Degradation of biodiversity and ecosystem functioning in subtropical grasslands, and thresholds for restoration
Final Report Abstract
The DFG-sponsored project was based on the assumption that ecological restoration aims at maximizing biodiversity and at restoring ecosystem functions. Current theory assumes that human-impacted ecosystems show distinct degradation stages that can be described by (i) deviation in abiotic conditions and biotic composition from reference ecosystems, (ii) deterioration of ecosystem functions, and (iv) resilience and restoration thresholds that control whether or not degraded ecosystems can return to a particular stage. This concept was used as a framework, to be tested within a project in highland grasslands of Rio Grande do Sul in southern Brazil. These subtropical grasslands are rich in biodiversity and they are under pressure due to changing land use, while there is an urgent need for research on grassland restoration. In Rio Grande do Sul, about 50% of the grasslands have been converted to agriculture, forestry or lost due to urban expansion. Only about 2% are within nature reserves where, on cessation of human action woody succession takes place. The grasslands exist in various degradation and restoration stages that most likely differ in their ability to support specific ecosystem functions, and the relative stability of these stages and potential transition thresholds were described. The project was a close cooperation of researchers at Technische Universität München, with expertise in restoration and terrestrial ecology, and researchers at the Universidade Federal do Rio Grande do Sul, Universidade Estadual do Rio Grande do Sul and Universidade Federal do Piauí in Brazil, with excellent knowledge on biodiversity and ecology of Brazilian grasslands. The project included large-scale surveys of degraded grasslands, rapid assessments of ecosystem functions and restoration field experiments in the highlands of Rio Grande do Sul. The project also investigated management practices that shift grasslands across resilience thresholds beyond which they are unable to return to the reference state without human assistance. The applied outcomes of the project are recommendations for grassland restoration and for management of hybrid and novel ecosystems. Overall, the project was highly successful in achieving the scientific goals, using and expanding our collaborations in Germany and Brazil. However, ecosystem assessments and the respective laboratory work consumed most of the available time and human resources during both field campaigns. Therefore, the work package on Objective 3, i.e. experimental testing for restoration thresholds, could not fully be performed. We intend to continue the applied aspects of restoring degraded grasslands and identifying suitable plant material for practical restoration.
Publications
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(2016) Forest–grassland biodiversity hotspot under siege: land conversion counteracts nature conservation. Ecosystem Health and Sustainability, 2, e01224
Hermann, J.M., Lang, M., Gonçalves, J. & Hasenack, H.
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(2016) Management intensity and temporary conversion to other land-use types affect plant diversity and species composition of subtropical grasslands in southern Brazil. Applied Vegetation Science, 19, 589–599
Koch, C., Conradi, T., Gossner, M. M., Hermann, J.M., Leidinger, J., Meyer, S. T., Overbeck, G. E., Weisser, W. W. & Kollmann, J.
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(2016) Setting priorities for monitoring and managing non-native plants: Toward a practical approach. Environmental Management, 58, 465–475
Koch, C., Jeschke, J.M., Overbeck, G.O. & Kollmann, J.
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(2016) Species pools and environmental sorting control different aspects of plant diversity and functional trait composition in recovering grasslands. Journal of Ecology, 104, 1314–1325
Conradi, T. & Kollmann, J.
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(2017) Emergence and establishment of native and non-native species in soils of remnant and converted highland grasslands – southern Brazil. Biota Neotropica, 17, e20160235
de Lima Müller, H., Lopez, R. & Hermann, J.M.
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(2017) Genetic differentiation and regional adaptation among seed origins used for grassland restoration: lessons from a multi-species reciprocal transplant experiment. Journal of Applied Ecology, 54, 127–136
Bucharova, A., Michalski, S., Hermann, J.M., Heveling, K., Durka, W., Hölzel, N., Kollmann, J. & Bossdorf, O.
