B01 - Structure, stability and functioning of macro-invertebrate communities in rainforest transformation systems in Sumatra (Indonesia)

Under the ongoing process of rainforest transformation into agricultural systems, the natural communities are severely impacted with expected profound effects on their structure, diversity and functioning. The proposed project addresses changes in the body-mass, abundance and trophic-level (based on 15N/14N ratios) structure and species diversity of the macro-invertebrate communities of soil-litter ecosystems along a rainforest transformation gradient (i.e., replicated sampling in tropical lowland forest, jungle rubber, rubber and oil palm plantations). These macro-invertebrate communities provide critically important ecosystem services such as litter decomposition. The bottom-up (litter stoichiometry) and top-down (predation) constraints on macro-invertebrate biomass densities will be tested in a collaborative field experiment. Moreover, this project will provide two integrative analyses to the CRC: (1) beta-diversity and species-area relationships, and (2) complex food webs. The beta-diversity analyses will analyse neutral (spatial) and (environmental) niche constraints on community similarity across multiple trophic levels. Subsequently, community similarity will be employed to compare the exponent of species-area relationships across different groups of organisms. These analyses will provide important information for scaling up ecological functions to larger spatial scales. The modelling part of the proposed project will integrate the empirical structures of this and the collaborating projects in a bioenergetic food-web model to predict the consequences of rainforest transformation for population stability, community persistence and ecosystem functions. Subsequently, predictions on litter decomposition are empirically tested employing a litter bag experiment across the transformation gradient.