Landscape-level assessment of ecological and socioeconomic functions of rainforest transformation systems in Sumatra (Indonesia)
von Jan Salecker
Datum der mündl. Prüfung:2020-02-14
Betreuer:Prof. Dr. Kerstin Wiegand
Gutachter:Prof. Dr. Holger Kreft
Gutachter:Prof. Dr. Volker Grimm
EnglischTropical landscapes have experienced drastic land-use change in recent decades. The transformation from natural vegetation to agricultural production systems has a variety of negative impacts on ecosystem functioning, but also increases the potential for economic benefits. Generating a mechanistic understanding of the processes driving these dynamics is an essential step in identifying potential synergies that can improve ecosystem functioning without drastically affecting economic prosperity. Our study sites are located in the province of Jambi on the Island of Sumatra, Indonesia, which is a model region for smallholder-driven land-use change. We want to identify trade-offs and synergies between economic prosperity and ecosystem functioning in Jambi’s smallholder landscapes. Further, we want to investigate how smallholder heterogeneity affects these trade-offs. We also want to investigate the temporal and spatial dynamics of these trade-offs. In order to initialize our model landscapes we developed EFForTS-LGraf, a processbased, agent-based landscape generator for smallholder landscapes. In order to answer our main research questions, we have developed EFForTS-ABM a spatially-explicit, agentbased, coupled socio-economic and ecological simulation model. The economic submodel simulates smallholder land-use management decisions based on a profit maximization assumption. The ecological submodel includes a simple account of carbon sequestration in above-ground and below-ground vegetation. In order to cover more aspects of ecosystem functions in EFForTS-ABM, we have analyzed biodiversity patterns of 14 taxa which will inform our upcoming biodiversity submodel. We have also developed the R package nlrx, which allows us to connect our two main software environments R and NetLogo. EFForTS-LGraf is able to generate realistic land-cover maps with properties that lie within the boundaries of landscapes from classified satellite images. The overall results of EFForTS-ABM reveal complex interactions between the economic and ecological spheres and strong effects of smallholder heterogeneity and market prices. Our analysis of biodiversity patterns of 14 taxa indicated strong differences in the composition of forest and agroforest communities versus rubber or oil palm plantations. However, the different taxonomic groups showed highly variable responses to land-use intensification. The nlrx package provides a valuable framework to run simulations with improved performance compared to previous approaches. Our findings underline the utility of coupled ecological-economic models, to act as exploratory tools which can advance our understanding of the mechanisms underlying the trade-offs and synergies of ecological and economic functions in tropical landscapes. Such an understanding is highly needed in order to develop and guide policy recommendations that lead to a more sustainable land-use in smallholder dominated landscapes of Indonesia.
Keywords: oil palm; rubber; indonesia; agent-based model; ABM; land-use change; ecosystem function; smallholder; social-ecological system