Suchergebnisse

Burnings and deforestation are severe disturbances to plants and may represent a stressful situation for plant growth, and they can also affect plant-pollinator interactions and the reproductive success of plants. In this study, we verified the variation in floral symmetry of Adenocalymma nodosum (Bignoniacea) in two areas, one post-fire and other after deforestation. We also verified the effects on plant-pollinator interactions and fruit set production. Results showed that A. nodosum flowers were more asymmetric in mowing areas than in fire areas. Asymmetrical flowers presented low nectar concentration and bee visitation rates. Although mowed environments produce fewer fruits and seeds than areas affected by fire, the change was not significant. Soil from the burnt area showed higher nutrient and organic matter concentration and less aluminum than that of mowed areas. Our results showed that A. nodosum flowers in the deforestation area are more asymmetric than those in the post-fire area. This result suggest that Cerrado plants may be less adapted to deforestation than to fire, since they have been facing fire events for thousand years in this biome. We suggest that the effects of environmental stress on the development and fitness of plants may provide an important breakthrough to the understanding of insect-plant interactions in Cerrado savanna, where burnings and deforestation are frequent anthropogenic effects.

Environmental restoration development facilities require knowledge of biodiversity (especially of vegetation. In addition, conservation remains a major challenge, hence the need to find new solutions. The current study aims at analyzing the dynamics of flora and timber trees surrounding the Waza National Park and consolidating lessons to improve conservation and sustainable management of timber resources. The methodology used is a combination of botanical and geographical approaches. Three landscape units characterize the WNP and its peripheral zone: savanna grassland, shrub savanna and wooded savanna. Flora and vegetation characteristics are different in the three landscape units. Floristic inventory identified 52 woody species. The mean absolute density of the whole zone is 81 individuals / ha. This density decreases with a decreasing gradient, from outside the park to inside. This gradient depends on the human pressure gradient which also decreases from the external to the internal park area, except when the gradient is reversed by certain factors such as cattle intrusion. The vertical structure shows that the least represented stems are stems for future planting and regeneration stems, with a very large difference from other stems. Regarding temporal dynamics, there is a regression of woody/timber vegetation cover. Each year, 478 ha of this cover disappear and 319 ha of soil degrade. To cope with the observed changes that are of anthropic, natural, bioecological or politico-institutional origin, management options have been proposed among which: zoning, implementation of a REDD + project, restoration land degraded, participatory management and eco-development. ; La connaissance de la biodiversité surtout végétale est nécessaire à la base des aménagements nécessaires à la restauration de l'environnement. La présente étude a pour objectif d'analyser la dynamique de la flore et de la végétation ligneuse à la périphérie du Parc National de Waza et en tirer des enseignements pour améliorer la conservation et la gestion durable des ressources ligneuses de ce parc.La méthodologie est une combinaison des approches botaniques et géographiques. Trois unités paysagères caractérisent le PNW et sa zone périphérique : la savane herbeuse, la savane arbustive et la savane arborée. Les caractéristiques de la flore et de la végétation sont différentes dans les trois unités paysagères. L'inventaire floristique a permis de recenser un total de 52 espèces ligneuses. La densité absolue moyenne de toute la zone est de 81 individus / ha. Cette densité diminue suivant un gradient décroissant, de l'extérieur vers l'intérieur du parc, sauf dans le cas où certains facteurs comme l'intrusion du bétail dans le parc inverse ce gradient. La structure verticale montre que les tiges les moins représentées sont les tiges d'avenir et les tiges de régénération. Au niveau de la dynamique temporelle, on assiste à une régression du couvert végétal ligneux. Chaque année 478 ha de ce couvert disparaissent et 319 ha de sols se dégradent. Pour faire face aux changements observés qui sont d'origine anthropiques, naturels, bioécologiques ou politico-institutionnels, des options d'aménagement ont été proposées parmi lesquelles : le zonage, la mise en œuvre d'un projet REDD+, la restauration des terres, la gestion participative et l'écodéveloppement.

Environmental restoration development facilities require knowledge of biodiversity (especially of vegetation. In addition, conservation remains a major challenge, hence the need to find new solutions. The current study aims at analyzing the dynamics of flora and timber trees surrounding the Waza National Park and consolidating lessons to improve conservation and sustainable management of timber resources. The methodology used is a combination of botanical and geographical approaches. Three landscape units characterize the WNP and its peripheral zone: savanna grassland, shrub savanna and wooded savanna. Flora and vegetation characteristics are different in the three landscape units. Floristic inventory identified 52 woody species. The mean absolute density of the whole zone is 81 individuals / ha. This density decreases with a decreasing gradient, from outside the park to inside. This gradient depends on the human pressure gradient which also decreases from the external to the internal park area, except when the gradient is reversed by certain factors such as cattle intrusion. The vertical structure shows that the least represented stems are stems for future planting and regeneration stems, with a very large difference from other stems. Regarding temporal dynamics, there is a regression of woody/timber vegetation cover. Each year, 478 ha of this cover disappear and 319 ha of soil degrade. To cope with the observed changes that are of anthropic, natural, bioecological or politico-institutional origin, management options have been proposed among which: zoning, implementation of a REDD + project, restoration land degraded, participatory management and eco-development. ; La connaissance de la biodiversité surtout végétale est nécessaire à la base des aménagements nécessaires à la restauration de l'environnement. La présente étude a pour objectif d'analyser la dynamique de la flore et de la végétation ligneuse à la périphérie du Parc National de Waza et en tirer des enseignements pour améliorer la conservation et la gestion durable des ressources ligneuses de ce parc.La méthodologie est une combinaison des approches botaniques et géographiques. Trois unités paysagères caractérisent le PNW et sa zone périphérique : la savane herbeuse, la savane arbustive et la savane arborée. Les caractéristiques de la flore et de la végétation sont différentes dans les trois unités paysagères. L'inventaire floristique a permis de recenser un total de 52 espèces ligneuses. La densité absolue moyenne de toute la zone est de 81 individus / ha. Cette densité diminue suivant un gradient décroissant, de l'extérieur vers l'intérieur du parc, sauf dans le cas où certains facteurs comme l'intrusion du bétail dans le parc inverse ce gradient. La structure verticale montre que les tiges les moins représentées sont les tiges d'avenir et les tiges de régénération. Au niveau de la dynamique temporelle, on assiste à une régression du couvert végétal ligneux. Chaque année 478 ha de ce couvert disparaissent et 319 ha de sols se dégradent. Pour faire face aux changements observés qui sont d'origine anthropiques, naturels, bioécologiques ou politico-institutionnels, des options d'aménagement ont été proposées parmi lesquelles : le zonage, la mise en œuvre d'un projet REDD+, la restauration des terres, la gestion participative et l'écodéveloppement.

