOC and CDOM sources are high, this method should not be used as it will lead to errors in the estimation of the bulk DOC concentration.

Tropical Freshwater Biology

African Journals Online (AJOL)

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

Temperature and rainfall interact to control carbon cycling in tropical forests.

Science.gov (United States)

Taylor, Philip G; Cleveland, Cory C; Wieder, William R; Sullivan, Benjamin W; Doughty, Christopher E; Dobrowski, Solomon Z; Townsend, Alan R

2017-06-01

Tropical forests dominate global terrestrial carbon (C) exchange, and recent droughts in the Amazon Basin have contributed to short-term declines in terrestrial carbon dioxide uptake and storage. However, the effects of longer-term climate variability on tropical forest carbon dynamics are still not well understood. We synthesised field data from more than 150 tropical forest sites to explore how climate regulates tropical forest aboveground net primary productivity (ANPP) and organic matter decomposition, and combined those data with two existing databases to explore climate - C relationships globally. While previous analyses have focused on the effects of either temperature or rainfall on ANPP, our results highlight the importance of interactions between temperature and rainfall on the C cycle. In cool forests (forests (> 20 °C) it consistently enhanced both ANPP and decomposition. At the global scale, our analysis showed an increase in ANPP with rainfall in relatively warm sites, inconsistent with declines in ANPP with rainfall reported previously. Overall, our results alter our understanding of climate - C cycle relationships, with high precipitation accelerating rates of C exchange with the atmosphere in the most productive biome on earth. © 2017 John Wiley & Sons Ltd/CNRS.

Carbon budget of Nyungwe Tropical Montane Rain Forest in Central Africa

Science.gov (United States)

Nyirambangutse, B.; Zibera, E.; Uwizeye, F. K.; Hansson, L.; Nsabimana, D.; Pleijel, H.; Uddling, J.; Wallin, G.

2015-12-01

African tropical rainforests host rich biodiversity and play many roles at different scales such as local, regional and global, in the functioning of the earth system. Despite that the African tropical forests are the world's second largest, it has been neglected in terms of understanding the storage and fluxes of carbon and other nutrients. The question of whether this biome is a net sink or source of atmospheric CO2 is still not answered, and little is known concerning the climate change response. Tropical montane forests are even more poorly sampled compared with their importance. Deeper understanding of these ecosystems is required to provide insights on how they might react under global change. To answer questions related to these issues for African tropical montane forests, 15 permanent 0.5 ha plots were established in 2011 in Nyungwe tropical montane rainforest gazetted as a National Park to protect its extensive floral and faunal diversity. The plots are arranged along an east-westerly transect and includes both primary and secondary forest communities. The study is connected to the global ecosystem monitoring network (GEM, http://gem.tropicalforests.ox.ac.uk/). The aim is to characterize spatial and temporal heterogeneity of carbon and nutrient dynamics processes. The role of microclimate, topography, human disturbances, and plant species to the variability of these pools and processes will be explored. We compare stocks and fluxes of carbon and nutrients of the secondary and primary forest communities. The carbon stock are determined by an inventory of height and diameter at breast height (dbh) of all trees with a dbh above 5 cm, wood density, biomass of understory vegetation, leaf area index, standing and fallen dead wood, fine root biomass and organic content of various soil layers (litter, organic and mineral soil down to 45 cm depth). The carbon fluxes are determined by measurements of photosynthesis and respiration of leaves, above and below ground

NPP Tropical Forest: Manaus, Brazil, 1963-1990 , R1

Data.gov (United States)

National Aeronautics and Space Administration — This data set includes six ASCII files (.txt format). Five files contain productivity values for several types of tropical Amazon rainforest near Manaus, Brazil...

Relationships between meiofaunal biodiversity and prokaryotic heterotrophic production in different tropical habitats and oceanic regions.

Science.gov (United States)

Pusceddu, Antonio; Gambi, Cristina; Corinaldesi, Cinzia; Scopa, Mariaspina; Danovaro, Roberto

2014-01-01

Tropical marine ecosystems are among the most diverse of the world oceans, so that assessing the linkages between biodiversity and ecosystem functions (BEF) is a crucial step to predict consequences of biodiversity loss. Most BEF studies in marine ecosystems have been carried out on macrobenthic diversity, whereas the influence of the meiofauna on ecosystem functioning has received much less attention. We compared meiofaunal and nematode biodiversity and prokaryotic heterotrophic production across seagrass, mangrove and reef sediments in the Caribbean, Celebes and Red Seas. For all variables we report the presence of differences among habitats within the same region, and among regions within the same habitat. In all regions, the richness of meiofaunal taxa in reef and seagrass sediments is higher than in mangrove sediments. The sediments of the Celebes Sea show the highest meiofaunal biodiversity. The composition of meiofaunal assemblages varies significantly among habitats in the same region. The nematode beta diversity among habitats within the same region is higher than the beta diversity among regions. Although one site per habitat was considered in each region, these results suggest that the composition of meiofaunal assemblages varies primarily among biogeographic regions, whereas the composition of nematode assemblages varies more considerably among habitats. Meiofauna and nematode biodiversity and prokaryotic heterotrophic production, even after the removal of covariate effects linked with longitude and the quantity and nutritional quality of organic matter, are positively and linearly linked both across regions and within each habitat type. Our results confirm that meiofauna and nematode biodiversity may influence benthic prokaryotic activity, which, in turn, implies that diversity loss could have negative impacts on ecosystem functioning in these systems.

Relationships between meiofaunal biodiversity and prokaryotic heterotrophic production in different tropical habitats and oceanic regions.

Directory of Open Access Journals (Sweden)

Antonio Pusceddu

Full Text Available Tropical marine ecosystems are among the most diverse of the world oceans, so that assessing the linkages between biodiversity and ecosystem functions (BEF is a crucial step to predict consequences of biodiversity loss. Most BEF studies in marine ecosystems have been carried out on macrobenthic diversity, whereas the influence of the meiofauna on ecosystem functioning has received much less attention. We compared meiofaunal and nematode biodiversity and prokaryotic heterotrophic production across seagrass, mangrove and reef sediments in the Caribbean, Celebes and Red Seas. For all variables we report the presence of differences among habitats within the same region, and among regions within the same habitat. In all regions, the richness of meiofaunal taxa in reef and seagrass sediments is higher than in mangrove sediments. The sediments of the Celebes Sea show the highest meiofaunal biodiversity. The composition of meiofaunal assemblages varies significantly among habitats in the same region. The nematode beta diversity among habitats within the same region is higher than the beta diversity among regions. Although one site per habitat was considered in each region, these results suggest that the composition of meiofaunal assemblages varies primarily among biogeographic regions, whereas the composition of nematode assemblages varies more considerably among habitats. Meiofauna and nematode biodiversity and prokaryotic heterotrophic production, even after the removal of covariate effects linked with longitude and the quantity and nutritional quality of organic matter, are positively and linearly linked both across regions and within each habitat type. Our results confirm that meiofauna and nematode biodiversity may influence benthic prokaryotic activity, which, in turn, implies that diversity loss could have negative impacts on ecosystem functioning in these systems.

Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

Directory of Open Access Journals (Sweden)

Émilie Saulnier-Talbot

Full Text Available African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2 adj  = 0.23, e.d.f. = 7, p<0.0001 in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions.

Impacts of tropical cyclones on Fiji and Samoa

Science.gov (United States)

Kuleshov, Yuriy; Prakash, Bipendra; Atalifo, Terry; Waqaicelua, Alipate; Seuseu, Sunny; Ausetalia Titimaea, Mulipola

2013-04-01

Weather and climate hazards have significant impacts on Pacific Island Countries. Costs of hazards such as tropical cyclones can be astronomical making enormous negative economic impacts on developing countries. We highlight examples of extreme weather events which have occurred in Fiji and Samoa in the last few decades and have caused major economic and social disruption in the countries. Destructive winds and torrential rain associated with tropical cyclones can bring the most damaging weather conditions to the region causing economic and social hardship, affecting agricultural productivity, infrastructure and economic development which can persist for many years after the initial impact. Analysing historical data, we describe the impacts of tropical cyclones Bebe and Kina on Fiji. Cyclone Bebe (October 1972) affected the whole Fiji especially the Yasawa Islands, Viti Levu and Kadavu where hurricane force winds have been recorded. Nineteen deaths were reported and damage costs caused by cyclone Bebe were estimated as exceeding F20 million (F 1972). Tropical cyclone Kina passed between Fiji's two main islands of Viti Levu and Vanua Levu, and directly over Levuka on the night of 2 January 1993 with hurricane force winds causing extensive damage. Twenty three deaths have been reported making Kina one of the deadliest hurricanes in Fiji's recent history. Severe flooding on Viti Levu, combined with high tide and heavy seas led to destruction of the Sigatoka and Ba bridges, as well as almost complete loss of crops in Sigatoka and Navua deltas. Overall, damage caused by cyclone Kina was estimated as F170 million. In Samoa, we describe devastation to the country caused by tropical cyclones Ofa (February 1990) and Val (December 1991) which were considered to be the worst cyclones to affect the Samoan islands since the 1889 Apia cyclone. In Samoa, seven people were killed due to cyclone Ofa, thousands of people were left homeless and entire villages were destroyed. Damage

Net Primary Productivity and Edaphic Fertility in Two Pluvial Tropical Forests in the Chocó Biogeographical Region of Colombia.

Science.gov (United States)

Quinto-Mosquera, Harley; Moreno, Flavio

2017-01-01

The net primary productivity (NPP) of tropical forests is a key process of the carbon cycle and therefore for the mitigation of global climate change. It has been proposed that NPP is limited by the availability of soil nutrients in lowland tropical forests and that belowground NPP decreases as edaphic fertility increases. This hypothesis was evaluated in two localities (Opogodó and Pacurita) of the Chocó Biogeographical region, one of the rainiest of the world, where the aboveground (litter and wood) and belowground (fine and coarse roots) components of NPP were measured. Fertility parameters (pH, nutrients, and texture) were also determined and related to NPP. Total NPP was similar between locations (23.7 vs. 24.2 t ha-1 year-1 for Opogodó and Pacurita, respectively). However, components of NPP showed differences: in Pacurita, with steeper topography, NPP of wood and coarse roots were higher; therefore, differences of topography and drainage between localities probably affected the NPP of wood. On the other hand, soils of Opogodó, where NPP of fine roots was higher, showed higher contents of sand, N+, and organic matter (OM). With the increase of pH, OM, N+, K, Mg, and sand, the NPP of leaves and fine roots as well as the percentage of NPP belowground also increased, which suggests NPP limitation by multiple nutrients. The increase of NPP belowground with the availability of edaphic nutrients evidenced a redistribution of the aboveground and belowground components of NPP with the increase of soil fertility in oligotrophic systems, probably as a mechanism to improve the capture of resources.

The Economic Importance of Forest Products in Enugu State, Nigeria

African Journals Online (AJOL)

The Economic Importance of Forest Products in Enugu State, Nigeria. ... International Journal of Tropical Agriculture and Food Systems ... The regression results, showed that access to modern forest products harvesting/processing technology (Te) and relative contribution of forest output in total household economy (Ro) ...

Applications of NASA TROPICS Data for Tropical Cyclone Analysis, Nowcasting, and Impacts

Science.gov (United States)

Zavodsky, B.; Dunion, J. P.; Blackwell, W. J.; Braun, S. A.; Green, D. S.; Velden, C.; Adler, R. F.; Cossuth, J.; Murray, J. J.; Brennan, M. J.

2017-12-01

The National Aeronautics and Space Administration (NASA) Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission is a constellation of state-of-the-science observing platforms that will measure temperature and humidity soundings and precipitation with spatial resolution comparable to current operational passive microwave sounders but with unprecedented temporal resolution. TROPICS is a cost-capped ($30M) Venture-class mission funded by the NASA Earth Science Division. The mission is comprised of a constellation of 3 unit (3U) SmallSats, each hosting a 12-channel passive microwave spectrometer based on the Micro-sized Microwave Atmospheric Satellite 2 (MicroMAS-2) developed at MIT LL. TROPICS will provide imagery near 91 and 205 GHz, temperature sounding near 118 GHz, and moisture sounding near 183 GHz. Spatial resolution at nadir will be around 27 km for temperature and 17 km for moisture and precipitation. The swath width is approximately 2000 km. TROPICS enables temporal resolution similar to geostationary orbit but at a much lower cost, demonstrating a technology that could impact the design of future Earth-observing missions. The TROPICS satellites for the mission are slated for delivery to NASA in 2019 with potential launch opportunities in 2020. The primary mission objective of TROPICS is to relate temperature, humidity, and precipitation structure to the evolution of tropical cyclone (TC) intensity. This abstract summarizes the outcomes of the 1st TROPICS Applications Workshop, held from May 8-10, 2017 at the University of Miami. At this meeting, a series of presentations and breakout discussions in the topical areas of Tropical Cyclone Dynamics, Tropical Cyclone Analysis and Nowcasting, Tropical Cyclone Modeling and Data Assimilation, and Terrestrial Impacts were convened to identify applications of the mission data and to begin to establish a community of end-users who will be able to

Neglected tropical diseases

Directory of Open Access Journals (Sweden)

David Molyneux

2013-08-01

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

The Path Forward from Paris: the Challenge for Tropical Countries

Science.gov (United States)

Nobre, C.

2016-12-01

The pledges of emissions reductions put forth at the COP21 in Paris fall short of ensuring the desired guardrail of 2 C warming, let alone the more stringent, but necessary, goal of 1.5 C warming if we want to minimize the increasing risks of climate change over both the short term of decades and the long term of centuries. Decarbonization of the global economy is mandatory, which implies a gargantuan challenge of decarbonizing the energy system. Given the likelihood of decreasing strength of the natural sinks in the global oceans and land biota as warming progresses, it may be necessary to reach nearly zero net emissions by midcentury and even negative net emissions by the end of the century. In addition to massive and rapid implementation of renewable energy systems, desirable mitigation trajectories involve large-scale reforestation and ecosystem restoration and also bioenergy capture and storage systems (BECCS). Tropical countries can play an important role to meet both goals as long as they are able to implement sustainable agriculture at the large scale that is nearly carbon-neutral and resilient to unavoidable climate change. And reaching sustainability in the agricultural sector—remembering that agricultural direct emissions and indirect emissions due to deforestation account for almost one quarter of global emissions—is under the constraint to meet food security for all, that is, food production has to grow 70% by midcentury, with concomitant reduction of waste in the food chain. I will take the example of mitigation options for Brazil—a large tropical country with per capita emissions of about 7.5 ton CO2-eq—to illustrate sustainable development trajectories of reaching carbon neutrality by midcentury. That will imply developing a modern, more productive carbon-neutral agriculture within the next two decades, reducing tropical deforestation to nearly zero within a decade, restoring ecosystems and increasing renewable energy use to over 80% of its

Opportunities for reducing greenhouse gas emissions in tropical peatlands.

Science.gov (United States)

Murdiyarso, D; Hergoualc'h, K; Verchot, L V

2010-11-16

The upcoming global mechanism for reducing emissions from deforestation and forest degradation in developing countries should include and prioritize tropical peatlands. Forested tropical peatlands in Southeast Asia are rapidly being converted into production systems by introducing perennial crops for lucrative agribusiness, such as oil-palm and pulpwood plantations, causing large greenhouse gas (GHG) emissions. The Intergovernmental Panel on Climate Change Guidelines for GHG Inventory on Agriculture, Forestry, and Other Land Uses provide an adequate framework for emissions inventories in these ecosystems; however, specific emission factors are needed for more accurate and cost-effective monitoring. The emissions are governed by complex biophysical processes, such as peat decomposition and compaction, nutrient availability, soil water content, and water table level, all of which are affected by management practices. We estimate that total carbon loss from converting peat swamp forests into oil palm is 59.4 ± 10.2 Mg of CO(2) per hectare per year during the first 25 y after land-use cover change, of which 61.6% arise from the peat. Of the total amount (1,486 ± 183 Mg of CO(2) per hectare over 25 y), 25% are released immediately from land-clearing fire. In order to maintain high palm-oil production, nitrogen inputs through fertilizer are needed and the magnitude of the resulting increased N(2)O emissions compared to CO(2) losses remains unclear.

Tropical Rainforests.

Science.gov (United States)

Nigh, Ronald B.; Nations, James D.

1980-01-01

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

Primary production and chlorophyll distributions in the subtropical and tropical waters of the Atlantic Ocean in the autumn of 2002

Science.gov (United States)

Vedernikov, V. I.; Gagarin, V. I.; Demidov, A. B.; Burenkov, V. I.; Stunzhas, P. A.

2007-06-01

In October and November 2002, high and relatively high values of the chlorophyll a concentration at the sea surface ( C chl) were observed in the English Channel (0.47 mg/m3), in the waters of the North Atlantic Current (0.25 mg/m3), in the tropical and subtropical anticyclonic gyres (0.07-0.42 mg/m3), and also in the southwestern region of the southern subtropical anticyclonic gyre (usually 0.11-0.23 mg/m3). The central regions of the southern subtropical anticyclonic gyre (SATG) and the North Atlantic tropical gyre (NATR) were characterized by lower values of C chl (0.02-0.08 mg/m3 for the SATG and 0.07-0.14 mg/m3 for the NATR). At most of the SATG stations, the values of the surface primary production ( C phs) varied from 2.5 to 5.5 mg C/m3 per day and were mainly defined by the fluctuations of C chl ( r = +0.78) rather than by those of the assimilation number ( r = +0.54). The low assimilation activity of phytoplankton in these waters (1.3-4.6 mg chl a per hour) pointed to a lack of nutrients. An analysis of the variability of their concentration and the composition of photosynthetic pigments showed that, in the waters north of 30° N, the growth of phytoplankton was mostly restricted by the deficiency of nitrogen, while, in more southern areas, at the majority of stations (about 60%), the phosphorus concentrations were the minimum. At the low concentrations of nitrates and nitrites, ammonium represented itself as a buffer that prevented planktonic algae from extreme degrees of nitric starvation. In the tropical waters and in the waters of the SATG, the primary production throughout the water column varied from 240 to 380 mg C/m2 30° per day. This level of productivity at stations with low values of C chl (photosynthesis based on in situ measurements point to the high efficiency of utilizing the penetrating solar radiation by phytoplankton on cloudy days.

Understanding Recent Trends in Freezing Level Height over the Tropical Andes Mountains of South America: An Investigation of Reanalysis Products and GEOSCCM Integrations.

Science.gov (United States)

Zaitchik, B. F.; Russell, A.; Gnanadesikan, A.

2015-12-01

As the global climate warms, the height of the 0°C isotherm - aka the freezing level height (FLH) - rises, especially over mountainous regions. Over the past few decades, FLH in the tropical Andes Mountains of South America has been rising at a rate that is 2 to 3 times faster than would be expected considering the zonally-averaged upper troposphere temperature trends and the recent cooling of Pacific Ocean sea surface temperatures. Rising FLH could have devastating impacts in this region where most of the dry season runoff comes from seasonal snow melt and glacial melt. Yet, is unclear why FLH is rising so rapidly in this particular area and what the quantitative implications will be for tropical Andean water resources. Reanalysis products tend to disagree on the spatial pattern and strength of FLH changes which confounds the issue by making it difficult to uncover the driving mechanisms of these local changes in FLH. Indeed, there are several possible factors that may be contributing to the unprecedented rise in FLH over the Andes (above and beyond the normally expected effects of greenhouse gases) of which the most likely actors are: changes in the state of the tropical Pacific Ocean, changes in sea surface temperatures in the Atlantic Ocean, shifts in the Hadley cell, indirect effects of stratospheric ozone depletion and recent recovery, and local thermodynamic land-atmosphere feedbacks. To better understand the changes in FLH, which will ultimately contribute to the effort to predict effects on Andean water resources, we analyze FLH in several forcing-separated integrations of the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). By separating out the various forcings (greenhouse gases, sea surface temperatures, ozone depleting substances, volcanic eruptions, and solar fluctuations), we are able to develop hypotheses for mechanistic drivers of FLH changes which can be rigorously tested. These efforts will contribute to the understanding of

Rethinking plant functional types in Earth System Models: pan-tropical analysis of tree survival across environmental gradients

Science.gov (United States)

Johnson, D. J.; Needham, J.; Xu, C.; Davies, S. J.; Bunyavejchewin, S.; Giardina, C. P.; Condit, R.; Cordell, S.; Litton, C. M.; Hubbell, S.; Kassim, A. R. B.; Shawn, L. K. Y.; Nasardin, M. B.; Ong, P.; Ostertag, R.; Sack, L.; Tan, S. K. S.; Yap, S.; McDowell, N. G.; McMahon, S.

2016-12-01

Terrestrial carbon cycling is a function of the growth and survival of trees. Current model representations of tree growth and survival at a global scale rely on coarse plant functional traits that are parameterized very generally. In view of the large biodiversity in the tropical forests, it is important that we account for the functional diversity in order to better predict tropical forest responses to future climate changes. Several next generation Earth System Models are moving towards a size-structured, trait-based approach to modelling vegetation globally, but the challenge of which and how many traits are necessary to capture forest complexity remains. Additionally, the challenge of collecting sufficient trait data to describe the vast species richness of tropical forests is enormous. We propose a more fundamental approach to these problems by characterizing forests by their patterns of survival. We expect our approach to distill real-world tree survival into a reasonable number of functional types. Using 10 large-area tropical forest plots that span geographic, edaphic and climatic gradients, we model tree survival as a function of tree size for hundreds of species. We found surprisingly few categories of size-survival functions emerge. This indicates some fundamental strategies at play across diverse forests to constrain the range of possible size-survival functions. Initial cluster analysis indicates that four to eight functional forms are necessary to describe variation in size-survival relations. Temporal variation in size-survival functions can be related to local environmental variation, allowing us to parameterize how demographically similar groups of species respond to perturbations in the ecosystem. We believe this methodology will yield a synthetic approach to classifying forest systems that will greatly reduce uncertainty and complexity in global vegetation models.

An eddy-permitting, dynamically consistent adjoint-based assimilation system for the tropical Pacific: Hindcast experiments in 2000

KAUST Repository

Hoteit, Ibrahim

2010-03-02

An eddy-permitting adjoint-based assimilation system has been implemented to estimate the state of the tropical Pacific Ocean. The system uses the Massachusetts Institute of Technology\\'s general circulation model and its adjoint. The adjoint method is used to adjust the model to observations by controlling the initial temperature and salinity; temperature, salinity, and horizontal velocities at the open boundaries; and surface fluxes of momentum, heat, and freshwater. The model is constrained with most of the available data sets in the tropical Pacific, including Tropical Atmosphere and Ocean, ARGO, expendable bathythermograph, and satellite SST and sea surface height data, and climatologies. Results of hindcast experiments in 2000 suggest that the iterated adjoint-based descent is able to significantly improve the model consistency with the multivariate data sets, providing a dynamically consistent realization of the tropical Pacific circulation that generally matches the observations to within specified errors. The estimated model state is evaluated both by comparisons with observations and by checking the controls, the momentum balances, and the representation of small-scale features that were not well sampled by the observations used in the assimilation. As part of these checks, the estimated controls are smoothed and applied in independent model runs to check that small changes in the controls do not greatly change the model hindcast. This is a simple ensemble-based uncertainty analysis. In addition, the original and smoothed controls are applied to a version of the model with doubled horizontal resolution resulting in a broadly similar “downscaled” hindcast, showing that the adjustments are not tuned to a single configuration (meaning resolution, topography, and parameter settings). The time-evolving model state and the adjusted controls should be useful for analysis or to supply the forcing, initial, and boundary conditions for runs of other models.

