Responses of Trunk Respiration to Environmental Factors and NSC Content in Natural Forests of Larix Gmelinii

Trunk respiration is an important part of the life activity of trees and also one of the pathways for carbon release from forest ecosystems..In order to reveal the dynamic changes of the trunk respiration rate of Larix gmelinii in the cold temperate zone and its influencing mechanism, this study used Li-Cor6400 portable photosynthesizer equipped with soil respiration measurement gas chamber(LI-6400-09) to measure the trunk respiration rate of Larix gmelinii in different age groups and environmental factors from May to September 2023, and collected tree cores for the determination of its NSC content, to analyse the characteristics of the changes in trunk respiration rate and the dominant factors during the growing season of Larix gmelinii in different age groups.The results of the study showed that: Larix gmelinii trunk respiration rate affected by seasonal changes in environmental factors showed a unimodal trend, the peak appeared in early August, Larix gmelinii trunk respiration rate decreased with increasing age;As the dominant factors of tree trunk respiration, trunk temperature and soil temperature and humidity play a key role in respiration rate; NSC content affects the respiration rate of the tree trunk to a certain extent, among which soluble sugar, as a direct energy substance for tree growth, has a better correlation with the respiration rate(P < 0. 01), However, since the NSC content varies with environmental factors, the co-regulatory effect of the two on the respiration rate needs to be considered comprehensively, which is of great significance for exploring the carbon release process in Larix gmelinii natural forest ecosystems.