Abstract:As an important component of terrestrial ecosystems, grasslands are one of the most widespread vegetation types worldwide, covering nearly a quarter of the world's land surface. The soil carbon reserves amount to one fifth of the global total; thus, grasslands play a significant role in climate change and the global carbon cycle. The area of different kinds of natural grasslands in China is approximately 400 million hm2, accounting for approximately 41.7% of the land area. The total carbon reserves of grasslands account for approximately 16.7% of the total carbon reserves of the terrestrial ecosystems, of which the soil accounts for 93.1%; thus, soil carbon reserves occupy an important position in the global carbon reserves. Soil respiration is the main link in the carbon cycle of terrestrial ecosystems, in which grassland soil respiration accounts for 5.6% of terrestrial soil respiration. Therefore, scholars have paid attention to carbon storage of grassland ecosystems. The Qilian Mountains have abundant grassland resources. Subalpine meadows are the dominant ecosystem in the Qilian Mountains Nature Reserve. Snow, as a significant component of the cryosphere, is one of the most important factors that affects soil respiration because of its regulation and control of soil temperature and soil water content. At present, research on soil respiration in the subalpine meadows is lacking, and research regarding the effect of snow on soil respiration is also limited. The Tianlaochi catchment was selected as our study area. We observed respiration rate (Rs) under snow cover with three different soil melting states (soil non-frozen state, soil frozen state, soil melt and frozen state) in subalpine meadows of the Qilian Mountains through five snow events using a soil carbon flux automatic measurement system LI-8100 (LI-COR, USA). The effect of snow at different soil melting states on Rs was analyzed. The results showed that:(1) snow decreases Rs in the ecosystem and in bare soil, but it improves Rs in the ecosystem on the following day if snow is melted in one day; (2) The relation of Rs with temperature exhibits an exponential function (P < 0.01), which with the relative surface humidity expresses a linear function. During snow cover, the correlation between Rs and temperature in the non-frozen soil was the best. (3) The effect of temperature on respiration rate was strong when the temperature was high, whereas the effect was a weak when the temperature was low.