A spatial model for the economic evaluation of biomass production systems

International Nuclear Information System (INIS)

Wei Liu; Phillips, V.D.; Singh, Devindar

1992-01-01

A system model for estimating short-rotation, intensive-culture woody biomass production costs, including establishment, maintenance, harvesting, and transport costs, was developed and applied to the island of Kauai. Using data from existing large-plot field trials, biomass yield of the tropical hardwood Eucalyptus saligna was predicted from site-specific factors such as local weather and soil conditions and management strategies. Possible harvesting systems were identified and associated harvesting costs were estimated. The distances from the plantation sites to a bio-conversion plant located at the Lihue sugar mill were calculated based on existing road networks. The delivered cost of biomass on a dollar per dry metric ton (Mg) basis was then calculated using a discounted cash flow method. A geographic information system was interfaced with the biomass system model to access a database and present results in map form. Under the most favorable management strategy modeled, approximately 330 x 10 3 dry Mg year -1 of Eucalyptus saligna could be produced from 12,000 ha at a delivered cost of $25-38 per dry Mg chips. (author)

Increasing production, the sustained yield method, and reserve structure of agrisilvicultural ecosystems in the moist tropics

Energy Technology Data Exchange (ETDEWEB)

Bruenig, E F

1980-09-01

While substantial improvements first of all require a profound change of political attitudes and the replacement of irrational ideological creeds, improvements of the food situation in addition needs the application of ecologically adapted and economically sound land use techniques. This in turn requires scientific knowledge of the interrelationships between site factors and the structure and functions of crop types. The principles of the structural design of tropical virgin forest ecosystems can be usefully adapted for the development of agroforestry crop types. Such crop types should be capable of producing a sustained yield of food, timber, fuel, medicinal substances, spices and other useful products and, in addition, produce favourable, stabilizing effects on the local, regional and finally global biosphere.

A New Coupled Ocean-Waves-Atmosphere Model Designed for Tropical Storm Studies: Example of Tropical Cyclone Bejisa (2013-2014) in the South-West Indian Ocean

Science.gov (United States)

Pianezze, J.; Barthe, C.; Bielli, S.; Tulet, P.; Jullien, S.; Cambon, G.; Bousquet, O.; Claeys, M.; Cordier, E.

2018-03-01

Ocean-Waves-Atmosphere (OWA) exchanges are not well represented in current Numerical Weather Prediction (NWP) systems, which can lead to large uncertainties in tropical cyclone track and intensity forecasts. In order to explore and better understand the impact of OWA interactions on tropical cyclone modeling, a fully coupled OWA system based on the atmospheric model Meso-NH, the oceanic model CROCO, and the wave model WW3 and called MSWC was designed and applied to the case of tropical cyclone Bejisa (2013-2014). The fully coupled OWA simulation shows good agreement with the literature and available observations. In particular, simulated significant wave height is within 30 cm of measurements made with buoys and altimeters. Short-term (right place (in the eyewall of the tropical cyclone) and with the right size distribution, which is critical for cloud microphysics.

Trade, tropical deforestation and policy interventions

International Nuclear Information System (INIS)

Barbier, E.B.; Rauscher, M.

1992-01-01

This paper examines several aspects of the links between the trade in tropical timber and deforestation from the perspective of an exporting country. The various versions of the model developed here have highlighted a number of important features of this linkage. First, if the producer country values its tropical forest solely as a source of timber export earnings then it will aim for a smaller forest stock in the long run than if it also considers the other values provided by the forest. Second, if importing nations want the exporting countries to conserve more of their forests, trade interventions appear to be second-best way of achieving this result. Third, increased market power by a large country exporter or group of exporters may actually lead to greater forest conservation. Finally, the existence of a foreign capital market may further ensure that the tropical timber country may conserve its forest stock in the long run. Several recent reviews of global forest sector policies have discussed implications similar to those analyzed theoretically in our model. Generally, the same conclusions have been reached. However, what is of increasing concern is that domestic market and policy failures within tropical forest countries continue to distort the incentives for more sustainable management of timber production and efficient development of processing capacity, while at the same time the international community increasingly contemplates the use of bans, tariffs and other trade measures to discourage 'unsustainable' tropical timber exploitation. As our paper has attempted to show, sometimes the more simple solutions lead neither to a straightforward, nor to the desired, results. 18 refs, 1 fig

Phytogeography of the tropical north-east African mountains

Directory of Open Access Journals (Sweden)

I. Friis

1983-11-01

Full Text Available The tropical north-east African mountains are tentatively divided into four phytochoria, the formal rank of which is not defined. The division is based on patterns of distribution and endemism in the region. The recognition of a distinct Afromontane phytochorion is now well established (Chapman & White, 1970; Werger, 1978; White, 1978. However, there is still very little information on the phytogeography of the individual mountains or mountain systems. This study hopes to fill a little of the gap by analysing distribution patterns and patterns of endemism in the flora of the tropical north-east African mountains. The north-east African mountain system is the largest in tropical Africa (see e.g. map in White, 1978. At the core of this system is the large Ethiopian massif, around which are located various mountains and mountain chains. These include the Red Sea Hills in the Sudan, the mountain chain in northern Somalia, the south-west Arabian mountains, and the Imatong mountains of south-east Sudan. The latter are often referred to the East African mountain system (White, 1978 but. as I will point out later, they also have a close connection with the south-west highlands of Ethiopia. The paper presents some results of my study of the mountain flora of tropical north-east Africa, particularly the forest species. Where no source is indicated, the data are from my own unpublished studies.

Earthworms in tropical tree plantations: effects of management and relations with soil carbon and nutrient use efficiency

Science.gov (United States)

X Zou; Grizelle Gonzalez

2001-01-01

With the vast amount of abandoned tropical land due to non- sustainable farming practices, tropical tree-plantations become an effective means in restoring soil productivity and preserving ecosystem biodiversity. Because earthworms are the dominant soil fauna in moist tropical regions and play an important role in improving soil fertility, understanding the mechanisms...

Automatic Type Recognition and Mapping of Global Tropical Cyclone Disaster Chains (TDC

Directory of Open Access Journals (Sweden)

Ran Wang

2016-10-01

Full Text Available The catastrophic events caused by meteorological disasters are becoming more severe in the context of global warming. The disaster chains triggered by Tropical Cyclones induce the serious losses of population and economy. It is necessary to make the regional type recognition of Tropical Cyclone Disaster Chain (TDC effective in order to make targeted preventions. This study mainly explores the method of automatic recognition and the mapping of TDC and designs a software system. We constructed an automatic recognition system in terms of the characteristics of a hazard-formative environment based on the theory of a natural disaster system. The ArcEngine components enable an intelligent software system to present results by the automatic mapping approach. The study data comes from global metadata such as Digital Elevation Model (DEM, terrain slope, population density and Gross Domestic Product (GDP. The result shows that: (1 according to the characteristic of geomorphology type, we establish a type of recognition system for global TDC; (2 based on the recognition principle, we design a software system with the functions of automatic recognition and mapping; and (3 we validate the type of distribution in terms of real cases of TDC. The result shows that the automatic recognition function has good reliability. The study can provide the basis for targeted regional disaster prevention strategy, as well as regional sustainable development.

Tropical Rainfall Measuring Mission: Monitoring the Global Tropics for 3 Years and Beyond. 1.1

Science.gov (United States)

Shepherd, Marshall; Starr, David OC. (Technical Monitor)

2001-01-01

The Tropical Rainfall Measuring Mission (TRMM) was launched in November 1997 as a joint U.S.-Japanese mission to advance understanding of the global energy and water cycle by providing distributions of rainfall and latent heating over the global tropics. As a part of NASA's Earth System Enterprise, TRMM seeks to understand the mechanisms through which changes in tropical rainfall influence global circulation. Additionally, a goal is to improve the ability to model these processes in order to predict global circulations and rainfall variability at monthly and longer time scales. Such understanding has implications for assessing climate processes related to El Nino/La Nina and Global Warming. TRMM has also provided unexpected and exciting new knowledge and applications in areas related to hurricane monitoring, lightning, pollution, hydrology, and other areas. This CD-ROM includes a self-contained PowerPoint presentation that provides an overview of TRMM and significant science results; a set of data movies or animation; and listings of current TRMM-related publications in the literature.

Mangroves among the most carbon-rich forests in the tropics

Science.gov (United States)

Donato, Daniel C.; Kauffman, J. Boone; Murdiyarso, Daniel; Kurnianto, Sofyan; Stidham, Melanie; Kanninen, Markku

2011-05-01

Mangrove forests occur along ocean coastlines throughout the tropics, and support numerous ecosystem services, including fisheries production and nutrient cycling. However, the areal extent of mangrove forests has declined by 30-50% over the past half century as a result of coastal development, aquaculture expansion and over-harvesting. Carbon emissions resulting from mangrove loss are uncertain, owing in part to a lack of broad-scale data on the amount of carbon stored in these ecosystems, particularly below ground. Here, we quantified whole-ecosystem carbon storage by measuring tree and dead wood biomass, soil carbon content, and soil depth in 25 mangrove forests across a broad area of the Indo-Pacific region--spanning 30° of latitude and 73° of longitude--where mangrove area and diversity are greatest. These data indicate that mangroves are among the most carbon-rich forests in the tropics, containing on average 1,023Mg carbon per hectare. Organic-rich soils ranged from 0.5m to more than 3m in depth and accounted for 49-98% of carbon storage in these systems. Combining our data with other published information, we estimate that mangrove deforestation generates emissions of 0.02-0.12Pg carbon per year--as much as around 10% of emissions from deforestation globally, despite accounting for just 0.7% of tropical forest area.

Diaspore bank of bryophytes in tropical rain forests: the importance of breeding system, phylum and microhabitat.

Science.gov (United States)

Maciel-Silva, Adaíses S; Válio, Ivany Ferraz Marques; Rydin, Håkan

2012-02-01

Diaspore banks are crucial for the maintenance and resilience of plant communities, but diaspore banks of bryophytes remain poorly known, especially from tropical ecosystems. This is the first study to focus on the role of diaspore banks of bryophytes in tropical rain forests. Our aim was to test whether microhabitat (substrate type) and species traits (breeding system, phylum) are important in explaining the diaspore bank composition. Using samples cultivated in the laboratory, we assessed the number of species and shoots emerging from bark, decaying wood and soil from two sites of the Atlantic rain forest (montane and sea level) in Brazil by comparing the contribution of species by phylum (mosses, liverworts) and breeding system (monoicous, dioicous). More species emerged from bark (68) and decaying wood (55) than from soil (22). Similar numbers of species were found at both sites. Mosses were more numerous in terms of number of species and shoots, and monoicous species dominated over dioicous species. Substrate pH had only weak effects on shoot emergence. Species commonly producing sporophytes and gemmae had a high contribution to the diaspore banks. These superficial diaspore banks represented the extant vegetation rather well, but held more monoicous species (probably short-lived species) compared to dioicous ones. We propose that diaspore bank dynamics are driven by species traits and microhabitat characteristics, and that short-term diaspore banks of bryophytes in tropical rain forests contribute to fast (re)establishment of species after disturbances and during succession, particularly dioicous mosses investing in asexual reproduction and monoicous mosses investing in sexual reproduction.

W Photoprotection in Tropical Marine Organisms

Science.gov (United States)

Armstrong, Roy A.

1997-01-01

Increasing levels of ultraviolet (UV) radiation reaching the earth's surface which results from stratospheric ozone depletions could have serious implications for terrestrial plants and for aquatic organisms within the euphotic zone. A documented 9% decline in ozone at mid-latitudes is considered to produce a 12% increase in harmful UV radiation. The biologically damaging effects of higher UV levels, particularly W-B (280-320 rim), could manifest earlier in the tropics because of the relative thinness of the earth's equatorial ozone layer. Tropical marine organisms are also living close to their upper tolerance levels of water temperature, However, despite the large potential effects on plants and animals, little is known about UV effects on tropical ecosystems. Long-term ecological studies are needed to quantify the effects of increased UV radiation on terrestrial and marine ecosystems and to produce reliable data for prediction. Plants have developed several mechanisms to protect themselves from harmful UV radiation, one of which is the production of secondary leaf pigments that absorb W-B radiation (screening pigments). A higher concentration of screening pigments (e.g. flavonoids) in leaves may be interpreted as a natural response to increased W radiation. If higher concentrations of flavonoids filter out the excessive W radiation, no damage will occur, as suggested by Caldwell et al. (1989) and Tevini (1993). Failure to screen all W-B may result in deleterious effects on photosynthesis, plant genetic material, and plant and leaf morphology and growth. Eventually this will have an impact on ecosystem processes, structure, species composition, and productivity. This paper describes an ongoing project that is assessing the responses of mangroves, seagrasses and corals to W radiation by studying pigment concentrations, biophysical parameters, and variations in spectral reflectance in the field and in W-reduction experiments. Preliminary results on the distribution

Simulation of maize growth under conservation farming in tropical environments.

NARCIS (Netherlands)

Stroosnijder, L.; Kiepe, P.

1998-01-01

This book is written for students and researchers with a keen interest in the quantification of the field soil water balance in tropical environments and the effect of conservation farming on crop production. Part 1 deals with the potential production, i.e. crop growth under ample supply of water

Assessment of water availability and its relationship with vegetation distribution over a tropical montane system

Science.gov (United States)

Streher, A. S.; Sobreiro, J. F. F.; Silva, T. S. F.

2017-12-01

Water availability is one of the main drivers of vegetation distribution, but assessing it over mountainous regions is difficult given the effects of rugged topography on hydroclimatic dynamics (orographic rainfall, soil water, and runoff). We assessed how water availability may influence the distribution of vegetation types in the Espinhaço Range, a South American tropical mountain landscape comprised of savannas, grasslands, rock outcrops, cloud forests, and semi-deciduous/deciduous forests. For precipitation, we used CHIRPS monthly and daily products (1981- 2016) and 112 rain gauge ground stations, and assessed potential evapotranspiration (PET) using the MODIS MOD16A3 (2000-2013) product. Vegetation types were classified according to the Global Ecoregions by WWF. We show that rainfall has well-defined rainy and dry seasons with a strong latitudinal pattern, there is evidence for local orographic effects. Dry forests (907 mm/yr; 8% cv) and caatinga vegetation (795 mm/yr; 7% cv) had the lowest average annual precipitation and low variance, whilst Atlantic tropical forest in the southeast (1267 mm/yr; 15% cv), cerrado savanna vegetation in the west (1086 mm/yr; 15% cv) and rupestrian grasslands above 800m (1261 mm/yr; 20% cv) received the highest annual precipitation, with the largest observed variance due to their wide latitudinal distribution. Forests and rupestrian grasslands in the windward side of the mountain had a higher frequency of intense rainfall events (> 20mm), accounting for 6% of the CHIRPS daily time series, suggesting orographic effects on precipitation. Annual average PET was highest for dry forests (2437 mm/yr) and caatinga (2461 mm/yr), intermediate for cerrado (2264 mm/yr) and lowest for Atlantic tropical forest (2083 mm/yr) and rupestrian grasslands (2136 mm/yr). All vegetation types received less rainfall than its PET capacity based on yearly data, emphasizing the need for ecophysiological adaptations to water use. Climate change threatens

Fungal and Oomycete Diseases of Tropical Tree Fruit Crops.

Science.gov (United States)

Drenth, André; Guest, David I

2016-08-04

The tropics produce a range of fruit from tree crops that cannot be grown in colder climates. Bananas, mangos, several nuts, spices, coffee, and cacao are widely traded and much sought after around the world. However, the sustainable production of these tropical tree fruit crops faces significant challenges. Among these, losses due to pests and diseases play a large part in reducing yields, quality, and profitability. Using bananas and cacao as key examples, we outline some of the reasons fungal and oomycete diseases cause such significant losses to tropical tree crops. Cultivation of monocultures derived from limited genetic diversity, environmental conditions conducive for disease development, high levels of disease incidence and severity, a lack of disease resistance in planting materials, shortages of labor, and inadequate infrastructure and investment pose significant challenges, especially for smallholder producers. The expansion of travel and trade has given rise to emerging infectious plant diseases that add further insecurity and pressure. We conclude that holistic actions are needed on multiple fronts to address the growing problem of disease in tropical fruit tree crops.

Proceedings of the session on tropical forestry for people of the Pacific, XVII Pacific Science Congress; May 27-28, 1991

Science.gov (United States)

Eugene C. Conrad; Leonard A. Newell

1992-01-01

The 17 papers in the Proceedings of the Session on Tropical Forestry for People of the Pacific cover the topics of the USDA Forest Service's tropical forestry research, forestry research in Asia and the Pacific, management of tropical forests for products and energy; forest and wildlife management, the South Pacific Forestry Development Programme, tropical...

Governance for quality management in tropical food chains

NARCIS (Netherlands)

Tilburg, van A.; Trienekens, J.H.; Ruben, R.; Boekel, van M.A.J.S.

2007-01-01

This paper provides a framework that focuses on the linkages between several key dimensions of supply chain organisation and performance of perishable tropical food products. The focus is on the relationship between governance regime and quality management, however, two other related variables are

Mutualism, hybrid inviability and speciation in a tropical ant-plant.

Science.gov (United States)

Léotard, G; Saltmarsh, A; Kjellberg, F; McKey, D

2008-07-01

Although biotic interactions are particularly intricate in the tropics, few studies have examined whether divergent adaptations to biotic interactions lead to speciation in tropical organisms. Ant-plant mutualisms are widespread in the tropics. Within Leonardoxa africana, two subspecies present contrasting defences against herbivores. Young leaves of subsp. africana are defended by mutualistic ants, whereas subsp. gracilicaulis satiates herbivores by synchronized leaf production. Subsp. africana possesses hollow internodes and many large foliar nectaries, housing and feeding ants. We detected no genetic introgression between the two subspecies in the contact zone between them. F1 hybrids were present. They were intermediate in phenotype, expressing reduced, nonfunctional but costly myrmecophilic traits. However, they suffered more herbivory than their parents. Hybrids remained small, failing to reach reproductive size, probably due to their maladapted defence phenotype. Hence, there could be a direct link between adaptation to mutualism and reproductive isolation: biotic interactions could be a driver of tropical diversity.

Optimization of biosurfactant production from Vibrio sp. BSM-30 isolated in tropical waters

Science.gov (United States)

Su, Zengjian; Li, Min; Zhang, Yuxiu

2017-01-01

The strain BSM-30 (Vibrio sp.), isolated from Chinese tropical waters, could be a biosurfactant producing bacteria according with results obtained by the oil spreading method. The culture conditions for biosurfactant production were tested respectively such as inoculation (2%,6%,10%,14% as setting), shaking speed(120 r/min,150 r/min,180 r/min as setting), temperature (25°C,30°C,35°C as setting), pH (7,8,9 as setting), salinity (1.5%, 2.5%, 3.0%, 4.5%, 5.5% as setting), which results showed that the best culture conditions for BS production were 10% inoculation quantity, 180 r/min, 25°C, pH 8, and 3.5% salinity. The optimization of carbon sources (20g/ of glucose, 20g/L of starch, 20g/L of paraffin oil 20g/L of diesel, 20g/L of oil as setting) and nitrogen sources (6g/L of NaNO3,7.1g/L of KNO3,5.6g/L of NH4NO3,9.3g/L of (NH4)2SO4, 4.2g/L of CO(NH2)2 as setting) were also tested, which results showed that the best nitrogen source and carbon source were (NH4) 2SO4 and soluble starch.

Tropical wetlands and REDD+: Three unique scientific challenges for policy

Directory of Open Access Journals (Sweden)

Daniel A Friess

2013-07-01

Full Text Available The carbon sequestration and storage value of terrestrial habitats is now increasingly appreciated, and is the basis for Payment for Ecosystem Service (PES policies such as REDD+. Tropical wetlands may be suitable for inclusion in such schemes because of the disproportionately large volume of carbon they are able to store. However, tropical wetlands offer a number of unique challenges for carbon management and policy compared to terrestrial forest systems: 1 Tropical wetlands are dynamic and subject to a wide range of physical and ecological processes that affect their long-term carbon storage potential – thus, such systems can quickly become a carbon source instead of a sink; 2 Carbon dynamics in tropical wetlands often operate over longer time-scales than are currently covered by REDD+ payments; and 3 Much of the carbon in a tropical wetland is stored in the soil, so monitoring, reporting and verification (MRV needs to adequately encapsulate the entire ecosystem and not just the vegetative component. This paper discusses these physical and biological concepts, and highlights key legal, management and policy questions that must be considered when constructing a policy framework to conserve these crucial ecosystems.

Nitrogen dynamics in organic and conventional cotton production systems in India

Science.gov (United States)

Duboc, O.; Adamtey, N.; Forster, D.; Cadisch, G.

