Premium
Permafrost degradation stimulates carbon loss from experimentally warmed tundra
Author(s) -
Natali Susan M.,
Schuur Edward A. G.,
Webb Elizabeth E.,
Pries Caitlin E. Hicks,
Crummer Kathryn G.
Publication year - 2014
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/13-0602.1
Subject(s) - tundra , permafrost , environmental science , ecosystem , global warming , growing season , carbon cycle , climate change , sink (geography) , ecosystem respiration , thermokarst , ecology , atmospheric sciences , arctic , carbon sink , greenhouse gas , soil carbon , terrestrial ecosystem , primary production , soil science , soil water , biology , geography , cartography , geology
A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years because cold and waterlogged conditions have protected soil organic material from microbial decomposition. As the climate warms this vast and frozen C pool is at risk of being thawed, decomposed, and released to the atmosphere as greenhouse gasses. At the same time, some C losses may be offset by warming‐mediated increases in plant productivity. Plant and microbial responses to warming ultimately determine net C exchange from ecosystems, but the timing and magnitude of these responses remain uncertain. Here we show that experimental warming and permafrost (ground that remains below 0°C for two or more consecutive years) degradation led to a two‐fold increase in net ecosystem C uptake during the growing season. However, warming also enhanced winter respiration, which entirely offset growing‐season C gains. Winter C losses may be even higher in response to actual climate warming than to our experimental manipulations, and, in that scenario, could be expected to more than double overall net C losses from tundra to the atmosphere. Our results highlight the importance of winter processes in determining whether tundra acts as a C source or sink, and demonstrate the potential magnitude of C release from the permafrost zone that might be expected in a warmer climate.