Tambrauw Regency is obliged to safeguard the policies of the central government, especially in food self-sufficiency efforts. Determine locations that have land suitability specifications for soybeans and analyze farming agribusiness as an important factor in agricultural development. The research activity was carried out in Kebar District and Senopi District. Peanut farmers are the focus of research, with the consideration that peanuts and soybeans are a family (leguminoseae). At this stage, the study of the characteristics and specifications of the Kebar District and Senopi District areas as potential areas for the development of soybean commodities was carried out. The study of the shape, pattern, type and pattern of farming, as well as the use of agricultural production facilities by the farming community is carriedout. Data and information from various branches of farming were held with community discussions in the form of FGD. Data analyzed descriptively. The results showed low availability of potassium in flat areas and forests and acidic soil pH in flat-savanna regions. The hindering area is the slope, and flat areas only lack potassium. Potential food crops to be developed are upland rice plants and yams. The results of evaluation of land suitability for horticultural plants (Peanuts, Mustard, Tomatoes and Chillies) show "quite suitable" to "according to the margins". The farming production of Kebar was dominated by agricultural commodities and provides enough income for the household economy.

1-The potential of resistant starch type 1 for nutritional food security -- 2-Evaluation of bioaccumulation of heavy metals in some fish species from the rice farms' channels of Pouss (Far-North, Cameroon) -- 3-Evaluation of the levels of nine heavy metals in five crops using AAS and XRF -- 4-The role of food in the health management of geriatrics -- 5-Genetically modified crops: perspectives and safety concerns in Africa -- 6-Indigenous leafy vegetables and health management in South Western Nigeria: A review based on Osun State -- 7-Combined application of subsurface drainage and fertilization, a method to reduce the effects of iron and sulfide toxicities in irrigated rice fields in Burkina Faso -- 8-Is food medicine? Lessons from a household survey on plants used to manage anaemia in Kilifi County, Kenya -- 9-Plantain bioactives: An underutilised food resource in Africa -- 10-New perspectives in the utilization of African leafy vegetables -- 11-The uptake of farming technological innovations for food security in Kejom Ketinguh of the North West region of Cameroon. A contribution to anthropology of food production -- 12-Food and nutrition insecurity in Africa: The primary drivers and sustainable strategies to improve the current status -- 13-Marker-assisted selection (MAS): Untapped potential for enhancing food and nutrition securities in Sub Saharan Africa -- 14-Harnessing the opportunities for sustainable small-scale rural farming towards attaining food security in Southern Africa -- 15-Improving food security in Africa through sustainable utilization of selected climate smart emerging crops: A case of Botswana and Namibia -- 16-Essentials of nutraceuticals and probiotics -- 17-Phenotypic characterisation of nine accessions of okra -- 18-Long-term restorative farming effects on soil biological properties for carbon stock, soil quality and yield in a Nigerian northern guinea savanna alfisols -- 19-Climate change: impact on food security for health management and its adaptation strategies for sustainability among households in Southeast, Nigeria -- 20-Climate change, growth in agriculture value added, food availability and economic growth nexus in the Gambia: A Granger causality and ARDL modeling approach -- 21-Adoption of genomics and breeding strategies to improve goat productivity in Southern Africa.

Part I. Background -- Chapter 1. Coupled Earth System and Human Processes - An Introduction to the Book and SPACES and the Book -- Chapter 2. Unique Southern African Terrestrial and Oceanic Biomes and Their Relation to Steep Environmental Gradients -- Chapter 3. Environmental Challenges to Meeting Sustainable Development Goals in Southern Africa -- Chapter 4. Overview of the Macro-Economic Drivers of the Region -- Part II. Drivers of Climatic Variability and Change in Southern Africa -- Chapter 5. Past Climate Variability in the Past Millennium -- Chapter 6. Southern Africa Climate over the Recent Decades: Description, Variability, and Trends -- Chapter 7. Projections of Future Climate Change in Southern Africa and the Potential for Regional Tipping Points -- Chapter 8. The Agulhas Current System as an Important Driver for Oceanic and Terrestrial Climate -- Chapter 9. Physical Drivers of Southwest African Coastal Upwelling and Its Response to Climate Variability and Change -- Chapter 10. Regional Land-Atmosphere Interactions in Southern Africa: Potential Impact and Sensitivity of Forest and Plantation Change -- Part III. Science in Support of Ecosystem Management -- Chapter 11. Studies of the Ecology of the Benguela Current Upwelling System – the TRAFFIC Approach -- Chapter 12. The Application of Palaeoenvironmental Research in Supporting Land Management Approaches and Conservation in South Africa -- Chapter 13. Soil Erosion Research and Soil Conservation Policy in South Africa -- Chapter 14. Biome Change in Southern Africa -- Chapter 15. Biodiversity and Ecosystem Functions in Southern African Savanna Rangelands: Threats, Impacts and Solutions -- Chapter 16. Managing Southern African Rangeland Systems in the Face of Drought – A Synthesis of Observation, Experimentation, and Modeling for Policy and Decision Support -- Chapter 17. A Fine Line Between Carbon Source and Sink – Potential CO2 Sequestration Through Sustainable Grazing Management in the Nama-Karoo -- Chapter 18. Trends and Barriers to Wildlife-Based Options for Sustainable Management of Savanna Resources – The Namibian Case -- Chapter 19. Feed Gaps among Cattle Keepers in Semiarid and Arid Southern African Regions: A Case Study in the Limpopo Province, South Africa -- Chapter 20. Agricultural Land-Use Systems and Management Challenges -- Chapter 21. The Need for Sustainable Agricultural Land-Use Systems: Benefits from Integrated Agroforestry Systems -- Chapter 22. Management Options for Macadamia Orchards with Special Focus on Water Management and Ecosystem Services -- Chapter 23. Potential of Improved Technologies to Enhance Land Management Practices of Small-Scale Farmers in Limpopo Province, South Africa -- Part IV. Monitoring and Modelling Tools -- Chapter 24. A New Era of Earth Observation for the Environment – Spatio-Temporal Monitoring Capabilities for Land Degradation -- Chapter 25. The Marine Carbon Footprint: Challenges in the Quantification of CO2 Uptake by the Biological Carbon Pump in the Benguela Upwelling System -- Chapter 26. Dynamics and Drivers of Net Primary Production (NPP) in Southern Africa Based on Estimates from Earth Observation and Process-Based Dynamic Vegetation Modelling -- Chapter 27. Comparison of Different Normalisers for Identifying Metal Enrichment of Sediment – A Case Study from Richards Bay Harbour, South Africa -- Chapter 28. Catchment and Depositional Studies for the Reconstruction of Past Environmental Change in Southern Africa -- Chapter 29. Observational Support for Regional Policy Implementation – Land Surface Change under Anthropogenic and Climate Pressure in Saldi Study Sites -- Part V. Synthesis and Outlook -- Chapter 30. Research Infrastructures as Anchor Points for Long-Term Environmental Observation -- Chapter 31. Lessons Learned from a North-South Science Partnership for Sustainable Development -- Chapter 32. Synthesis and Outlook on Future Research and Scientific Education in Southern Africa.