2012-04-01

Ongoing population growth still represents a challenge to agricultural production (food, fiber and fuel material supply). In spite of the undeniable achievements reached with the "green revolution" technologies, there is a growing awareness among scientists and policy makers that diverse and integrated approaches which are both productive and sustainable are now necessary to meet the agricultural challenges. Integrated and organic agriculture are such alternatives which need to be better investigated and implemented. While long-term experiments in temperate regions have assessed the effect of organic agriculture on different crops and soil quality, there is currently a lack of reliable data from tropical regions, such as findings arising from long-term systems comparison trials. This has necessitated a long-term system comparison trials in Kenya, Bolivia and India by the Research Institute of Organic Agriculture (FiBL) and its partners (icipe, BioRe, Ecotop and Institute of Ecology) (www.systems-comparison.fibl.org). In India the project is based in Madhya Pradesh, in which organic and conventional production systems are being compared in a 2-yr crop rotation - cotton (yr 1) and soybean-wheat (yr 2). The field trial is planned for a time span of 10-20 years, in order to investigate long-term effects of those production systems on yields, soil characteristics, or economic return. A PhD study is incorporated into this project to investigate the effect of the production systems on soil characteristics. The main focus will be on nitrogen cycling under the different production systems. Particular attention will be given to nitrogen use efficiencies and the synchrony of nitrogen availability (e.g. nitrogen mineralization with the polyethylene bag technique, monitoring of soil mineral N) with plant nitrogen uptake, for which allometric equations will be calibrated in order to circumvent destructive sampling on the plots of the long-term experiment. Nitrogen losses

PRODUCTIVITY AND TICK LOAD IN Bos Indicus X B. taurus CATTLE IN A TROPICAL DRY FOREST SILVOPASTORAL SYSTEM

Directory of Open Access Journals (Sweden)

Raquel Sofía Salazar Benjumea

2015-04-01

Full Text Available Rhipicephalus (Boophilus microplus ticks cause significant economic losses to the Colombian cattle sector: reduction in meat and milk production, blood losses and transmission of blood parasites. The degree of infestation depends on the breed, physiological state and nutrition of the animal and on microclimatic characteristics, which affect the tick life cycle. Diverse studies suggest that given the characteristics of intensive silvopastoral systems (ISS, tick loads within these systems are lower. In this study, the tick loads of grazing animals were monitored for five animal groups: three at an ISS and two at traditional farms located on the Valley of Ibague (Tolima. within the ISS, there were greater tick loads in high production cows (P = 0.026 and a positive relationship (P < 0.05 between milk production and tick load in August sampling. Greater tick counts were also observed in the in San Javier (traditional farm group compared to all other animal groups. We conclude that the dynamics of ticks is a complex phenomenon affected by many factors, whose association determines the observed tick population at any given time.

Anoxic conditions drive phosphorus limitation in humid tropical forest soil microorganisms

Science.gov (United States)

Gross, A.; Pett-Ridge, J.; Weber, P. K.; Blazewicz, S.; Silver, W. L.

2017-12-01

The elemental stoichiometry of carbon (C), nitrogen (N) and phosphorus (P) of soil microorganisms (C:N:P ratios) regulates transfers of energy and nutrients to higher trophic levels. In humid tropical forests that grow on P-depleted soils, the ability of microbes to concentrate P from their surroundings likely plays a critical role in P-retention and ultimately in forest productivity. Models predict that climate change will cause dramatic changes in rainfall patterns in the humid tropics and field studies have shown these changes can affect the redox state of tropical forest soils, influencing soil respiration and biogeochemical cycling. However, the responses of soil microorganisms to changing environmental conditions are not well known. Here, we incubated humid tropical soils under oxic or anoxic conditions with substrates differing in both C:P stoichiometry and lability, to assess how soil microorganisms respond to different redox regimes. We found that under oxic conditions, microbial C:P ratios were similar to the global optimal ratio (55:1), indicating most microbial cells can adapt to persistent aerated conditions in these soils. However, under anoxic conditions, the ability of soil microbes to acquire soil P declined and their C:P ratios shifted away from the optimal ratio. NanoSIMS elemental imaging of single cells extracted from soil revealed that under anoxic conditions, C:P ratios were above the microbial optimal value in 83% of the cells, in comparison to 41% under oxic conditions. These data suggest microbial growth efficiency switched from being energy limited under oxic conditions to P-limited under anoxic conditions, indicating that, microbial growth in low P humid tropical forests soils may be most constrained by P-limitation when conditions are oxygen-limited. We suggest that differential microbial responses to soil redox states could have important implications for productivity of humid tropical forests under future climate scenarios.

Greenhouse Gas Emissions from Hydroelectric Reservoirs in Tropical Regions

International Nuclear Information System (INIS)

Pinguelli Rosa, L.; Aurelio dos Santos, M.; Oliveira dos Santos, E.; Matvienko, B.; Sikar, E.

2004-01-01

This paper discusses emissions by power-dams in the tropics. Greenhouse gas emissions from tropical power-dams are produced underwater through biomass decomposition by bacteria. The gases produced in these dams are mainly nitrogen, carbon dioxide and methane. A methodology was established for measuring greenhouse gases emitted by various power-dams in Brazil. Experimental measurements of gas emissions by dams were made to determine accurately their emissions of methane (CH4) and carbon dioxide (CO2) gases through bubbles formed on the lake bottom by decomposing organic matter, as well as rising up the lake gradient by molecular diffusion. The main source of gas in power-dams reservoirs is the bacterial decomposition (aerobic and anaerobic) of autochthonous and allochthonous organic matter that basically produces CO2 and CH4. The types and modes of gas production and release in the tropics are reviewed

An assessment of the ECMWF tropical cyclone ensemble forecasting system and its use for insurance loss predictions

Science.gov (United States)

Aemisegger, F.; Martius, O.; Wüest, M.

2010-09-01

Tropical cyclones (TC) are amongst the most impressive and destructive weather systems of Earth's atmosphere. The costs related to such intense natural disasters have been rising in recent years and may potentially continue to increase in the near future due to changes in magnitude, timing, duration or location of tropical storms. This is a challenging situation for numerical weather prediction, which should provide a decision basis for short term protective measures through high quality medium range forecasts on the one hand. On the other hand, the insurance system bears great responsibility in elaborating proactive plans in order to face these extreme events that individuals cannot manage independently. Real-time prediction and early warning systems are needed in the insurance sector in order to face an imminent hazard and minimise losses. Early loss estimates are important in order to allocate capital and to communicate to investors. The ECMWF TC identification algorithm delivers information on the track and intensity of storms based on the ensemble forecasting system. This provides a physically based framework to assess the uncertainty in the forecast of a specific event. The performance of the ECMWF TC ensemble forecasts is evaluated in terms of cyclone intensity and location in this study and the value of such a physically-based quantification of uncertainty in the meteorological forecast for the estimation of insurance losses is assessed. An evaluation of track and intensity forecasts of hurricanes in the North Atlantic during the years 2005 to 2009 is carried out. Various effects are studied like the differences in forecasts over land or sea, as well as links between storm intensity and forecast error statistics. The value of the ECMWF TC forecasting system for the global re-insurer Swiss Re was assessed by performing insurance loss predictions using their in-house loss model for several case studies of particularly devastating events. The generally known

Progress in tropical isotope dendroclimatology

Science.gov (United States)

Evans, M. N.; Schrag, D. P.; Poussart, P. F.; Anchukaitis, K. J.

2005-12-01

The terrestrial tropics remain an important gap in the growing high resolution proxy network used to characterize the mean state and variability of the hydrological cycle. Here we review early efforts to develop a new class of proxy paleorainfall/humidity indicators using intraseasonal to interannual-resolution stable isotope data from tropical trees. The approach invokes a recently published model of oxygen isotopic composition of alpha-cellulose, rapid methods for cellulose extraction from raw wood, and continuous flow isotope ratio mass spectrometry to develop proxy chronological, rainfall and growth rate estimates from tropical trees, even those lacking annual rings. Isotopically-derived age models may be confirmed for modern intervals using trees of known age, radiocarbon measurements, direct measurements of tree diameter, and time series replication. Studies are now underway at a number of laboratories on samples from Costa Rica, northwestern coastal Peru, Indonesia, Thailand, New Guinea, Paraguay, Brazil, India, and the South American Altiplano. Improved sample extraction chemistry and online pyrolysis techniques should increase sample throughput, precision, and time series replication. Statistical calibration together with simple forward modeling based on the well-observed modern period can provide for objective interpretation of the data. Ultimately, replicated data series with well-defined uncertainties can be entered into multiproxy efforts to define aspects of tropical hydrological variability associated with ENSO, the meridional overturning circulation, and the monsoon systems.

Mycorrhizal associations in agroforestry systems

NARCIS (Netherlands)

Carvalho, de A.M.X.; Castro Tavares, de R.; Cardoso, I.M.; Kuyper, T.W.

2010-01-01

Agroforestry systems can be a viable alternative to the preservation of natural resources while contributing to sustainable food production in the tropics. These perennial systems promote beneficial biological interactions between micro-organisms and plant species, especially those formed by

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

Science.gov (United States)

Spessa, Allan; Fisher, Rosie

2010-05-01

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

Banana production systems: identification of alternative systems for more sustainable production.

Science.gov (United States)

Bellamy, Angelina Sanderson

2013-04-01

Large-scale, monoculture production systems dependent on synthetic fertilizers and pesticides, increase yields, but are costly and have deleterious impacts on human health and the environment. This research investigates variations in banana production practices in Costa Rica, to identify alternative systems that combine high productivity and profitability, with reduced reliance on agrochemicals. Farm workers were observed during daily production activities; 39 banana producers and 8 extension workers/researchers were interviewed; and a review of field experiments conducted by the National Banana Corporation between 1997 and 2002 was made. Correspondence analysis showed that there is no structured variation in large-scale banana producers' practices, but two other banana production systems were identified: a small-scale organic system and a small-scale conventional coffee-banana intercropped system. Field-scale research may reveal ways that these practices can be scaled up to achieve a productive and profitable system producing high-quality export bananas with fewer or no pesticides.

Power plant fuel switching and air quality in a tropical, forested environment

Science.gov (United States)

Medeiros, Adan S. S.; Calderaro, Gisele; Guimarães, Patricia C.; Magalhaes, Mateus R.; Morais, Marcos V. B.; Rafee, Sameh A. A.; Ribeiro, Igor O.; Andreoli, Rita V.; Martins, Jorge A.; Martins, Leila D.; Martin, Scot T.; Souza, Rodrigo A. F.

2017-07-01

How a changing energy matrix for electricity production affects air quality is considered for an urban region in a tropical, forested environment. Manaus, the largest city in the central Amazon Basin of Brazil, is in the process of changing its energy matrix for electricity production from fuel oil and diesel to natural gas over an approximately 10-year period, with a minor contribution by hydropower. Three scenarios of urban air quality, specifically afternoon ozone concentrations, were simulated using the Weather Research and Forecasting (WRF-Chem) model. The first scenario used fuel oil and diesel for electricity production, which was the reality in 2008. The second scenario was based on the fuel mix from 2014, the most current year for which data were available. The third scenario considered nearly complete use of natural gas for electricity production, which is the anticipated future, possibly for 2018. For each case, inventories of anthropogenic emissions were based on electricity generation, refinery operations, and transportation. Transportation and refinery operations were held constant across the three scenarios to focus on effects of power plant fuel switching in a tropical context. The simulated NOx and CO emissions for the urban region decrease by 89 and 55 %, respectively, after the complete change in the energy matrix. The results of the simulations indicate that a change to natural gas significantly decreases maximum afternoon ozone concentrations over the population center, reducing ozone by > 70 % for the most polluted days. The sensitivity of ozone concentrations to the fuel switchover is consistent with a NOx-limited regime, as expected for a tropical forest having high emissions of biogenic volatile organic compounds, high water vapor concentrations, and abundant solar radiation. There are key differences in a shifting energy matrix in a tropical, forested environment compared to other world environments. Policies favoring the burning of

Power plant fuel switching and air quality in a tropical, forested environment

Directory of Open Access Journals (Sweden)

A. S. S. Medeiros

2017-07-01

Full Text Available How a changing energy matrix for electricity production affects air quality is considered for an urban region in a tropical, forested environment. Manaus, the largest city in the central Amazon Basin of Brazil, is in the process of changing its energy matrix for electricity production from fuel oil and diesel to natural gas over an approximately 10-year period, with a minor contribution by hydropower. Three scenarios of urban air quality, specifically afternoon ozone concentrations, were simulated using the Weather Research and Forecasting (WRF-Chem model. The first scenario used fuel oil and diesel for electricity production, which was the reality in 2008. The second scenario was based on the fuel mix from 2014, the most current year for which data were available. The third scenario considered nearly complete use of natural gas for electricity production, which is the anticipated future, possibly for 2018. For each case, inventories of anthropogenic emissions were based on electricity generation, refinery operations, and transportation. Transportation and refinery operations were held constant across the three scenarios to focus on effects of power plant fuel switching in a tropical context. The simulated NOx and CO emissions for the urban region decrease by 89 and 55 %, respectively, after the complete change in the energy matrix. The results of the simulations indicate that a change to natural gas significantly decreases maximum afternoon ozone concentrations over the population center, reducing ozone by > 70 % for the most polluted days. The sensitivity of ozone concentrations to the fuel switchover is consistent with a NOx-limited regime, as expected for a tropical forest having high emissions of biogenic volatile organic compounds, high water vapor concentrations, and abundant solar radiation. There are key differences in a shifting energy matrix in a tropical, forested environment compared to other world environments. Policies

Impact of chlorophyll bias on the tropical Pacific mean climate in an earth system model

Science.gov (United States)

Lim, Hyung-Gyu; Park, Jong-Yeon; Kug, Jong-Seong

2017-12-01

Climate modeling groups nowadays develop earth system models (ESMs) by incorporating biogeochemical processes in their climate models. The ESMs, however, often show substantial bias in simulated marine biogeochemistry which can potentially introduce an undesirable bias in physical ocean fields through biogeophysical interactions. This study examines how and how much the chlorophyll bias in a state-of-the-art ESM affects the mean and seasonal cycle of tropical Pacific sea-surface temperature (SST). The ESM used in the present study shows a sizeable positive bias in the simulated tropical chlorophyll. We found that the correction of the chlorophyll bias can reduce the ESM's intrinsic cold SST mean bias in the equatorial Pacific. The biologically-induced cold SST bias is strongly affected by seasonally-dependent air-sea coupling strength. In addition, the correction of chlorophyll bias can improve the annual cycle of SST by up to 25%. This result suggests a possible modeling approach in understanding the two-way interactions between physical and chlorophyll biases by biogeophysical effects.

[Tropical causes of epilepsy].

Science.gov (United States)

Carod-Artal, F J

Eighty-five percent of all epileptics live in tropical regions. Prenatal risk factors, traumatic brain injuries and different parasitic infestations of the central nervous system (CNS) are the reasons behind the high prevalence of epilepsy. This work reviews the main parasitic infestations causing epilepsy in the tropics. Neurocysticercosis is the main cause of focal epilepsy in early adulthood in endemic areas (30-50%). All the phases of cysticerci (viable, transitional and calcified) are associated with epileptic seizures. Anti-cysticercus treatment helps get rid of cysticerci faster and reduces the risk of recurrence of seizures in patients with viable cysts. Symptomatic epilepsy can be the first manifestation of neuroschistosomiasis in patients without any systemic symptoms. The pseudotumoral form can trigger seizures secondary to the presence of granulomas and oedemas in the cerebral cortex. The eggs of Schistosoma japonicum are smaller, reach the CNS more easily and trigger epileptic seizures more frequently. Toxocariasis and sparganosis are other parasitic infestations that can give rise to symptomatic seizures. The risk factors for suffering chronic epilepsy after cerebral malaria are a positive familial history of epilepsy and a history of episodes of fever and cerebral malaria that began with coma or which progressed with multiple, prolonged epileptic seizures. About 20% of patients with cerebral infarction secondary to Chagas disease present late vascular epilepsy as a complication. Very few studies have been conducted to examine the prognosis, risk of recurrence and modification of the natural course of seizures associated with tropical parasitic infestations, except for the case of neurocysticercosis.

Tropical systems from the southwest Indian Ocean making landfall over the Limpopo River Basin, southern Africa: a historical perspective

CSIR Research Space (South Africa)

Malherbe, J

2011-03-01

Full Text Available The study provides perspective on the contribution of landfalling tropical systems (cyclones, depressions, storms and lows) from the southwest Indian Ocean (SWIO) towards rainfall over the eastern interior of southern Africa, over the period 1948...

The role of tropical cyclones in precipitation over the tropical and subtropical North America

Science.gov (United States)

Dominguez, Christian; Magaña, Victor

2018-03-01

Tropical cyclones (TCs) are essential elements of the hydrological cycle in tropical and subtropical regions. In the present study, the contribution of TCs to seasonal precipitation around the tropical and subtropical North America is examined. When TC activity over the tropical eastern Pacific (TEP) or the Intra Americas Seas (IAS) is below (above-normal), regional precipitation may be below (above-normal). However, it is not only the number of TCs what may change seasonal precipitation, but the trajectory of the systems. TCs induce intense precipitation over continental regions if they are close enough to shorelines, for instance, if the TC center is located, on average, less than 500 km-distant from the coast. However, if TCs are more remote than this threshold distance, the chances of rain over continental regions decrease, particularly in arid and semi-arid regions. In addition, a distant TC may induce subsidence or produce moisture divergence that inhibits, at least for a few days, convective activity farther away than the threshold distance. An analysis of interannual variability in the TCs that produce precipitation over the tropical and subtropical North America shows that some regions in northern Mexico, which mostly depend on this effect to undergo wet years, may experience seasonal negative anomalies in precipitation if TCs trajectories are remote. Therefore, TCs (activity and trajectories) are important modulators of climate variability on various time scales, either by producing intense rainfall or by inhibiting convection at distant regions from their trajectory. The impact of such variations on water availability in northern Mexico may be relevant, since water availability in dams recovers under the effects of TC rainfall. Seasonal precipitation forecasts or climate change scenarios for these regions should take into account the effect of TCs, if regional adaptation strategies are implemented.

The use of the United States FDA programs as a strategy to advance the development of drug products for neglected tropical diseases.

Science.gov (United States)

Sachs-Barrable, Kristina; Conway, Jocelyn; Gershkovich, Pavel; Ibrahim, Fady; Wasan, Kishor M

2014-11-01

Neglected tropical diseases (NTDs) are infections which are endemic in poor populations in lower- and middle-income countries (LMIC). Approximately one billion people have now or are at risk of getting an NTD and yet less than 5% of research dollars are focused on providing treatments and prevention of these highly debilitating and deadly conditions. The United States Food and Drug Administration (FDA) Orphan Drug Designation program (ODDP) provides orphan status to drugs and biologics, defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases and/or disorders that affect fewer than 200 000 people in the United States, or that affect more than 200 000 persons but are not expected to recover the costs of developing and marketing a treatment drug. These regulations have led to the translation of rare disease knowledge into innovative rare disease therapies. The FDA Guidance for Industry on developing drugs for the treatment and prevention of NTDs describes the following regulatory strategies: Orphan Product Designation, Fast Track Designation, Priority Review Designation, Accelerated Approval and Tropical Disease Priority Review Voucher. This paper will discuss how these regulations and especially the ODDP can improve the clinical development and accessibility of drug products for NTDs.

Autochthonous white rot fungi from the tropical forest: Potential of ...

African Journals Online (AJOL)

STORAGESEVER

2008-06-17

Jun 17, 2008 ... local biodiversity in tropical area appears as a potentially productive approach for identifying promising ... senting thirteen species and ten different genera (Table ..... which has clear connexions with white biotechnology.

Ohcratoxin producing Aspergillus spp. Isolated from tropical soils in Sarawak, Malaysia

Directory of Open Access Journals (Sweden)

J.S.S. Seelan

2010-03-01

Full Text Available Aspergillus strains isolated from tropical soils were selected for additional characterization and for ochratoxin analysis, which was determined by ELISA method and high performance liquid chromatography (HPLC profiles. Because of its great morphological variability and mycotoxin production availability, 18 isolates of Aspergillus species were selected for this study. Only two isolates of these tropical soils, A. sulphureus and A. carbonarius, showed positive results for ohcratoxin (OA in lower concentration (0.05-0.10 µg/ml. Ochratoxin production by these species was confirmed by high performance liquid chromatography. HPLC analysis for ochratoxin producing A. sulphureus and A. carbonarius showed retention time, Rt value = 4.417 and Rt value = 4.081 respectively.

High yielding tropical energy crops for bioenergy production: Effects of plant components, harvest years and locations on biomass composition.

Science.gov (United States)

Surendra, K C; Ogoshi, Richard; Zaleski, Halina M; Hashimoto, Andrew G; Khanal, Samir Kumar

2018-03-01

The composition of lignocellulosic feedstock, which depends on crop type, crop management, locations and plant parts, significantly affects the conversion efficiency of biomass into biofuels and biobased products. Thus, this study examined the composition of different parts of two high yielding tropical energy crops, Energycane and Napier grass, collected across three locations and years. Significantly higher fiber content was found in the leaves of Energycane than stems, while fiber content was significantly higher in the stems than the leaves of Napier grass. Similarly, fiber content was higher in Napier grass than Energycane. Due to significant differences in biomass composition between the plant parts within a crop type, neither biological conversion, including anaerobic digestion, nor thermochemical pretreatment alone is likely to efficiently convert biomass components into biofuels and biobased products. However, combination of anaerobic digestion with thermochemical conversion technologies could efficiently utilize biomass components in generating biofuels and biobased products. Copyright © 2017 Elsevier Ltd. All rights reserved.

Increasing carbon storage in intact African tropical forests

NARCIS (Netherlands)

Lewis, S.L.; Lopez-Gonzalez, G.; Sonké, B.; Affum-Baffoe, K.; Ewango, C.E.N.

2009-01-01

The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide1, 2. The role of tropical forests is critical because they are carbon-dense and highly productive3, 4. Inventory plots across Amazonia show that

Upper ocean physical processes in the Tropical Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Rao, L.V.G.; Ram, P.S.

This monograph is the outcome of an attempt by the authors to present a synthesis of the studies on physical processes in the Tropical Indian Ocean (TIO) in relation to air-sea interaction, monsoon/climate variability and biological productivity...

NPP Tropical Forest: Khao Chong, Thailand, 1962-1965, R1

Data.gov (United States)

National Aeronautics and Space Administration — This data set contains one net primary productivity (NPP) data file and three climate data files (.txt format) for a fully closed tropical rainforest in the Khao...

Perspectives for an integrated understanding of tropical and temperate high-mountain lakes

Directory of Open Access Journals (Sweden)

Jordi Catalan

2016-03-01

Full Text Available High mountain lakes are extreme freshwater ecosystems and excellent sentinels of current global change. They are likely among the most comparable ecosystems across the world. The largest contrast occurs between lakes in temperate and tropical areas. The main difference arises from the seasonal patterns of heat exchange and the external loadings (carbon, phosphorus, metals. The consequence is a water column structure based on temperature, in temperate lakes, and oxygen, in tropical lakes. This essential difference implies that, in tropical lakes, one can expect a more sustained productivity throughout the year; a higher nutrient internal loading based on the mineralization of external organic matter; higher nitrification-denitrification potential related to the oxyclines; and a higher metal mobilization due to the permanently reduced bottom layer. Quantifying and linking these and other biogeochemical pathways to particular groups of organisms is in the current agenda of high-mountain limnology. The intrinsic difficulties of the taxonomic study of many of the organisms inhabiting these systems can be now overcome with the use of molecular techniques. These techniques will not only provide a much less ambiguous taxonomic knowledge of the microscopic world, but also will unveil new biogeochemical pathways that are difficult to measure chemically and will solve biogeographical puzzles of the distribution of some macroscopic organism, tracing the relationship with other areas. Daily variability and vertical gradients in the tropics are the main factors of phytoplankton species turnover in tropical lakes; whereas seasonality is the main driver in temperate communities. The study of phytoplankton in high-mountain lakes only makes sense in an integrated view of the microscopic ecosystem. A large part of the plankton biomass is in heterotrophic, and mixotrophic organisms and prokaryotes compete for dissolved resources with eukaryotic autotrophs. In fact

New recommendations for building in tropical climates

Energy Technology Data Exchange (ETDEWEB)

Waal, H.B. de (ISOVER BV, Cappelle a/d IJssel (Netherlands))

1993-07-01

Traditional recommendations for building a thermally efficient or comfortable building in a tropical climate are briefly summarized. They suffer from three main drawbacks; they are not quantitative, partly incorrect and only for two climates; the hot dry and the warm humid. A new climate classification, made up of forty tropical climates is presented. Eight building elements, which affect the thermal system of a building, are distinguished. The method by which the new recommendations are derived, is discussed. The new recommendations are briefly presented. (Author)

Potential lignocellulose resources and their utilization by ruminants in tropical regions

International Nuclear Information System (INIS)

Sansoucy, R.; Mahadevan, P.

