Abstract:

Taking Hunan oak natural forest as the research object,this paper adopted 22 stand structure indexes and 3 stand total average growth indexes (average height,basal area and volume),and used Pearson correlation analysis to screen key structural factors.On this basis,a structural equation model was constructed to explore the influence of stand structure on stand growth.The results showed that: 1) stand age had a very significant effect on the three growth indicators (P<0.001);2) Mixing degree and stand density had a significant effect on basal area growth (P<0.001);3) Mixing degree,variation coefficient of diameter at breast height and stand density had a very significant impact on the volume growth (P<0.001),and species composition had a significant impact on it (P<0.01),among them,mixing degree had the greatest impact,and the impact coefficient was as high as 0.515;4) Mixing degree,stand density and species composition indirectly affected the volume growth by directly affecting the basal area growth and the coefficient of variation of DBH size.The research shows that improving the mixing degree of stand species,reasonably controlling the distribution of stand density and tree size,and optimizing the composition of tree species can promote the growth of stand.

Key words: structural equation model, oak natural forest, stand structure, stand increment