Phase 1 of the CRC focused on differences in ecological and socioeconomic functions of land-use changes due to rainforest conversion into rubber and oil palm plantations in Indonesia.
Building on the established infrastructure and knowledge, Phase 2 will focus on Heterogeneity as a new umbrella theme. This is because environmental heterogeneity has been identified as a universal driver of species richness across taxa, biomes and spatial scales (Fahrig et al. 2010, Stein et al. 2014, Tews et al. 2004) and thus consideration of environmental heterogeneity is fundamental for estimating biodiversity and ecological functions in space and time (e.g., Liang et al. 2014). Heterogeneity may also create hotspots in ecosystem functioning, e.g. related to biogeochemical cycles of carbon, nitrogen and water. One such hotspot that is expected to play a relevant role in Jambi province are riparian areas, i.e. areas close to rivers that experience strong variability in water status impacting e.g., carbon cycle, greenhouse gas production, biodiversity and productivity. Yet, socioeconomic heterogeneity – in terms of social backgrounds of people (e.g., ethnicity, migration status), local policies and institutions (e.g., land rights) and other related factors – matters too and can have important implications for land-use decisions and their impacts (e.g., Krishna et al. 2015). Both environmental and socioeconomic heterogeneity are important for land-use decisions (e.g., Evans and Kelley 2004) and the CRC provides a unique opportunity for an integrated study of these dimensions.
The different dimensions will be covered through an extended experimental design (e.g., new management experiment, riparian site analysis) and also an extended socioeconomic survey design (e.g., additional coverage of non-farm rural households and rural-urban linkages). Spatial heterogeneity is captured through the experimental design of the CRC (see Study locations and experimental design). Temporal heterogeneity will be analysed through generating and using time series and panel data. Consideration of heterogeneity is critical for predicting the consequences of broad-scale land-use changes (Lohrer et al. 2015).
Further, as compared to Phase 1 the analysis of oil palm plantations – the land-use system that expanded most in recent years in Indonesia – will be investigated in more detail in Phase 2. First, the gap enrichment experiment (B11 Hölscher/Kreft/Wollni) that was started in Phase 1 – with different tree species planted into an existing oil palm plantation – will gain in importance during Phase 2. The newly planted trees are now reaching a size at which biodiversity effects are gradually becoming measurable. Second, in Phase 2 we will establish a new experiment focusing on the analysis of major management practices of oil palm plantations, i.e. fertilizer and pesticide input (Management experiment).
The data from the different parts of the CRC all contribute to an integrated analysis of ecological and socioeconomic synergies and trade-offs. Such integration will be fostered by new interdisciplinary projects that we added for Phase 2. The new project A07 Knohl/Veldkamp will integrate all data relevant for biogeochemical processes from the first phase into one common modelling framework to explore the impact of various land-use scenarios on the biogeochemical cycles of carbon, nitrogen and water. The insights on biogeochemical process dynamics will be integrated into the ecological-economic model of project B10 Wiegand/Lay.