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为了解雪灾对亚热带常绿阔叶林群落结构的影响,我们于2008年初对古田山24ha固定监测样地进行了调查。经统计,约1/3的树木遭受重度损伤,1/3的树木遭受轻度损伤。选择生境类型、胸径、物种的物候型、生长型4个因子,用多项逻辑斯蒂回归分析了这些因子对个体损伤的影响。结果表明:低海拔山谷受损最严重,树木倒伏、折断的倾向最大,高海拔山脊受损最轻。胸径影响树木的受损程度和类型,大致来说,随着胸径的增大,树木受损的比例增大,折断、断梢相对于压弯的可能性逐渐增大,断枝相对折断、断梢的可能性也逐渐增大。常绿物种较落叶物种受损更重。由于上层乔木的庇护,灌木树种受损较为轻微。采用除趋势对应分析(DCA)比较了雪灾前后群落结构的变化,结果表明:在40m×40m尺度上,群落的变化与随机变化的零假设有显著差异,这说明冰雪灾害对个体的损伤不是随机的,而是有物种选择性的,如甜槠(Castanopsis eyrei)、木荷(Schima superba)和马尾松(Pinus massoniana)等物种受灾情况显著低于随机损伤的零假设,而青冈(Cyclobalanopsis glauca)、石栎(Lithocarpus glaber)、马银花(Rhododendron ovatum)等物种显著地高于随机损伤的零假设,群落的物种组成在雪灾后发生了显著的变化。
In order to understand the impact of snowstorm on the structure of subtropical evergreen broad-leaved forest communities, we investigated the 24ha fixed monitoring plots of Gutian Mountain in early 2008. According to statistics, about 1/3 of the trees suffered heavy damage and 1/3 of the trees suffered slight damage. Four habitat types, DBH, phenology and growth of species were selected, and the influence of these factors on individual injury was analyzed by multiple logistic regression. The results show that the lowest altitude valleys have the most serious damage, the lodging tendency of the trees is the highest, and the damage of the ridge at the high altitude is the lightest. The DBH affects the degree and type of tree damage. Generally speaking, as the DBH increases, the proportion of tree damage increases, the probability of breakage and breakage increases relative to the bending, and the breakage of the tree branches breaks relatively. The possibility of the tip is also gradually increased. Evergreen species are more damaged than deciduous species. Shrub species are less damaged due to the shelter of the upper tree. The change of community structure before and after snow disaster was compared by using DCA. The results showed that there was a significant difference between the change of community and the null hypothesis of stochastic change on 40m × 40m scale, which indicated that the individual damage caused by snow disaster was not random , But species-selective, such as the null hypothesis that catastrophe species such as Castanopsis eyrei, Schima superba and Pinus massoniana are significantly less affected by random damage than Cyclobalanopsis glauca, Lithocarpus glaber, Rhododendron ovatum were significantly higher than the null hypothesis of random damage. The species composition of the community changed significantly after the snowstorm.