陆地生态系统碳- 水耦合机制初探

陆地生态系统的碳循环和水循环是当前全球变化研究的热点。大量的研究已经表明两者之间具有密切的 耦合作用。但是目前对于两者的耦合关系和耦合机制还缺乏系统的分析和总结。本文在综合相关研究的基础上，对 陆地生态系统碳- 水耦合的基本过程和基本作用机制作了概括。我们认为陆地生态系统碳- 水耦合过程共包括土 壤- 植被节点、植被- 大气节点(气孔节点)、土壤- 大气节点和生化节点4 个碳- 水耦合节点。碳- 水间的生化反应、气 孔对光合- 蒸腾的共同控制和优化调控作用、生态系统对碳、水循环的同向驱动机制分别是陆地生态系统碳- 水耦 合的生物化学、生物物理学和生态学基础，共同构成了碳- 水耦合的基本作用机制。我们还用水分利用效率(WUE) 概念对碳- 水耦合过程中的碳/水耦合比例关系作了探讨。

A Review on the Coupled Carbon and Water Cycles in the Terrestrial Ecosystems

Carbon and water cycles absorbed much attention in the global change researches. There were many observations indicating that they were robustly coupled in the terrestrial ecosystems. Here we reviewed the correlations between carbon and water cycles from leaf to canopy and to larger scales. Moreover, we discussed the general mechanisms of the coupling relationships between carbon and water cycles. The chain between carbon and water cycles was analyzed into four links: soil-plant link, plant-atmosphere link (stomata link), soil-atmosphere link and biochemical link. The causes for the strong correlations between carbon and water could be generalized as three fundamental functions: 1) the chemosynthesis between carbon and water; 2) the stomatal controls on gas exchange and its optimal function; and 3) the common driving forces and similar controls for carbon and water cycles in the terrestrial ecosystems. Water use efficiency defined as the ratio of carbon assimilation to water use also was discussed as a suitable term indicating the quantity relationship between carbon and water.