1983-01-01

The nature and estimated quantities of potential lignocellulose resources in tropical regions are described. The most abundant sources of these materials are the natural grasslands, crop residues and by-products, e.g. sugar cane, cereals and fruits, and, to a limited extent, cultivated grasses, e.g. guinea and elephant grass. The availability of these resources to livestock is limited by a variety of environmental and logistic factors, e.g. seasonality of production and problems of collection and transport. Additionally, the nutritive value of pastures and fodders in the tropics is relatively lower than in temperate regions owing to their higher fibre and lower N and P content, with consequent lowering of intake and digestibility. Crop residues also have low N and high lignin contents and are generally deficient in fermentable energy, fermentable N, protein and micronutrients. The possibilities for improving the nutritive value of tropical feeds are discussed; these include supplementation with urea, molasses and minerals, good quality forage, and/or ''by-pass'' nutrients, e.g. oil cakes, and treatment by various physical, chemical or biological methods. (author)

Production of Modularised Product Systems

DEFF Research Database (Denmark)

Jacobsen, Peter

2004-01-01

but a solution. Modularisation is one tool used in designing the products. Designing and controlling a production system making customized products in an economical way is not an easy task. In order to fulfil the Lean and Agile manufacturing philosophies the production is often carried out in networks. Here...

Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

Energy Technology Data Exchange (ETDEWEB)

Cusack, D.; Silver, W.L.; Torn, M.S.; McDowell, W.H.

2011-04-15

Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

The Value of Tropical Biodiversity in Rural Melanesia

Directory of Open Access Journals (Sweden)

Simon Foale

2016-11-01

Full Text Available In this paper we discuss differences in the ways transnational conservationists and Melanesian farmers, hunters and fishers value "biodiversity". The money for conservation projects in developing countries originates from people who are embedded in a capitalist system, which allows engagement with nature as an abstract entity. Their western education has given them a scientific/ evolutionary-based worldview, which attributes intrinsic value to all species (and particular arrangements of species, e.g. rainforests and coral reefs, irrespective of economic value or ecosystem function. Because this value system is mostly not shared by the custodians of the biodiversity that conservationists want to save, alternative tactics and arguments are utilised. These inevitably take the form of so-called "win-win" economic rationales for preserving biodiversity, most of which do not work well (e.g. bioprospecting, ecotourism, non-timber forest products, environmental certification schemes, payments for ecosystem services, etc., for reasons which we detail. Agriculture- and aquaculture-based livelihoods appear to enjoy more success than the "win-win" options but do not necessarily obviate or deter further biodiversity loss. Artisanal use of species-poor but productive and resilient pelagic fisheries is increasing. These ecological and economic realities bring into sharp focus the importance of understanding differences in value systems for successful biodiversity conservation in the tropics.

Vegetation-climate feedback causes reduced precipitation and tropical rainforest cover in CMIP5 regional Earth system model simulation over Africa

Science.gov (United States)

Wu, M.; Smith, B.; Samuelsson, P.; Rummukainen, M.; Schurgers, G.

2012-12-01

We applied a coupled regional climate-vegetation model, RCA-GUESS (Smith et al. 2011), over the CORDEX Africa domain, forced by boundary conditions from a CanESM2 CMIP5 simulation under the RCP8.5 future climate scenario. The simulations were from 1961 to 2100 and covered the African continent at a horizontal grid spacing of 0.44°. RCA-GUESS simulates changes in the phenology, productivity, relative cover and population structure of up to eight plant function types (PFTs) in response to forcing from the climate part of the model. These vegetation changes feed back to simulated climate through dynamic adjustments in surface energy fluxes and surface properties. Changes in the net ecosystem-atmosphere carbon flux and its components net primary production (NPP), heterotrophic respiration and emissions from biomass burning were also simulated but do not feed back to climate in our model. Constant land cover was assumed. We compared simulations with and without vegetation feedback switched "on" to assess the influence of vegetation-climate feedback on simulated climate, vegetation and ecosystem carbon cycling. Both positive and negative warming feedbacks were identified in different parts of Africa. In the Sahel savannah zone near 15°N, reduced vegetation cover and productivity, and mortality caused by a deterioration of soil water conditions led to a positive warming feedback mediated by decreased evapotranspiration and increased sensible heat flux between vegetation and the atmosphere. In the equatorial rainforest stronghold region of central Africa, a feedback syndrome characterised by reduced plant production and LAI, a dominance shift from tropical trees to grasses, reduced soil water and reduced rainfall was identified. The likely underlying mechanism was a decline in evaporative water recycling associated with sparser vegetation cover, reminiscent of Earth system model studies in which a similar feedback mechanism was simulated to force dieback of tropical

Leer a Silva a contrapelo: de sobremesa como novela tropical

Directory of Open Access Journals (Sweden)

Felipe Martínez Pinzón

2012-12-01

Full Text Available Fernández' civilizatory fantasy in J.A. Silva's De Sobremesa provides a position from which to re-read discourses about space and place written by elite Colombian geographers and ethnographers. From a vantage point infused in parody, this fantasy deploys the metaphorical arsenal used by elites to encode the Colombian tropics. Thus, Silva unmasks contemporary intellectuals as travelers whose spatial imagination was literary, prophesizes the consequences of conceiving the tropics from a temperate worldview, and mocks the possibility of conceiving national culture as a natural product.

Tropical Cyclone Paka's Initial Explosive Development (10-12 December, 1997)

Science.gov (United States)

Rodgers, Edward B.; Halverson, Jeff; Simpson, Joanne; Olson, William; Pierce, Harold

1999-01-01

Convection associated with an equatorial westerly wind burst was first observed late November during the strong El Nino of 1997 at approximately 2000 km southwest of the Hawaiian Islands. This region of convection lead to the formation of twin tropical cyclones, one in the southern hemisphere named Pam and the other in the northern hemisphere named Paka. During the first week in December, tropical cyclone Paka, the system of concern, reached tropical storm stage as it moved rapidly westward at relatively low latitudes. During the 10-12 of December, Paka rapidly developed into a typhoon.

Radioimmunoassay and related techniques to improve artificial insemination programmes for cattle reared under tropical and sub-tropical conditions. Proceedings of a final research co-ordination meeting

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-05-01

Artificial insemination (AI) is widely used for improvement of cattle production in developed countries. Its use in developing countries is less widespread and the results obtained are far from satisfactory. Under tropical small-farm conditions, a number of socio-economic, organizational, biological and technical factors make the service more difficult to provide and also less efficient. If the major constraints can be identified and overcome, this technology would become more widely adopted and contribute to an increased production of milk and meat, leading to better food security and poverty alleviation. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture therefore convened a consultants meeting in May 1994 to advise on the applicability of radioimmunoassay (RIA) for measuring progesterone in milk of dairy cattle to identify the major causes of conception failure and reproductive wastage when AI is used under the conditions prevailing in developing countries. The consultants recommended the initiation of a co-ordinated research project (CRP) on this topic, and developed a comprehensive technical document including the sampling protocol and the range of information that needs to be recorded in order to obtain conclusive results. A five year CRP on the ''Use of RIA and Related Techniques to Identify Ways of Improving Artificial Insemination Programmes for Cattle Reared Under Tropical and Sub-Tropical Conditions'' was initiated in early 1995. The CRP resulted in the development and standardization of methodologies and protocols, including the computer software program termed AIDA (Artificial Insemination Database Application), to determine current status and identify constraints. These methodologies and protocols are now being applied on a wider scale in Member States through regional TC projects in Asia and Africa and country TC projects in Latin America. Contributing to the wider application of progesterone RIA for field level problem solving

Radioimmunoassay and related techniques to improve artificial insemination programmes for cattle reared under tropical and sub-tropical conditions. Proceedings of a final research co-ordination meeting

International Nuclear Information System (INIS)

2001-05-01

Artificial insemination (AI) is widely used for improvement of cattle production in developed countries. Its use in developing countries is less widespread and the results obtained are far from satisfactory. Under tropical small-farm conditions, a number of socio-economic, organizational, biological and technical factors make the service more difficult to provide and also less efficient. If the major constraints can be identified and overcome, this technology would become more widely adopted and contribute to an increased production of milk and meat, leading to better food security and poverty alleviation. The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture therefore convened a consultants meeting in May 1994 to advise on the applicability of radioimmunoassay (RIA) for measuring progesterone in milk of dairy cattle to identify the major causes of conception failure and reproductive wastage when AI is used under the conditions prevailing in developing countries. The consultants recommended the initiation of a co-ordinated research project (CRP) on this topic, and developed a comprehensive technical document including the sampling protocol and the range of information that needs to be recorded in order to obtain conclusive results. A five year CRP on the ''Use of RIA and Related Techniques to Identify Ways of Improving Artificial Insemination Programmes for Cattle Reared Under Tropical and Sub-Tropical Conditions'' was initiated in early 1995. The CRP resulted in the development and standardization of methodologies and protocols, including the computer software program termed AIDA (Artificial Insemination Database Application), to determine current status and identify constraints. These methodologies and protocols are now being applied on a wider scale in Member States through regional TC projects in Asia and Africa and country TC projects in Latin America. Contributing to the wider application of progesterone RIA for field level problem solving

Influences of tropical-extratropical interaction on the multidecadal AMOC variability in the NCEP climate forecast system

Energy Technology Data Exchange (ETDEWEB)

Huang, Bohua; Schneider, Edwin K.; Klinger, Barry [Gorge Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Hu, Zeng-Zhen; Xue, Yan [National Centers for Environmental Prediction/NOAA, Climate Prediction Center, Camp Springs, MD (United States); Wu, Zhaohua [Florida State University, Department of Earth, Ocean, and Atmospheric Science, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL (United States)

2012-08-15

We have examined the mechanisms of a multidecadal oscillation of the Atlantic Meridional Overturning Circulation (AMOC) in a 335-year simulation of the Climate Forecast System (CFS), the climate prediction model developed at the National Centers for Environmental Prediction (NCEP). Both the mean and seasonal cycle of the AMOC in the CFS are generally consistent with observation-based estimates with a maximum northward volume transport of 16 Sv (10{sup 6} m{sup 3}/s) near 35 N at 1.2 km. The annual mean AMOC shows an intermittent quasi 30-year oscillation. Its dominant structure includes a deep anomalous overturning cell (referred to as the anomalous AMOC) with amplitude of 0.6 Sv near 35 N and an anomalous subtropical cell (STC) of shallow overturning spanning across the equator. The mechanism for the oscillation includes a positive feedback between the anomalous AMOC and surface wind stress anomalies in mid-latitudes and a negative feedback between the anomalous STC and AMOC. A strong AMOC is associated with warm sea surface temperature anomaly (SSTA) centered near 45 N, which generates an anticyclonic easterly surface wind anomaly. This anticyclonic wind anomaly enhances the regional downwelling and reinforces the anomalous AMOC. In the mean time, a wind-evaporation-SST (WES) feedback extends the warm SSTA to the tropics and induces a cyclonic wind stress anomaly there, which drives a tropical upwelling and weakens the STC north of the equator. The STC anomaly, in turn, drives a cold upper ocean heat content anomaly (HCA) in the northern tropical Atlantic and weakens the meridional heat transport from the tropics to the mid-latitude through an anomalous southward western boundary current. The anomalous STC transports cold HCA from the subtropics to the mid-latitudes, weakening the mid-latitude deep overturning. (orig.)

Detecting Climate Variability in Tropical Rainfall

Science.gov (United States)

Berg, W.

2004-05-01

A number of satellite and merged satellite/in-situ rainfall products have been developed extending as far back as 1979. While the availability of global rainfall data covering over two decades and encompassing two major El Niño events is a valuable resource for a variety of climate studies, significant differences exist between many of these products. Unfortunately, issues such as availability often determine the use of a product for a given application instead of an understanding of the strengths and weaknesses of the various products. Significant efforts have been made to address the impact of sparse sampling by satellite sensors of variable rainfall processes by merging various satellite and in-situ rainfall products. These combine high spatial and temporal frequency satellite infrared data with higher quality passive microwave observations and rain gauge observations. Combining such an approach with spatial and temporal averaging of the data can reduce the large random errors inherent in satellite rainfall estimates to very small levels. Unfortunately, systematic biases can and do result in artificial climate signals due to the underconstrained nature of the rainfall retrieval problem. Because all satellite retrieval algorithms make assumptions regarding the cloud structure and microphysical properties, systematic changes in these assumed parameters between regions and/or times results in regional and/or temporal biases in the rainfall estimates. These biases tend to be relatively small compared to random errors in the retrieval, however, when random errors are reduced through spatial and temporal averaging for climate applications, they become the dominant source of error. Whether or not such biases impact the results for climate studies is very much dependent on the application. For example, all of the existing satellite rainfall products capture the increased rainfall in the east Pacific associated with El Niño, however, the resulting tropical response to

VHF/UHF radar observations of tropical mesoscale convective systems over southern India

Directory of Open Access Journals (Sweden)

K. Kishore Kumar

2005-07-01

Full Text Available Several campaigns have been carried out to study the convective systems over Gadanki (13.5° N, 79.2° E, a tropical station in India, using VHF and UHF radars. The height-time sections of several convective systems are investigated in detail to study reflectivity, turbulence and vertical velocity structure. Structure and dynamics of the convective systems are the main objectives of these campaigns. The observed systems are classified into single- and multi-cell systems. It has been observed that most of the convective systems at this latitude are multi-cellular in nature. Simultaneous VHF and UHF radar observations are used to classify the observed precipitating systems as convective, intermediary and stratiform regions. Composite height profiles of vertical velocities in these regions were obtained and the same were compared with the profiles obtained at other geographical locations. These composite profiles of vertical velocity in the convective regions have shown their peaks in the mid troposphere, indicating that the maximum latent heat is being released at those heights. These profiles are very important for numerical simulations of the convective systems, which vary significantly from one geographical location to the other.

Keywords. Meteorology and atmospheric dynamics (Mesoscale meteorology; Convective processes – Radio science (Remote sensing

VHF/UHF radar observations of tropical mesoscale convective systems over southern India

Directory of Open Access Journals (Sweden)

K. Kishore Kumar

2005-07-01

Full Text Available Several campaigns have been carried out to study the convective systems over Gadanki (13.5° N, 79.2° E, a tropical station in India, using VHF and UHF radars. The height-time sections of several convective systems are investigated in detail to study reflectivity, turbulence and vertical velocity structure. Structure and dynamics of the convective systems are the main objectives of these campaigns. The observed systems are classified into single- and multi-cell systems. It has been observed that most of the convective systems at this latitude are multi-cellular in nature. Simultaneous VHF and UHF radar observations are used to classify the observed precipitating systems as convective, intermediary and stratiform regions. Composite height profiles of vertical velocities in these regions were obtained and the same were compared with the profiles obtained at other geographical locations. These composite profiles of vertical velocity in the convective regions have shown their peaks in the mid troposphere, indicating that the maximum latent heat is being released at those heights. These profiles are very important for numerical simulations of the convective systems, which vary significantly from one geographical location to the other. Keywords. Meteorology and atmospheric dynamics (Mesoscale meteorology; Convective processes – Radio science (Remote sensing

Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

Digital Repository Service at National Institute of Oceanography (India)

Chakraborty, P.; Acharyya, T.; Babu, P.V.R.; Bandyopadhyay, D.

towards the fluctuating pH. These findings are environmentally relevant to understand the likely impact of salt water intrusion and pH variation on phytoplankton communities in a tropical freshwater system....

International Journal of Tropical Agriculture and Food Systems

African Journals Online (AJOL)

... and Food Systems (IJOTAFS) publishes high-quality peer reviewed articles, in English, in all areas of agriculture and food production and processing including tree production, pesticide science, post harvest biology and technology, seed science, irrigation, agricultural engineering, water resources management, marine ...

Agro-industrial by-products as ruminant feed

International Nuclear Information System (INIS)

Jayasuriya, M.C.N.

1986-01-01

A marked imbalance exists in many parts of the world between the number of ruminants and the availability of good quality fodder. The low feeding value of natural pastures, their seasonality of production, and the increasing cost of feed grain, have increased the dependence of ruminant animals on crop residues and by-products of agriculture for their nutrient requirements. Intensive animal production systems suitable for developed temperate regions have not been successful in the developing tropical countries, where appropriate farming systems for livestock production should have an integrated approach, combining both crop and livestock husbandry. Adoption of nutritional principles with a view to eliminating or reducing imbalances and optimizing rumen function have yielded excellent results, illustrating the future potential of fibrous residues and other agricultural by-products in ruminant feeding systems in developing countries. (author)

Using molt cycles to categorize the age of tropical birds: an integrative new system

Science.gov (United States)

Jared D. Wolfe; Thomas B. Ryder; Peter Pyle

2010-01-01

Accurately differentiating age classes is essential for the long-term monitoring of resident New World tropical bird species. Molt and plumage criteria have long been used to accurately age temperate birds, but application of temperate age-classification models to the Neotropics has been hindered because annual life-cycle events of tropical birds do not always...

Bacterial production and growth rate estimation from [3H]thymidine incorporation for attached and free-living bacteria in aquatic systems

International Nuclear Information System (INIS)

Iriberri, J.; Unanue, M.; Ayo, B.; Barcina, I.; Egea, L.

1990-01-01

Production and specific growth rates of attached and free-living bacteria were estimated in an oligotrophic marine system, La Salvaje Beach, Vizcaya, Spain, and in a freshwater system having a higher nutrient concentration, Butron River, Vizcaya, Spain. Production was calculated from [methyl- 3 H]thymidine incorporation by estimating specific conversion factors (cells or micrograms of C produced per mole of thymidine incorporated) for attached and free-living bacteria, respectively, in each system. Conversion factors were not statistically different between attached and free-living bacteria: 6.812 x 10 11 and 8.678 x 10 11 μg of C mol -1 for free-living and attached bacteria in the freshwater system, and 1.276 x 10 11 and 1.354 x 10 11 μg of C mol -1 for free-living and attached bacteria in the marine system. Therefore, use of a unique conversion factor for the mixed bacterial population is well founded. However, conversion factors were higher in the freshwater system than in the marine system. This could be due to the different tropic conditions of the two systems. Free-living bacteria contributed the most to production in the two systems (85% in the marine system and 67% in the freshwater system) because of their greater contribution to total biomass. Specific growth rates calculated from production data and biomass data were similar for attached and free-living bacteria

Animal Health in the Tropics

Directory of Open Access Journals (Sweden)

M.R. Jainudeen

1996-01-01

Full Text Available Most developing countries in Africa and Asia are located in the tropics (23° north and south of the equator. The poor productivity of ruminants in these countries is mostly due to inadequate nutrition, infectious diseases, low rates of reproduction, poor genotype, high ambient temperatures and socioeconomic constraints. In addition to infectious diseases which have long since been eradicated or brought under control in developed countries, there are diseases unique to the tropical environment. In the past, the diagnosis of most diseases was based on serological tests. The enzyme-linked immunosorbent assay (ELISA, a rapid method of identifying viral and bacterial infections, is contributing to the eradication or control of most epidemic diseases which inflict high mortality. Less attention has; however, been given to subclinical diseases which adversely affect reproduction, growrh rates and reduced performance (draught power, milk and meat. The interaction of veterinary epidemiology and agricultural economics has helped epidemiologists and veterinarians to focus on the economic importance of animal diseases. The emerging trends in animal health include new diagnostic methods using DNA probes, new vaccines, sustainable parasite control schemes and herd health monitoring. The study of infectious diseases of veterinary importance will continue to he supported by modern techniques of molecular biology. Veterinary curricula should emphasis both animal health and production in the context of current national development occurring in the livestock sector.

The role of trees in agroecology and sustainable agriculture in the tropics.

Science.gov (United States)

Leakey, Roger R B

2014-01-01

Shifting agriculture in the tropics has been replaced by sedentary smallholder farming on a few hectares of degraded land. To address low yields and low income both, the soil fertility, the agroecosystem functions, and the source of income can be restored by diversification with nitrogen-fixing trees and the cultivation of indigenous tree species that produce nutritious and marketable products. Biodiversity conservation studies indicate that mature cash crop systems, such as cacao and coffee with shade trees, provide wildlife habitat that supports natural predators, which, in turn, reduce the numbers of herbivores and pathogens. This review offers suggestions on how to examine these agroecological processes in more detail for the most effective rehabilitation of degraded land. Evidence from agroforestry indicates that in this way, productive and environmentally friendly farming systems that provide food and nutritional security, as well as poverty alleviation, can be achieved in harmony with wildlife.

Tropical myeloneuropathies: the hidden endemias.

Science.gov (United States)

Román, G C; Spencer, P S; Schoenberg, B S

1985-08-01

Tropical myeloneuropathies include tropical ataxic neuropathy and tropical spastic paraparesis. These disorders occur in geographic isolates in several developing countries and are associated with malnutrition, cyanide intoxication from cassava consumption, tropical malabsorption (TM), vegetarian diets, and lathyrism. TM-malnutrition was a probable cause of myeloneuropathies among Far East prisoners of war in World War II. Clusters of unknown etiology occur in India, Africa, the Seychelles, several Caribbean islands, Jamaica, and Colombia. Treponemal infection (yaws) could be an etiologic factor in the last two. Tropical myeloneuropathies, a serious health problem, are multifactorial conditions that provide unsurpassed opportunities for international cooperation and neurologic research.

Current trends of tropical fruit waste utilization.

