木林子天然林林分结构的时间动态变化特征

Temporal dynamic characteristics of stand structure of natural forest in Mulinzi Nature Reserve

为探索大尺度上木林子自然保护区内天然林-亚热带常绿落叶阔叶混交林林分结构特征与发展趋势,分别于2014和2019年在木林子大样地中选择同一块9 hm2样地进行林木特征值测度,分析乔木树种重要值及空间结构参数[角尺度(W_(i))、大小比数(U_(i))、混交度(M_(i))]的变化,阐述林分结构多元动态特征。结果表明,经过5 a的自然生长,木林子大样地乔木树种的重要值变动较小,整体林分水平空间分布格局更趋向于聚集分布发展;林分优势度保持在0.5左右,具有一定优势与发展潜力;林分整体混交良好,基本与5 a前持平,但发展变化趋势不显著。综合来看,木林子天然林仍处于演替进程中,尚未达到自然顶级群落水平,林分中处于随机分布的绝对优势参照树伴生4株不同树种的结构单元(M_(i)=1.00,W_(i)=0.50,U_(i)=0.00)为天然林中更具优势的空间结构组合。在天然林保护与恢复过程中,为提高森林质量,使林分空间结构趋于理想状态,可对林分中同种聚集分布的绝对劣态木(M_(i)=0.00,W_(i)=1.00,U_(i)=1.00)施以适度人为干扰,进而优化林分结构,精准提高森林质量。

To explore the stand structure characteristics and development trend of subtropical deciduous-evergreen broadleaf mixed natural forests at a large scale, the 9 hm2 natural forest stand in Mulinzi Nature Reserve was investigated by measuring tree characteristic values in 2014 and 2019, and the multivariate dynamic characteristics of stand structure were described by analyzing changes in the important values of tree species and the spatial structure parameters uniform angle index (W_(i)), dominance (U_(i)), and mingling (M_(i)). The results showed that the important values of tree species in the 9 hm2 stand experienced little change, and the horizontal spatial distribution pattern of the whole stand tended to have a gathered distribution after five years of natural growth. The dominance of the whole stand was approximately 0.5, which implied that the natural forest stand had certain advantages and development potential. The forest was mixed well in 2019, as it was five years prior, but the development trend was not significant. The forest is still in the process of succession, and has not reached the level of the natural climax community on the whole. The structure unit was characterized as having absolute dominance, random distribution, and four different tree species (M_(i)=1.00, W_(i)=0.50, U_(i)=0.00) which was more advantageous in the natural forest. In the process of natural forest protection and restoration, to improve forest quality and achieve the ideal state of the spatial structure of the stand, the absolute inferior trees (M_(i)=0.00, W_(i)=1.00, U_(i)=1.00) from the same species in the stand would preferably be subjected to moderate human interference to optimize the stand structure and accurately improve the forest quality.