Soil nitrogen determines greenhouse gas emissions from northern peatlands under concurrent warming and vegetation shifting

Junwei Luan,Shirong Liu,Mei Wang,Jianghua Wu,Nigel Roulet

doi:10.1038/s42003-019-0370-1

Abstract

Boreal peatlands store an enormous pool of soil carbon that is dependent upon – and vulnerable to changes in – climate, as well as plant community composition. However, how nutrient availability affects the effects of climate and vegetation change on ecosystem processes in these nutrient-poor ecosystems remains unclear. Here we show that although warming promoted higher CH4 emissions, the concurrent addition of N counteracted most (79%) of this effect. The regulation effects of the vegetation functional group, associated with the substrate quality, suggest that CH4 emissions from peatlands under future warming will be less than expected with predicted shrub expansion. In contrast, N2O flux will be enhanced under future warming with predicted shrub expansion. Our study suggests that changes in greenhouse gas emissions in response to future warming and shifts in plant community composition depend on N availability, which reveals the complex interactions that occur when N is not a limiting nutrient.

Highlights

Boreal peatlands store an enormous pool of soil carbon that is dependent upon – and vulnerable to changes in – climate, as well as plant community composition
It was illustrated that the effect of warming on greenhouse gases (GHGs) fluxes in peatlands are modulated by plant community composition[25]
We hypothesized that the combined effects of warming and vegetation shifting on ecosystem processes largely depend on N availability

Summary

Introduction

Boreal peatlands store an enormous pool of soil carbon that is dependent upon – and vulnerable to changes in – climate, as well as plant community composition. Our study suggests that changes in greenhouse gas emissions in response to future warming and shifts in plant community composition depend on N availability, which reveals the complex interactions that occur when N is not a limiting nutrient. Northern peatlands store ~30% (~600 Gt) of the world’s terrestrial soil carbon (C)[1], equivalent to half of the total atmospheric C2 This enormous store of soil C results from persistently greater rates of plant production than decomposition, due to the high water content, poor nutrient[3], and recalcitrant litter such as Sphagnum moss[4], all of which reduce decomposition. For example shrubs, sedges, and Sphagnum mosses, have been illustrated to show disparate responses to experimental N addition[31,32], e.g., increased aboveground vascular plant biomass (e.g., Vaccinium oxycoccus33), reduced peat-forming Sphagnum[32], or change in species composition[34]. Unraveling the underlying mechanism is crucial because the global N deposition is predicted to double by 205035

Methods

Results

Conclusion