Science.gov (United States)

Cheok, Choon Yoong; Mohd Adzahan, Noranizan; Abdul Rahman, Russly; Zainal Abedin, Nur Hanani; Hussain, Norhayati; Sulaiman, Rabiha; Chong, Gun Hean

2018-02-11

Recent rapid growth of the world's population has increased food demands. This phenomenon poses a great challenge for food manufacturers in maximizing the existing food or plant resources. Nowadays, the recovery of health benefit bioactive compounds from fruit wastes is a research trend not only to help minimize the waste burden, but also to meet the intensive demand from the public for phenolic compounds which are believed to have protective effects against chronic diseases. This review is focused on polyphenolic compounds recovery from tropical fruit wastes and its current trend of utilization. The tropical fruit wastes include in discussion are durian (Durio zibethinus), mangosteen (Garcinia mangostana L.), rambutan (Nephelium lappaceum), mango (Mangifera indica L.), jackfruit (Artocarpus heterophyllus), papaya (Carica papaya), passion fruit (Passiflora edulis), dragon fruit (Hylocereus spp), and pineapple (Ananas comosus). Highlights of bioactive compounds in different parts of a tropical fruit are targeted primarily for food industries as pragmatic references to create novel innovative health enhancement food products. This information is intended to inspire further research ideas in areas that are still under-explored and for food processing manufacturers who would like to minimize wastes as the norm of present day industry (design) objective.

Quality maintenance Tropical Plants

Directory of Open Access Journals (Sweden)

Gláucia Moraes Dias

2016-11-01

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

Analysis and modeling of tropical convection observed by CYGNSS

Science.gov (United States)

Lang, T. J.; Li, X.; Roberts, J. B.; Mecikalski, J. R.

2017-12-01

The Cyclone Global Navigation Satellite System (CYGNSS) is a multi-satellite constellation that utilizes Global Positioning System (GPS) reflectometry to retrieve near-surface wind speeds over the ocean. While CYGNSS is primarily aimed at measuring wind speeds in tropical cyclones, our research has established that the mission may also provide valuable insight into the relationships between wind-driven surface fluxes and general tropical oceanic convection. Currently, we are examining organized tropical convection using a mixture of CYGNSS level 1 through level 3 data, IMERG (Integrated Multi-satellite Retrievals for Global Precipitation Measurement), and other ancillary datasets (including buoys, GPM level 1 and 2 data, as well as ground-based radar). In addition, observing system experiments (OSEs) are being performed using hybrid three-dimensional variational assimilation to ingest CYGNSS observations into a limited-domain, convection-resolving model. Our focus for now is on case studies of convective evolution, but we will also report on progress toward statistical analysis of convection sampled by CYGNSS. Our working hypothesis is that the typical mature phase of organized tropical convection is marked by the development of a sharp gust-front boundary from an originally spatially broader but weaker wind speed change associated with precipitation. This increase in the wind gradient, which we demonstrate is observable by CYGNSS, likely helps to focus enhanced turbulent fluxes of convection-sustaining heat and moisture near the leading edge of the convective system where they are more easily ingested by the updraft. Progress on the testing and refinement of this hypothesis, using a mixture of observations and modeling, will be reported.

Effects of phosphorus and nitrogen additions on tropical soil microbial activity in the context of experimental warming

Science.gov (United States)

Foley, M.; Nottingham, A.; Turner, B. L.

2017-12-01

Soil warming is generally predicted to increase microbial mineralization rates and accelerate soil C losses which could establish a positive feedback to climatic warming. Tropical rain forests account for a third of global soil C, yet the responseto of tropical soil C a warming climate remains poorly understood. Despite predictions of soil C losses, decomposition of soil organic matter (SOM) in tropical soils may be constrained by several factors including microbial nutrient deficiencies. We performed an incubation experiment in conjunction with an in-situ soil warming experiment in a lowland tropical forest on Barro Colorado Island, Panama, to measure microbial response to two key nutrient additions in shallow (0-10cm) and deep (50-100 cm) soils. We compared the response of lowland tropical soils to montane tropical soils, predicting that lowland soils would display the strongest response to phosphorus additions. Soils were treated with either carbon alone (C), nitrogen (CN), phosphorus (CP) or nitrogen and phosphorus combined (CNP). Carbon dioxide (CO2) production was measured by NaOH capture and titrimetric analysis for 10 days. Cumulative CO2 production in montane soils increased significantly with all additions, suggesting these soils are characterized by a general microbial nutrient deficiency. The cumulative amount of C respired in deep soils from the lowland site increased significantly with CP and CNP additions, suggesting that microbial processes in deep lowland tropical soils are phosphorus-limited. These results support the current understanding that lowland tropical forests are growing on highly weathered, phosphorus-deplete soils, and provide novel insight that deep tropical SOM may be stabilized by a lack of biologically-available phosphorus. Further, this data suggests tropical soil C losses under elevated temperature may be limited by a strong microbial phosphorus deficiency.

Tropical diseases of the myocardium: a review

Directory of Open Access Journals (Sweden)

Groom ZC

2017-04-01

Full Text Available Zoe C Groom,1 Aristotle D Protopapas,2 Vasileios Zochios3,4 1Costello Medical Consulting Limited, Cambridge, 2Department of Surgery, Division of Surgery and Cancer, Imperial College London, London, 3Department of Intensive Care Medicine, Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust, 4College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK Abstract: Cardiovascular diseases are widely distributed throughout the world. Human parasitic infections are ubiquitous. Tropical parasites are increasingly recognized as causes of cardiovascular diseases. In this review, we address the most frequently reported parasites that directly infect the myocardium, including Trypanosoma cruzi, the protozoal causative agent of American trypanosomiasis (Chagas disease, and Taenia solium, the cestode causative agent of taeniasis and cysticercosis. We also discuss tropical endomyocardial fibrosis, trichinellosis and schistosomiasis. Health systems, attitudes, the perceptions of both patients and physicians as well as socioeconomic factors should all be explored and recognized as crucial factors for improving the control of cardiovascular diseases in the tropics. Clinicians throughout the world must remain aware of imported parasites as potential causes of cardiac diseases. Keywords: cardiomyopathy, Chagas disease, myocardium, parasitic infection, tropical infections

Towards a Statistical Model of Tropical Cyclone Genesis

Science.gov (United States)

Fernandez, A.; Kashinath, K.; McAuliffe, J.; Prabhat, M.; Stark, P. B.; Wehner, M. F.

2017-12-01

Tropical Cyclones (TCs) are important extreme weather phenomena that have a strong impact on humans. TC forecasts are largely based on global numerical models that produce TC-like features. Aspects of Tropical Cyclones such as their formation/genesis, evolution, intensification and dissipation over land are important and challenging problems in climate science. This study investigates the environmental conditions associated with Tropical Cyclone Genesis (TCG) by testing how accurately a statistical model can predict TCG in the CAM5.1 climate model. TCG events are defined using TECA software @inproceedings{Prabhat2015teca, title={TECA: Petascale Pattern Recognition for Climate Science}, author={Prabhat and Byna, Surendra and Vishwanath, Venkatram and Dart, Eli and Wehner, Michael and Collins, William D}, booktitle={Computer Analysis of Images and Patterns}, pages={426-436}, year={2015}, organization={Springer}} to extract TC trajectories from CAM5.1. L1-regularized logistic regression (L1LR) is applied to the CAM5.1 output. The predictions have nearly perfect accuracy for data not associated with TC tracks and high accuracy differentiating between high vorticity and low vorticity systems. The model's active variables largely correspond to current hypotheses about important factors for TCG, such as wind field patterns and local pressure minima, and suggests new routes for investigation. Furthermore, our model's predictions of TC activity are competitive with the output of an instantaneous version of Emanuel and Nolan's Genesis Potential Index (GPI) @inproceedings{eman04, title = "Tropical cyclone activity and the global climate system", author = "Kerry Emanuel and Nolan, {David S.}", year = "2004", pages = "240-241", booktitle = "26th Conference on Hurricanes and Tropical Meteorology"}.

Breeding objectives for pigs in Kenya. I: bio-economic model development and application to smallholder production systems.

Science.gov (United States)

Mbuthia, Jackson M; Rewe, Thomas O; Kahi, Alexander K

2015-02-01

A deterministic bio-economic model was developed and applied to evaluate biological and economic variables that characterize smallholder pig production systems in Kenya. Two pig production systems were considered namely, semi-intensive (SI) and extensive (EX). The input variables were categorized into biological variables including production and functional traits, nutritional variables, management variables and economic variables. The model factored the various sow physiological systems including gestation, farrowing, lactation, growth and development. The model was developed to evaluate a farrow to finish operation, but the results were customized to account for a farrow to weaner operation for a comparative analysis. The operations were defined as semi-intensive farrow to finish (SIFF), semi-intensive farrow to weaner (SIFW), extensive farrow to finish (EXFF) and extensive farrow to weaner (EXFW). In SI, the profits were the highest at KES. 74,268.20 per sow per year for SIFF against KES. 4026.12 for SIFW. The corresponding profits for EX were KES. 925.25 and KES. 626.73. Feed costs contributed the major part of the total costs accounting for 67.0, 50.7, 60.5 and 44.5 % in the SIFF, SIFW, EXFF and EXFW operations, respectively. The bio-economic model developed could be extended with modifications for use in deriving economic values for breeding goal traits for pigs under smallholder production systems in other parts of the tropics.

Impact of Moist Physics Complexity on Tropical Cyclone Simulations from the Hurricane Weather Research and Forecast System

Science.gov (United States)

Kalina, E. A.; Biswas, M.; Newman, K.; Grell, E. D.; Bernardet, L.; Frimel, J.; Carson, L.

2017-12-01

The parameterization of moist physics in numerical weather prediction models plays an important role in modulating tropical cyclone structure, intensity, and evolution. The Hurricane Weather Research and Forecast system (HWRF), the National Oceanic and Atmospheric Administration's operational model for tropical cyclone prediction, uses the Scale-Aware Simplified Arakawa-Schubert (SASAS) cumulus scheme and a modified version of the Ferrier-Aligo (FA) microphysics scheme to parameterize moist physics. The FA scheme contains a number of simplifications that allow it to run efficiently in an operational setting, which includes prescribing values for hydrometeor number concentrations (i.e., single-moment microphysics) and advecting the total condensate rather than the individual hydrometeor species. To investigate the impact of these simplifying assumptions on the HWRF forecast, the FA scheme was replaced with the more complex double-moment Thompson microphysics scheme, which individually advects cloud ice, cloud water, rain, snow, and graupel. Retrospective HWRF forecasts of tropical cyclones that occurred in the Atlantic and eastern Pacific ocean basins from 2015-2017 were then simulated and compared to those produced by the operational HWRF configuration. Both traditional model verification metrics (i.e., tropical cyclone track and intensity) and process-oriented metrics (e.g., storm size, precipitation structure, and heating rates from the microphysics scheme) will be presented and compared. The sensitivity of these results to the cumulus scheme used (i.e., the operational SASAS versus the Grell-Freitas scheme) also will be examined. Finally, the merits of replacing the moist physics schemes that are used operationally with the alternatives tested here will be discussed from a standpoint of forecast accuracy versus computational resources.

Pneumonia in the tropics.

Science.gov (United States)

Lim, Tow Keang; Siow, Wen Ting

2018-01-01

Pneumonia in the tropics poses a heavy disease burden. The complex interplay of climate change, human migration influences and socio-economic factors lead to changing patterns of respiratory infections in tropical climate but also increasingly in temperate countries. Tropical and poorer countries, especially South East Asia, also bear the brunt of the global tuberculosis (TB) pandemic, accounting for almost one-third of the burden. But, as human migration patterns evolve, we expect to see more TB cases in higher income as well as temperate countries, and rise in infections like scrub typhus from ecotourism activities. Fuelled by the ease of air travel, novel zoonotic infections originating from the tropics have led to global respiratory pandemics. As such, clinicians worldwide should be aware of these new conditions as well as classical tropical bacterial pneumonias such as melioidosis. Rarer entities such as co-infections of leptospirosis and chikungunya or dengue will need careful consideration as well. In this review, we highlight aetiologies of pneumonia seen more commonly in the tropics compared with temperate regions, their disease burden, variable clinical presentations as well as impact on healthcare delivery. © 2017 Asian Pacific Society of Respirology.

Shade tree diversity enhances coffee production and quality in agroforestry systems in the Western Ghats

NARCIS (Netherlands)

Nesper, Maike; Kueffer, Christoph; Krishnan, Smitha; Kushalappa, Cheppudira G.; Ghazoul, Jaboury

2017-01-01

Intensification of multispecies coffee agroforests reduces shade tree diversity with implications for tropical biodiversity. We investigated how tree biodiversity and its effects on coffee production and quality changes along a gradient of intensification (from diverse multispecies to Grevillea

Nematode parasite control of livestock in the tropics/subtropics: the need for novel approaches.

Science.gov (United States)

Waller, P J

1997-10-01

Because parasites are more abundant, small ruminants in the tropical/subtropical regions of the world experience much greater ravages from internal parasitic disease than those in the temperate regions. In the tropics/subtropics, the limiting ecological factor influencing the severity of parasitism is rainfall, as temperatures almost always favour hatching and development of the free-living stages. Attempts to expand sheep and goat production by replacing traditional village production systems, which rarely involve anthelmintic treatment, with large-scale intensive commercial enterprises invariably induce complete reliance on anthelmintics to control nematode parasites. This has led to the widespread development of high level, multiple anthelmintic resistance throughout the tropics/subtropics, and in certain regions this has reached the ultimate disastrous scenario of total chemotherapeutic failure. Immediate concerted efforts are needed to resolve this crisis. Significant benefits are likely to emerge from research into non-chemotherapeutic approaches to nematode parasite control, such as grazing management, worm vaccines, breed selection and biological control. However, it is likely that none, in isolation or collectively, will completely replace the need for effective anthelmintics. What is needed is the integration of all methods of parasite control as they come to hand, with the underlying aim of reducing the use and thus preserving the effectiveness of anthelmintics. Although cheap and simple procedures, based on sound epidemiological principles, can achieve dramatic benefits in worm control, they have been poorly adopted by livestock owners. Clearly then, the greatest need is for technology transfer and education programmes, but these activities are generally found to be chronically under-resourced.

Tropical Cyclone Propagation

National Research Council Canada - National Science Library

Gray, William

1994-01-01

This paper discusses the question of tropical cyclone propagation or why the average tropical cyclone moves 1-2 m/s faster and usually 10-20 deg to the left of its surrounding (or 5-7 deg radius) deep layer (850-300 mb) steering current...

Earthworms and litter management contributions to ecosystem services in a tropical agroforestry system.

Science.gov (United States)

Fonte, Steven J; Six, Johan

2010-06-01

important implications for the provision of ecosystem services (e.g., C sequestration, soil fertility, and plant production) by tropical agroforestry systems.

Arthropod pests of dried fish and fish by product in a tropical urban ...

African Journals Online (AJOL)

A four months research survey of arthropod pests infesting dried fish sold in a tropical urban community market (Ogige), Nsukka, Ngeria showed that 10 genera o dried freshwater fish (Synodontis, Hemisynodontis, Oreochromis, Hepsetus, Gymnarchus, Labeo, Protopterus, Heterobranchus, Alestes, Heterotis) and two ...

Bibliometry of Costa Rica biodiversity studies published in the Revista de Biología Tropical/International Journal of Tropical Biology and Conservation (2000-2010: the content and importance of a leading tropical biology journal in its 60th Anniversary

Directory of Open Access Journals (Sweden)

Vanessa Nielsen-Muñoz

2012-12-01

Full Text Available Central America is recognized as a mega diverse “hot-spot” and one of its smaller countries, Costa Rica, as one of the world’s leaders in the study and conservation of tropical biodiversity. For this study, inspired by the 60th anniversary of the journal Revista de Biología Tropical, we tabulated all the scientific production on Costa Rican biodiversity published in Revista de Biología Tropical between 2000 and 2010. Most articles are zoological (62% and 67% of authors had only one publication in the jounal within that period. A 54% of articles were published in English and 46% in Spanish. A 41% of articles were written in collaboration among Costa Rican institutions and 36% in collaboration with foreign institutions. The Collaboration Index was 2.53 signatures per article. Visibility in American sources was 56% in Google Scholar and 42.66% in the Web of Science, but the real visibility and impact are unknown because these sources exclude the majority of tropical journals. Revista de Biología Tropical is the main output channel for Costa Rican biology and despite its small size, Costa Rica occupies the 10th. place in productivity among Latin American countries, with productivity and impact levels that compare favorably with larger countries such as Brazil, Mexico, Argentina and Chile.América Central es reconocida como región mega- diversa y uno de sus países más pequeños, Costa Rica, se encuentra entre los líderes mundiales en el estudio y conservación de la biodiversidad tropical. Este estudio, inspirado por el 60 aniversario de la Revista de Biología Tropical, actualiza nuestro conocimiento bibliométrico sobre la materia. Hicimos un listado de toda la producción científica sobre la biodiversidad de Costa Rica en la Revista entre 2000 y 2010. La mayoría de los artículos son zoológicos (62% y el 67% de los autores sólo tuvo una publicación en la revista durante ese periodo. Un 54% de los artículos fueron publicados en

Analysis agriculture's impact in a system of lakes on a karst environment with tropical climate.

Science.gov (United States)

Olea Olea, Selene; Escolero Fuentes, Oscar

2015-04-01

This paper has as main object to analyze the impact of agriculture in the water quality of the "Lagos de Montebello" area; which is located in the Southeast of Mexico. This area is prominent by its tropical climate and a karstic environment. The issue arises in a lake system affected by pollution in the later years, which has turned its former clear water into a highly sedimented muddy water in the topographically lower terrains while no polluted on the higher ones; therefore it is intended to determine if the rise in agricultural activity in the lower terrains has induced this phenomenon. The impact of agriculture has been historically studied in temperate climates with karstic environments; nevertheless it has not been very well studied in tropical climates; which are the reason of this proposal to perform a study to analyze the impact of the intensive agriculture running in the area. To develop this project we studied the area regarding to the types of crops that has being established in the zone, being mostly tomato, corn, and bean; and the fertilizers and pesticides applied to them. A groundwater monitoring plan was designed with a variety of phases such as: piezometers building, measurement of groundwater levels, measurement of field parameters, with a two months intervals (Ph, temperature, electric conductivity, total dissolved solids), and water samplings for laboratory analysis (major ions, nutrients, total organic carbon, pesticides) at twice a year, once during rainy season and then on drought. The rates of pollution agents infiltration depends on the type of soil retention and volume of water. The materials found in the soil by the piezometers are clay, silt, sand and variations between them. We determined that the geochemical qualities of the groundwater vary from calcic bicarbonate to calcic sulfated. The results reached with this monitoring provides a preliminary diagnosis on the possible causes and other implications that intensive agriculture in a

Neglected tropical diseases outside the tropics.

Directory of Open Access Journals (Sweden)

Francesca F Norman

Full Text Available BACKGROUND: The neglected tropical diseases (NTDs cause significant morbidity and mortality worldwide. Due to the growth in international travel and immigration, NTDs may be diagnosed in countries of the western world, but there has been no specific focus in the literature on imported NTDs. METHODS: Retrospective study of a cohort of immigrants and travelers diagnosed with one of the 13 core NTDs at a Tropical Medicine Referral Unit in Spain during the period April 1989-December 2007. Area of origin or travel was recorded and analyzed. RESULTS: There were 6168 patients (2634 immigrants, 3277 travelers and 257 VFR travelers in the cohort. NTDs occurred more frequently in immigrants, followed by VFR travelers and then by other travelers (p<0.001 for trend. The main NTDs diagnosed in immigrants were onchocerciasis (n = 240, 9.1% acquired mainly in sub-Saharan Africa, Chagas disease (n = 95, 3.6% in immigrants from South America, and ascariasis (n = 86, 3.3% found mainly in immigrants from sub-Saharan Africa. Most frequent NTDs in travelers were: schistosomiasis (n = 43, 1.3%, onchocerciasis (n = 17, 0.5% and ascariasis (n = 16, 0.5%, and all were mainly acquired in sub-Saharan Africa. The main NTDs diagnosed in VFR travelers were onchocerciasis (n = 14, 5.4%, and schistosomiasis (n = 2, 0.8%. CONCLUSIONS: The concept of imported NTDs is emerging as these infections acquire a more public profile. Specific issues such as the possibility of non-vectorial transmission outside endemic areas and how some eradication programmes in endemic countries may have an impact even in non-tropical western countries are addressed. Recognising NTDs even outside tropical settings would allow specific prevention and control measures to be implemented and may create unique opportunities for research in future.

The potential of intercropping food crops and energy crop to improve productivity of a degraded agriculture land in arid tropics

Directory of Open Access Journals (Sweden)

I.K.D. Jaya

2014-04-01

Full Text Available Degraded agricultural lands in the arid tropics have low soil organic carbon (SOC and hence low productivity. Poor farmers that their livelihoods depend highly on these types of lands are suffering. Cropping strategies that are able to improve the soil productivity are needed. In the present study, some intercropping models of food crops with bio-energy crop of castor (Ricinus communis L. were tested to assess their potential to improve the degraded land productivity. The intercropping models were: (1 castor - hybrid maize, (2 castor – short season maize, (3 castor – mungbean, and (4 castor –short season maize – mungbean. The results show that yields of the component crops in monoculture were relatively the same as in intercropping, resulted in a high Land Equivalent Ratio (LER. The highest LER (3.07 was calculated from intercropping castor plants with short season maize crops followed by mungbean with intercropping productivity of IDR 15,097,600.00 ha-1. Intercropping has a great potential to improve degraded agriculture land productivity and castor is a promising plant to improve biodiversity and area coverage on the land.

Tropical Cyclogenesis in a Tropical Wave Critical Layer: Easterly Waves

Science.gov (United States)

Dunkerton, T. J.; Montgomery, M. T.; Wang, Z.

2009-01-01

The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside.

Effects of an evaporative cooling system on plasma cortisol, IGF-I, and milk production in dairy cows in a tropical environment

Science.gov (United States)

Titto, Cristiane Gonçalves; Negrão, João Alberto; Titto, Evaldo Antonio Lencioni; Canaes, Taissa de Souza; Titto, Rafael Martins; Pereira, Alfredo Manuel Franco

2013-03-01

Access to an evaporative cooling system can increase production in dairy cows because of improved thermal comfort. This study aimed to evaluate the impact of ambient temperature on thermoregulation, plasma cortisol, insulin-like growth factor 1 (IGF-I), and productive status, and to determine the efficiency of an evaporative cooling system on physiological responses under different weather patterns. A total of 28 Holstein cows were divided into two groups, one with and the other without access to a cooling system with fans and mist in the free stall. The parameters were analyzed during morning (0700 hours) and afternoon milking (1430 hours) under five different weather patterns throughout the year (fall, winter, spring, dry summer, and rainy summer). Rectal temperature (RT), body surface temperature (BS), base of tail temperature (TT), and respiratory frequency (RF) were lower in the morning ( P milk production during spring and summer ( P < 0.01).

Tropical Fruit Irradiation-From Research to Commercial Application

International Nuclear Information System (INIS)

Moy, James H.

