1 research outputs found
Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
Whether climate change will turn cold biomes from large long-term carbon sinks into
sources is hotly debated because of the great potential for ecosystem-mediated feedbacks
to global climate. Critical are the direction, magnitude and generality of climate responses
of plant litter decomposition. Here, we present the first quantitative analysis of the major
climate-change-related drivers of litter decomposition rates in cold northern biomes
worldwide. Leaf litters collected from the predominant species in 33 global change
manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously
in two contrasting arctic life zones. We demonstrate that longer-term, large-scale
changes to leaf litter decomposition will be driven primarily by both direct warming
effects and concomitant shifts in plant growth form composition, with a much smaller
role for changes in litter quality within species. Specifically, the ongoing warminginduced
expansion of shrubs with recalcitrant leaf litter across cold biomes would
constitute a negative feedback to global warming. Depending on the strength of other
(previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this
may partly counteract direct warming enhancement of litter decomposition