Intro -- Title page -- Copyright page -- Preface to the Seventh Edition -- About the Companion Website -- Part I: The Past and Present -- 1: Introduction -- The development of ideas -- The development of human population and stages of cultural development -- Hunting and gathering -- Humans as cultivators, keepers and metal workers -- Modern industrial and urban civilizations -- 2: The Human Impact on Vegetation -- Introduction -- The use of fire -- Fires: natural and anthropogenic -- Some consequences of fire suppression -- Some effects of fire on vegetation -- The role of grazing -- Deforestation -- Secondary rain forest -- The human role in the creation and maintenance of savanna -- The spread of desert vegetation on desert margins -- The maquis of the Mediterranean lands -- The prairies and other mid-latitude and high-altitude grasslands -- Post-glacial vegetational change in Britain and Europe -- Lowland heaths -- Introduction, invasion and explosion -- Air pollution and its effects on plants -- Forest decline -- Miscellaneous causes of plant decline -- The change in genetic and species diversity -- Conclusion: threats to plant life -- 3: Human Influence on Animals -- Domestication of animals -- Dispersal and invasions of animals -- Human influence on the expansion of animal populations -- Causes of animal contractions and decline: pollution -- Habitat change and animal decline -- Other causes of animal decline -- Animal extinctions in prehistoric times -- Modern-day extinctions -- 4: The Human Impact on the Soil -- Introduction -- Salinity: natural sources -- Human agency and increased salinity -- Irrigation salinity -- Dryland salinity -- Urban salinity -- Interbasin water transfers -- Coastal zone salinity -- Consequences of salinity -- Reclamation of salt-affected lands -- Lateritization -- Accelerated podzolization and acidification.

Resumen: El desarrollo agrícola de la altillanura Colombiana llevado a cabo con apoyo del gobierno es una meta ambiciosa por múltiples razones, empezando con la infertilidad intrínseca de los suelos que ha limitado el desarrollo agrícola hasta la fecha. Es importante diseñar un modelo de desarrollo agrícola que sea ecoeficiente, es decir rentable del punto de vista económico, equitativo del punto de vista social y sostenible del punto de vista ambiental. En este estudio, se diseñaron indicadores para evaluar y monitorear la ecoeficiencia de los cuatro sistemas de producción más usados por los productores que invirtieron en el área: cultivos transitorios, cultivos perenes (palma africana y hevea) y pastizales mejorados y se les comparo con la sabana natural, como sistema de referencia. El objetivo del estudio fue la construcción de indicadores de ecoeficiencia en los sistemas de producción: cultivos transitorios (soya, maíz, y arroz), cultivos permanentes (caucho y palma de aceite), pasturas mejoradas y la sabana natural, a partir de la generación de subindicadores sintéticos con valores entre 0.10 y 1.00, asociados a los grupos de variables de regulación hídrica, fertilidad química de suelo, biodiversidad (macrofauna), regulación climática (gases efecto invernadero y almacenamiento de carbono) y de variables el componente socioeconómico. El indicador de ecoeficiencia es la suma de un indicador de servicios ecosistemicos, de desarrollo social y de eficiencia económica. El estudio socioeconómico se hizo en 120 fincas que representan la diversidad de situaciones encontradas en el área. Análisis iniciales de la base de datos inicial de 227 preguntas organizadas en 13 bloques establecida por el CIAT, se extrajeron 5 variables representativas del entorno social (edad, tenencia de la tierra, trabajadores permanentes hombre y/o mujeres, capacitación recibida) y se usaron para diseñar un indicador de Capital Humano. Otro grupo de 11 variables se usó para describir el entorno económico con un indicador de sistemas de producción. Finalmente, un grupo de 7 variables, que describen la composición de la finca en diferentes coberturas vegetales, se usó para diseñar un indicador de paisaje. De los análisis multivariados (ACP y ACM) de cada grupo se calcularon indicadores variando de 0,1 a 1,0 siguiendo la metodología de Velásquez et al., (2007). Se hicieron también tipologías de las fincas de acuerdo a cada indicador, basadas en análisis de cluster. Se realizaron análisis de coinercias para evaluar la relación entre los juegos de variables, encontrándose una estrecha relación entre el capital humano disponible (número de trabajadores permanentes, edad y capacitación del productor), el sistema de producción, más o menos tecnificado que se usa, y la calidad del paisaje medida por la proporción de sistemas naturales, bosques y cultivos perenes presentes. El impacto ambiental de los sistemas de uso se evaluó en 75 parcelas localizadas en 41 fincas diferentes, distribuidas en el transecto entre Puerto López, Puerto Gaitán, incluyendo CNI Carimagua. Se evaluaron los cuatro sistemas productivos pastura mejorada, cultivos transitorios y cultivos perennes (caucho y palma de aceite) con respecto a la sabana natural. A partir de un extenso diagnóstico agroecológico, se diseñaron 5 sub indicadores: fertilidad química de suelos, funciones hídricas, biodiversidad (macrofauna de suelo), regulación climática (almacenamiento de carbono, emisiones de GEI) y estabilidad estructural del suelo (macroagregación y morfología del suelo). Estos 5 sub indicadores se combinaron después para constituir un indicador de servicios ecosistemicos que mide el impacto ambiental de los sistemas de producción. Cada uno de los indicadores generados separó los sistemas de uso de forma altamente significativa. Mientras que la pastura mejorada en promedio mejora la biodiversidad de la macrofauna (0.73 ±0.05) y la agregación (0.76 ± 0.02) del suelo limitando su erosión en comparación con la sabana natural, la palma de aceite mejora las funciones hídricas del suelo y el almacenamiento de C y los cultivos anuales mejoran la calidad química (0.78 ± 0.03) estos sistemas de producción desmejoran las otras funciones, aunque de formas distintas según el tipo de producción. Se observó así que cada sistema de uso tiene la capacidad de mejorar por lo menos uno de los servicios eco-sistémicos medidos, además de aumentar el indicador económico (máximo para los cultivos transitorios con un valor de 0.91 ± 0.09) y mejorar los índices sociales (valor promedio máximo con los cultivos perenes 0.46 ± 0.28). Existe sin embargo una variabilidad grande entre los sistemas, probablemente debida a la diversidad de los paisajes creados y al valor del capital humano presente. El componente socioeconómico presentó patrones muy interesantes asi (1) La ecoeficiencia aumenta de forma regular con el capital humano, (2) La ecoeficiencia aumenta con la intensificacion del uso de la tierra (indicador económico), hasta un punto de inflexión que corresponde a un valor del indicador de sistemas de producción de 0.9 y parece disminuir de forma abrupta justo después; (3) La ecoeficiencia aumenta con la intensificación del paisaje, pero disminuye fuertemente en los paisajes más intensificados. Estos resultados muestran globalmente una gran variabilidad en los datos de ecoeficiencia. Es clara la influencia de los sistemas de cultivo implementados sobre los parámetros ambientales y el capital humano. Sin embargo, se nota una relación fuerte con el paisaje creado, con una disminución de la ecoeficiencia ya notable en las fincas que tienen menores proporciones