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However, methods for classifying testate amoebae into trophic groups are poorly developed.

Therefore, differential changes in the abundance of feeding types might provide insight into structural changes of soil microbial food webs with rainforest conversion. Furthermore, testate amoebae have a variety of feeding types and trophic positions. Testate amoebae are sensitive to disturbance and therefore changes in their numbers and community structure reflect changes in abiotic and biotic factors associated with rainforest conversion. Testate amoebae are among the main protist groups in acidic soils including those of typical lowland tropical rainforests. We investigated changes in protists density, biomass and species number with rainforest conversion allowing to identify changes in community functioning and the factors responsible for these changes. The effects of rainforest conversion on protists are, in fact, virtually unknown despite their outstanding importance in trophic interactions with microorganisms and their role in nutrient cycling. Nevertheless, in general, there is little study of the conversion of tropical lowland rainforest to other land uses and the associated changes in soil biodiversity and soil biota functioning. These are fundamental processes and, therefore, changes in the numbers and functional identities of protists may have major effects on ecosystem functioning. By grazing on bacteria, protists release nutrients fixed in bacterial biomass, thereby increasing mineralization of carbon and nitrogen. Bacteria are grazed by other organisms, most importantly soil protists and nematodes. Fungi and bacteria are thus particularly influential and constitute the base of soil food webs. A particularly wide spectrum of these biochemical transformations are carried out by saprotrophic soil microorganisms. These interactions drive the major functions of terrestrial ecosystems, such as nutrient mineralization and plant productivity. The belowground decomposer food web systems are composed of microorganisms, micro-, meso- and macrofauna, interacting with each other and the environment in a complex network. This applies, in particular, to the functioning of the highly diverse belowground system. However, despite the large-scale conversion of rainforests worldwide, little is known about the biodiversity and ecological functioning of the land uses replacing lowland rainforest. On Sumatra, for example, 12 million ha of forest have been converted over the past 30 years, predominantly into oil palm and rubber plantations.

Nevertheless, tropical forest conversion is increasing rapidly, particularly in South East Asia. Tropical forests have very high biodiversity so there is particular and increasing concern about their conversion into agricultural and plantation systems. The biodiversity of natural ecosystems is indispensable for providing ecosystem functions, but is threatened by anthropogenic activities such as the conversion of forests into agricultural production systems. Blumenbach Institute of Zoology and Anthropology, Göttingen, GermanyĪffiliation: Institut Pertanian Bogor-IPB, Department of Soil Sciences and Land Resources, Damarga Campus, Bogor, Indonesia Affiliation: Georg August University Göttingen, J.F.