太阳辐射对陆地生态系统凋落物分解影响的研究进展

Research advance in effects of solar radiation on litter decomposition in terrestrial ecosystems

凋落物分解在很大程度上决定着陆地生态系统的碳平衡动态。太阳辐射不仅是陆地植被光合固碳和生产力必不可少的能量来源,而且能够通过光降解作用直接或间接地促进有机质分解,促进温室气体排放,加快生态系统碳周转。光降解近些年被证实为凋落物分解的另一关键驱动因素,对陆地生态系统碳循环产生重要影响。为了丰富和发展凋落物分解理论,本文综述了光降解的作用机理,归纳了其主要驱动因素,并比较了不同尺度上凋落物光降解对环境及气候变化的响应差异。光降解作用主要包括光矿化、光抑制和光促进过程,这3种作用机制在不同环境条件下对凋落物分解的影响存在显著差异。光降解对凋落物分解的影响程度与太阳辐射特征、凋落物性状、温度、水分、微生物和植被覆盖等因素密切相关,多因素之间的相互作用使得光降解作用更加复杂。最后,本综述甄别了凋落物光降解研究中存在的主要问题,展望了未来的研究方向,着重强调需要深入探究光降解作用途径及其内在机制,量化光降解与环境因子交互效应,并对传统碳周转模型进行优化。

Litter decomposition significantly influences the carbon(C)dynamics of terrestrial ecosystems.Solar radiation is not only essential for photosynthetic C fixation and primary productivity,but also can directly or indi-rectly promote litter decomposition through photodegradation.Recently,photodegradation has been identified as a key factor driving litter decomposition and potentially impacts terrestrial C cycle.To enrich and develop the theory of litter decomposition,we summarized the mechanisms and main driving factors of photodegradation,and compared the responses of photodegradation to environment and climate changes at different scales.Photodegradation primarily includes photomineralization,photoinhibition,and photofaciliation,each affecting litter decomposition differently under various environmental conditions.Photodegradation is closely related to factors such as solar radiation,litter traits,temperature,moisture,microorganisms,and vegetation cover.The interactions among these factors compli-cate the patterns of photodegradation.Finally,we identified the main issues in litter photodegradation research and prospected future research directions.We emphasized the needs for in-depth exploration of photodegradation path-ways and intrinsic mechanisms,quantification of its interactive effects with environmental factors,and optimization of traditional carbon turnover models.