Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes

Abstract

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 warming-induced 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.

Changes in the timing and duration of the near-surface soil freeze/thaw status from 1956 to 2006 across China

“…Other studies have shown that increasing temperature results in the lengthening of the growing season and improved productivity (Kimball et al, 2006;Barichivich et al, 2013). These effects may partly counteract the negative effects of climate warming (Cornelissen et al, 2007). Additionally, Kumar et al (2013) suggested that the impact of climate change on soil microbes in Arctic regions may be impossible to predict.…”

Changes in foliar litter decomposition of woody plants with elevation across an alpine forest–tundra ecotone in eastern Tibet Plateau

“…For example, needles, hardwood leaves, grass, and forbs showed different mass loss rates, 10.0, 15.6, 21.0, and 39.0 %, respectively, under snow cover in a balsam fir (A. balsamea) forest over a 6-month snow-covered season (Taylor and Jones 1990). Moreover, the decomposition rate of different plant types is generally in the order of forbs [ graminoids [ deciduous shrubs [ evergreen shrubs (Cornelissen 1996;Cornelissen et al 2007). In general, our results are consistent with the above studies to some degree, as the litter of deciduous shrubs decomposed significantly faster than that of evergreen shrubs and trees.…”

“…For example, graminoids and herbs have been gradually replaced by shrubs in alpine ecosystems (Cornelissen et al 2007;Baptist et al 2010), leading to alterations of plant community structure and species composition (Lenoir et al 2008), as well as plant litter decomposition (Gavazov 2010).…”

Controls on Coarse Wood Decay in Temperate Tree Species: Birth of the LOGLIFE Experiment

“…In this approach, litters of multiple species are incubated simultaneously, in the same litter matrix ('litterbed'), so that mass loss rates can be interpreted directly in terms of species' litter 'decomposability'. After the first study of this kind on leaf litter in a temperate flora (Cornelissen 1996), this common garden approach made some key advances at Abisko Research Station in sub-Arctic Sweden under the guidance and directorship of Terry Callaghan (Quested et al 2003;Cornelissen et al 2007;Freschet et al 2012c) and eventually in many biomes of the world. Together these studies revealed that the range of variation in leaf litter decomposition rates among species within sites worldwide was generally greater than the range of variation of a given litter type across climatic zones from the Arctic to the Tropics (Cornwell et al 2008).…”