de espacios naturales y bosques, aunque los cultivos perenes puedan ayudar a mejorar la condición ambiental hasta cierto punto. Palabras clave: Oxisoles, Servicios ecosistemicos, Gases efecto invernadero, Caracterización socioeconómica y Análisis multivariado ; Abstract: The agricultural development of the Colombian altillanura, carried out with government support, is an ambitious goal for many reasons, starting with the intrinsic infertility of the soils that has limited the agricultural development up to now. It is important to design an ecofficient agricultural development model, that is economically profitable, equitable from a social point of view and environmentally sustainable. In this study, indicators were designed to evaluate and monitor the eco-efficiency of the four production systems most used by the producers who invested in the area: transitional crops, perennial crops (African palm and hevea) and improved pastures compared with Natural savanna as a reference system. The objective of the study was the construction of eco-efficiency indicators in the production systems: transitional crops (soybean, maize, and rice), permanent crops (rubber and oil palm), improved pastures and natural savanna, from generation Of synthetic sub-indicators with values between 0.10 and 1.00, associated to the groups of variables of water regulation, soil chemical fertility, biodiversity (macrofauna), climate regulation (greenhouse gases and carbon storage) and socioeconomic variables. The eco-efficiency indicator is the sum of an indicator of ecosystem services, social development and economic efficiency. The socioeconomic study was done in 120 farms that represent the diversity of situations found in the area. Five initial variables of the social environment (age, land tenure, permanent male and/or female workers, training received) were extracted from the initial database of 227 questions organized in 13 blocks established by CIAT and were used to design a Human Capital indicator. Another group of 11 variables were used to describe the economic environment with an indicator of Production Systems. Finally, a group of 7 variables, which describe the composition of the farm in different vegetation cover, was used to design a landscape indicator. From the multivariate analysis (PCA and ACM) of each group, indicators ranging from 0.1 to 1.0 were calculated following the methodology of Velasquez et al. (2007). Typologies of the farms were also made according to each indicator, based on clusters analysis to assist in the interpretation. Significant covariations were measured showing a close relationship between the available human capital (number of permanent workers, age and training of the producer), the production system, more or less technified, that is used, and the quality of the landscape measured by the relative proportions of natural systems, forests and perennial crops present. Ecosytem services of land use systems was evaluated in 75 plots located in 41 different farms, distributed in the transect between Puerto López, Puerto Gaitán and Carimagua. The four production systems improved pasture, transient crops and perennial crops (rubber and oil palm) were evaluated with respect to the natural savanna. Based on an extensive agroecological diagnosis, 5 sub indicators were designed: chemical soil fertility, water functions, biodiversity (soil macrofauna), climate regulation (carbon storage, GHG emissions) and soil structural stability (macroaggregation and morphology of floor). These 5 sub indicators were added later to constitute an indicator of ecosystem services that measures the environmental impact of production systems. Each of the indicators generated separated the systems of use in a highly significant way. While improved pasture on average improves the biodiversity of macrofauna (0.73 ± 0.05) and aggregation (0.76 ± 0.02) of the soil by limiting its erosion compared to the natural savanna, the oil palm improves the water functions of the soil and the Storage of C and annual crops improve the chemical quality (0.78 ± 0.03) these production systems deteriorate the other functions, but in different ways according to the type of production. It was observed that each system of use has the capacity to improve at least one of the measured ecosystemic services, besides increasing the economic indicator (maximum for transitory crops with a value of 0.91 ± 0.09) and to improve the social indexes (Maximum value with perennial crops 0.46 ± 0.28). There is, however, a large variability between the systems, probably due to the diversity of landscapes created and the value of present human capital. The socio-economic component presents very interesting patterns as well (1) Eco-efficiency increases on a regular basis with human capital, (2) Eco-efficiency increases with the intensification of land use (economic indicator), to an inflection point corresponding to a Value of the indicator of production systems of 0.9 and seems to decrease abruptly just after; (3) Eco-efficiency increases with the intensification of the landscape, but decreases strongly in the intensified landscapes These results globally show great variability in eco-efficiency data. The influence of cropping systems on environmental parameters and human capital is clear. However, there is a strong relationship with the landscape created, with a decrease in ecoefficiency already Key words: Oxisols, Ecosystem services, Greenhouse Gases, Socioeconomic Characterization and Multivariate Analysis. ; Doctorado

This is the final version. Available on open access from AGU via the DOI in this record ; The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.2883 ; Variability in climate exerts a strong influence on vegetation productivity (gross primary productivity; GPP), and therefore has a large impact on the land carbon sink. However, no direct observations of global GPP exist, and estimates rely on models that are constrained by observations at various spatial and temporal scales. Here, we assess the consistency in GPP from global products which extend for more than three decades; two observation-based approaches, the upscaling of FLUXNET site observations (FLUXCOM) and a remote sensing derived light-use efficiency model (RS-LUE), and from a suite of terrestrial biosphere models (TRENDYv6). At local scales, we find high correlations in annual GPP amongst the products, with exceptions in tropical and high northern latitudes. On longer timescales, the products agree on the direction of trends over 58% of the land, with large increases across northern latitudes driven by warming trends. Further, tropical regions exhibit the largest interannual variability in GPP, with both rainforests and savannas contributing substantially. Variability in savanna GPP is likely predominantly driven by water availability, although temperature could play a role via soil moisture – atmosphere feedbacks. There is, however, no consensus on the magnitude and driver of variability of tropical forests, which suggest uncertainties in process representations and underlying observations remain. These results emphasise the need for more direct long-term observations of GPP along with an extension of in-situ networks in underrepresented regions (e.g. tropical forests). Such capabilities would support efforts to better validate relevant processes in models, to more accurately estimate GPP. ; European Union ; European Space Agency ; Natural Environment Research Council (NERC) ; NASA

