Precipitation alters temperature effects on ecosystem respiration in Tibetan alpine meadows

There is scant evidence for the interactive effect of warming and precipitation change on ecosystem respiration (Re), particularly regarding for alpine meadow ecosystems where there are high belowground biomass and soil organic carbon stocks. Such knowledge is crucial for predicting terrestrial carbon cycling under climate change. We transplanted meadow blocks reciprocally among three altitudes (4650 m, 4950 m and 5200 m) in the central Tibetan Plateau and examined the controls on Re in 1.5 and 2.5 years after the transplantation. Under the same degree of experimental warming by the downward transplantation, the Re increased and decreased significantly when the precipitation was higher and lower at destination sites than at the home sites, respectively. However, the experimental cooling by the upward transplantation consistently reduced the Re regardless of the precipitation change. Further analysis showed that the increase of Re under the experimental warming was closely related to the increase of aboveground biomass, whereas the reduction of Re under the cooling was highly correlated with the decrease of soil temperature. Moreover, the temperature sensitivity of the Re was decreased by the experimental warming but increased by the experimental cooling. These results suggest that effects of climate warming on the ecosystem respiration are highly associated with precipitation changes in the temperature-limited meadow ecosystems.