气候变暖背景下土壤呼吸研究的几个重要问题

土壤呼吸是土壤有机碳返还至大气的主要形式,其对气候变暖的响应一直备受关注。近30年来,已有大量增温试验和模型就气候变暖对土壤呼吸的影响及其机制做了详细的探讨。但目前研究主要集中在土壤呼吸对浅层土壤增温的响应,对深层土壤的关注不足,且鲜有涉及土壤动物和土壤冻融过程,这些可能会减弱未来气候变暖背景下的CO₂排放的预测能力。本研究提出几个目前气候变暖背景下土壤呼吸研究亟待解决的问题,包括:1)深层土壤呼吸对增温的响应;2)土壤动物对土壤呼吸的贡献及影响;3)土壤冻融过程对土壤呼吸的影响。通过综述这3个研究领域的现状,指出了当前该领域研究中存在的不足,提出了一些具体的改进措施并对今后的研究方向进行了展望,有助于深入理解土壤呼吸对气候变暖的响应过程和提高陆地生态系统碳循环模型的预测精度。

Several important issues of soil respiration under climate warming

Soil respiration (R_s) is a major pathway through which soil organic carbon returns to the atmosphere, and its response to climate warming has always been the focus of attention in global change ecology researches. During the past thirty years, great progress has been made in understanding mechanisms by which climate warming affects R_s and the impacts of warming on R_s, based on numerous temperature-raising experiments and models. However, most studies are focused on the direct effects of topsoil warming on R_s, and little attention has been paid to processes in the subsoil, and even less to the indirect effects of climate warming through soil animals and soil freezing-thawing processes, which could reduce the confidence in predictions of CO₂ emission under climate warming. Thus, this paper proposes several issues urgently require resolution: 1) the response of deep soil respiration to temperature rise; 2) the effects of soil animals on soil respiration; and 3) the effects of soil freezing-thawing processes on soil respiration. For these three questions, this paper summarizes the research advances, identifies the existing knowledge deficiencies, provides details of opportunities for improvement, and presents suggestions for future research directions. This outline will certainly be helpful for understanding the response of soil respiration to warming and as a catalyst for building more precise carbon cycle models of terrestrial ecosystems.