Vulnerabilität und Resilienz von Weidesystemen unter dem Einfluss von Bewirtschaftung, Boden und Klima
Zusammenfassung der Projektergebnisse
The project aimed to analyses and model changes in rangeland vegetation, with specific emphasis on its resilience and vulnerability as affected by livestock management and environmental conditions. The work will focus on South African savannah and grassland biomes and their system shifts to alternative states under different types of range management. The vegetation of East and South African savannahs has been shaped by the complex interaction of geo-biophysical processes and human impact. For both regions a controversial discussion in ongoing, as to whether massive degradation threatens the sustainability of livelihoods in these regions. Rangeland vegetation (grassland and savannah used for grazing cattle) its resilience and vulnerability is mainly affected by environmental conditions (soil and climate) and by livestock management. Extent and interaction of these drivers causes or prevents shifts towards unfavorable degraded or bush encroached system states which are not well understood. These states, where either total ecosystem productivity is very low, or where grasses have been largely replaced by inedible shrubs, have profound impacts on local livelihoods that are strongly dependent of rangelands for their livestock production. Vulnerability and resilience of different livestock systems and associated management factors on vegetation composition and production of rangeland have been studied in two different regions in South Africa, Bloemfontein and Kuruman. We tested the impact of climate, soil conditions and management factors on vegetation structure and productivity. We applied a functional ecology approach considering functional traits and functional types at plot and field scale. In parallel, we used satellite data from different sensors to monitor vegetation dynamics. Here, a novel approach based on NDVI dynamics was introduced, which allows the spatial mapping of crop and grassland phenology in order to identify abnormalities in climate and management. The aim was to assess intra- and interseasonal variability, and the ability of plant production to recover from disturbances and to evaluate the impact of land management on rangeland resilience. The project addressed the following research questions: How does management in different tenure systems influence productivity of rangeland / grassland and how can its resilience be evaluated? - How can indicators of resilience and vulnerability be assessed based on temporal changes in vegetation condition as derived from functional traits and types of plants? - What spatially explicit information on vegetation properties relevant for resilience can be derived from satellite remote sensing? - How to simulate biomass considering important influencing factors and feedback loops with a dynamic process-based rangeland model considering different management intensities? - How to parametrize and validate this model with independent data from manipulation experiments? - How to integrate this model into an agent-based model to evaluate effects of management on rangelands within a farming system context?
Projektbezogene Publikationen (Auswahl)
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(2014) Are there consistent grazing indicators in drylands? Testing plant functional types of various complexity in South Africa’s grassland and savanna biomes, PLOS ONE, 9, e104672
Linstädter, A., J. Schellberg, K. Brüser, C.A. Moreno Garcia, R.J. Oomen, C.C. du Preez, J.C. Ruppert, F. Ewert
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(2014) Convergence between ANPP estimation methods in grasslands - a practical solution to the comparability dilemma. Ecological Indicators 36, 524-531
Ruppert, J.C., A. Linstädter
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(2014) Discrimination and characterization of management systems in semi-arid rangelands of South Africa using RapidEye time series. International Journal of Remote Sensing, 35 (5): 1653-1673
Brüser, K., H. Feilhauer, A. Linstädter, J. Schellberg, R.J. Oomen, J.C. Ruppert, F. Ewert
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(2014) Response of community-aggregated plant functional traits along grazing gradients: insights from African semi-arid grasslands, Applied Vegetation Science, 17 (3): 470-481
Moreno Garcia, C.A., J. Schellberg, F. Ewert, K. Brüser, P. Canales Prati, A. Linstädter, R J. Oomen, J.C. Ruppert, S. B. Perelman
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(2015) Grass strategies and grassland community responses to environmental drivers: a review. Agronomy for Sustainable Development 35, 1297-1318
Da Pontes, L.S., V. Maire, J. Schellberg, F. Louault
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(2015) How to avoid unsustainable side effects of managing climate risk in drylands – the supplementary feeding controversy. Agricultural Systems 139, 153-165
Müller, B., Schulze, J., Kreuer, D., Linstädter, A., Frank, K.
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(2015) Monitoring vegetation dynamics with medium resolution MODIS-EVI time series at sub-regional scale in southern Africa. International Journal of Applied Earth Observation and Geoinformation 38, 175-183
Dubovyk, O., T. Landmann, B.F.N. Erasmus, A. Tewes, J. Schellberg
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(2015), Using RapidEye and MODIS Data Fusion to Monitor Vegetation Dynamics in Semi-Arid Rangelands in South Africa, Remote Sensing, 7 (6): 6510-6534
Tewes, A., et al.
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(2016) Effect of management on rangeland phytomass, cover and condition in two biomes in South Africa. African Journal of Range & Forage Science 33 (3): 185-198
Oomen, R.J., A. Linstädter, J.C. Ruppert, K. Brüser, J. Schellberg, F. Ewert
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(2016) Modelling rangeland productivity in response to degradation in a semi-arid climate, Ecological Modelling, 322: 54-70
Oomen, R.J., F. Ewert, H.A. Snyman
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(2016) Uncertainty in future irrigation water demand and risk of crop failure for maize in Europe. Environmental Research Letters 11, 074007
Webber, H., T. Gaiser, R. Oomen, E. Teixeira, G. Zhao, D. Wallach, A. Zimmermann, F. Ewert
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(2016), Phenomapping of rangelands in South Africa using time series of RapidEye data, International Journal of Applied Earth Observation and Geoinformation, 53: 90-102
Parplies, A., et al.
