Global-scale pattern of peatland Sphagnum growth driven by photosynthetically active radiation and growing season length

[摘要] High-latitude peatlands contain about one third of the world's soil organiccarbon, most of which is derived from partly decomposed Sphagnum(peat moss) plants. We conducted a meta-analysis based on a global data set ofSphagnum growth measurements collected from published literature toinvestigate the effects of bioclimatic variables on Sphagnum growth.Analysis of variance and general linear models were used to relateSphagnum magellanicum and S. fuscum growth rates tophotosynthetically active radiation integrated over the growing season (PAR0)and a moisture index. We found that PAR0 was the main predictor ofSphagnum growth for the global data set, and effective moisture wasonly correlated with moss growth at continental sites. The strong correlationbetween Sphagnum growth and PAR0 suggests the existence of a globalpattern of growth, with slow rates under cool climate and short growingseasons, highlighting the important role of growing season length inexplaining peatland biomass production. Large-scale patterns of cloudinessduring the growing season might also limit moss growth. Although considerableuncertainty remains over the carbon balance of peatlands under a changingclimate, our results suggest that increasing PAR0 as a result of globalwarming and lengthening growing seasons, without major change in cloudiness,could promote Sphagnum growth. Assuming that production anddecomposition have the same sensitivity to temperature, this enhanced growthcould lead to greater peat-carbon sequestration, inducing a negative feedbackto climate change.

[学科分类] 地球化学与岩石