虫害叶损失造成的树木非结构性碳减少与树木生长、死亡的关系研究进展

The relationship between the reduction of nonstructural carbohydrate induced by defoliator and the growth and mortality of trees

大规模虫害爆发可造成区域森林死亡,近年的气候变化进一步增加了虫害的频度和危害程度。森林和林地植物死亡会导致植被生产力降低,改变生态系统结构和功能,使森林由一个净的碳汇转变为一个碳源。因此,加深虫害对树木危害机制的认识有重要意义。虫害造成的叶损失(虫害叶损失)降低树木光合作用能力,增加非结构性碳(NSC)消耗,使得树木体内碳储备降低,NSC降低到一定程度会导致树木因碳饥饿而死亡。外部环境和树木自身的补偿性机制也会对这个过程产生正或负的影响。在近年气候变化背景下,树木死亡在全球尺度上增多,重新激起了人们对碳饥饿的重视,碳饥饿被视为解释树木死亡的主要生理机制之一。该文介绍了碳饥饿的定义,综述了虫害叶损失减少树木NSC储备与树木生长、死亡的关系,以及树木虫害和叶损失与气候变化之间的关系,并对今后的研究进行了展望。

Large scale herbivorous insect outbreaks can cause death of regional forests, and the events are expected to be exacerbated with climate change. Mortality of forest and woodland plants would cause a series of serious conse-quences, such as decrease in vegetation production, shifts in ecosystem structure and function, and transformation of forest function from a net carbon sink into a net carbon source. There is thus a need to better understand the impact of insects on trees. Defoliation by insect pests mainly reduces photosynthesis （source decrease） and in-creases carbon consumption （sink increase）, and hence causes reduction of nonstructural carbohydrate （NSC）. When the reduction in NSC reaches to a certain level, trees would die of carbon starvation. External environment and internal compensatory mechanisms can also positively or negatively influence the process of tree death. At present, the research of carbon starvation is a hotspot because the increase of tree mortality globally with climate change, and carbon starvation is considered as one of the dominating physiological mechanisms for explaining tree death. In this study, we reviewed the definition of carbon starvation, and the relationships between the reduc-tion of NSC induced by defoliation and the growth and death of trees, and the relationships among insect out-breaks, leaf loss and climate change. We also presented the potential directions of future studies on insect-caused defoliation and tree mortality.