Les sites métallifères naturels représentent des cas d'étude uniques pour la recherche scientifique en géo-pédologie, en biologie et en éco-évolution des métallophytes. Le sud-est de la République Démocratique du Congo (R.D.C.) présente les gisements de cuivre et de cobalt parmi les plus importants au monde et considérés comme des ressources minières de hautes valeurs économiques. Les affleurements sont issus de successions géologiques durant des millions d'années. Ils forment aujourd'hui une centaine de collines isolées dans une région de 300 km de long et 50 km de large dominée par la forêt claire sèche et nommée l'Arc Cuprifère Katangais. Au sommet des collines, la proximité entre la surface du sol et l'affleurement entraine un excès de cuivre et cobalt dans la fraction biodiponible de la solution du sol qui est quasi inexistant en bas de pente. Ces teneurs dépassant les limites de tolérance pour la plupart des végétaux constituent un facteur de stress déterminant les communautés et la présence d'espèces endémiques. Plus de 550 taxa dont environ 10% identifiés comme endémiques sont répartis dans deux communautés végétales herbacées distinctes identifiées comme des savanes steppiques sur les sols peu minéralisés et des steppes sur les sols fortement minéralisés. L'impact des activités minières a aujourd'hui des conséquences majeures au niveau environnemental et sociétal menant à la disparition des sites métallifères naturels et à la pollution de sites naturels non-métallifères dont certains sont proches des habitations. Etant donné les menaces sur les espèces végétales endémiques de l'Arc Cuprifère Katangais, plusieurs stratégies de conservation in situ et ex situ ont été mises en place au cours de ces 10 dernières années en collaboration avec différentes institutions. En plus, les métallophytes constituent de véritables ressources pour la mise en place de biotechnologies telles que la phytoremédiation en raison de leur capacité de tolérance ou d'accumulation. Les sols métallifères anthropogéniques de la région pourraient donc constituer de nouveaux sites conciliant la conservation des métallophytes et la remédiation des sols pollués. Cet enjeu double exige de déterminer les relations entre les espèces et les facteurs environnementaux conditionnant leur distribution dans les sites naturels et leur performance dans les sites anthropogéniques. Cette thèse a pour but de caractériser la niche édaphique des métallophytes de l'Arc Cuprifère Katangais afin de proposer des actions associant leur conservation et la phytostabilisation des sols pollués de la région. Dans un premier axe, deux concepts fondamentaux en écologie ont été développés, la théorie des niches écologiques et le concept d'endémisme édaphique, afin de caractériser les relations entre les métallophytes et leur environnement édaphique à l'échelle des individus, des populations, des espèces et des communautés. Plusieurs espèces endémiques menacées ont été choisies comme modèles d'étude afin de déterminer l'origine de leur présence quasi-exclusive sur des sols métallifères. Un second axe a testé le succès d'introduction de ces espèces dans des stratégies de phytostabilisation en association avec une graminée pionnière Microchloa altera. Une évaluation des autres graminées de cette flore selon les critères de sélection exigés par cette stratégie a été effectuée afin de soumettre des propositions concrètes pour l'utilisation des métallophytes de l'Arc Cuprifère Katangais dans des stratégies de phytostabilisation des sols pollués. Cette thèse a mis en évidence l'existence d'une diversité de niches réalisées le long des gradients en cuivre et cobalt au sein des communautés avec une présence de taxa endémiques dans des concentrations en cuivre et cobalt généralement plus élevées que les autres sols de la région. La comparaison avec les niches fondamentales des espèces a montré que certains taxa endémiques seraient dépendants de la présence de cuivre dans le sol, qualifiés d'endémiques spécialistes tandis que d'autres seraient exclus de la végétation dominante, nommés endémiques refuges. Cette diversité d'espèces endémiques et non endémiques présentant des niches écologiques distinctes démontre que ces communautés herbacées recèlent un véritable potentiel pour les conserver dans des habitats pollués. Les essais en conditions contrôlées et en conditions réelles ont d'ailleurs démontré la possibilité d'associer ces espèces endémiques et non endémiques à des stratégies de phytostabilisation dans la région tout en pointant l'importance de leur sélection et des caractéristiques des sites à phytostabiliser. ; Natural metalliferous habitats represent unique study cases for scientific research as geopedology, biology and eco-evolution of metallophytes. Southeastern Democratic Republic of Congo hosts among the most important copper and cobalt deposits of the world, having a high economic value. Copper and cobalt outcroups have been formed during billion years by geological successions. More than one hundred hills are now scattered in an area of 300 km long and 50 km large in vegetation matrix consisting on an open forest called Miombo. This area is called Katangan Copperbelt. At the top of hills, the close proximity between the deposit and the soil surface lead to a high concentration of bioavailable copper and cobalt in soil solution exceeding the tolerance threshold of most of plants. More than 550 taxa including 10 % are identified as endemics and compose two distinct herbaceous plant formations: the steppic savanna is found on the lowest minralised soils and the steppe occurs in the highest mineralized soils at the top of hills. Mining activities have dramatic consequences on environement and public health, leading to the destruction of natural meatlliferous habitats and to the creation of anthropogenic polluted sites. Considering the threat on endemic plant species of the Katangan Copperbelt, several in situ and ex situ conservation strategies have been implemented for the last ten years in collaboration with several institutions. Furthermore, metallophytes constitute remarkable resources for the biotechnologies such as phytoremediation due to their metal tolerance or their accumulation ability. Anthropogenic metalliferous sites of the Katangan Copperbelt could be considered for the conservation of metallophyte with a perspective of remediation of polluted soils. Both challenges require the characterization of the environmental factors determining the distribution of plant species in natural sites and their performance in anthropogenic sites. This thesis aims at characterising the edaphic niche of metallophytes from the Katangan Copperbelt in order to propose actions combining the conservation of metallophyte and the phytostabilisation of polluted soils. The first axis focused on the study of two fundamental concepts in ecology, the theory of ecological niche and the concept of edaphic endemism, in order to understand the plant-soil relationships. Threatened endemic species were chosen as study case to determine the cause of the restricted distributions of metallophytes on metalliferous soils. The second axis tested the success of the establishment of endemic metallophytes in phytostabilisation strategies using the grass Microchloa altera. An assessment of the potential of other grasses was performed based on the specific criterions needed in phytostabilisation in order to identify candidate species for conservation–phystabilisation strategies.

