## 3 Results  
### Seasonal Variations in \(R_{\rm s}\)  
An overall preliminary correlation analysis showed that the soil temperature (\(T_{\rm s}\)) at 5 cm and nighttime land surface temperature (LST) observed by MODIS onboard the Terra satellite correlated with soil respiration (\(R_{\rm s}\)) best among all investigated temperature factors; therefore, we chose these two indexes as the representative temperature factors relating to \(R_{\rm s}\). As shown in Figure 2, during the measuring year, seasonal variations of \(R_{\rm s}\), \(T_{\rm s}\), NDVI, and LST were similar, with all of these generating an approximately symmetrical bell type distribution along the temporal scale. Owing to the effects of solar radiation, \(T_{\rm s}\) was lowest in winter and spring (5.18 \(\pm\) 2.36 \({}^{\circ}\)C in April) (mean \(\pm\) SE), after which it dramatically increased as solar radiation and air temperature increased, reaching the highest value by the end of June and early July (17.38 \(\pm\) 0.67 \({}^{\circ}\)C). \(T_{\rm s}\) began to decrease in late July, with the greatest rate of decrease occurring from September to October. Additionally, the monthly coefficient of variation (CV) of \(T_{\rm s}\) was comparatively higher in the phenological phase of the beginning and late growing period, while it maintained a low and steady value in the growing season (Figure 3). Under the influence of solar radiation and surface reflection, the seasonal variations in LST were in accordance with \(T_{\rm s}\), but comparatively lower. The maximum value of NDVI appeared from July to August, while its mean value during the measuring period was 0.55 \(\pm\) 0.18 (mean \(\pm\) SE), which was comparatively lower than other types of ecosystems (Figure 2c). In addition, the monthly CV of the NDVI was relatively low, being almost below 20% during each month. The seasonal dynamics of soil moisture (\(M_{\rm s}\)) throughout the measuring period were not as pronounced as those for the other factors mentioned above. Rather, \(M_{\rm s}\) showed a fluctuating pattern, accompanied by a trend of high and low alternations that varied significantly in response to natural precipitation. Overall, \(M_{\rm s}\) was lower in late spring and early summer and higher in mid-summer, autumn and winter, with a mean value during the measuring period of 45.57% \(\pm\) 8.09%. The monthly CVs of \(M_{\rm s}\) and NDVI appeared to have a high and low fluctuating state within a small range, ranging from 6% in November to 31% in July for \(M_{\rm s}\) and from 5% in October to 29% in November for NDVI (Figure 3). Soil respiration exhibited an obvious bell type seasonal variation similar to \(T_{\rm s}\) or LST, clearly illustrating the dynamics of \(R_{\rm s}\) were closely related to temperature with time at the site. The \(R_{\rm s}\) value was lower in the early growing season (1-2 \(\upmu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)), after which it gradually increased because of the rising temperature and biomass (4-8 \(\upmu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)), peaking at over 7 \(\upmu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\). Figure 3: The monthly coefficient of variation (CV) of soil respiration (\(R_{\rm s}\)), soil temperature (\(T_{\rm s}\)), nighttime land surface temperature (LST) observed by Terra satellite, normalized difference vegetation index (NDVI), and soil moisture (\(M_{\rm s}\)) from 2007 to 2015. Figure 2: Seasonal dynamics of (**a**) soil respiration (\(R_{\rm s}\)), (**b**) soil temperature (\(T_{\rm s}\)), nighttime land surface temperature (LST) observed by Terra satellite, (**c**) normalized difference vegetation index (NDVI), and (**d**) soil moisture (\(M_{\rm s}\)) in the sub-alpine meadow from 2007 to 2015. CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\) in June and July. After that, \(R_{\rm s}\) tapered gradually to less than 1 \(\upmu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\) in November. The mean value was \(4.17\pm 0.29\)\(\upmu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\) during the nine-year observation period.