Premium
Seasonal variations in methane fluxes in response to summer warming and leaf litter addition in a subarctic heath ecosystem
Author(s) -
Pedersen Emily Pickering,
Elberling Bo,
Michelsen Anders
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg003782
Subject(s) - subarctic climate , environmental science , ecosystem , carbon sink , abiotic component , sink (geography) , growing season , litter , global warming , carbon dioxide , snow , flux (metallurgy) , environmental chemistry , climate change , ecology , chemistry , biology , physics , cartography , organic chemistry , meteorology , geography
Methane (CH 4 ) is a powerful greenhouse gas controlled by both biotic and abiotic processes. Few studies have investigated CH 4 fluxes in subarctic heath ecosystems, and climate change‐induced shifts in CH 4 flux and the overall carbon budget are therefore largely unknown. Hence, there is an urgent need for long‐term in situ experiments allowing for the study of ecosystem processes over time scales relevant to environmental change. Here we present in situ CH 4 and CO 2 flux measurements from a wet heath ecosystem in northern Sweden subjected to 16 years of manipulations, including summer warming with open‐top chambers, birch leaf litter addition, and the combination thereof. Throughout the snow‐free season, the ecosystem was a net sink of CH 4 and CO 2 (CH 4 −0.27 mg C m −2 d −1 ; net ecosystem exchange −1827 mg C m −2 d −1 ), with highest CH 4 uptake rates (−0.70 mg C m −2 d −1 ) during fall. Warming enhanced net CO 2 flux, while net CH 4 flux was governed by soil moisture. Litter addition and the combination with warming significantly increased CH 4 uptake rates, explained by a pronounced soil drying effect of up to 32% relative to ambient conditions. Both warming and litter addition also increased the seasonal average concentration of dissolved organic carbon in the soil. The site was a carbon sink with a net uptake of 60 g C m −2 over the snow‐free season. However, warming reduced net carbon uptake by 77%, suggesting that this ecosystem type might shift from snow‐free season sink to source with increasing summer temperatures.