Accurately assessing and predicting the response of the ecosystem carbon cycle to climate change is a major challenge in the climate change-terrestrial carbon feedback. Historical meteorological data and model simulations show large seasonal asymmetries in land surface temperature increases, such as the significant spring and autumn warming experienced in the northern hemisphere in recent years. However, previous research on the terrestrial carbon cycle of spring and autumn warming has been inconsistent, and mainly focused on plant phenology, vegetation growth and ecosystem-scale carbon cycle, but there is still a lack of direct field experimental evidence on how soil carbon emissions respond to seasonal asymmetric warming and how this response will affect ecosystem carbon balance.
In this study, the effects and mechanisms of seasonal asymmetric warming on soil carbon release were explored through a spring and autumn warming control experiment set up in a scientific research and teaching farm of Henan University. The results show that simultaneous warming in spring and autumn can synergistically reduce soil respiration. In addition, the response of summer soil respiration to spring and autumn warming treatment dominated the interannual variation of treatment effects, indicating that the residual effect of seasonal asymmetric warming on ecosystem carbon cycle existed at both the seasonal and interannual scales. The inhibition of soil respiration by spring warming and autumn warming is not caused by water deprivation caused by warming, but due to the different responses of plant functional groups to seasonal asymmetric warming, resulting in changes in plant community structure and decreased plant photosynthesis and productivity, which subsequently reduces the substrate and energy required for underground plant root respiration and microbial respiration, and ultimately reduces soil respiration. This study provides direct experimental evidence for the interaction of spring and autumn warming on ecosystem carbon cycle, and emphasizes the accurate assessment and simulation of the impact of seasonal asymmetric warming on terrestrial carbon sinks, and future studies need to consider the interaction between specific warming seasons and the residual effects on ecosystems.
The first author of this research paper is Ning Shijie, a third-year graduate of the Laboratory of Global Change Ecology, College of Life Sciences, Henan University, and the corresponding author is Professor Wan Shiqiang.
