害虫对森林碳汇的影响及其机理

森林是陆地生态系统中最主要的固碳者。但森林常受到各种干扰, 使其固碳能力下降, 甚至变成碳源。文中主要介绍了叶部害虫、干部害虫和根部害虫干扰对森林碳汇的影响及其机理方面的研究进展。森林昆虫种类繁多, 危害方式及机理也各不相同。叶部害虫通过食叶或吸取汁液破坏叶绿素直接影响光合作用。研究表明, 与光合作用相关基因的表达下调或上调, 光合作用减弱或增强, 目前尚无一致的结论。在林分水平上, 失叶通常导致碳贮量下降。小蠹虫等蛀干害虫危害致树木死亡, 将森林由碳库变成碳源。根部害虫不但使根生物量下降, 还会影响植物光合作用, 但机理尚不清楚。害虫暴发后改变了土壤理化性质, 但在一定时间范围内对土壤呼吸并无显著影响, 其机理尚待揭示。

Impact and Mechanism of Insect Pests on Forest Carbon Sequestration

Forest is the largest carbon sink in terrestrial ecosystems. However, forests are often interfered by different factors, which lead to the reduced capacity of forests to sequestrate carbon and turn forest into a carbon source. This paper reviewed the research advances on the impact of forest insect pests living on leaves, stems and roots on carbon sequestration as well as the impact mechanism. Various forest insects have various feeding manners and resulting various impacts with various mechanisms. Leaf insects affect photosynthesis via defoliation or sucking sap. The research indicated that there is no agreed conclusion on if the photosynthesis increases or decreases as the result of the up-regulation or down-regulation of the expression of genes related to photosynthesis. On stand level, defoliation by insects usually results in a decrease of carbon stock. Stem borers, such as bark beetles, often kill trees and turn a forest from a carbon sink to a carbon source. Root insects not only decrease the biomass of root, but also affect the photosynthesis with unveiled mechanism. The outbreaks of insects change both the physiological and the chemical properties of forest soil. However, it does not affect the respiration of forest soil significantly in a certain time period, and the reason needs to be studied in future.