Abstract:

In the context of global climate change, species composition, spatial structure, biodiversity, carbon sequestration, oxygen release and other functions of forest ecosystems are often affected by local or exotic pests and diseases. The effects of forest pests and diseases on ecosystem carbon sequestration are mainly concentrated in the following aspects: 1) The reduction of photosynthetic efficiency. When trees are damaged by pests and diseases, photosynthetic indicators such as photosynthetic rate, stomatal conductance and transpiration decrease, photosynthetic related genes are downregulated, and the dark reaction ability involved in photosynthesis is weakened or even inhibited due to the interference. 2) The decrease in photosynthate has an impact on both above and below ground ecosystems. When photosynthates decrease, trees themselves redistribute the sucrose in their bodies to meet the needs of forest metabolism. The root biomass, soil autotrophic respiration ability and long-term underground carbon sequestration of forest trees are all reduced due to the decrease of photosynthates. 3）Plant tissues are damaged, which affects the growth, reproduction and survival of the host, thereby reducing biodiversity, destroying forest structure and reducing functional redundancy. 4) After the forest ecosystem is disturbed by pests and diseases, the growth ability of surviving plants and the decomposition ability of microorganisms are affected for a long time, thus changing the carbon sequestration ability of the forest for a long time and increasing the carbon emissions of the forest stand. 5) Insects and microbes can speed up the decomposition of dead wood and release carbon. Wood-feeding insects can not only directly feed on and consume dead wood, but also indirectly affect the decomposition of dead wood through interactions with microbial communities. An increasing number of studies have shown that forest pests and diseases can reduce forest area, reduce carbon sequestration capacity and increase carbon flux, thus transforming forests from “carbon sink” to “carbon source”.

Key words: forest carbon sink, forest ecosystem, pest and disease disturbance, photosynthesis, carbon fixation, carbon flux