2005-09-01

Food irradiation is an emerging technology for the 21st century. Extensive research and development worldwide in the past 40 years have proved the versatility and efficacy. With low, medium to high dose, and using either a gamma, electrons, or x-ray source, radiation can: 1) disinfest plant products and spices; 2) extend shelf life of tubers, bulbs, and selected tropical fruits; 3) decontaminate meats and seafood; 4) sterilize spices and special meals; and 5) improve product utilization. Criteria for testing its efficacy include effectiveness, efficiency, and the ability to retain product quality. The use of irradiation as a quarantine treatment of tropical fruits is potentially attractive to countries growing these fruits. A two-prong research plan should aim at proving radiation's effectiveness in preventing emergence of all insect pests that might be on a fruit, and determining that all quality attributes of a host fruit are retained after irradiation, subsequent storage and shipment. ommercial application involves conducting an economical feasibility study; market research and testing; selection of radiation source and irradiator type; training of personnel for plant operations, radiation safety and dosimetry monitoring; designing of packages and choosing the most cost-effective means of transporting treated fruits to market destinations. When all of hese are achieved, it should lead to a continuous and profitable operation. Researchers at the University of Hawaii using a gamma irradiator from the mid-1960s to early 2000s had amassed a volume of data to prove the efficacy of radiation disinfestations. And installation of a commercial x-ray irradiator in 2000 on the Island of Hawaii has enabled fruit farmers and packers to use this technology for exporting tropical fruits to distant markets

Computing Tropical Varieties

DEFF Research Database (Denmark)

Speyer, D.; Jensen, Anders Nedergaard; Bogart, T.

2005-01-01

The tropical variety of a d-dimensional prime ideal in a polynomial ring with complex coefficients is a pure d-dimensional polyhedral fan. This fan is shown to be connected in codimension one. We present algorithmic tools for computing the tropical variety, and we discuss our implementation...

Reversal of Increasing Tropical Ocean Hypoxia Trends With Sustained Climate Warming

Science.gov (United States)

Fu, Weiwei; Primeau, Francois; Keith Moore, J.; Lindsay, Keith; Randerson, James T.

2018-04-01

Dissolved oxygen (O2) is essential for the survival of marine animals. Climate change impacts on future oxygen distributions could modify species biogeography, trophic interactions, biodiversity, and biogeochemistry. The Coupled Model Intercomparison Project Phase 5 models predict a decreasing trend in marine O2 over the 21st century. Here we show that this increasing hypoxia trend reverses in the tropics after 2100 in the Community Earth System Model forced by atmospheric CO2 from the Representative Concentration Pathway 8.5 and Extended Concentration Pathway 8.5. In tropical intermediate waters between 200 and 1,000 m, the model predicts a steady decline of O2 and an expansion of oxygen minimum zones (OMZs) during the 21st century. By 2150, however, the trend reverses with oxygen concentration increasing and OMZ volume shrinking through 2300. A novel five-box model approach in conjunction with output from the full Earth system model is used to separate the contributions of biological and physical processes to the trends in tropical oxygen. The tropical O2 recovery is caused mainly by reductions in tropical biological export, coupled with a modest increase in ventilation after 2200. The time-evolving oxygen distribution impacts marine nitrogen cycling, with potentially important climate feedbacks.

Effects of canopy photosynthesis saturation on the estimation of gross primary productivity from MODIS data in a tropical forest

DEFF Research Database (Denmark)

Propastin, P.; Ibrom, Andreas; Knohl, A.

2012-01-01

The Moderate Resolution Imaging Spectroradiometer (MODIS) gross primary production (GPP) product (GPPMOD17A2) was evaluated against GPP from the eddy covariance flux measurements (GPPm) at a CO2 flux tower test site in a tropical rainforest in Sulawesi, Indonesia. The dynamics of 8-day GPPMOD17A2...... conditions. Obviously, these seasonal differences are caused by too large seasonal amplitudes in GPPMOD17A2. The observed inconsistencies of the GPPMOD17A2with GPPm were traced to the inputs of the MODIS GPP algorithm, including fraction of absorbed photosynthetically active radiation (fAPAR) and light use...... efficiency (εg). This showed that underestimation of low values is caused by several uncertainties in the MODIS fAPAR input, whereas overestimation at high irradiance is caused by the MODIS light use efficiency approach which does not account for saturation of canopy photosynthesis under clear sky conditions...

Mass-Balance Constraints on Nutrient Cycling in Tropical Seagrass Beds

NARCIS (Netherlands)

Erftemeijer, P.L.A.; Middelburg, J.J.

1995-01-01

A relatively simple mass balance model is presented to study the cycling of nutrients (nitrogen and phosphorus) in tropical seagrass beds. The model is based on quantitative data on nutrient availability, seagrass primary production, community oxygen metabolism, seagrass tissue nutrient contents,

Pervasive phosphorus limitation of tree species but not communities in tropical forests

Science.gov (United States)

Turner, Benjamin L.; Brenes-Arguedas, Tania; Condit, Richard

2018-03-01

Phosphorus availability is widely assumed to limit primary productivity in tropical forests, but support for this paradigm is equivocal. Although biogeochemical theory predicts that phosphorus limitation should be prevalent on old, strongly weathered soils, experimental manipulations have failed to detect a consistent response to phosphorus addition in species-rich lowland tropical forests. Here we show, by quantifying the growth of 541 tropical tree species across a steep natural phosphorus gradient in Panama, that phosphorus limitation is widespread at the level of individual species and strengthens markedly below a threshold of two parts per million exchangeable soil phosphate. However, this pervasive species-specific phosphorus limitation does not translate into a community-wide response, because some species grow rapidly on infertile soils despite extremely low phosphorus availability. These results redefine our understanding of nutrient limitation in diverse plant communities and have important implications for attempts to predict the response of tropical forests to environmental change.

Tropical varieties, maps and gossip

NARCIS (Netherlands)

Frenk, B.J.

2013-01-01

Tropical geometry is a relatively new field of mathematics that studies the tropicalization map: a map that assigns a certain type of polyhedral complex, called a tropical variety, to an embedded algebraic variety. In a sense, it translates algebraic geometric statements into combinatorial ones. An

Global economic trade-offs between wild nature and tropical agriculture.

Science.gov (United States)

Carrasco, Luis R; Webb, Edward L; Symes, William S; Koh, Lian P; Sodhi, Navjot S

2017-07-01

Global demands for agricultural and forestry products provide economic incentives for deforestation across the tropics. Much of this deforestation occurs with a lack of information on the spatial distribution of benefits and costs of deforestation. To inform global sustainable land-use policies, we combine geographic information systems (GIS) with a meta-analysis of ecosystem services (ES) studies to perform a spatially explicit analysis of the trade-offs between agricultural benefits, carbon emissions, and losses of multiple ecosystem services because of tropical deforestation from 2000 to 2012. Even though the value of ecosystem services presents large inherent uncertainties, we find a pattern supporting the argument that the externalities of destroying tropical forests are greater than the current direct economic benefits derived from agriculture in all cases bar one: when yield and rent potentials of high-value crops could be realized in the future. Our analysis identifies the Atlantic Forest, areas around the Gulf of Guinea, and Thailand as areas where agricultural conversion appears economically efficient, indicating a major impediment to the long-term financial sustainability of Reducing Emissions from Deforestation and forest Degradation (REDD+) schemes in those countries. By contrast, Latin America, insular Southeast Asia, and Madagascar present areas with low agricultural rents (ARs) and high values in carbon stocks and ES, suggesting that they are economically viable conservation targets. Our study helps identify optimal areas for conservation and agriculture together with their associated uncertainties, which could enhance the efficiency and sustainability of pantropical land-use policies and help direct future research efforts.

An Intrathermocline Eddy and a tropical cyclone in the Bay of Bengal

OpenAIRE

Gordon, Arnold L.; Shroyer, Emily; Murty, V. S. N.

2017-01-01

The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean eddies. On 5 December 2013 a sub-surface vortex or Intrathermocline Eddy (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface eddy from the eastern Bay of Bengal. While Lehar?s interact...

The Variation of Tropical Cyclone Rainfall within the North Atlantic and Pacific as Observed from Satellites

Science.gov (United States)

Rodgers, Edward; Pierce, Harold; Adler, Robert

1999-01-01

Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations in the North Atlantic and in three equal geographical regions of the North Pacific (i.e., Western, Central, and Eastern North Pacific). These satellite-derived rainfall amounts are used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and inter-annual distribution of the 1987-1989, 1991-1998 North Atlantic and Pacific rainfall during June-November when tropical cyclones are most abundant. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from the Defence Meteorological Satellite Program (DMSP) Special Sensor Microwave/ Radiometer (SSM/I) observations within 444 km radius of the center of those North Atlantic and Pacific tropical cyclones that reached storm stage and greater. These rain rate observations are then multiplied by the number of hours in a given month. Mean monthly rainfall amounts are also constructed for all the other North Atlantic and Pacific raining systems during this eleven year period for the purpose of estimating the geographical distribution and intensity of rainfall contributed by non-tropical cyclone systems. Further, the combination of the non-tropical cyclone and tropical cyclone (i.e., total) rainfall is constructed to delineate the fractional amount that tropical cyclones contributed to the total North Pacific rainfall.

Ocean Response to Tropical Storms as Observed by a Moored Ocean Observing System in the Deep Gulf of Mexico

Science.gov (United States)

Oropeza, F.; Jaramillo, S.; Fan, S.

2013-05-01

As part of the support activities for a deepwater development in the Gulf of Mexico, a moored ocean observing system (OOS) was deployed in a water depth of approximately 2500m, 300km south of the Louisiana Coast. From June 2007 to May 2009, the system comprised seven single point Aanderaa Recording Current Meters (RCM), deployed at 450m, 700m, 1,100m, 1,500m, 2,000m, 2,400m and 2,490m below surface, and an RDI 75kHz Longranger Acoustic Doppler Current Profiler (ADCP), deployed between 249 and 373m below surface in upward-looking mode. Since May 2009, the OOS was upgraded to a Wavescan Buoy based moored system including meteorological sensors for: atmospheric pressure, air temperature, wind speed and direction; directional waves sensor; a Doppler Current Sensor (DCS) at 1.5 m depth for surface currents; and two downward-looking ADCP's covering the upper 1,000m of the water column. This OOS has been operating without interruptions from 2007 to the present and has registered data associated with nine tropical storms, including the direct passage of Hurricane Ike, in September of 2008, and loop current events with speeds of up to 4 knots. It has provided one of the most comprehensive set of velocity observations in the Gulf of Mexico, especially, the near surface currents, during pre-storm conditions, response, and ocean relaxation following hurricanes/tropical storms. Based on these observations the upper ocean responses to the energy input from tropical storms are characterized in terms of the associated mixing processes and momentum balances.

[From 'triumphalism' to 'postcolonialism': trends in the historiography of tropical medicine].

Science.gov (United States)

Mertens, Myriam

2009-01-01

This article highlights some of the most remarkable trends in the historiography of tropical medicine. Focusing on the literature that deals with the 19th and 20th centuries, it describes how by the 1980's triumphalist, apologetic histories were replaced by critical studies that revealed the less positive sides of tropical medicine. It also talks about the increasing influence in medical historiography of the postcolonial body of thought and its dynamic perspective on colonial categories and relations. This postcolonialism turns out to be a fruitful approach, as is shown especially by recent studies that focus on the production of tropical medical knowledge. In fact, the historiography of tropical medicine increasingly contributes to the growing body of literature on science and imperialism that looks for postcolonial alternatives to the diffusionist paradigm. This concern to reject diffusionism (which views imperialism as the basis for the spread of European science to the non-western world) has been noticeable particularly in the Anglo-Saxon academic world. This article calls for the adoption of similar approaches in other historiographic traditions.

Combining ability of tropical maize cultivars in organic and conventional production systems Capacidade de combinação de milho tropical em sistemas de produção orgânico e convencional

Directory of Open Access Journals (Sweden)

Lucimar Rodrigues de Oliveira

2011-05-01

Full Text Available The objectives were to identify maize germplasm for the organic productions system and to compare the genetic effects of the grain yield of maize cultivars in organic and conventional production systems. Diallel crosses were made between six maize cultivars and the hybrid combinations were evaluated in conventional and organic production systems. The hybrid combinations produced different grain yields in the two production systems. The interaction between general combining ability and production systems was significant for grain yield, ear height and number of ears. This indicates that the additive genetic effects differ in organic and conventional production systems. The specific combining abilities (SCA were significant for grain yield and plant height, indicating a significant difference between the non-additive effects. However, the SCA x production systems interactions were not significant for those traits. It was concluded that for the development of maize cultivars for the organic production system, selection must be made in the specific environment for the expression of favorable alleles that confer advantages for adapting to this system; the general combining ability of genitors is different for the two production systems, but the specific combining ability isn't different in organic and conventional systems.Os objetivos foram identificar germoplasma de milho para o sistema de produção orgânica e comparar os efeitos genéticos da produtividade de grãos de cultivares de milho em sistemas de produção orgânico e convencional. Para isso, cruzamentos dialélicos foram realizados entre seis cultivares de milho e as combinações híbridas avaliadas em sistemas de produção orgânico e convencional. Os híbridos apresentaram diferentes produtividades de grãos nos dois sistemas de produção. A interação entre a capacidade geral de combinação (CGC e os sistemas de produção (SP foi significativa para produtividade de gr

A warming tropical central Pacific dries the lower stratosphere

Science.gov (United States)

Ding, Qinghua; Fu, Qiang

2018-04-01

The amount of water vapor in the tropical lower stratosphere (TLS), which has an important influence on the radiative energy budget of the climate system, is modulated by the temperature variability of the tropical tropopause layer (TTL). The TTL temperature variability is caused by a complex combination of the stratospheric quasi-biennial oscillation (QBO), tropospheric convective processes in the tropics, and the Brewer-Dobson circulation (BDC) driven by mid-latitude and subtropical atmospheric waves. In 2000, the TLS water vapor amount exhibited a stepwise transition to a dry phase, apparently caused by a change in the BDC. In this study, we present observational and modeling evidence that the epochal change of water vapor between the periods of 1992-2000 and 2001-2005 was also partly caused by a concurrent sea surface temperature (SST) warming in the tropical central Pacific. This SST warming cools the TTL above by enhancing the equatorial wave-induced upward motion near the tropopause, which consequently reduces the amount of water vapor entering the stratosphere. The QBO affects the TLS water vapor primarily on inter-annual timescales, whereas a classical El Niño southern oscillation (ENSO) event has small effect on tropical mean TLS water vapor because its responses are longitudinally out of phase. This study suggests that the tropical central Pacific SST is another driver of TLS water vapor variability on inter-decadal timescales and the tropical SST changes could contribute to about 30% of the step-wise drop of the lower stratospheric water vapor from 1992-2000 to 2001-2005.

Prospects and Challenges in tropical isotope dendroclimatology

Science.gov (United States)

Evans, M. N.; Anchukaitis, K. J.; White, S. R.; Ektvedt, T. M.; Penniston, R. C.; Rheaume, M. M.; Bowman, D. M.

2008-12-01

We review a stable isotope-based approach to the development, modeling, interpretation, and analysis of hydrometeorological estimates from tropical trees. The strategy overcomes the common problem of missing, intermittent or non-annual ring structure in tropical trees by relying instead on the observation of the annual wet-dry seasonality typical to tropical environments as mirrored in the oxygen isotopic composition of wood-derived α-cellulose. We explore regions for which forward modeling of the proxy system would expect us to resolve hydrometeorological variations associated with the El Niño-Southern Oscillation (ENSO) phenomenon, rather than being limited to regions with tree species or environments producing verifiable annual ring chronologies. A modified protocol allows for rapid, simple and non-toxic micro-extraction of pure α-cellulose, which is isotopically indistinguishable from that produced by more classical means. We describe a new reactor for the pyrolysis of α-cellulose in an induction heater, which permits isotopic analysis of α-cellulose samples as small as 30μg, and as many as 100 automated sample analyses per day. A forward model adapted for tropical environments can be used to test and refine the interpretation of the isotopic data, and to predict locales for which we should be able to maximize the paleoclimatic potential of future sample collections. We have found the modeled isotopic chronometer and raingage in agreement with independent chronological controls in a variety of environments and tree species in Costa Rica, Indonesia, Brazil, Peru and Australia. Development of long hydrometeorological records from the terrestrial tropics is underway not only by our group, but by a growing number of collaborators and colleagues. Together we should be able to build a network of paleoprecipitation records and better understand the linkages between tropical surface ocean temperatures and large-scale drought.

Multi-Scale Aspects of Tropical Cyclone Predictability

Science.gov (United States)

Doyle, J. D.; Moskaitis, J.; Black, P. G.; Hendricks, E. A.; Reinecke, A.; Amerault, C. M.

2014-12-01

The intensification of tropical cyclones (TCs) may be sensitive to aspects of large-scale forcing, as well as internal mesoscale dynamics. In this presentation, the degree to which tropical cyclone intensity and structure is sensitive to small perturbations to the basic properties of the synoptic-scale environment, as well as in the immediate vicinity of the storm, is explored using both adjoint- and ensemble-based approaches. In particular, we explore the relationship between tropical cyclone intensity changes and upper-level outflow. We make use of observations from two recent field campaigns: i) the NASA Hurricane and Severe Storms Sentinel (HS3), which featured two fully instrumented Global Hawk unmanned aerial systems, and ii) the ONR Tropical Cyclone Intensity (TCI-14) experiment that utilized the NASA WB-57. We make use of the Navy's high-resolution tropical cyclone prediction system COAMPS-TC to provide ensemble forecasts, numerical experiments with and without the assimilation of specific observation types (e.g., satellite, dropsondes, high-frequency radiosonde), as well as mesoscale nested adjoint sensitivity and observation impact calculations, all of which provide insight into the initial state sensitivity and predictability issues. We assess the impact of observations in sensitive regions in the TC environment (including outflow regions away from the TC inner core) on predictions of TC intensity and structure. Overall the results underscore the importance of multiple scales that influence the predictability of TC intensification. During HS3, the assimilation of Global Hawk dropsondes has been shown to reduce the maximum wind error from 15 knots to less than 10 knots at 48 h for Hurricane Nadine (2012). In this particular case, the adjoint model shows strong sensitivity in the TC outflow near the entrance region of an upper-level jet. The impact of dropsondes from data denial experiments and adjoint-based observation impact calculations will be

Knowledge gaps in tropical Southeast Asian seagrass systems

Science.gov (United States)

Ooi, Jillian Lean Sim; Kendrick, Gary A.; Van Niel, Kimberly P.; Affendi, Yang Amri

2011-03-01

Seagrasses are habitats with significant ecological and economic functions but we have limited knowledge of seagrasses in Southeast Asia, the hypothesized centre-of-origin for tropical seagrasses. There have been only 62 ISI-cited publications on the seagrasses of Southeast Asia in the last three decades and most work has been in few sites such as Northwest Luzon in the Philippines and South Sulawesi in Indonesia. Our understanding of the processes driving spatial and temporal distributions of seagrass species here has focussed primarily on backreef and estuarine seagrass meadows, with little work on forereef systems. We used Pulau Tinggi, an island off the southeast coast of Peninsular Malaysia, as an example of a subtidal forereef system. It is characterized by a community of small and fast growing species such as Halophila ovalis (mean shoot density 1454.6 ± 145.1 m -2) and Halodule uninervis (mean shoot density 861.7 ± 372.0 m -2) growing in relatively low light conditions (mean PAR 162.1 ± 35.0 μmol m -2 s -1 at 10 m depth to 405.8 ± 99.0 μmol m -2 s -1 at 3 m water depth) on sediment with low carbonate (mean 9.24 ± 1.74 percentage dry weight), organic matter (mean 2.56 ± 0.35 percentage dry weight) and silt-clay content (mean 2.28 ± 2.43 percentage dry weight). The literature reveals that there is a range of drivers operating in Southeast Asian seagrass systems and we suggest that this is because there are various types of seagrass habitats in this region, i.e. backreef, forereef and estuary, each of which has site characteristics and ecological drivers unique to it. Based on our case study of Pulau Tinggi, we suggest that seagrasses in forereef systems are more widespread in Southeast Asia than is reflected in the literature and that they are likely to be driven by recurring disturbance events such as monsoons, sediment burial and herbivory.

Tropical Cyclone Ensemble Data Assimilation

Science.gov (United States)

2012-09-30

the global system. The improvement is almost uniform in the extratropics , while in the tropics clear improvements tend to occur in the immediate...surrounding of storms . The latter result suggests that the limited area analysis provides a better representation of the interactions between the...circulation of the storm and the wind field in its immediate vicinity. 2

Productivity raising approaches in the logistic production system

Directory of Open Access Journals (Sweden)

Miroslav Rakyta

2001-01-01

Full Text Available This paper deals with the productivity of the logistic production system. The aim is to define the intermediate state of the production machines and equipment (OOE, identification of the material flows, idle time and breakdown forecasting, with the following purchase of the required spare parts. The goal of the system is the satisfaction of the customer´s needs and the minimalisation of not fulfilling the required terms for delivery with simultaneous increasing of the logistic production system productivity.

Governance for quality management in smallholder-based tropical food chains

NARCIS (Netherlands)

Tilburg, van A.; Trienekens, J.H.; Ruben, R.; Boekel, van M.A.J.S.

2008-01-01

Abstract The paper provides a framework that focuses on the linkages between several key dimensions of supply chain organization and performance of perishable tropical food products. The focus is on the relationship between governance regime and quality management. However, two other but related

Predicting soil properties in the tropics

NARCIS (Netherlands)

Minasny, B.; Hartemink, A.E.

2011-01-01

It is practically impossible to measure soil properties continuously at each location across the globe. Therefore, it is necessary to have robust systems that can predict soil properties at a given location. That is needed in many tropical countries where the dearth of soil property measurements is

Nitrous oxide production from temperate and tropical oyster species in response to nutrient loading

Science.gov (United States)

Chan, H.; Garate, M.; Moseman-Valtierra, S.

2016-02-01

Anthropogenic pollution, such as nitrogen (N), has the potential to increase greenhouse gas (GHG) emissions in marine ecosystems. Some organisms can be used as important biological indicators for GHG emissions to their environment based on their feeding habits. With large inputs of these anthropogenic pollutants, emissions of nitrous oxide (N2O), a potent GHG, can be potentially increased from temperate invertebrates, though not much is known about tropical invertebrates. Thus, we compared N2O emissions in response to N additions from the temperate oyster species Crassostrea virginica and compared it to a tropical species, Isognomon alatus, found in Puerto Rico. Oysters were exposed to two seawater treatments: (1) no nutrient addition (control) and (2) 100µM ammonium nitrate. Each treatment had 4-5 replicates. Measurements for dissolved N2O and nutrients were taken at the start of the incubation and then at two, four, and five hours by collecting water samples of each tank. Dissolved N2O concentrations were analyzed using gas chromatography. We hypothesized that the N addition treatment would produce more N2O for both Rhode Island and Puerto Rico. We found that there was no significant difference between the control and N enriched treatments for C. virginica over the short timespan, although the N enriched treatment did have a steady trend in increasing in N2O concentration over time. Further analysis is needed for the I. alatus, though we expect an increase in N2O emissions due to warmer water temperatures, which might enhance microbial metabolism and production of N2O. This differs from work previously done in a long-term experiment on C. virginica, which showed that N2O significantly in the N enriched treatment over 28-days. Our study shows that short-term pulses of N may not potentially increase N2O emissions, though further analysis is needed for longer-term exposures.

