气候变暖对哀牢山常绿阔叶林根际土壤碳过程的影响研究

Forest rhizosphere is crucial for belowground material cycle, and soil carbon turnover is the most active process of rhizosphere material cycle. If the process of rhizosphere soil carbon input and output mediated by root life activity was insufficiently understood and quantified, it would be difficult to fully and deeply understand belowground carbon cycle, and the uncertainty of estimating soil carbon budget would be increased, especially the uncertainty of the rhizosphere carbon process under climate warming. Therefore, Lithocarpus hancei,the dominant species of an evergreen broad-leaved forest in Ailao Mountains is chosen as the studying subject, and the life process of root turnover, root exudates, microbial and respiration as the leading clue in this project. Simulating warming experiment by infrared heaters is used to study the impact of soil carbon induced by fine root turnover, root exudates, root microbialroot, root respiration and soil respiration. This project aims at revealing the effect of climate warming on rhizosphere soil carbon turnover and its related mechanism, evaluating the effects of climate warming on rhizosphere soil carbon pool, and providing basic data and new knowledge for fully and deeply understanding forest soil carbon process under climate warming, and exactly estimating carbon budget for the regional ecosystem.

森林根际是地下物质循环的关键，根际土壤的碳转移过程最为活跃。如果不充分认识因根系生命活动介导的根际土壤碳过程，实际上将难以全面和深入认识地下碳循环过程，同时也将增加森林生态系统土壤碳库收支估算的不确定性，尤其是气候变暖背景下根际的碳过程更加不确定。因此，本项目选择哀牢山亚热带中山湿性常绿阔叶林原始林优势种硬壳柯(Lithocarpus hancei)作为研究对象，以根系的周转、分泌物、微生物和呼吸活动过程为主线，通过红外线加热器模拟增温实验，重点研究气候变暖背景下细根周转、根系分泌物、根系微生物、根系呼吸和土壤呼吸对土壤碳转移过程的影响，目的在于揭示气候变暖对根际土壤碳转移的影响及机制，并评估气候变暖对根际土壤碳库的影响，为全面、深入认识气候变换的森林土壤碳过程，以及精确评估区域生态碳收支提供基础数据和新认识。

背景：土壤呼吸作用(RS)在大气二氧化碳浓度中扮演着重要角色，因此在全球气候模式中起着重要作用。由于RS与气候的相互作用，研究RS对气候变暖的响应具有重要的意义。.方法：采用红外辐射模拟气候变暖，通过土壤增温试验，探讨我国西南地区亚热带森林RS及其温度敏感性(Q10)对气候变暖的响应。.结果：增温处理导致土壤温度和RS值分别增加了1.4℃和7.3%,土壤含水量降低了4.2% (% / %)。单因素和双因素回归均显示，增温实验使Q10值分别增加了89.1%和67.4%；水分对Q10的影响与土壤水敏系数呈抛物线关系；RS和Q10均未表现出对气候变暖的适应，表明全球变暖将加速土壤碳的释放。