光降解在凋落物分解中的作用

Roles of photodegradation in litter decomposition

近年来,越来越多的研究者认识到光降解可能在凋落物分解中发挥着重要作用。本文对光降解的作用机制,光降解在碳循环、养分循环中的作用,光降解与微生物分解的关系,以及影响光降解的因素进行了综述。光降解对凋落物分解过程同时具有正效应和负效应,正效应指光降解通过氧化有机质,或是改变凋落物自身理化性质使其更易淋溶和分解,负效应指高光辐射对分解者产生不利影响从而抑制微生物分解。在光降解过程中光化学矿化产生CO2是生态系统碳流失的主要机制。除紫外光外,可见光中的蓝、绿光波段也对凋落物的降解产生影响。光降解作用的大小受到水分状况、凋落物化学性质和凋落物的暴露面积的影响。最后,讨论了该领域有待深入研究的方向,指出今后应当重点对光降解研究方法,光降解与环境因子的交互作用,光降解作用的空间差异,光降解与微生物分解的相互关系及其作用强度进行研究。

In recent years, it has recognized that photodegradation possibly plays a key role in litter decomposition. This paper summarized the action mechanisms of photodegradation, roles of photodegradation in carbon and nutrient cycling, relationships between photodegradation and microbial decomposition, and factors affecting photodegradation. Photodegradation has both positive and negative effects on litter decomposition. The positive effects lie in the photolysis and photooxidation of organic matter, leading to the changes of litter chemistry, fragmentation, and facilitation to leaching, whereas the negative effects are related to the inhibition of microbial decomposition induced by strong light radiation. The CO2 produced by the photochemical mineralization in the process of photodegradation is the main mechanism of the C loss from ecosystems. Besides UV, the blue and green light-wave bands in visible light can affect litter photodegradation. The photodegradation is affected by water status, litter chemical properties, and litter exposed area. It was suggested that the related research priorities in the future could be the research methods of photodegradation, the interactions between photodegradation and environmental factors, the spatial variance of photodegradation, and the relationships between photodegradation and microbial decomposition in the process of litter decomposition.