Abstract:

Objective: This study aims to investigate the annual effects of logging disturbance on carbon storage in the canopy layer of typical natural secondary coniferous-broadleaved mixed forests in northeast China, providing a theoretical support for carbon sequestration management. Method: Four 1 hm² plots were selected in Jilin Province. The initial survey was conducted in 2011, followed by logging operations in the winter of the same year. Retention trees were re-measured in 2013, 2015, 2018, and 2021. Bivariate linear regression was used to explore the effects of logging intensity, species diversity, functional diversity, phylogenetic diversity, and community-weighted mean trait values on carbon storage and carbon increment. A multiple linear regression model was employed to compare the contribution of each variable, and a structural equation model was used to test the direct and indirect effects of each variable on carbon storage and increment. Result: 1) In the multiple linear regression model of carbon storage and increment, logging intensity accounted for 25% and 5% of the total explanatory variance, respectively. Plant species diversity (species, functional, phylogenetic diversity) contributed 67% and 58% of the total explanatory variance, respectively, for carbon storage and increment. Community-weighted mean trait values accounted for 8% and 37% of the total explanatory variance, respectively, for carbon storage and increment. 2) In the structural equation model of carbon storage, logging intensity had significant negative effects on phylogenetic diversity, functional diversity, maximum tree height weighted trait value, and carbon storage, with path coefficients of ?0.221, ?0.454, ?0.337, and ?0.229, respectively. Logging intensity had a significantly positive effect on wood density weighted trait value, with a path coefficient of 0.368. The direct effect of logging intensity on species diversity was not significant. Species diversity and functional diversity had significant positive effects on carbon storage, with path coefficients of 0.306 and 0.235, respectively. Phylogenetic diversity and community-weighted mean trait values did not have a significant direct effect on carbon storage. 3) In the structural equation model of carbon storage increase, maximum tree height weighted trait value had a significant positive effect, functional diversity was unrelated to carbon storage increase, and the relationships between other variables were the same as in the carbon storage model. Conclusion: Species diversity, functional diversity, and community weighted mean have a direct impact on carbon storage and carbon increment. During forest management, increasing plant species and promoting functional diversity can enhance the carbon sequestration capacity of forests. The cutting intensity is sufficient to directly and indirectly reduce carbon storage and carbon increment through functional diversity and community weighted mean; Therefore, in forest management, reasonable logging is of great significance for improving the carbon sequestration capacity of forests.

Key words: logging disturbance, plant species diversity, community-weighted mean trait values, forest carbon storage, forest carbon increment