Is there a relationship between biodiversity and ecosystem functioning in stream detritivores through its stoichiometry?
Many studies have revealed relationships between biodiversity and ecosystem functioning. However, the underlying mechanisms are not understood well. Litter decomposition is a key ecosystem processes in fresh waters. Carbon(C) : Nutrient ratio of leaf litters vary widely among species, and these stoichiometric differences affect litter decomposition rate. Recently it is revealed that C : Nutrient ratio of detritivores also vary widely among species. We predicted that detritivores with nutrient-rich body might tend to consume litters with low C : nutrients ratio. On the other hand, detritivores with nutrient-poor body might tend to consume litters uniformly. Therefore, we hypothesized stoichiomeric differences among detritivores and its diversity might affect litter decomposition rate. To verify this hypothesis, we conducted a microcosm experiment. We manipulated stoichiometric diversity of ditritivore, and put in microcosms with leaf litter mixtures. 30 days after the initiation of experiment, we calculated the litter decomposition rate per microcosm, and compared among treatments.
Our results showed detritivores with nutrient-rich body tend to consume litter with low C : nutrients ratio, and detritivores with nutrient-poor body tend to consume litters uniformly. Furthermore, higher detritivore richness with contain these two types increase decomposition efficiency. Our results showed stoichiometric diversity should affect litter decomposition efficiency in stream ecosystem. If stoichiometric diversity can alter litter decomposition efficiency, the stoichiometry might contribute structuring the freshwater ecosystem.