A meta-analysis of drought effects on litter decomposition in streams

Abstract

Droughts, or severe reductions of water flow, are expected to become more frequent and intense in rivers in many regions under the ongoing climate change scenario. It is therefore important to understand stream ecosystem functioning under drought conditions. We performed a meta-analysis of studies addressing drought effects on litter decomposition in streams (50 studies contributing 261 effect sizes) to quantify overall drought effects on this key ecosystem process and to identify the main moderators controlling these effects. Drought reduced litter decomposition by 43% overall, which can impact energy and matter fluxes along heterotrophic food webs. The magnitude of drought effects on litter decomposition depended on the type of drought (natural drought > human-induced drought), type of decomposer community (microbes + macroinvertebrates > microbes) under natural drought, climate (warm and humid > temperate and Mediterranean) under human-induced drought, and on litter identity. The magnitude of drought effects on litter decomposition also increased with the severity of the drought. The effects of ongoing climate change will likely be strongest in streams with abundant shredders undergoing natural drought, especially if the streams become temporary. The composition of the riparian vegetation may modulate the magnitude of drought effects on litter decomposition, which may have management applications.

Litter Decomposition of a Deciduous Tectona philippinensis and an Evergreen Parashorea malaanonan Across Contrasting Sites

“…A study also revealed higher decomposition rates of Anadenanthera peregrina in the rainy season, which was attributed to enhanced vegetative growth and the nutrient resorption (Valente et al 2023). Moreover, a meta-analysis found a significant % reduction in litter decomposition by 43% depending on drought type and intensity, decomposer community, climate conditions, and litter quality (Ferreira et al 2023). Litter decomposition is generally reduced during the dry season due to altered soil moisture and nutrient availability, which play an essential role in facilitating microbial and enzymatic processes for the degradation of organic matter (Hernandez and Park 2024).…”