Oil production system

Energy Technology Data Exchange (ETDEWEB)

Ballantyne, J F

1983-12-21

A new oil producing system is proposed which consists of a group of underwater wells, an underwater riser and a floating storage facility for the production of the wells. The group of wells and the riser are interconnected through a manifold system in such a way that the production from any well or from the entire group of wells go to the base (foundation) of the riser. From above the riser is connected with the floating storage facility which is equipped, besides tanks for storing the well products, with a separation device for separating the oil and the accompanying gas. The gas is used as a fuel for producing electric power required by the dynamic positioning systems. The products from each well are tested by means of a regulable coupling controlled by means of a cable, which is passed from the surface through the riser. The wellhead equipment for the unslanted wells is mounted on a template previously installed on the sea floor. From the template the well products enter the riser through the manifold unit system.

Interannual Weakening of the Tropical Pacific Walker Circulation Due to Strong Tropical Volcanism

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Miao, Jiapeng; Wang, Tao; Wang, Huijun; Sun, Jianqi

2018-06-01

In order to examine the response of the tropical Pacific Walker circulation (PWC) to strong tropical volcanic eruptions (SVEs), we analyzed a three-member long-term simulation performed with HadCM3, and carried out four additional CAM4 experiments. We found that the PWC shows a significant interannual weakening after SVEs. The cooling effect from SVEs is able to cool the entire tropics. However, cooling over the Maritime Continent is stronger than that over the central-eastern tropical Pacific. Thus, non-uniform zonal temperature anomalies can be seen following SVEs. As a result, the sea level pressure gradient between the tropical Pacific and the Maritime Continent is reduced, which weakens trade winds over the tropical Pacific. Therefore, the PWC is weakened during this period. At the same time, due to the cooling subtropical and midlatitude Pacific, the Intertropical Convergence Zone (ITCZ) and South Pacific convergence zone (SPCZ) are weakened and shift to the equator. These changes also contribute to the weakened PWC. Meanwhile, through the positive Bjerknes feedback, weakened trade winds cause El Niño-like SST anomalies over the tropical Pacific, which in turn further influence the PWC. Therefore, the PWC significantly weakens after SVEs. The CAM4 experiments further confirm the influences from surface cooling over the Maritime Continent and subtropical/midlatitude Pacific on the PWC. Moreover, they indicate that the stronger cooling over the Maritime Continent plays a dominant role in weakening the PWC after SVEs. In the observations, a weakened PWC and a related El Niño-like SST pattern can be found following SVEs.

Forecasting and Warning of Tropical Cyclones in China

Directory of Open Access Journals (Sweden)

Bangzhong Wang

2007-10-01

Full Text Available With the development of the global economy, the impact of tropical cyclones has become far-reaching. Thus they are a fundamental issue to be addressed both nationally and globally. The socio-economic impact is particularly noticeable in developing countries, especially China. This paper begins with the effects of cyclones on regional and global economies. Then a brief introduction to the past and current situations and progress in cyclones forecasting and warning in China are presented. Finally the paper gives recommendations about improving and perfecting the tropical cyclone forecasting and warning systems.

European cloth and "tropical" skin: clothing material and British ideas of health and hygiene in tropical climates.

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Johnson, Ryan

2009-01-01

As Britain's imperial and colonial ambitions intensified toward the end of the nineteenth century, the preservation of white European health in tropical climates became an increasingly important concern. Since at least the seventeenth century, the "tropics" had been seen as spaces holding vast potential wealth but also death and disease. To combat these deadly but desirable landscapes, the British built a considerable commodity culture around the preservation of white European health, and for many, tropical clothing was one of the most important and essential items in their "kits." This article investigates the composition and use of such clothing in relation to British ideas of health and hygiene in tropical climates. First, it considers debates that ensued over the best material--wool, cotton, linen, silk, or a combination of these materials--and the role of "black" skin and local practice in the development of tropical clothing. Second, it demonstrates the importance of location in any discussion of tropical medicine and hygiene, and the tension and ambiguity that still surrounded British ideas of health and hygiene in the tropical colonies. Third, it argues that tropical clothing was important in the maintenance of climatic etiologies despite advances in parasitology and sanitary science. Finally, it considers the relationship of tropical clothing to the formation of a unique colonial identity. To British men and women embarking for any number of tropical destinations, proper clothing was not a banal and mundane component of their outfitting. For many, the clothing signified a departure from the safe and "civil" climes of Britain for adventure in the expanding tropical empire.

Assessing the Regional Frequency, Intensity, and Spatial Extent of Tropical Cyclone Rainfall

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Bosma, C.; Wright, D.; Nguyen, P.

2017-12-01

While the strength of a hurricane is generally classified based on its wind speed, the unprecedented rainfall-driven flooding experienced in southeastern Texas during Hurricane Harvey clearly highlights the need for better understanding of the hazards associated with extreme rainfall from hurricanes and other tropical systems. In this study, we seek to develop a framework for describing the joint probabilistic and spatio-temporal properties of extreme rainfall from hurricanes and other tropical systems. Furthermore, we argue that commonly-used terminology - such as the "500-year storm" - fail to convey the true properties of tropical cyclone rainfall occurrences in the United States. To quantify the magnitude and spatial extent of these storms, a database consisting of hundreds of unique rainfall volumetric shapes (or "voxels") was created. Each voxel is a four-dimensional object, created by connecting, in both space and time, gridded rainfall observations from the daily, gauge-based NOAA CPC-Unified precipitation dataset. Individual voxels were then associated with concurrent tropical cyclone tracks from NOAA's HURDAT-2 archive, to create distinct representations of the rainfall associated with every Atlantic tropical system making landfall over (or passing near) the United States since 1948. Using these voxels, a series of threshold-excess extreme value models were created to estimate the recurrence intervals of extreme tropical cyclone rainfall, both nationally and locally, for single and multi-day timescales. This voxel database also allows for the "indexing" of past events, placing recent extremes - such as the 50+ inches of rain observed during Hurricane Harvey - into a national context and emphasizing how rainfall totals that are rare at the point scale may be more frequent from a regional perspective.

[Biomedical research in Revista de Biologia Tropical].

Science.gov (United States)

Gutiérrez, José María

2002-01-01

The contributions published in Revista de Biología Tropical in the area of Biomedical Sciences are reviewed in terms of number of contributions and scope of research subjects. Biomedical Sciences, particularly Parasitology and Microbiology, constituted the predominant subject in the Revista during the first decade, reflecting the intense research environment at the School of Microbiology of the University of Costa Rica and at Hospital San Juan de Dios. The relative weight of Biomedicine in the following decades diminished, due to the outstanding increment in publications in Biological Sciences; however, the absolute number of contributions in Biomedical Sciences remained constant throughout the last decades, with around 80 contributions per decade. In spite of the predominance of Parasitology as the main biomedical subject, the last decades have witnessed the emergence of new areas of interest in the Revista, such as Pharmacology of natural products, Toxinology, especially related to snake venoms, and Human Genetics. This retrospective analysis evidences that Biomedical Sciences, particularly those related to Tropical Medicine, were a fundamental component during the first years of Revista de Biología Tropical, and have maintained a significant presence in the scientific output of this journal, the most relevant scientific publication in biological sciences in Central America.

Potential Vorticity Streamers as Precursors to Tropical Cyclone Genesis in the Western Pacific

Science.gov (United States)

2012-03-01

study a developing system with an extratropical precursor (TCS-037) developing into Tropical Storm 16W (TS 16W)” (Schönenberger 2010). This subsection...tropopause maps), the TC genesis event is termed a tropical transition (TT) case. If no such extratropical feature 38 is present, the storm in... extratropical origin is deemed to play an important role in the dynamical evolution leading to tropical cyclogenesis. In contrast, non-TT storms

Net ecosystem carbon dioxide exchange in tropical rainforests - sensitivity to environmental drivers and flux measurement methodology

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Fu, Z.; Stoy, P. C.

2017-12-01

Tropical rainforests play a central role in the Earth system services of carbon metabolism, climate regulation, biodiversity maintenance, and more. They are under threat by direct anthropogenic effects including deforestation and indirect anthropogenic effects including climate change. A synthesis of the factors that determine the net ecosystem exchange of carbon dioxide (NEE) across multiple time scales in different tropical rainforests has not been undertaken to date. Here, we study NEE and its components, gross primary productivity (GPP) and ecosystem respiration (RE), across thirteen tropical rainforest research sites with 63 total site-years of eddy covariance data. Results reveal that the five ecosystems that have greater carbon uptakes (with the magnitude of GPP greater than 3000 g C m-2 y-1) sequester less carbon - or even lose it - on an annual basis at the ecosystem scale. This counterintuitive result is because high GPP is compensated by similar magnitudes of RE. Sites that provided subcanopy CO2 storage observations had higher average magnitudes of GPP and RE and consequently lower NEE, highlighting the importance of measurement methodology for understanding carbon dynamics in tropical rainforests. Vapor pressure deficit (VPD) constrained GPP at all sites, but to differing degrees. Many environmental variables are significantly related to NEE at time scales greater than one year, and NEE at a rainforest in Malaysia is significantly related to soil moisture variability at seasonal time scales. Climate projections from 13 general circulation models (CMIP5) under representative concentration pathway (RCP) 8.5 suggest that many current tropical rainforest sites on the cooler end of the current temperature range are likely to reach a climate space similar to present-day warmer sites by the year 2050, and warmer sites will reach a climate space not currently experienced. Results demonstrate the need to quantify if mature tropical trees acclimate to heat and

FAQ HURRICANES, TYPHOONS, AND TROPICAL CYCLONES

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? A6) What is a sub-tropical cyclone? A7) What is an extratropical cyclone ? A8) What is storm surge easterly wave and what causes them? A5) What is a tropical disturbance, tropical depression, tropical storm and how is it different from storm tide ? A9) What is a "CDO" ? A10) What is a TUTT ? A11

Extent of Integration of Priority Interventions into General Health Systems: A Case Study of Neglected Tropical Diseases Programme in the Western Region of Ghana.

Science.gov (United States)

Mensah, Ernest O; Aikins, Moses K; Gyapong, Margaret; Anto, Francis; Bockarie, Moses J; Gyapong, John O

2016-05-01

The global health system has a large arsenal of interventions, medical products and technologies to address current global health challenges. However, identifying the most effective and efficient strategies to deliver these resources to where they are most needed has been a challenge. Targeted and integrated interventions have been the main delivery strategies. However, the health system discourse increasingly favours integrated strategies in the context of functionally merging targeted interventions with multifunctional health care delivery systems with a focus on strengthening country health systems to deliver needed interventions. Neglected Tropical Diseases (NTD) have been identified to promote and perpetuate poverty hence there has been global effort to combat these diseases. The Neglected Tropical Diseases Programme (NTDP) in Ghana has a national programme team and office, however, it depends on the multifunctional health delivery system at the regional and district level to implement interventions. The NTDP seeks further health system integration to accelerate achievement of coverage targets. The study estimated the extent of integration of the NTDP at the national, regional and district levels to provide evidence to guide further integration. The research design was a descriptive case study that interviewed key persons involved in the programme at the three levels of the health system as well as extensive document review. Integration was assessed on two planes-across health system functions-stewardship and governance, financing, planning, service delivery, monitoring and evaluation and demand generation; and across three administrative levels of the health system-national, regional and district. A composite measure of integration designated Cumulative Integration Index (CII) with a range of 0.00-1.00 was used to estimate extent of integration at the three levels of the health system. Service delivery was most integrated while financing and planning were

Impacts of Particulate Matter on Gulf of Mexico Tropical Cyclones

Science.gov (United States)

Cao, W.; Rohli, R. V.

2017-12-01

The purpose of this project is to analyze the relationship between tropical cyclones of the Gulf of Mexico-Atlantic basin and fine particulate matter (PM2.5). The daily mean PM2.5 concentration values were collected from United States Environmental Protection Agency (EPA). Tropical cyclone data were collected from Tropical Prediction Center Best Track Reanalysis in Unisys Weather®. The GRIdded Binary (GRIB-formatted) data were downloaded from the Data Support Section of the Computational and Information Systems Laboratory at the National Center for Atmospheric Research (NCAR). Through ArcGIS®, the tropical cyclone tracks were compared with the interpolated daily mean PM2.5 concentration value. Results suggest that the tracks tend to avoid areas with higher PM2.5 concentrations, and the intensity was weakened significantly after passing the PM2.5-rich area. Through simulation using the Weather Research and Forecasting (WRF) model, the pressure and vertical structure of Hurricane Lili were weakened after passing the most PM2.5-rich area in Louisiana. Also, little evidence is found for the possibility of precipitation generated by the approaching tropical cyclone to cleanse the atmosphere of PM2.5 before storm passage. These results have important implications for tropical cyclone prediction as storms approach polluted areas or other places where PM2.5 particles are abundant, not only including urban environments but also in coastal areas where proscribed burns take place during tropical cyclone season, such as during sugarcane harvesting in southern Louisiana.

Warm Rain Processes Over the Tropical Oceans and Implications on Climate Change

Science.gov (United States)

Lau, William K. M.; Wu, H. T.

2004-01-01

In this talk, we will first show results from TRMM regarding the characteristics of warm rains over the tropical oceans, and the dependence of rate of warm rain production on sea surface temperature. Results lead to the hypothesis that warm rain production efficiency, i.e., autoconversion, may be increased in a warm climate. We use the GEOS-II GCM to test this hypothesis. Our modeling results show that in a climate with increased rate of autoconversion, the total rain amount is increased, with warm rain contributing to a larger portion of the increase. The abundant rainout of warm precipitation at middle to low levels causes a reduction of high cloud cover due to the depletion of water available for ice-phase rain production. As a result, more isolated, but more intense penetrative convection develops. Results also show that increased autoconversion reduces the convective adjustment time scale tends, implying a faster recycling of atmospheric water. Most interestingly, the increased low level heating associated with warm rain leads to more energetic Madden and Julian oscillations in the tropics, with well-defined eastward propagation. While reducing the autoconversion leads to an abundant mix of westward and eastward tropical disturbance on daily to weekly time scales. The causes of the sensitivity of the dynamical regimes to the microphysics parameterization in the GCM will be discussed.

Pan-Tropical Analysis of Climate Effects on Seasonal Tree Growth

Science.gov (United States)

Wagner, Fabien; Rossi, Vivien; Aubry-Kientz, Mélaine; Bonal, Damien; Dalitz, Helmut; Gliniars, Robert; Stahl, Clément; Trabucco, Antonio; Hérault, Bruno

2014-01-01

Climate models predict a range of changes in tropical forest regions, including increased average temperatures, decreased total precipitation, reduced soil moisture and alterations in seasonal climate variations. These changes are directly related to the increase in anthropogenic greenhouse gas concentrations, primarily CO2. Assessing seasonal forest growth responses to climate is of utmost importance because woody tissues, produced by photosynthesis from atmospheric CO2, water and light, constitute the main component of carbon sequestration in the forest ecosystem. In this paper, we combine intra-annual tree growth measurements from published tree growth data and the corresponding monthly climate data for 25 pan-tropical forest sites. This meta-analysis is designed to find the shared climate drivers of tree growth and their relative importance across pan-tropical forests in order to improve carbon uptake models in a global change context. Tree growth reveals significant intra-annual seasonality at seasonally dry sites or in wet tropical forests. Of the overall variation in tree growth, 28.7% was explained by the site effect, i.e. the tree growth average per site. The best predictive model included four climate variables: precipitation, solar radiation (estimated with extrasolar radiation reaching the atmosphere), temperature amplitude and relative soil water content. This model explained more than 50% of the tree growth variations across tropical forests. Precipitation and solar radiation are the main seasonal drivers of tree growth, causing 19.8% and 16.3% of the tree growth variations. Both have a significant positive association with tree growth. These findings suggest that forest productivity due to tropical tree growth will be reduced in the future if climate extremes, such as droughts, become more frequent. PMID:24670981

Global demand for gold is another threat for tropical forests

International Nuclear Information System (INIS)

Alvarez-Berríos, Nora L; Mitchell Aide, T

2015-01-01

The current global gold rush, driven by increasing consumption in developing countries and uncertainty in financial markets, is an increasing threat for tropical ecosystems. Gold mining causes significant alteration to the environment, yet mining is often overlooked in deforestation analyses because it occupies relatively small areas. As a result, we lack a comprehensive assessment of the spatial extent of gold mining impacts on tropical forests. In this study, we provide a regional assessment of gold mining deforestation in the tropical moist forest biome of South America. Specifically, we analyzed the patterns of forest change in gold mining sites between 2001 and 2013, and evaluated the proximity of gold mining deforestation to protected areas (PAs). The forest cover maps were produced using the Land Mapper web application and images from the MODIS satellite MOD13Q1 vegetation indices 250 m product. Annual maps of forest cover were used to model the incremental change in forest in ∼1600 potential gold mining sites between 2001–2006 and 2007–2013. Approximately 1680 km 2 of tropical moist forest was lost in these mining sites between 2001 and 2013. Deforestation was significantly higher during the 2007–2013 period, and this was associated with the increase in global demand for gold after the international financial crisis. More than 90% of the deforestation occurred in four major hotspots: Guianan moist forest ecoregion (41%), Southwest Amazon moist forest ecoregion (28%), Tapajós–Xingú moist forest ecoregion (11%), and Magdalena Valley montane forest and Magdalena–Urabá moist forest ecoregions (9%). In addition, some of the more active zones of gold mining deforestation occurred inside or within 10 km of ∼32 PAs. There is an urgent need to understand the ecological and social impacts of gold mining because it is an important cause of deforestation in the most remote forests in South America, and the impacts, particularly in aquatic systems

Re-imagining the future of diagnosis of Neglected Tropical Diseases

Directory of Open Access Journals (Sweden)

Rosanna W. Peeling

Full Text Available Neglected Tropical Diseases (NTDs affect an estimated 1 billion people in 149 countries. The World Health Organization (WHO prioritised 17 NTDs for control and elimination by 2020 and defined a Road Map to help countries reach these goals. Improved diagnostics for NTDs are essential for guiding treatment strategies at different thresholds of control, interruption of transmission, elimination and post-elimination surveillance. While substantial progress has been made in the last decade with chemotherapy, the same cannot be said of diagnostics, largely due to the perceived lack of a commercially viable market for NTD diagnostics.New sample in-answer out nucleic acid amplification technologies that can be performed at the point-of-care offer improved performance over current technologies and the potential to test for multiple pathogens using a single specimen. Finding commonalities for different NTDs in terms of geographic overlap, sentinel populations and treatment strategy will allow NTD programs to leverage these innovations to build cost-effective multiplex surveillance platforms. Connectivity solutions linking data from diagnostic laboratories and POC test readers/devices provide opportunities for automated surveillance systems to make health systems more efficient, improving patient outcomes and assessing impact of interventions in real time. New models of public–private product development partnerships are critical in leveraging diagnostic innovation in other priority area for better diagnosis, control and elimination of NTDs. Keywords: Neglected tropical diseases, Diagnostics, Control, Elimination, Surveillance

Rediscovery of the doldrums in storm-resolving simulations over the tropical Atlantic

Science.gov (United States)

Klocke, Daniel; Brueck, Matthias; Hohenegger, Cathy; Stevens, Bjorn

2017-12-01

The doldrums — a zone of calm and variable winds in the deep tropics between the trades — were of key importance to nineteenth century maritime travel. As a result, the region was a focus in atmospheric science at that time. However, as sailing ships were replaced by steamboats, scientific interest shifted to the heavy precipitating storms within the doldrums: the deep convective systems of the intertropical convergence zone. Now, in storm-system-resolving simulations over a period of two months that cover a large part of the tropical Atlantic, the doldrums are one of the most prominent features. The doldrums are substantially less pronounced in coarser-resolution simulations that use a parameterization for convection, despite their large-scale extent. We conclude that explicitly representing the storm scale dynamics and their coupling to the surface wind on the storm-system scales helps to maintain the systems of winds that define the doldrums. We suggest that the lack of these wind systems could explain the persistent tropical precipitation biases in climate models.

Diets in methane emissions during rumination process in cattle production systems

Directory of Open Access Journals (Sweden)

Luz Elena Santacoloma Varón

2011-05-01

Full Text Available The population of ruminants in the world is increasing, since its products constitute a source of protein of high nutritional value for the human population; nevertheless, this increase, will contribute in great proportion to the global warming and to the deterioration of the ozone layer, since between the subproducts of the ruminal fermentation, carbonic gas and methane are found. &e last one is produced by the anaerobic bacteria present in the rumen that di'erent types of substrata use, principally H2 and CO2. &e action of the bacteria producers of methane depends to a great extent on the type of substrata presented in the diet, and of the chemical and physical characteristics of the same one. &erefore, it is possible to diminish the e'ects that the productive systems of ruminants have on the environment, o'ering the animals nutritional alternatives that besides reducing the emission of methane to the atmosphere, will also reduce the energetic losses that for this concept it presents in the ruminants. In the present review the idea of using forages of the tropic that contain secondary metabolics that could concern the population of protozoan’s combined with forages of high nutritional value is presented and the idea of obtaining very good proved productive results is possible to simultaneously diminishes the gas emission of methane to the atmosphere

Effects of the thermal environment on animal production in the tropics

International Nuclear Information System (INIS)

Robertshaw, D.

1986-01-01

The problems of heat stress in animal production can be solved by an interdisciplinary approach whereby the engineer, animal scientist and animal physiologist can all interact. By understanding the principles associated with heat flow between an animal and its environment it is possible to predict the potential success of an animal production system. This review analyses the nature of the thermal environment and the way in which it can affect production. Methods for alleviating heat stress are also described. (author)

Genomic-based-breeding tools for tropical maize improvement.

