Quantitative response of leaf‐litter decomposition rate to water abstraction in a gradient: Implications for environmental flow management

Abstract

AbstractWater abstraction significantly impacts streams and rivers, in turn affecting ecosystem structure and function. Previous studies have mostly focused on the response of structural indicators (e.g., invertebrate community composition) to water abstraction but have often neglected the indicators of ecosystem processes (e.g., decomposition rates). In this study, we investigated the relationship of leaf‐litter decomposition rate (k) with flow reduction in a manipulated ecosystem experiment. The flow reduction rate across our experimental reaches was about 25%. The results showed that water diversion significantly reduced the discharge, width and depth of the stream, but did not affect water quality. The leaf‐litter decomposition rate varied from 0.001day‐1 to 0.026 day‐1 and decreased along with flow reduction. The results elucidate the impact of water abstraction on the decomposition of leaf‐litter in streams. A quantitative relationship between the flow rate (Q) and the decomposition rate (k), mathematically expressed as k = 0.0231 exp(ΔQ1.232), was derived. Furthermore, a framework was developed for setting the minimum environmental flow based on the assessment of river health by using leaf‐litter processing rates.