Water nutrient concentration and temperature control microbial-driven decomposition of leaf litter in oceanic island streams.

Litter decomposition fuels food webs in forest streams. Thus, understanding the effects of water nutrients and temperature on litter decomposition and decomposers is key for predicting stream functioning under environmental change. We incubated leaf litter of woody species in streams to assess the effects of nutrient concentrations and temperature on microbial-driven litter decomposition and microbial activities. The relationship between biotic and abiotic variables was generally best described by a quadratic model: there was a hump-shaped relationship between biotic variables and nitrate concentrations and a U-shaped relationship between biotic variables and temperature. The stimulatory effect of high nutrient availability was limited by low temperature, while high nutrient availability alleviated low-temperature effects on litter decomposition and decomposers.