Der Klimawandel und insbesondere die globale Erwärmung gehören aktuell zu den größten Herausforderungen an Politik und Wissenschaft. Steigende CO2-Emissionen sind hierbei maßgeblich für die Klimaerwärmung verantwortlich. Ein regulierender Faktor beim CO2-Austausch mit der Atmosphäre ist die Vegetation, welche als CO2-Senke aber auch als CO2-Quelle fungieren kann. Diese Funktionen können durch Analysen der Landbedeckungsänderung in Kombination mit Modellierungen der Kohlenstoffbilanz quantifiziert werden, was insbesondere von aktuellen und zukünftigen politischen Instrumenten wie CDM (Clean Development Mechanism) oder REDD (Reducing Emissions from Deforestation and Degradation) gefordert wird. Vor allem in Regionen mit starker Landbedeckungsänderung und hoher Bevölkerungsdichte sowie bei geringem Wissen über die Produktivität und CO2-Speicherpotentiale der Vegetation, bedarf es einer Erforschung und Quantifizierung der terrestrischen Kohlenstoffspeicher. Eine Region, für die dies in besonderem Maße zutrifft, ist Westafrika. Jüngste Studien haben gezeigt, dass sich einerseits die Folgen des Klimawandels und Umweltveränderungen sehr stark in Westafrika auswirken werden und andererseits Bevölkerungswachstum eine starke Änderung der Landbedeckung für die Nutzung als agrarische Fläche bewirkt hat. Folglich sind in dieser Region die terrestrischen Kohlenstoffspeicher durch Ausdehnung der Landwirtschaft und Waldrodung besonders gefährdet. Große Flächen agieren anstelle ihrer ursprünglichen Funktion als CO2-Senke bereits als CO2-Quelle. [.] ; Global warming associated with climate change is one of the greatest challenges of today's world. One regulating factor of CO2 exchange with the atmosphere is the vegetation cover. Measurements of land cover changes in combination with modeling of the carbon balance can therefore contribute to determining temporal variations of CO2 sources and sinks, which is an essential necessity of existing and prospective political instruments like CDM (Clean Development Mechanism) or REDD (Reducing Emissions from Deforestation and Degradation). The need for quantifiable terrestrial carbon stocks is especially high for regions, where rates of land cover transformation and population density are high and knowledge on vegetation productivity is low. One region which is characterized by these criteria is West Africa. Therefore, carbon stocks in this region are seriously endangered by land cover change like the expansion of agriculture and forest logging. Large areas already act as carbon sources on a yearly basis instead of their previous function as carbon sink. Since only a few studies have analyzed the terrestrial carbon stocks in Africa and especially regional analysis in West Africa are missing, the following study focuses on regional scale modeling of the actual terrestrial carbon stocks. Additionally, the potential carbon stocks of unmanaged land cover and the potential for CO2 payments have been analyzed in this work. To quantify and assess carbon fluxes as well as the loss of carbon, net primary productivity of vegetation has been modeled, based on the plants characteristics to fix carbon from the atmosphere during photosynthesis. Modeling vegetation dynamics and net primary productivity has been realized by using MODIS 250m time series for semi-humid and semi-arid savanna ecosystems in West Africa. This study aimed to quantify CO2 exchanges of the Savanna regions in the Volta basin by applying and adapting the Regional Biomass Model (RBM). The RBM was developed by Jochen Richters (2005) at a resolution of 1000m for the Namibian Kaokoveld. In this study the model was optimized to the scale of 232m to consider the heterogeneous landscape in West Africa (RBM+). New input parameters with higher accuracies and resolution were generated instead of using the global standard products. The most important parameters for the modeling are FPAR and the fractional cover of herbaceous and woody vegetation. To enhance the MODIS FPAR product, linear interpolation and downscaling algorithms were applied. The main objective of the downscaling is a better representation of the finely scattered vegetation by the 232m resolution FPAR. The second optimized parameter, the fractional cover of herbaceous and woody vegetation was represented by the Vegetation Continuous Fields product (VCF) from MODIS in the originally version of the RBM. This global product reflects the vegetation structure of West Africa poorly, since few high resolution training data is available for this region, and the dynamic savanna vegetation can hardly be classified by not regionally adapted methods. Additionally, the data is only available with 500m resolution. Therefore, in this study a new product with 232m resolution was developed which represents the spatial heterogeneity well and, due to the regional adaptation, shows higher accuracies. The percentage cover of woody and herbaceous vegetation and bare soil on 232m MODIS data was calculated in a multi scale approach. Based on very high resolution data, represented by Quickbird and Ikonos with 0.6-4m resolution, and high resolution data from Landsat with 30m resolution, the percentage coverage was estimated for representative focus regions. These classifications were used as a training data set to determine the percentage coverage on the 232m scale with MODIS time series for the whole study region. Based on these optimized and adapted input parameters, the net primary productivity was modeled. Data from a meteorological station and an Eddy-Covariance-Flux allowed a detailed validation of the input parameters and of the model results. The model led to good results as it only overestimated the net primary productivity for the two analyzed years 2005 and 2006 by 8.8 and 2.0 %, respectively. The second aim of the study was an analysis of the potential for long term terrestrial carbon sinks. Classifications of the actual and of the potential land cover were calculated for this analysis. Considering the overall long time CO2 fixation behavior of trees, which depends on their age, longterm carbon stocks for 100 years were simulated. As carbon fixing could be paid by emission trading, which is in future depending on the political Post-Kyoto programs, potential alternative income was calculated with different price scenarios for the three countries. A comparison with the gross domestic products of these countries and with developing aid, showed the significance of CO2 trading in this region.

Pflanzenfunde aus archäologischen Ausgrabungen im Norden Burkina Fasos dokumentieren die regionale Geschichte der Pflanzennutzung und damit zusammenhängende Wechselwirkungen zwischen Mensch und Umwelt. Das untersuchte Material besteht überwiegend aus verkohlten Früchten und Samen, die durch das Schlämmen von Kultursedimenten aus mehr als 20 Fundplätzen gewonnen wurden. Sie decken einen Zeitraum von etwa 4000 Jahren ab, der von der Endsteinzeit bis in die jüngste Neuzeit reicht. Die Analysen der archäobotanischen Inventare ermöglichen es, mehrere Phasen der Pflanzennutzung auszuweisen, die mit spezifischen Lebens- und Siedlungsweisen der Bevölkerung assoziiert sind. Eine ausschließlich wildbeuterische Wirtschaftsform wird für die älteste der untersuchten Fundstellen, den Lagerplatz Corcoba, angenommen. Dort nutzten mobile Gesellschaften um 2000 BC reiche Fischressourcen und sammelten systematisch die Früchte von Gehölzen. Im Inventar des Fundplatzes Tin Akof ist um 1800 BC erstmals eine Kulturpflanze, die Perlhirse (Pennisetum glaucum) nachweisbar. Sie markiert den Beginn der produzierenden Wirtschaftsweise. Es wird ein Anbau in kleinem Maßstab rekonstruiert, wobei Feldbau nur eine von mehreren praktizierten Subsistenzstrategien war. Vermutlich handelte es sich bei den Bewohnern von Tin Akof um seminomadische Viehhalter, die aus dem Sahararaum einwanderten und das bereits domestizierte Getreide einführten. Ab der Zeitenwende tritt in der Eisenzeit