Stoichiometry of litter decomposition under the effects of global change: A meta-analysis.

Abstract

Abstract The cycling of nutrients from plant litter has relevant implications on the functioning of terrestrial ecosystems by controlling the availability of nutrients and net primary production. The effects of global change have been widely studied for most aspects of ecosystem functioning, but the direct implications on the stoichiometry and nutrient dynamics of litter decomposition are still poorly understood. We conducted a meta-analysis to determine how warming, changes of water availability, and enrichments of N and P interfere with the immobilisation/mineralisation of nutrients and the stoichiometric relationships during litter decomposition. Our database consisted of 194 experiments from 43 studies that experimentally simulated (i) warming, (ii) drought, (iii) irrigation, (iv) N enrichment, (v) P enrichment, and (vi) combined N and P (N + P) enrichment. We compared the early stages (approximately half a year) and late stages (approximately one year) of decomposition; and the specific effects taking into account the climate, the species used and the ecosystem type. We explored the different effects of all treatments and highlight three of them. (i) Warming and nutrient enrichment induce a faster release of C during decomposition, prominent in grassland and coniferous forests of continental climates, and with a potential feedback loop to climate change. (ii) C:P and overall C:N ratios generally decreased in most of the scenarios of global change analyzed at short- and long-term during litter decomposition, while the N:P ratios are more resilient to change. (iii) P limitation might be exacerbated in in warming continental climates; arid environments experiencing droughts; temperate environments with increasing water availability; and temperate broadleaved forest experiencing N and P enrichment. Our results provide information about the fate of litter decomposition and its nutrient and stoichiometric dynamics in response to drivers of global change. However, further experimentation and analysis considering all interacting drivers are warranted.