“Decreasing stoichiometric resource quality drives compensatory feeding across trophic levels in tropical litter invertebrate communities”

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Malte Jochum, Andrew D. Barnes, David Ott, Birgit Lang, Bernhard Klarner, Achmad Farajallah, Stefan Scheu, and Ulrich Brose

Support for compensatory feeding being an important consumer response to low-quality resources across trophic levels

Tropical invertebrate consumer communities increase feeding rates on a low-quality diet

Leaf litter on the ground in one of the EFForTS project core sites in the Jambi Province, Sumatra, Indonesia.
(Credit: Malte Jochum)

When exposed to low-quality food resources, consumer communities have a limited number of options: They might alter the chemical composition of their own body tissue, avoid habitats with low-quality resources, or simply eat more (i.e., perform compensatory feeding). In a study appearing in The American Naturalist, a research team lead by Dr. Malte Jochum investigates how invertebrates living in the leaf litter of different semi-natural and agricultural sites on the island of Sumatra, Indonesia, cope with different-quality resources. In 2012, the researchers collected 7,472 animals across 32 field sites of the EFForTS project, a large German-Indonesian collaboration funded by the German Research Foundation (DFG) in tropical lowland rainforest, rubber, and oil palm plantations. Dr Jochum and colleagues find little evidence that consumer communities alter their chemical body composition or simply avoid habitats with low-quality resources. Instead, the study finds a strong indication that consumer communities across different trophic levels—namely predators and animals eating dead plant material—increase their feeding rates where resource quality is poor. Thus, while previous studies mostly document compensatory feeding for consumers feeding on plant resources, the new results from Sumatra indicate that this mechanism might be ubiquitous across trophic levels. These findings are of particular importance in light of global agricultural expansion and intensification and climate change, as they provide insights into how ecological communities might respond to changes in the chemical quality of the resources that are available in altered ecosystems. Small changes in basal resources could thus trigger changes that cascade upward to top predators, yielding more pervasive impacts than previously realized. Read the Article