不同更新方式对常绿落叶阔叶混交林迹地主要树种生态位的影响

The Effects of Different Regeneration Patterns on the Main Tree Species Niche of Montane Mixed Evergreen and Deciduous Broadleaved Forests

运用Shannow-wiener生态位宽度指数和Pianka生态位重叠指数,对常绿落叶阔叶混交林迹地不同更新方式群落主要树种的生态位特征进行了比较研究。结果表明:不同更新方式对常绿落叶阔叶混交林迹地群落主要树种生态位有重要影响。人工更新群落中乔木檫木(Sassafras tsumu)虽有最高的生态位,为1.748,但已受林下常绿灌木的挤压,将会变窄。人工促进天然更新群落中檫木生态位为1.671,因受微毛柃(Eurya hebeclados)、短柱柃(Eurya brevistyla)等树种挤压居第三位,群落已向良性方向演替。天然更新群落中乔木层落叶树种大穗鹅耳枥(Carpinus fargesii)最高,为1.667,常绿树种青冈(Cycloblanopsis glauca)的生态位已从人工更新群落中的0.601和人工促进天然更新群落中的1.081上升到1.584,群落中的落叶树种与常绿树种均较大,群落主要树种的生态位结构趋于合理。落叶阔叶树种檫木、光皮桦(Betula luminifera)在天然更新群落中的生态位重叠值较低,分别为0.387和0.292,而常绿阔叶树种青冈则相反,在天然更新群落中的生态位重叠值较高,为0.537。不同更新方式群落中树种生态位宽度及树种间生态位重叠的差异源于人为干扰过程中对非目的树种生态位的压缩与释放程度以及树种间对资源竞争的结果。通过树种间生态位调控可以优化群落结构。

Niche characteristics of main tree species of communities in different regeneration patterns about montane mixed evergreen and deciduous broadleaved forests were analyzed by means of Shannow-wiener niche breadth and Pianka niche overlap indexes. The results showed that different regeneration ratterns have an significant effect on the main tree species niche of montane mixed evergreen and deciduous broadleaved forests. Niche of Sassafras tsumu were the highest in the artifi＇cial renewal forests , but they squeezed by the undergrowth of evergreen shrubs, their niche width will be narrowed. Niche of Sassafras tsumu was the third in the artificially-promoted natural regeneration forests by the extrusion of Eurya hebeclados and Eurya brevistyla, and the community has a benign direction of succession. Niche breadth of Carpinus fargesii in upper deciduous trees was the highest in the natural regeneration forests,lower evergreen trees and shrubs occupy a larger niche, the main species niche structure tended to be rational. Niche overlaps of deciduous broadleaved trees Sassafras tsumu and Betula luminifera were larger, which that for evergreen broadleaved trees Cycloblanopsis glauca is just the opposite. Differences of niche breadth and niche overlaps of tree species of communities in different regeneration patterns were caused by the degree of compression and release of non-purpose tree species niche in the process of anthropogenic interference and the results of the competition for resources between species. The community structure can be optimized through niche regulation between the various species.