| The study of ecosystem restoration in degraded forests can provide valid scientific basis and helpful references for future forest restoration and management. This study selected four kinds of communities to carry out investigation, which formed from different restoration approaches on mountains of eastern Yunnan, setting39plots of10m×10m and195shrub and herb plots of2mx2m. Based on field surveys of communities, this study applied cluster analysis method to community classification, achieving a comparative study of different types of communities in terms of species composition, DBH class structure and heighness class structure of trees, similarity index of communities, diversity index and the characteristics of community phylogenetic structures. In reflecting the species composition and community phylogenetic structural characteristics of various secondary forests in mountainous Eastern Yunnan, the results were as follows.1. The cluster analysis based on the species important value of the dominant synusia classified the39quadrats into four community types, the results of which coincided with the physiognomy characteristics from field observations. They were Pyracantha fortuneana shrubs, Pinus armandii forest, Alnus ferdinandi-coburgii forest and secondary evergreen broad-leaved forest.2. The structural analysis of DBH class and heighness class showed that the planted Pinus armandii and Alnus ferdinandi-coburgii updated from sprout tillers were recessionary populations among the three forest communities, while the Lithocarpus dealbatus and Quercus senescens from regeneration succession were expanding populations. Therefore, with the succession going on, the overstory composition of the three forest communities will gradually evolve into convergence, and finally turn out to be evergreen broad-leaved forest dominated by Lithocarpus dealbatus and Quercus senescens in Fagaceae.3. The community survey made a record of71genera,12families and205species of vascular plants. In terms of stem density and basal area, the secondary evergreen broad-leaved forest (4811indiv./ha,25.5m2/ha) and Alnus ferdinandi-coburgii forest (3166indiv./ha,42.4m2/ha) both from natural recovery were superior to Pinus armandii forest from artificial restoration (1183indiv./ha,23.6m2/ha); Similarly, this also applied to the abundance and diversity of trees and shrubs. However, the case of understory herbs was on the contrary:the Pinus armandii forest from artificial restoration (101species,7species/m2) was superior to Alnus ferdinandi-coburgii forest (49species,3species/m2) and secondary evergreen broad-leaved forest (30species,1species/m2). The analysis of Sorensen similarity index showed that the difference between artificial recovery and natural recovery was greater than the difference between two types of natural recovery.4. The analysis of community phylogenetic structure indicated that:under different restoration approaches, Pinus armandii forest, Alnus ferdinandi-cobrgii forest and secondary evergreen broad-leaved forest were phylogenetically clustered, suggesting the dominance of habitat filtering; Pyracantha fortuneana shrubs growing at an early stage of forest recovery were phylogenetically random and herbaceous plants were at random in large scales, which might be the result of habitat filtering and competitive exclusion. The phylogenetic structures of plant communities with different life-forms were varied, indicating that the dominant factors in plant community assembly varied with plant life-forms.5. The results of phylogenetic diversity and species diversity were similar. Planted trees had hindered the invasion of other trees, promoting the updating and settlement of understory herbs. As a kind of ecological memory in the recovery of community, the past farming had not only provided spare niches for a variety of herbs, but also promoted the clustering of community phylogenetic structures. |
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