Annual ecosystem respiration is resistant to changes in freeze–thaw periods in semi‐arid permafrost

作者：Qi Wang, Wangwang Lv, Bowen Li, Yang Zhou, Lili Jiang, Shilong Piao, Yanfen Wang, Lirong Zhang, Fandong Meng, Peipei Liu, Huan Hong, Yaoming Li, Tsechoe Dorji, Caiyun Luo, Zhenhua Zhang, Philippe Ciais, Josep Peñuelas, Paul Kardol, Huakun Zhou, Shiping Wang · 发表于：Global Change Biology · 年份：2019 · DOI：10.1111/gcb.14979 · 被引用次数：31 · 研究领域：Climate change and permafrost、Cryospheric studies and observations、Peatlands and Wetlands Ecology

to the atmosphere through ecosystem respiration (Re) under future climate scenarios. However, the mechanisms of the responses of freeze-thaw periods to climate change and their coupling with Re in situ are poorly understood. Here, using 2 years of continuous data, we test how changes in F-T events relate to annual Re under four warming levels and precipitation addition in a semi-arid grassland with discontinuous alpine permafrost. Warming shortened the entire F-T period because the frozen period shortened more than the extended freezing period. It decreased total Re during the F-T period mainly due to decrease in mean Re rate. However, warming did not alter annual Re because of reduced soil water content and the small contribution of total Re during the F-T period to annual Re. Although there were no effects of precipitation addition alone or interactions with warming on F-T events, precipitation addition increased total Re during the F-T period and the whole year. This decoupling between changes in soil freeze-thaw events and annual Re could result from their different driving factors. Our results suggest that annual Re could be mainly determined by soil water content rather than by change in freeze-thaw periods induced by warming in semi-arid alpine permafrost.