Abstract

Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils, and are thus important in the terrestrial C cycle. We have synthesized data on the carbon dioxide (CO2) exchange obtained from eddy covariance measurements from 12 wetland sites, covering 1-7 years at each site, across Europe and North America, ranging from ombrotrophic and minerotrophic peatlands to wet tundra ecosystems, spanning temperate to arctic climate zones. The average summertime net ecosystem exchange of CO2 (NEE) was highly variable between sites. However, all sites with complete annual datasets, seven in total, acted as annual net sinks for atmospheric CO2. To evaluate the influence of gross primary production (GPP) and ecosystem respiration (R-eco) on NEE, we first removed the artificial correlation emanating from the method of partitioning NEE into GPP and R-eco. After this correction neither R-eco (P = 0.162) nor GPP (P = 0.110) correlated significantly with NEE on an annual basis. Spatial variation in annual and summertime R-eco was associated with growing season period, air temperature, growing degree days, normalized difference vegetation index and vapour pressure deficit. GPP showed weaker correlations with environmental variables as compared with R-eco, the exception being leaf area index (LAI), which correlated with both GPP and NEE, but not with R-eco. Length of growing season period was found to be the most important variable describing the spatial variation in summertime GPP and R-eco; global warming will thus cause these components to increase. Annual GPP and NEE correlated significantly with LAI and pH, thus, in order to predict wetland C exchange, differences in ecosystem structure such as leaf area and biomass as well as nutritional status must be taken into account.

Keywords

carbon; carbon dioxide; eddy covariance; mire; net ecosystem exchange; peatland; photosynthesis; respiration; tundra; wetland

Published in

Global Change Biology
2010, Volume: 16, number: 9, pages: 2436-2448
Publisher: WILEY-BLACKWELL

SLU Authors

• Nilsson, Mats

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

SDG13 Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1111/j.1365-2486.2009.02104.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/48043