B09 - Aboveground biodiversity patterns and processes across rainforest transformation landscapes

Improving ecological and socio-economical functionality of tropical human-dominated landscapes is a major challenge. In this project, we focus on aboveground animal biodiversity patterns and related ecological functions at local and landscape scales, comparing lowland forest, rubber plantations and oil palm plantations in riparian vs non-riparian sites, as well as with variation in local management and biodiversity enrichment with indigenous tree species. We test the hypothesis that functional diversity of insects, bats and birds suffers more from habitat transformation than taxonomic diversity and less so in riparian than non-riparian sites. We analyse herbivory (crop damage), predation pressure (experimental exposure of insect and dummy prey), fruit consumption (exposure of fruits and dummy fruits), seed dispersal and arthropod consumption by birds and bats (via faeces), pollination (pollen analyses from insects, birds, bats and trap nests) and host-parasitoid relationships (using standardized nesting resources for bees and wasps). The construction of quantitative interaction networks allows relating food web complexity to land-use patterns. Using the oil palm management experiment, we hypothesize that weed control affects functional and taxonomic biodiversity more than increased levels of fertilization, as habitat heterogeneity and thus species sorting in oil palm plots is mainly driven by non-crop plant communities. Weed control, but not fertilization, may be reduced without diminishing crop yield, which would allow identifying thresholds with low economic costs and high ecological benefit. Using the platform of the oil palm tree enrichment experiment, we expect the number of additional tree species to increase biodiversity more in large than small enrichment plots, resulting in a synergistic effect of tree species richness and plot size on ecosystem functioning. We also join the economists´ study of oil palm certification, comparing ISPO with RSPO standards, to evaluate the relative role of local improvements and simple vs complex landscape structure for taxonomic and functional biodiversity. The structural heterogeneity of the surrounding landscape can be more important for local biodiversity and processes than the difference between transformation systems. To model the dependence of biodiversity on landscape heterogeneity as well as social-economic context, we will collect bird community data in the villages and households surveyed by the socio-economic groups. Our project is intimately linked with plant and belowground ecological groups working on the core plots as well as socioeconomic groups working at household and village level.