关键词: 单位面积胸高断面积, 林木分化程度, 生物多样性, 地形因子, 生产力, 死亡量

Abstract:

Objective: Taking the fixed sample plot of Jiaohe mixed coniferous and broad-leaved forest in Jilin as the object, this study explores the impact and maintenance role of biological and abiotic factors on forest productivity, providing scientific basis and theoretical guidance for the sustainable management of the mixed coniferous and broad-leaved forest in Northeast China. Method: Multiple regression analysis was used to quantify the impact of explanatory variables (biological factors including unit area basal area, forest differentiation degree, biodiversity, and abiotic factor, namely topographical factor) on the response variable(biomass increment of survivors, biomass increment of recruits, biomass mortality). Determine the relative importance of the above three biomass changes on the net biomass change through variance decomposition. Result: For biomass increment of survivors, all explanatory variables together explained 12.07% of its total variance, with a significant positive effect of basal area per unit stand area and a significant negative effect of slope. For biomass increment of recruits, all explanatory variables together explained 22.62% of its total variance. The coefficient of DBH variation and phylogenetic diversity had significant positive effects on the biomass increment of recruits. Basal area per unit stand area, elevation, and slope showed significant negative relationships with the biomass increment of recruits. For biomass mortality, all explanatory variables together explained 3.51% of its total variance, with a significant positive effect of basal area per unit stand area. The fraction of the total variance of net change in biomass that could be explained by biomass increment of recruits, biomass increment of survivors and biomass mortality was 0.01%, 20.87% and 74.54%, respectively. The relative contribution of biomass mortality to the net biomass change was the largest, but its predictability was low. Conclusion: Basal area per unit stand area had different effects on different processes of biomass dynamics . Basal area per unit stand area promoted biomass mortality as well as the growth of survivors but suppressed the growth of recruits. The tree differentiation degree and phylogenetic diversity enhanced the growth of recruits. Among the topographic factors, the growth of survivors was negatively related with the slope, the growth of recruits was negatively related with the elevation and the slope .The net biomass change was mainly influenced by biomass mortality and biomass increment of survivors.

Key words: basal area per unit stand area, tree differentiation degree, biodiversity, topographic factors, productivity, biomass mortality