湖南栎类天然林林分结构对林分生长的影响研究

Study on the Influence of Stand Structure on Stand Growth of Oak Natural Forest in Hunan Province Based on Structural Equation Model

以湖南栎类天然林为研究对象,采用22个林分结构指标和3个林分总平均生长量指标(平均树高、胸高断面积、蓄积量),利用Pearson相关分析筛选关键结构因子,构建结构方程模型,探究林分结构对林分生长的影响规律。结果显示:1)林龄对3种生长量指标均具有极显著的影响(P<0.001);2)混交度、林分密度对断面积总平均生长量具有极显著的影响(P<0.001);3)混交度、胸径大小变异系数、林分密度对蓄积生长量具有极显著的影响(P<0.001),物种组成对其具有显著的影响(P<0.01),其中混交度的影响最大,影响系数高达0.515;4)混交度、林分密度、物种组成通过直接影响断面积总平均生长量和胸径大小变异系数的方式来间接影响蓄积生长量。研究表明:改善林分树种混交度,合理控制林分密度与林木大小分布,优化树种组成对林分的生长有促进作用。

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.