摘要
森林地下碳分配(TBCA)是森林碳循环的重要通量,对森林碳吸存有十分重要作用.TBCA是森林生态系统GPP中一个最大的汇,可占GPP的21%～61%,土壤呼吸的2/3来自TBCA.目前国际上常用的TBCA测定方法为碳平衡法,在假定地下碳库处于稳定状态时,TB-CA可由土壤呼吸减去凋落物量获得,但该方法存在一系列问题.影响森林TBCA的因素有生产力、森林类型、树龄和森林演替阶段、土壤养分和水分有效性、林分密度和树种组成、气候变化因素等.TBCA中各个组成部分均较难以测定和量化,通常假定TBCA中根系呼吸与根系生产力各约占50%,而TBCA中菌根菌和根系分泌物的贡献则仍不清楚.有关TBCA各组分去向及影响机理的研究亦很少.TBCA未来的研究应致力于揭示TBCA的根本驱动因子和其对全球变化的响应机理,以及TBCA转化为土壤新碳的效率及控制因素;同时应提高TBCA测定方法的确定性,特别是应将碳同位素法、微根管法及碳平衡法三者相结合.
Total belowground carbon allocation （TBCA） represents an important carbon flux in forest ecosystems thus relates closely to carbon sequestration. It makes up 21% - 61% of GPP and acts as a maximum sink of GPP. Two thirds of soil CO2 efflux comes from TBCA. TBCA is usually estimated by carbon balance method, in which TBCA could be calculated as soil respiration minus litterfall when belowground carbon pool assumed to be steady. However, problems arise in the application of the method. This is because TBCA could be influenced by various factors such as forest productivity, forest type, stand age and succession stage, soil nutrient and moisture availability, stem density, species composition and climate changes ted and quantified. So far it is usually Further, different components of TBCA can hardly be separaassumed that among TBCA the contributions of root respiration and production are both approximately 50%, but those of fungal and root exudates are left unknown. Also, little is known with respect to fates and controls of TBCA components. Future efforts should be emphasized on ultimate factors that control TBCA, TBCA＇s response to global changes, and its efficiency and key factor of converting to new soil carbon. New techniques should also be developed in order to improve the certainty in the estimation of TBCA, especially those that would realize the combination of C isotope technique, minirhizotron, and carbon balance method.
出处
《亚热带资源与环境学报》
2007年第1期34-42,共9页
Journal of Subtropical Resources and Environment
基金
国家自然科学基金资助项目(30300272)
关键词
地下碳分配
根系生产力
根系呼吸
气候变化
Total belowground carbon allocation
root production
root respiration
climate changes
