Susanti, Winda Ika

Soil fauna in lowland rainforest and agricultural systems of Sumatra: Changes in community composition and trophic structure with focus on Collembola

Soil organisms are associated with major ecosystem services including water storage, decomposition and nutrient cycling, detoxification of toxicants, and control of pathogenic organisms. Species of meso- and macrofauna modify soil structure by burrowing and thereby alter the structure of microbial communities. Linking soil communities to ecosystem functions is important to improve understanding of biological systems. In tropical regions, however, research on soil animal communities is lacking behind with scarce knowledge on species composition and links within communities of natural and transformed ecosystems.
As decomposer organisms Collembola occupy a crucial place in soil communities by feeding on various food sources and being prey for a wide range of predators. Collembola affect soil processes such as decomposition rates and N mineralization and shape the community composition of microorganisms in particular fungi. Due to large morphological diversity, different groups of springtails occupy different trophic niches and are involved in different ecosystem functions. However, little is known about the role of Collembola species and factors that structure Collembola communities in tropical ecosystems.
Application of fertilizers, pesticides and mechanical disturbance of soil in landscapes with intensive agriculture resulted in the loss of soil biodiversity and ecosystem functions in temperate as well as tropical ecosystems. The loss of species inevitably alters interactions in soil food webs and changes the flow of energy through soil communities with major consequences for the stability of the ecosystem. Studies on the soil biodiversity and the consequences of its loss for species interactions in soil are particularly scarce in tropical countries such as Indonesia, which contrasts the pronounced deforestation and intensification of land use over the last decades.
In my PhD project I am investigating changes in abundance, community structure and trophic interactions of soil animals as affected by rainforest transformation and agricultural land-use such as rubber and oil palm plantations in Sumatra, Indonesia. Major groups of soil invertebrates are studied on broad taxonomic level with focus on Collembola studied at high taxonomic resolution. For studying trophic interactions classical methods of community analysis are combined with novel techniques including stable isotope and fatty acid analysis.