抚育采伐强度对天然落叶松林林分结构和蓄积的影响

Effect of Tending Cutting Intensity on the Stand Structure and Accumulation of Natural Larch Forest

以大兴安岭83块不同抚育强度的天然落叶松林(Larix gmelinii)样地为研究对象,抚育强度分为对照(CK)、轻度采伐(平均为10%)、中度采伐(平均为20%)、重度采伐(>30%),应用结构方程模型分析抚育采伐强度对林分结构和蓄积的影响。结果表明:在以林分结构(ξ1)为评价指标的结构方程模型(模型1)中,抚育采伐对林分结构和林分单位蓄积分别有正向影响和负向影响,其相关系数分别为0.108、-0.221。林分结构对林分单位蓄积有正向影响,相关系数为0.285。在以林分非空间结构(ξ2)及空间结构(ξ3)为评价指标的结构方程模型(模型2)中,抚育采伐对林分非空间结构和空间结构分别有负向影响和正向影响,相关系数分别为-0.019、0.113。林分非空间结构、林分空间结构两者与林分单位蓄积相关系数分别为0.377、0.093,均呈正相关,且林分空间结构对林分单位蓄积的影响小于林分非空间结构对林分单位蓄积的影响。林分空间结构对林分非空间结构有正向影响,相关系数为0.892。抚育采伐对林分单位蓄积有负向影响,相关系数为-0.210。模型1和模型2均能很好地描述抚育采伐强度与林分结构、林分蓄积的关系,模型2比模型1更能全面的评价抚育采伐对林分结构中非空间结构及空间结构两方面的影响。

Taking 83 natural larch forests(Larix gmelinii) plots with different tending intensities in Daxing’an Mountains as the research object, by using the structural equation model, the influence of tending cutting intensity on stand structure and accumulation was analyzed. Tending intensity was divided into control(CK), mild cutting(10% on average), moderate cutting(20% on average), and heavy intensity cutting(>30%). The tending cutting has positive and negative effects on stand structure and stand unit accumulation respectively in the structural equation model(Model 1) with forest stand structure(ξ1) with the evaluation index and the correlation coefficients of 0.108 and-0.221, respectively. The stand structure has a positive effect on stand unit accumulation, and the correlation coefficient is 0.285. In the structural equation model(Model 2) with forest stand non-spatial structure(ξ2) and spatial structure(ξ3) as evaluation indexes, tending cutting has negative and positive effects on stand non-spatial structure and spatial structure with the correlation coefficients of-0.019 and 0.113, respectively. The correlation coefficients of stand non-spatial structure and stand spatial structure with stand unit accumulation are 0.377 and 0.093, respectively, which are positively correlated, the influence of stand spatial structure on stand unit accumulation is less than that of stand non-spatial structure. The stand spatial structure has a positive effect on the stand non-spatial structure, and the correlation coefficient is 0.892. Tending cutting has a negative impact on stand unit accumulation with the correlation coefficient of-0.210. Models 1 and 2 can well describe the intensity of tending cutting and stand structure, stand accumulation relationship. Model 2 has more capacities to comprehensively evaluate the influence of tending cutting on stand non-spatial structure and spatial structure than Model 1.