eine neue, sesshafte Kultur in Erscheinung. Ihre Siedlungen befanden sich vorzugsweise auf sandigen, leicht kultivierbaren Böden in der Nähe permanenter Gewässer. Die Nahrungsproduktion basierte auf der Kultivierung von Perlhirse, daneben wurden Hibiscus cf. sabdariffa und die Hülsenfrüchte Vigna subterranea und V. unguiculata angebaut. Als Anbausysteme lassen sich Mischkulturen mit Perlhirse als Hauptfrucht und Kulturbaumparks, die vom Menschen geschätzte Gehölze (u.a. Vitellaria paradoxa) aus der ursprünglichen Savannenvegetation einbeziehen, rekonstruieren. Die gemischte Wirtschaftsweise umfasste Viehhaltung, aber auch wildbeuterische Praktiken wie das Sammeln von Wildpflanzen, insbesondere von Baumfrüchten. Hinweise auf Handelskontakte liegen aus der zweiten Hälfte des ersten Jahrtausends AD vor. Sie lassen sich zum Teil mit dem Ausbau transsaharischer Handelsnetze im Verlauf der Islamisierung Westafrikas verknüpfen. Sorghum bicolor und die Wassermelone (Citrullus lanatus) wurden möglicherweise auf diese Weise eingeführt. Die Eisenzeit erweist sich insgesamt als stabile Epoche mit langer Siedlungskontinuität. Gleichwohl zeigen die detailliert untersuchten Fundsequenzen sich wandelnde Nutzungsmuster und eine Intensivierung der Landwirtschaft. Im 14. Jahrhundert werden die für die Epoche typischen Siedlungshügel im gesamten Gebiet verlassen. Mögliche Ursachen sind politische Veränderungen in benachbarten Regionen. Erst aus der jüngsten Neuzeit liegen wieder archäobotanische Belege vor. Die Ergebnisse aus Burkina Faso bestätigen die archäobotanischen Forschungen in anderen Gebieten Westafrikas, nach denen Feldbau relativ spät um 2000 BC begann und Perlhirse die erste domestizierte Kulturpflanze darstellt. Die stabile Bedingungen in der Eisenzeit führten vielerorts zur Entstehung von Städten und Handelszentren. Diese Entwicklung ist im ländlichen Raum, zu der auch die Arbeitsregion zählt, weniger deutlich ausgeprägt, aber dennoch fassbar. Die archäobotanischen Inventare der Endsteinzeit und Eisenzeit dokumentieren ein, im Vergleich zu heute, niederschlagsreicheres Klima und einen geringeren anthropozoogenen Einfluss auf die natürliche Vegetation. ; Plant remains from archaeological excavations in northern Burkina Faso document the regional history of plant exploitation and associated interactions of man and his environment. The studied material consists mainly of charred fruits and seeds. They were obtained by bucket flotation of the cultural deposits of more than 20 archaeological sites, covering a period from about 4000 years and ranging from the Later Stone Age nearly up to the present. The analyses of archaeobotanical records allow one to define several phases of plant exploitation which are associated with specific ways of life and settlement patterns. The oldest site of the data set, the camp site Corcoba, indicates a hunter-gatherer economy. At about 2000 BC, mobile groups exploited rich fish resources and gathered systematically the fruits and seeds of the woody vegetation. The site Tin Akof, dating around 1800 BC, provides the first evidence of cultivated plants. Thus, finds of pearl millet (Pennisetum glaucum) mark the beginning of plant production in the Later Stone Age. Presumably, farming was practised on a small scale and furnished only a part of the mixed subsistence of the settlers. The cereal obviously was introduced in it's domesticated form and could have been brought in by seminomadic herders who immigrated from the desiccating Sahara. Around 0 BC/AD, new sedentary cultures, familiar with the production and use of iron, emerge. Their settlements were located close to permanent water sources and sandy soils, which are easy to cultivate. Food production was apparently based on the cultivation of pearl millet. Hibiscus cf. sabdariffa and the pulses Vigna subterranea and V. unguiculata enlarged the crop range. Mixed cropping and agroforesting systems can be reconstructed, comprising trees and shrubs of the original savanna vegetation (e.g. Vitellaria paradoxa). The mixed economy included breeding of livestock, but also hunting and gathering of wild plants, especially of tree crops. Hints on trading contacts exist for the second half of the first millennium AD. At least the later ones might be connected with the flourishing trans-Saharan trade following the Islamic penetration into sub-Saharan West Africa. By this way Sorghum bicolor and the water melon (Citrullus lanatus) possibly entered the archaeological record. Iron Age appears to be a phase of stability and continuity. However, the detailed studies of archaeobotanical records point to changing patterns of landuse and an intensification of agriculture within the period. In the 14th century the typical Iron Age settlement mounds were abandoned. A possible explanation are political changes in the neighbouring regions. Sites with archaeobotanical remains are not detectable until subrecent times. The results from Burkina Faso corroborate the state of archaeobotanical research in West Africa, suggesting a relatively late advent of agriculture around 2000 BC with pearl millet being the first domesticated plant. Similar to other savanna sites, Iron Age times are a phase of prosperity, in which trading points and urban centres emerged. These developments are less apparent, but nevertheless visible in rural regions like the area studied. In comparison to the recent situation Later Stone Age and Iron Age plant remains point to higher rainfalls and a lower anthropozoogenous impact on the natural vegetation.

Rapid population growth in West Africa has led to expansion in croplands due to the need to grow more food to meet the rising food demand of the burgeoning population. These expansions negatively impact the sub-region's ecosystem, with implications for water and soil quality, biodiversity and climate. In order to appropriately monitor the changes in croplands and assess its impact on the ecosystem and other environmental processes, accurate and up-to-date information on agricultural land use is required. But agricultural land use mapping (i.e. mapping the spatial distribution of crops and croplands) in West Africa has been challenging due to the unavailability of adequate satellite images (as a result of excessive cloud cover), small agricultural fields and a heterogeneous landscape. This study, therefore, investigated the possibilities of improving agricultural land use mapping by utilizing optical satellite images with higher spatial and temporal resolution as well as images from Synthetic Aperture Radar (SAR) systems which are near-independent of weather conditions. The study was conducted at both watershed and regional scales. At watershed scale, classification of different crop types in three watersheds in Ghana, Burkina Faso and Benin was conducted using multi-temporal: (1) only optical images (RapidEye) and (2) optical plus dual polarimetric (VV/VH) SAR images (TerraSAR-X). In addition, inter-annual or short term (2-3 years) changes in cropland area in the past ten years were investigated using historical Landsat images. Results obtained indicate that the use of only optical images to map different crop types in West Africa can achieve moderate classification accuracies (57% to 71%). Overlaps between the cropping calendars of most crops types and certain inter-croppings pose a challenge to optical images in achieving an adequate separation between those crop classes. Integration of SAR images, however, can improve classification accuracies by between 8 and 15%, depending on the number of available images and their acquisition dates. The sensitivity of SAR systems to different crop canopy architectures and land surface characteristics improved the separation between certain crop types. The VV polarization of TerraSAR-X was found to better discrimination between crop types than the VH. Images acquired between August and October were found to be very useful for crop mapping in the