Alpine meadow ecosystem on the Qinghai-Tibetan Plateau, as a huge soil carbon reservoir, is considered to be sensitive to global change. Any small changes in their SOM decomposition, which is mainly mediated by soil microbial activity, can in turn lead to large effects on global change. Given widespread nutrient limitation of alpine meadow, response of soil microbial activity to N and P addition will determine a major feedback to SOM decomposition. In this study, we tested the effects of N/P addition on soil microbial activity and its temperature sensitivity in a simulated addition experiment located at the Haibei Alpine Meadow Ecosystem Research Station. The experiment established four treatments, N addition (NA, 100 kg N ha-1 a-1), P addition (PA, 50 kg P ha-1 a-1), N plus P addition (NPA) and Control without nutrient addition. Soil microbial activity was determined with substrate induced heat production curve, and two microcarlorimetric parameters Pmax (maximal substrate induced heat flow) and k (specific growth rate of soil microorganisms) were used to calculate Q10. Compared with Control, there was a decreasing trend in temperature sensitivity via N/P enrichment. Q10 value of k was 1.66 in Control, and declined to 1.47, 1.57, 1.60 in the NPA treatment (p=0.110), NA treatement (p=0.414) and PA treatment (p=0.453), respectively. Q10 value of Pmax was 2.61 in Control, and declined to 2.25 and 2.28 in the NPA treatment (p=0.105) and PA treatment (p=0.074). From the current short-term results, N/P enrichment affected soil microbial activity and a higher nutrient availability tended to decrease its temperature sensitivity in alpine meadow soil.
