Experimental warming of a mountain tundra increases soil CO(2) effluxes and enhances CH(4) and N(2)O uptake at Changbai Mountain, China

Climatic warming is expected to particularly alter greenhouse gas (GHG) emissions from soils in cold ecosystems such as tundra. We used 1 m(2) open-top chambers (OTCs) during three growing seasons to examine how warming (+0.8–1.2 °C) affects the fluxes of carbon dioxide (CO(2)), methane (CH(4)) and nitrous oxide (N(2)O) from alpine tundra soils. Results showed that OTC warming increased soil CO(2) efflux by 141% in the first growing season and by 45% in the second and third growing season. The mean CH(4) flux of the three growing seasons was −27.6 and −16.7 μg CH(4)-C m(−2)h(−1) in the warmed and control treatment, respectively. Fluxes of N(2)O switched between net uptake and emission. Warming didn’t significantly affect N(2)O emission during the first and the second growing season, but stimulated N(2)O uptake in the third growing season. The global warming potential of GHG was clearly dominated by soil CO(2) effluxes (>99%) and was increased by the OTC warming. In conclusion, soil temperature is the main controlling factor for soil respiration in this tundra. Climate warming will lead to higher soil CO(2) emissions but also to an enhanced CH(4) uptake with an overall increase of the global warming potential for tundra.