sub-region due to structural differences in some crop types during this period. At the regional scale, inter-annual or short term changes in cropland area in the Sudanian Savanna agro-ecological zone in West Africa were assessed by upscaling historical cropland information derived at the watershed scale (using Landsat imagery) unto a coarse spatial resolution, but geographically large, satellite imagery (MODIS) using regression based modeling. The possibility of using such regional scale cropland information to improve government-derived agricultural statistics was investigated by comparing extracted cropland area from the fractional cover maps with district-level agricultural statistics from Ghana The accuracy of the fractional cover maps (MAE between 14.2% and 19.1%) indicate that the heterogeneous agricultural landscape of West Africa can be suitably represented at the regional or continental scales by estimating fractional cropland cover on low resolution Analysis of the results revealed that cropland area in the Sudanian Savanna zone has experienced inter-annual or short term fluctuations in the past ten years due to a variety of factors including climate factors (e.g. floods and droughts), declining soil fertility, population increases and agricultural policies such as fertilizer subsidies. Comparison of extracted cropland area from the fractional cover maps with government's agricultural statistics (MoFA) for seventeen districts (second administrative units) in Ghana revealed high inconsistencies in the government statistics, and highlighted the potential of satellite derived cropland information at regional scales to improve national/sub-national agricultural statistics in West Africa. The results obtained in this study is promising for West Africa, considering the recent launch of optical (Landsat 8) and SAR sensors (Sentinel-1) that will provide free data for crop mapping in the sub-region. This will improve chances of obtaining adequate satellite images acquired during the cropping season for agricultural land use mapping and bolster opportunities of operationalizing agricultural land use mapping in West Africa. This can benefit a wide range of biophysical and economic models and improve decision making based on their results. ; Das schnelle Bevölkerungswachstum im Westen Afrikas hat, durch das erhöhte Bedürfnis nach Lebensmittel der expandierenden Bevölkerung, zu einer steigenden Lebensmittelnachfrage und damit zur Ausweitung von Ackerland geführt. Diese Expansionen haben negative Einflüsse auf das Ökosystem der Subregion, die Konsequenzen für Wasser- und Bodenqualität, sowie für Biodiversität und das Klima nach sich ziehen. Um die Veränderungen der Ackerflächen überwachen und die Folgen für das Ökosystem und anderer Umweltprozesse richtig abschätzen zu können, werden genaue und aktuelle Informationen über die landwirtschaftliche Nutzung benötigt. Das kartographieren landwirtschaftlicher Flächennutzung (z.B. das Abbilden der räumlichen Verteilung von Feldfrüchten und Ackerflächen) in Westafrika wurde durch die mangelhafte Verfügbarkeit geeigneter Satellitendaten (durch das Auftreten massiver Wolkenbedeckung), der geringen Größe der landwirtschaftlichen Flächen, sowie der heterogenen Landschaft, erschwert. Aus diesen Gründen untersucht diese Studie das Potential landwirtschaftlich genutzte Flächen, durch die Nutzung von optischen Satellitensystemen mit höherer geometrischer und temporaler Auflösung und Aufnahmen des Synthetic Aperture Radar (SAR) als ein nahezu wetterunabhängiges System, aufzunehmen. Diese Studie wurde sowohl auf der Skala von Wassereinzugsgebieten als auch von Regionen erstellt (Agrarökologische Zone in der sudanesischen Savanne). Auf der Skala der Wassereinzugsgebiete wurden Klassifikationen verschiedener Feldfrüchte in drei Einzugsgebieten in Ghana, Burkina Faso und Benin, mithilfe multitemporaler Abbildungen, bestehend aus entweder (1) nur optischer Abbildungen (Rapideye) oder (2) optischer und dual polarimetric (VV/VH) SAR Aufnahmen (TerraSAR-X), durchgeführt. Zusätzlich wurden interannuelle oder kurzzeitige (2-3 Jahre) Veränderungen in der Ausdehnung von Ackerflächen über die vergangenen zehn Jahre hinweg mittels historischer Landsataufnahmen untersucht. Die Ergebnisse zeigen, dass das Kartographieren verschiedener Feldfrüchte in Westafrika durch nur optische Abbildungen eine moderate Klassifikationsgenauigkeit von 57% bis 71% widergibt. Überlappungen zwischen dem Anbauplan der meisten Feldfrüchte und dem Zwischenfruchtanbau stellen eine Herausforderung für optische Abbildungen dar, um eine angemessene Unterscheidung der Feldfrüchte zu erreichen. Die Hinzunahme von SAR Aufnahmen kann die Klassifikationsgenauigkeit, abhängig von der Anzahl verfügbarer Szenen und deren Aufnahmedatum, jedoch um 8% bis 15% erhöhen. Die Empfindlichkeit der SAR Systeme gegenüber unterschiedlichem Aufbau der Fläche von Feldfrüchten und der Charakteristika der Landoberfläche verbesserten die Trennbarkeit unterschiedlicher Feldfrüchte. Wie sich herausstellte hat die VV Polarisation von TerraSAR-X eine bessere Trennung der Feldfrüchte bewirkt als die VH Polarisation. Außerdem zeigt sich, dass Aufnahmen zwischen August und Oktober sehr nützlich zur Abbildung von Feldfrüchten in der Subregion sind, da in dieser Zeit strukturelle Unterschiede einiger Feldfrüchte beobachtet werden können. Auf regionalem Maßstab wurden interanuelle oder kurzzeitige Veränderungen der Ackerflächen in der agrarökologischen Zone der sudanesischen Savanne in Westafrika durch das hochskalieren historischer Informationen zu den Ackerflächen auf der Skala der Wassereinzugsgebiete (aus Landsat Aufnahmen) auf eine gröbere Auflösung, aber geographisch weite Satellitenszene (MODIS), unter Zuhilfenahme eines auf Regression basierenden Modells, berechnet. Die Möglichkeit regionalskalierte Informationen zu Ackerflächen zu nutzen um staatlich erstellte landwirtschaftliche Statistiken zu verbessern wurde untersucht, indem die extrahierte Fläche der Äcker aus fraktionierten Karten zur Landbedeckung mit landwirtschaftlichen Statistiken auf Distrikt-Level miteinander verglichen werden. Die Genauigkeit der fraktionierten Landbedeckungskarten (Mean Absolute Error zwischen 14,2% und 19,1%) weist darauf hin, dass die heterogene Agrarlandschaft Westafrikas auf einem regionalen oder kontinentalen Maßstab, durch die Abschätzung fraktionierter Ackerflächen aus gering aufgelösten Satellitendaten, angemessen repräsentiert werden kann. Die Analyse der Ergebnisse zeigt, dass die Ackerflächen der Agrarökologischen Zone der sudanesischen Savanne interannuelle oder kurzzeitige Schwankungen in den vergangenen zehn Jahren unterlegen waren. Diese Schwankungen ergeben sich durch bestimmte Faktoren wie: klimatische Faktoren (z.B. Überschwemmungen oder Dürren), sinkende Bodenfruchtbarkeit, Bevölkerungswachstum und landwirtschaftliche Politik wie der Subvention von Düngemitteln. Der Vergleich von fraktionierter Landbedeckungskarten mit staatlich erstellten landwirtschaftlichen Statistiken (MoFA) in 17 Distrikten in Ghana ergaben große Unregelmäßigkeiten in den staatlichen Statistiken und zeigten das Potential von aus Satellitendaten abgeleiteten Informationen zu Ackerflächen auf regionalem Maßstab um nationale oder subnationale landwirtschaftliche Statistiken in Westafrika zu verbessern. Angesichts der baldigen Starts der optischen (Landsat 8) und SAR (Sentinel-1) Sensoren, die frei zugängliche Daten für die Kartierung von Feldfrüchten in der Subregion liefern werden, sind die Ergebnisse, die in dieser Studie gewonnen wurden, vielversprechend für Westafrika. Dadurch steigen die Chancen, dass adäquate Satellitenszenen für das Abbilden landwirtschaftlicher Landnutzung während der Anbauzeitraums bezogen und operationalisiert werden können. Dies hat zur Folge, dass ein breites Spektrum biophysikalischer und ökonomischer Modelle davon profitieren und die Entscheidungsfindung durch die Ergebnisse optimiert wird.