Effects of experimental warming and increased precipitation on soil respiration in an alpine meadow in the Northern Tibetan Plateau.

Uncertainty on the response of soil respiration (Rs) to warming and increased precipitation on the Tibetan Plateau can limit our ability to predict how alpine ecosystems will respond to future climate change. Based on a warming (control, low- and high-level) and increased precipitation (control, low- and high-level) experiment, the response of Rs to experimental warming and increased precipitation was examined in an alpine meadow in the Northern Tibetan Plateau from 2014 to 2017. The low-level warming increased soil temperature (Ts) by 1.19°C and decreased soil moisture (SM) by 0.02m3m-3, whereas the high-level warming increased Ts by 2.88°C and decreased SM by 0.04m3m-3 over the four growing seasons in 2014-2017. The low- and high-level increased precipitation did not affect Ts, but increased SM by 0.02m3m-3 and 0.04m3m-3, respectively, over the four growing seasons in 2014-2017. No significant main and interactive effects of experimental warming and increased precipitation on Rs were observed over the four growing seasons in 2014-2017. In contrast, there was a significant inter-annual variation of Rs in 2014-2017. There was a marginally significant quadratic relationship between the effect of experimental warming on Rs and warming magnitude. There was a negligible difference of Rs between the low- and high-level increased precipitation over the four growing seasons in 2014-2017 and Rs also showed a quadratic relationship with precipitation. Therefore, experimental warming and increased precipitation did not change Rs and Rs responded nonlinearly to experimental warming and increased precipitation in the alpine meadow in the Northern Tibetan Plateau. Growing season precipitation may play a more important role than experimental warming and increased precipitation in affecting Rs in the alpine meadow in the Northern Tibetan Plateau.