No abstract

Patterns and elevational controls on the response of soil organic matter (SOM) decomposition to temperature in alpine forest soils are critical to efforts to quantify the regional carbon cycle-climate feedback, but are not well known.Here, we report rates of SOM decomposition (R S ) and temperature sensitivity (Q 10 ) determined in a short-term laboratory incubation with gradual warming from 5 to 29 C of soils from different elevations in the Qilian Mountains, China (2600, 2800, 3000, and 3200 m). The results showed the R S significantly increased with increasing elevation (p < 0.001), in which R S was significantly greater at 3200 m than that at the other elevations but had no significant difference in R S among elevations below 3200 m. Across all elevations, R S first showed an increasing trend at temperatures <20 C and then declined substantially (>20 C), most likely in response to the content of labile C (greater at the start of incubation and declining over time). Q 10 of SOM decomposition increased significantly with increasing elevation and decreasing incubation temperature (p < 0.001). Meanwhile, soil organic carbon (SOC), total nitrogen, and 1-to 2-mm aggregate-associated organic carbon (OC) were the main control factors affecting R S and Q 10 along an elevational gradient. These results indicate that high-altitude soils in alpine forests of the Qilian Mountains are relatively more sensitive to warming and have greater potential to release CO 2 due to higher SOC contents and 1-to 2-mm aggregate-associated OC than lowaltitude soils. The findings could serve as a reference for how regional C pools may respond to future warming in alpine forests of the Qilian Mountains.