Responses of SOM decomposition to changing temperature in Zoige alpine wetland, China.

Alpine wetlands are considered to be very sensitive to future climate warming. Understanding changes in decomposition rates ( Rs) of soil organic matter (SOM) and temperature sensitivity ( Q) in alpine wetlands, under the scenarios of a warming climate and decreasing soil moisture, is important for predicting their carbon (C) budget. Here, we established three sampling transects from wetland edge to meadow in the Zoige alpine wetlands in China, which represented the gradients of decreasing soil moisture. We conducted an incubation experiment (5-25 °C) to explore changes in Q with the degradation process from alpine wetland to alpine meadow. The results showed that temperature significantly influenced Rs in all locations. Rs first increased from site I to site IV and then decreased from site IV to site V. However, Q and activation energy ( E) showed no apparent trends with soil coming from sites along a moisture gradient. Overall, the Q values in the wetland (sites 1.50) were significantly lower than that of the meadow (1.83); similar trends were observed for E. In addition, E exhibited a negative logarithmic relationship with C quality indices in all locations, which suggested that the C quality-temperature hypothesis is applicable to both alpine wetlands and meadows. These findings provide a theoretical foundation for predicting the potential influences of warming climate on soil C turnover and storage in alpine wetlands. [ABSTRACT FROM AUTHOR]