不同干扰模式对受害马尾松人工纯林林分结构的影响

Effects of different disturbance patterns on stand structure of infected pure Pinus massoniana plantation

在浙江安吉选择松材线虫病危害的马尾松人工纯林,分别进行暂不采伐直至10年后统一伐除受害木的集中干扰、采伐受害松木的适度干扰、采伐受害松木与周边松木及生长势弱松木的强度干扰,探讨不同干扰模式使受害马尾松林恢复健康的可能性.16年后的试验结果表明:3种模式下受害林分马尾松的重要值为集中干扰>适度干扰>强度干扰,阔叶树的重要值则正好相反;与集中干扰相比,适度和强度干扰后的马尾松、阔叶树的平均胸径分别提高1.2、1.7倍和1.3、1.9倍,平均树高分别提高了1.5、2.0倍和1.2、1.8倍,林分每公顷蓄积量分别是集中干扰样地的5.2和3.8倍;适度和强度干扰的各径阶株数均远高于集中干扰样地,胸径结构近似于反J型曲线,也形成了复层林,物种丰富度和多样性指数均显著高于集中干扰样地,林木个体差异及林分复杂性指数均表现为适度干扰>强度干扰>集中干扰.适度和强度干扰下单层马尾松同龄纯林均演替为复层马尾松-阔叶树混交异龄林.3种模式均是正向阔叶化演替,演替速度为强度干扰>适度干扰>集中干扰.表明适度干扰更有利于病害马尾松林分恢复,间伐马尾松纯林能加快阔叶混交化进程以抵御松材线虫病的入侵.

To explore the effects of different disturbance patterns on restoring the health of an infected stand,concentrated disturbance of not cutting trees before 10 years after infection,moderate disturbance of cutting infected pine trees,and strong distrubance of cutting infected pine trees,the neighboring trees and poorly growing pine trees were compared in a pure Pinus massomiana plantation infected by Bursaphelenchus xylophlius in Anji,Zhejiang,China. After 16 years,the importance values of P. massoniana in the three treatments were: concentrated disturbance > moderate disturbance > strong disturbance. However,the importance values of broad-leaved trees showed the opposite trend. Compared with the concentrated disturbance,the average DBH of P. massoniana in the moderate and strong disturbance treatments were 1.2 and 1.7 times higher,respectively,and those of broad-leaved species were 1. 3 and 1. 9 times higher,respectively. The average height of pine trees in the moderate and strong disturbance treatments increased 1.5 and 2.0 times,respectively,and those of broad-leaved species 1. 2 and 1. 8 times,respectively. The tree volume per hectare in moderate and strong disturbance treatments were 5.2 and 3.8 times that of concentrated disturbance treatment,respectively. In the moderate and strong disturbance treatments,the number of trees in each diameter class was greater than in the concentrated disturbance treatment. The stand diameter distribution in the multi-storied moderate and strong disturbance treatments followed an inverse J-shaped curve. The species richness and biodiversity were significantly higher in the moderate and strong disturbance treatments than in the concentrated disturbance treatment. The individual size inequality and structural complexity indices followed the order of moderate disturbance > strong disturbance > concentrated disturbance. Under moderate and strong disturbance treatments,the single-storied and evenly aged pure P. massoniana plantation became multi-storied and unevenly aged mixed stands. All the three disturbance patterns promoted the succession of broad-leaved trees,with the pace of succession in the order of strong disturbance > moderate disturbance > concentrated disturbance. In conclusion,moderate disturbance achieved better restoration. Thinning pure P. massoniana plantation could accelerate the succession of a mixed stand to enhance resistance against Bursaphelenchus xylophlius invasion.