Abstract: Soil respiration is an important index evaluating ecosystem stability of forests in the context of climate change. In this study, we analyzed soil physical and chemical properties, soil respiration rate in main growing seasons, and changes in soil water and heat conditions in Abies nephrolepis forests at different altitudes (2100, 2200 and 2300 m) in Wutai Mountains. Regression models were established to analyze the relationship between soil temperature, moisture and soil respiration rate. The results showed that A. nephrolepis forest soil was neutral and acidic. With increasing altitude, soil pH, organic carbon, total nitrogen, total phosphorus, available phosphorus content and soil moisture increased, while soil temperature and soil respiration ratedecreased. From July to October, soil temperature and soil respiration rate decreased by 49.0% and 64.9%, respectively, while soil moisture increased by 11.7%. Soil temperature and soil moisture explained 76.9% (P<0.001) and 25.8% of the variation in soil respiration rate, respectively, which together explained 71.2% of variation in soil respiration rate (P<0.001). Therefore, soil temperature was the main factor affecting soil respiration ofA. nephrolepisforest in Wutai Mountains, while soil moisture played a minor role. The results of RDA analysis showed that soil organic carbon, total nitrogen content, total phosphorus content, and available phosphorus content were the main nutrient factors affecting soil respiration rate.

Key words: altitude, soil temperature, soil moisture, soil respiration rate, temperature sensitivity.