RCR

In collaboration with several research groups from the  Universities of Bonn and Cologne, the INRES Crop Science works in the DFG-funded collaboration research project (Forschergruppe) entitled "Resilience, Collapse and Reorganisation in Social-Ecological Systems of East- and South Africa's Savannahs". The project starts on 1st  March 2010.

Our work encompasses the sub-project "Vulnerability and Resilience of Rangeland Vegetation as Affected by Livestock Management, Soils and Climate". In the project we aim to analyse and model changes in rangeland vegetation, with specific emphasis on its resilience and vulnerability as affected by livestock managment 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 vulneraility is mainly affected by environmental conditions (soil and climate) and by livestock management. Extent and interaction of  these drivers causes or prevents shifts towards unfavourable 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 dependen of rangelands for their livestock production.

Our work links closely to investigations on soil vulnerability and land management strategies by the soil Science group at the University of Bonn for the same regions. Effects of different livestock systems and associated management factors on rangeland vegetation composition and production will be studied. These factors include type and density of livestock, grazing intensity and timing, and other forms of vegetation managment such as wood harvesting for charcoal, or measures to control bush encroachment. Specific attention is given to soil-vegetation interactions to better understand changes in rangeland vegetation as determined by livestock management, soil characterics and climate, as well as the feedback effects of vegetation change on soil properties. Interactions between these key drivers of vegetation change (disturbances, soil resource dynamics, and stochastic rainfall) and their effects on vegetation structure and production will be studied in multi-factorial natural experiments, and modelled with a dynamic vegetation/grassland model.

Our reserch areas are arranged along a gradient of aridity and contrasting tenure systems with different range managment practices being considered. We will apply the concept of plant functional types to classify plant species to support the analysis and modelling of multi-species systems. Plant production, its intra- and interseasonal variability, and the ability of plant production to recover from disturbances will be used as indicators to assess rangeland resilience as affected by land management. Using the vegetation model we will explore potential thresholds to system shifts for the indicators considered and to assess the impacts of different management strategies on the indicators.

Prof. Frank Ewert

Priv. Doz. Dr. Jürgen Schellberg, Roelof Oomen, Anja Linstädter, Katharina Brüser, Jan Ruppert

 See project homepage: http://www.fg1501.uni-koeln.de/

Oomen, R.J., F. Ewert, H.A. Snyman, 2016. Modelling rangeland productivity in response to degradation in a semi-arid climate. Ecological Modelling 322, 54-70. DOI:10.1016/j.ecolmodel.2015.11.001.

Oomen, R.J., A. Linstädter, J.C. Ruppert, K. Brüser, J. Schellberg, F. Ewert, 2016. Effect of management on rangeland phytomass, cover and condition in two biomes in South Africa. African Journal of Range & Forage Science 33, 185-198. DOI:10.2989/10220119.2016.1218368.

Parplies, A., O. Dubovyk, A. Tewes, J.-P. Mund, J. Schellberg, 2016. Phenomapping of rangelands in South Africa using time series of RapidEye data. International Journal of Applied Earth Observation and Geoinformation 53, 90-102. DOI:10.1016/j.jag.2016.08.001.

Webber, H., T. Gaiser, R. Oomen, E. Teixeira, G. Zhao, D. Wallach, A. Zimmermann, F. Ewert, 2016. Uncertainty in future irrigation water demand and risk of crop failure for maize in Europe. Environmental Research Letters 11, 074007. DOI:10.1088/1748-9326/11/7/074007.

Tewes, A., F. Thonfeld, M. Schmidt, R.J. Oomen, Xiaolin Zhu, O. Dubovyk, G. Menz, J. Schellberg, 2015. Using RapidEye and MODIS data fusion to monitor vegetation dynamics in semi-arid rangelands in South Africa. Remote Sensing 7, 6510-6534. DOI:10.3390/rs70606510.

Linstädter, A., J. Schellberg, K. Brüser, C.A. Moreno Garcia, R.J. Oomen, C.C. du Preez, J.C. Ruppert, F. Ewert, 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. DOI:10.1371/journal.pone.0104672.

Morenco Garcia, C.A., J. Schellberg,  F. Ewert, K. Brüser,  P. Canales Prati, A. Linstädter, R J. Oomen, J.C. Ruppert, S. B. Perelman, 2014. Response of community-aggregated plant functional traits along grazing gradients: insights from African semi-arid grasslands. Applied Vegetation Science 17, 470-481. DOI:10.1111/avsc.12092.

Brüser, K., H. Feilhauer, A. Linstädter, J. Schellberg, R.J. Oomen, J.C. Ruppert, F. Ewert, 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. DOI:10.1080/01431161.2014.882028.

Ruppert, J.C., A. Linstädter, 2014. Convergence between ANPP estimation methods in grasslands - a practical solution to the comparability dilemma. Ecological Indicators 36, 524-531. DOI:10.1016/j.ecolind.2013.09.008.

Brüser, K., J. Schellberg, F. Ewert, 2011. Fernerkundungsbasierte Analyse raum-zeitlicher Vegetationsmuster Südafrikanischen Weidelands. Arbeitskreis Fernerkundung, 29/30 September 2011, Würzburg, Germany. => zum Poster  => zum Tagungsbeitrag

Brüser, K., J. Schellberg, R. Oomen, J. Ruppert, A. Linstädter, F. Ewert, 2011. Remote sensing based analysis of spatio-temporal vegetation patterns in South African rangeland at different scales, Tropentag, 5-7 Oktober 2011, Bonn, Germany.  => zum Tagungsbeitrag