Precipitation is projected to increase with global warming in most regions, while a few regions have dried on the Tibetan Plateau. Numbers of studies found that climate warming have significantly increased CH4 uptake in alpine grassland on the Tibetan Plateau. However, little research has been done about how the alteration of precipitation or the interactive effect of warming and altered precipitation on CH4 uptake. We conducted an experimental warming (increasing 1.5-1.8 oC at the soil depth of 5 cm) and alter precipitation (decreasing 50% and increasing 50%) studies to determine the effects of warming and alter precipitation on soil CH4 uptake.The CH4 fluxes were measured yearround using static chambers and gas chromatography.
Results/Conclusions
With no precipitation change, warming had no significant effect on soil CH4 uptake in 2012 (drought year), whereas significantly increased soil annual communitive CH4 uptake by 25% (13% during growing season and 59% during non-growing season) in 2013 and by 55% in 2014 (wetter year, 16% during growing season and 266% during non-growing season). Under decreasing 50% precipitation conditions, warming significantly increased soil communitive CH4 uptake by 22.7% (13.6%-46.3%) in 2012-2014, but only increased soil communitive CH4 uptake by 73.4% during non-growing season. Under increasing 50% precipitation conditions,warming only significantly increased soil communitive CH4 uptake by 25.8% during growing season in 2013. We found that the responses of methane uptake to climate warming were negatively correlated with precipitation (p=0.04). In addition, the CH4 uptakes during the growing season were well negatively correlated with soil moisture, whereas the CH4 fluxes during the non-growing season were positively correlated with soil temperature. Our results suggest that more attention should be paid to the role of precipitation in the study of warming effects on soil CH4 uptake and the different stimulating mechanisms during growing season and non-growing season to understand and predict the response of alpine ecosystem CH4 emissions to climate change on the Tibetan Plateau.