Science.gov (United States)

Chakradhar, Thammineni; Hindu, Vemuri; Reddy, Palakolanu Sudhakar

2017-12-01

Maize has traditionally been the main staple diet in the Southern Asia and Sub-Saharan Africa and widely grown by millions of resource poor small scale farmers. Approximately, 35.4 million hectares are sown to tropical maize, constituting around 59% of the developing worlds. Tropical maize encounters tremendous challenges besides poor agro-climatic situations with average yields recorded <3 tones/hectare that is far less than the average of developed countries. On the contrary to poor yields, the demand for maize as food, feed, and fuel is continuously increasing in these regions. Heterosis breeding introduced in early 90 s improved maize yields significantly, but genetic gains is still a mirage, particularly for crop growing under marginal environments. Application of molecular markers has accelerated the pace of maize breeding to some extent. The availability of array of sequencing and genotyping technologies offers unrivalled service to improve precision in maize-breeding programs through modern approaches such as genomic selection, genome-wide association studies, bulk segregant analysis-based sequencing approaches, etc. Superior alleles underlying complex traits can easily be identified and introgressed efficiently using these sequence-based approaches. Integration of genomic tools and techniques with advanced genetic resources such as nested association mapping and backcross nested association mapping could certainly address the genetic issues in maize improvement programs in developing countries. Huge diversity in tropical maize and its inherent capacity for doubled haploid technology offers advantage to apply the next generation genomic tools for accelerating production in marginal environments of tropical and subtropical world. Precision in phenotyping is the key for success of any molecular-breeding approach. This article reviews genomic technologies and their application to improve agronomic traits in tropical maize breeding has been reviewed in

Review of Tropical-Extratropical Teleconnections on Intraseasonal Time Scales

Science.gov (United States)

Stan, Cristiana; Straus, David M.; Frederiksen, Jorgen S.; Lin, Hai; Maloney, Eric D.; Schumacher, Courtney

2017-12-01

The interactions and teleconnections between the tropical and midlatitude regions on intraseasonal time scales are an important modulator of tropical and extratropical circulation anomalies and their associated weather patterns. These interactions arise due to the impact of the tropics on the extratropics, the impact of the midlatitudes on the tropics, and two-way interactions between the regions. Observational evidence, as well as theoretical studies with models of complexity ranging from the linear barotropic framework to intricate Earth system models, suggest the involvement of a myriad of processes and mechanisms in generating and maintaining these interconnections. At this stage, our understanding of these teleconnections is primarily a collection of concepts; a comprehensive theoretical framework has yet to be established. These intraseasonal teleconnections are increasingly recognized as an untapped source of potential subseasonal predictability. However, the complexity and diversity of mechanisms associated with these teleconnections, along with the lack of a conceptual framework to relate them, prevent this potential predictability from being translated into realized forecast skill. This review synthesizes our progress in understanding the observed characteristics of intraseasonal tropical-extratropical interactions and their associated mechanisms, identifies the significant gaps in this understanding, and recommends new research endeavors to address the remaining challenges.

Regional impacts of ocean color on tropical Pacific variability

OpenAIRE

W. Anderson; A. Gnanadesikan; A. Wittenberg

2009-01-01

The role of the penetration length scale of shortwave radiation into the surface ocean and its impact on tropical Pacific variability is investigated with a fully coupled ocean, atmosphere, land and ice model. Previous work has shown that removal of all ocean color results in a system that tends strongly towards an El Niño state. Results from a suite of surface chlorophyll perturbation experiments show that the mean state and variability of the tropical Pacific is highly se...

Design and performance of a novel innovative roofing system for tropical landed houses

International Nuclear Information System (INIS)

Al-Obaidi, Karam M.; Ismail, Mazran; Abdul Rahman, Abdul Malek

2014-01-01

Highlights: • Constructing a new design of sustainable roofing systems. • An innovative roofing system (IRS) for tropical landed houses is proposed. • Separate solar heat from useful natural light by physical form. • The IRS can maintain an illuminance level of approximately 86–100% below 2000 lux. • The IRS can reduce the attic air temperature by 5.4 °C and the indoor air temperature by 2.1 °C. - Abstract: An innovative roofing system (IRS) is designed to deliver an abundant and uniform amount of cool natural light from the roof with reduced heat gain effect for tropical residential buildings (3 m height) in Malaysia. Studies revealed that several passive and active solar techniques can be integrated to form a roofing system to separate solar heat from useful natural light at the attic zone before heat reaches the occupied space. The IRS design is specified and proposed by using glazing technology (polycarbonate), pigment technique (reflective and radiative), as well as ventilation process (hybrid turbine ventilator) applied at the attic zone to represent a new model of sustainable roofing design. The aim of this research is to demonstrate the effectiveness of the design concept without the need for any chemical, complex, or expensive solar design techniques. The methodology was conducted on a series of field studies in a standard room model at Universiti Sains Malaysia. Three different roofing systems are investigated to identify the IRS performance in both dark and daylight conditions to determine the effect of natural light on the indoor environment. The outcomes of the design show that the IRS was able to reduce the indoor air temperature compared with conventional roofing system by approximately 2.1 °C under daylight condition. Results showed that the difference in the IRS (daylight–dark) condition was 0.31 °C compared to that in the conventional roofing system at 0.8 °C. Furthermore, the level of mean radiant temperature compared with

Anthelmintic resistance impact on tropical beef cattle productivity: effect on weight gain of weaned calves.

Science.gov (United States)

Borges, Fernando A; Almeida, Gabriel D; Heckler, Rafael P; Lemes, Raul T; Onizuka, Marcel K V; Borges, Dyego G L

2013-03-01

The performance of grazing cattle in tropical areas is deeply influenced by parasitism, and the increasing reports of resistance are a threat to effective nematode control. The present study aimed to evaluate the effect of avermectins on the performance of weaned calves naturally infected by ivermectin-resistant gastrointestinal nematodes. The effect of four commercial endectocides (ivermectin 2.25 % + abamectin 1.25 %, ivermectin 3.15 %, doramectin 3.15 %, and doramectin 1 %) on parasitism and performance of a hundred weaned Nellore calves were evaluated during 112 days. The most effective anthelmintic showed efficacy of 84 % and resulted in an increase (P < 0.05) of live weight gain of 11.85 kg, compared to untreated group, 9.05 and 9.41 kg compared to those treated with more ineffective avermectins which showed efficacy of 0 and 48.2 %, respectively. A significant (P < 0.05) and weak negative correlation (r = -0.22) between the eggs per gram (EPG) and body weight was observed, indicating that even the low mean EPG (175 ± 150) observed at day 0 in the control group, with predominance of Haemonchus sp., was responsible for production losses. These results indicate that control of nematode parasites in beef cattle in the weaning phase may not result in increased productivity when carried out without technical criteria.

Harnessing Big Data for Communicable Tropical and Sub-Tropical Disorders: Implications From a Systematic Review of the Literature

Directory of Open Access Journals (Sweden)

Vincenza Gianfredi

2018-03-01

Full Text Available AimAccording to the World Health Organization (WHO, communicable tropical and sub-tropical diseases occur solely, or mainly in the tropics, thriving in hot, and humid conditions. Some of these disorders termed as neglected tropical diseases are particularly overlooked. Communicable tropical/sub-tropical diseases represent a diverse group of communicable disorders occurring in 149 countries, favored by tropical and sub-tropical conditions, affecting more than one billion people and imposing a dramatic societal and economic burden.MethodsA systematic review of the extant scholarly literature was carried out, searching in PubMed/MEDLINE and Scopus. The search string used included proper keywords, like big data, nontraditional data sources, social media, social networks, infodemiology, infoveillance, novel data streams (NDS, digital epidemiology, digital behavior, Google Trends, Twitter, Facebook, YouTube, Instagram, Pinterest, Ebola, Zika, dengue, Chikungunya, Chagas, and the other neglected tropical diseases.Results47 original, observational studies were included in the current systematic review: 1 focused on Chikungunya, 6 on dengue, 19 on Ebola, 2 on Malaria, 1 on Mayaro virus, 2 on West Nile virus, and 16 on Zika. Fifteen were dedicated on developing and validating forecasting techniques for real-time monitoring of neglected tropical diseases, while the remaining studies investigated public reaction to infectious outbreaks. Most studies explored a single nontraditional data source, with Twitter being the most exploited tool (25 studies.ConclusionEven though some studies have shown the feasibility of utilizing NDS as an effective tool for predicting epidemic outbreaks and disseminating accurate, high-quality information concerning neglected tropical diseases, some gaps should be properly underlined. Out of the 47 articles included, only 7 were focusing on neglected tropical diseases, while all the other covered communicable tropical/sub-tropical

Harnessing Big Data for Communicable Tropical and Sub-Tropical Disorders: Implications From a Systematic Review of the Literature.

Science.gov (United States)

Gianfredi, Vincenza; Bragazzi, Nicola Luigi; Nucci, Daniele; Martini, Mariano; Rosselli, Roberto; Minelli, Liliana; Moretti, Massimo

2018-01-01

According to the World Health Organization (WHO), communicable tropical and sub-tropical diseases occur solely, or mainly in the tropics, thriving in hot, and humid conditions. Some of these disorders termed as neglected tropical diseases are particularly overlooked. Communicable tropical/sub-tropical diseases represent a diverse group of communicable disorders occurring in 149 countries, favored by tropical and sub-tropical conditions, affecting more than one billion people and imposing a dramatic societal and economic burden. A systematic review of the extant scholarly literature was carried out, searching in PubMed/MEDLINE and Scopus. The search string used included proper keywords, like big data, nontraditional data sources, social media, social networks, infodemiology, infoveillance, novel data streams (NDS), digital epidemiology, digital behavior, Google Trends, Twitter, Facebook, YouTube, Instagram, Pinterest, Ebola, Zika, dengue, Chikungunya, Chagas, and the other neglected tropical diseases. 47 original, observational studies were included in the current systematic review: 1 focused on Chikungunya, 6 on dengue, 19 on Ebola, 2 on Malaria, 1 on Mayaro virus, 2 on West Nile virus, and 16 on Zika. Fifteen were dedicated on developing and validating forecasting techniques for real-time monitoring of neglected tropical diseases, while the remaining studies investigated public reaction to infectious outbreaks. Most studies explored a single nontraditional data source, with Twitter being the most exploited tool (25 studies). Even though some studies have shown the feasibility of utilizing NDS as an effective tool for predicting epidemic outbreaks and disseminating accurate, high-quality information concerning neglected tropical diseases, some gaps should be properly underlined. Out of the 47 articles included, only 7 were focusing on neglected tropical diseases, while all the other covered communicable tropical/sub-tropical diseases, and the main determinant of

STRATEGIES FOR INCREASING PRODUCTIVITY IN PRODUCTION SYSTEMS

Directory of Open Access Journals (Sweden)

Diego Pacheco

2014-05-01

Full Text Available The main objective of this article is to point a set of practical strategies that can be adopted to increase the capacity of constraints resources on production systems, when the constraint is inside the factory and not is in the market. To serve this purpose will be presented strategies based on best practices of the Theory of Constraints, Lean Manufacturing and Total Productive Maintenance. This article also presents the mains tools for the deployment of these methodologies. The survey results have provided an objective set of practical strategy that can be used to increase the capacity and productivity of production systems according to the needs of each manufacturing system.

Marketing of Non-Timber Forest Products in Kajola Local ...

African Journals Online (AJOL)

Marketing of Non-Timber Forest Products in Kajola Local Government Area of Oyo State, Nigeria. ... International Journal of Tropical Agriculture and Food Systems ... The results of the marketing margin reveal that charcoal commanded the highest margin of ₦2500, followed by bush meat (₦300), while wrapping had the ...

O pessegueiro no sistema de pomar compacto: IV. Intensidade e época de raleio dos frutos dos cultivares Tropical e Aurora-1 The peach meadow orchard system: IV. Intensity and time of hand fruit thinning of Tropical and Aurora-1 cultivars

Directory of Open Access Journals (Sweden)

Wilson Barbosa

1991-01-01

Full Text Available A intensidade e a época do raleio dos frutos do pessegueiro podem influenciar diretamente a qualidade do produto, razão pela qual foram pesquisadas em um pomar compacto (4.167 plantas por hectare, sob poda drástica anual de renovação da copa. O experimento foi executado na Estação Experimental de Jundiaí (23°08'S e 46°55'W, do Instituto Agronômico (IAC, sob clima do tipo Cwa, mesotérmico úmido, também denominado de tropical de altitude, com cerca de 80 horas anuais de frio abaixo de 7°C. Utílizaram-se os cultivares Tropical, de maturação bem precoce (fins de setembro, e Aurora-1, de maturação precoce (meados de outubro. Efetuou-se o raleio com 30, 40 e 50 dias pós-antese (DPA, deixando-se 30, 60 e 90 frutos por planta. Os melhores resultados, reunindo fatores qualitativos e quantitativos, foram obtidos no raleio aos 30 DPA, mantendo-se 60 frutos por planta. Neste tratamento, o 'Tropical' apresentou frutos com peso médio de 60,9 gramas, o que equivale à produção de 3,654kg/planta (15,2t/ha; com o 'Aurora-1', o peso médio dos frutos foi de 72,0 gramas, correspondendo à produção de 4,320kg/planta (18,0t/ha. Aqualidade final do produto diminuiu à medida que se atrasou a época do raleio e, principalmente, quando se manteve maior quantidade de frutos por planta. O 'Tropical' adaptou-se melhor ao sistema de pomar compacto: floresceu no 9° mês e seus frutos amadureceram no 12ª mês após a poda drástica da copa.The effect of intensity and time of hand thinning on the mean fruit weight and productivity was studied on 'Tropical' and 'Aurora-V peaches. The trees were cultivated under the meadow orchard system, 4,167 plants per hectare, with drastic pruning. The experimental plot was located at the Estação Experimental of Jundiaí (23°08'S and 46°55W of the Instituto Agronômico of Campinas, State of São Paulo, Brazil, with 80 tours per year of temperature below 7°C. The time of hand thinning was 30, 40 and 50 days

Regional impacts of ocean color on tropical Pacific variability

Science.gov (United States)

Anderson, W.; Gnanadesikan, A.; Wittenberg, A.

2009-08-01

The role of the penetration length scale of shortwave radiation into the surface ocean and its impact on tropical Pacific variability is investigated with a fully coupled ocean, atmosphere, land and ice model. Previous work has shown that removal of all ocean color results in a system that tends strongly towards an El Niño state. Results from a suite of surface chlorophyll perturbation experiments show that the mean state and variability of the tropical Pacific is highly sensitive to the concentration and distribution of ocean chlorophyll. Setting the near-oligotrophic regions to contain optically pure water warms the mean state and suppresses variability in the western tropical Pacific. Doing the same above the shadow zones of the tropical Pacific also warms the mean state but enhances the variability. It is shown that increasing penetration can both deepen the pycnocline (which tends to damp El Niño) while shifting the mean circulation so that the wind response to temperature changes is altered. Depending on what region is involved this change in the wind stress can either strengthen or weaken ENSO variability.

Emergence of nutrient limitation in tropical dry forests: hypotheses from simulation models

Science.gov (United States)

Medvigy, D.; Waring, B. G.; Xu, X.; Trierweiler, A.; Werden, L. K.; Wang, G.; Zhu, Q.; Powers, J. S.

2017-12-01

It is unclear to what extent tropical dry forest productivity may be limited by nutrients. Direct assessment of nutrient limitation through fertilization experiments has been rare, and paradigms pertaining to other ecosystems may not extend to tropical dry forests. For example, because dry tropical forests have a lower water supply than moist tropical forests, dry forests can have lower decomposition rates, higher soil carbon and nitrogen concentrations, and a more open nitrogen cycle than moist forests. We used a mechanistic, numerical model to generate hypotheses about nutrient limitation in tropical dry forests. The model dynamically couples ED2 (vegetation dynamics), MEND (biogeochemistry), and N-COM (plant-microbe competition for nutrients). Here, the MEND-component of the model has been extended to include nitrogen (N) and phosphorus (P) cycles. We focus on simulation of sixteen 25m x 25m plots in Costa Rica where a fertilization experiment has been underway since 2015. Baseline simulations are characterized by both nitrogen and phosphorus limitation of vegetation. Fertilization with N and P increased vegetation biomass, with N fertilization having a somewhat stronger effect. Nutrient limitation was also sensitive to climate and was more pronounced during drought periods. Overflow respiration was identified as a key process that mitigated nutrient limitation. These results suggest that, despite often having richer soils than tropical moist forests, tropical dry forests can also become nutrient-limited. If the climate becomes drier in the next century, as is expected for Central America, drier soils may decrease microbial activity and exacerbate nutrient limitation. The importance of overflow respiration underscores the need for appropriate treatment of microbial dynamics in ecosystem models. Ongoing and new nutrient fertilization experiments will present opportunities for testing whether, and how, nutrient limitation may indeed be emerging in tropical dry

No evidence that boron influences tree species distributions in lowland tropical forests of Panama.

Science.gov (United States)

Turner, Benjamin L; Zalamea, Paul-Camilo; Condit, Richard; Winter, Klaus; Wright, S Joseph; Dalling, James W

2017-04-01

It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama. Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a regional network of forest dynamics plots. Experimental manipulation of boron supply to seedlings of three tropical tree species revealed no evidence of boron deficiency or toxicity at concentrations likely to occur in tropical forest soils. Foliar boron did not correlate with soil boron along a local scale gradient of boron availability. Fifteen years of boron addition to a tropical forest increased plant-available boron by 70% but did not significantly change tree productivity or boron concentrations in live leaves, wood or leaf litter. The annual input of boron in rainfall accounts for a considerable proportion of the boron in annual litterfall and is similar to the pool of plant-available boron in the soil, and is therefore sufficient to preclude boron deficiency. We conclude that boron does not influence tree species distributions in Panama and presumably elsewhere in the lowland tropics. No claim to original US government works New Phytologist © 2016 New Phytologist Trust.

Isotopes in tropical agriculture

Energy Technology Data Exchange (ETDEWEB)

NONE

1962-04-15

Ways in which the use of radioisotopes and radiation can help to improve the agriculture of tropical Africa were discussed by a panel of experts. The panel included scientists from Africa, Europe, and the United States, most of whom had had actual experience dealing with agricultural problems in various parts of tropical Africa. The experts agreed that radioisotopes and radiation might now be employed to particular advantage in tropical Africa to improve crop nutrition and combat insect pests. Other applications discussed were in the fields of hydrology, plant breeding and food preservation

Isotopes in tropical agriculture

International Nuclear Information System (INIS)

1962-01-01

Ways in which the use of radioisotopes and radiation can help to improve the agriculture of tropical Africa were discussed by a panel of experts. The panel included scientists from Africa, Europe, and the United States, most of whom had had actual experience dealing with agricultural problems in various parts of tropical Africa. The experts agreed that radioisotopes and radiation might now be employed to particular advantage in tropical Africa to improve crop nutrition and combat insect pests. Other applications discussed were in the fields of hydrology, plant breeding and food preservation

Using Remotely Sensed Fluorescence and Soil Moisture to Better Understand the Seasonal Cycle of Tropical Grasslands

Science.gov (United States)

Smith, Dakota Carlysle

Seasonal grasslands account for a large area of Earth's land cover. Annual and seasonal changes in these grasslands have profound impacts on Earth's carbon, energy, and water cycles. In tropical grasslands, growth is commonly water-limited and the landscape oscillates between highly productive and unproductive. As the monsoon begins, soils moisten providing dry grasses the water necessary to photosynthesize. However, along with the rain come clouds that obscure satellite products that are commonly used to study productivity in these areas. To navigate this issue, we used solar induced fluorescence (SIF) products from OCO-2 along with soil moisture products from the Soil Moisture Active Passive satellite (SMAP) to "see through" the clouds to monitor grassland productivity. To get a broader understanding of the vegetation dynamics, we used the Simple Biosphere Model (SiB4) to simulate the seasonal cycles of vegetation. In conjunction with SiB4, the remotely sensed SIF and soil moisture observations were utilized to paint a clearer picture of seasonal productivity in tropical grasslands. The remotely sensed data is not available for every place at one time or at every time for one place. Thus, the study was focused on a large area from 15° E to 35° W and from 8°S to 20°N in the African Sahel. Instead of studying productivity relative to time, we studied it relative to soil moisture. Through this investigation we found soil moisture thresholds for the emergence of grassland growth, near linear grassland growth, and maturity of grassland growth. We also found that SiB4 overestimates SIF by about a factor of two for nearly every value of soil moisture. On the whole, SiB4 does a surprisingly good job of predicting the response of seasonal growth in tropical grasslands to soil moisture. Future work will continue to integrate remotely sensed SIF & soil moisture with SiB4 to add to our growing knowledge of carbon, water, and energy cycling in tropical grasslands.

Methods to quantify the impacts of water erosion on productivity of tropical soils

International Nuclear Information System (INIS)

Obando, Franco H

2000-01-01

A review on methods to quantify the impacts of water erosion on soil properties and crop yield is presented. On the basis of results of soil losses through plastic shading meshes on oxisols in the eastern plains of Colombia, the experimental design to quantify erosion induced losses in soil productivity suggested by Stocking (1985) for tropical soils is modified. With the purpose of producing contrasting levels of natural erosion, simple 33% and 45% shading rates meshes, and superposed 33% and 45% meshes were used. These were stretched out on stocking 5 m x 10 m run-off plots at 40 cm height from soil surface. Annual soil losses produced under the above mentioned shading meshes treatments did not present significant differences. It was demonstrated that 33%, 45% as well as superposed 33% and 45% produce an equivalent surface cover, CVE, greater than 90% comparable to that produced by zero grazing Brachiaria decumbens pasture. Such results allowed presenting modifications to the stocking design. It is recommended to use alternated stripes of bare soil and shading meshes of different width to produce contrasting levels of equivalent soil surface cover and consequently contrasting erosion rates. Design of the modified stocking run-off plots, including collecting channels, collecting tanks and a Geib multibox divisor are presented

Production monitoring system for understanding product robustness

DEFF Research Database (Denmark)

Boorla, Srinivasa Murthy; Howard, Thomas J.

2016-01-01

study is used to demonstrate how the monitoring system can be used to efficiently guide corrective action to improve product performance. It is claimed that the monitoring system can be used to dramatically cut the time taken to identify, planand execute corrective action related to typical quality......In the current quality paradigm, the performance of a product is kept within specification by ensuring that its parts are within specification. Product performance is then validated after final assembly. However, this does not control how robust the product performance is, i.e. how much...... it will vary between the specification limits. In this paper, a model for predicting product performance is proposed, taking into account design, assembly and process parameters live from production. This empowers production to maintain final product performance, instead of part quality. The PRECI‐IN case...

Consumer Preference Towards Fruit Leather Attributes of Madurese Exotic Tropical Fruits

OpenAIRE

Elys Fauziyah

2018-01-01

Madura island has high potential for producing tropical fruits, but it still not being well managed especially concerning with the value added Fruit leather is a product created by using various fruits and simple technology application. Fruit leather is categorized as new product on the market, therefore it is important to know consumer preference towards fruit leather attributes so that producer can design an acceptable product in the market. The research investigated attributes within the l...

A concise biogas plant construction suitable for Ghana and other tropical countries

Energy Technology Data Exchange (ETDEWEB)