Asymmetrical warming of growing/non-growing season increases soil respiration during growing season in an alpine meadow

Abstract

Soil respiration (Rs) is an important carbon flux in the global carbon cycle, and understanding the influence of global warming on Rs is critical for precise prediction future climate change. Actually, global warming is expected to be seasonally asymmetric, however, it is still unclear on the response of Rs to asymmetrical warming of growing/non-growing season in alpine regions. In this study, an experiment with asymmetrical warming of growing/non-growing season (including three treatments, CK: control; GLNG: warming magnitude of growing season lower than non-growing season; GHNG: warming magnitude of growing season higher than non-growing season) was performed in an alpine meadow of the Northern Tibet since June 2015. The ‘GLNG’ and ‘GHNG’ treatments increased mean Rs by 71.22% (1.89 μmol CO2 m−2 s−1) and 34.32% (0.91 μmol CO2 m−2 s−1) during growing season in 2019, respectively. However, the ‘GLNG’ and ‘GHNG’ treatments did not significantly affect mean Rs during growing season in 2015, 2016, 2017 and 2018, respectively. The variation coefficient of growing season mean Rs was 32.95% under the CK treatment in 2015–2019. Therefore, warming may have a lagging effect on Rs. The warming scene with a greater warming during non-growing season may have a stronger effect on Rs than the warming scene with a greater warming during growing season. Inter-annual variation of Rs may be greater than the warming effect on Rs in alpine meadows.