中国东部常绿阔叶林退化群落分析及恢复重建研究的一些问题

人类干扰活动导致常绿阔叶林的类型和数量减少,替而代之的是大面积处于不同退化程度的次生林、次生灌丛等,因此加大对其退化特征以及恢复重建的研究已是非常必要而迫切的任务。在对此类植被进行广泛调查基础上,结合数量分类法(在区域尺度上)对退化常绿阔叶林进行类型划分和群落特征的界定,并对一些影响群落恢复和改造的问题进行了讨论。这些问题是(1)不同的人类干扰方式对常绿阔叶林退化群落的形成发生深刻的影响,因此关注人类干扰方式,尤其是土地利用方式的变化和常绿阔叶林退化群落形成之间的关系应当进行重点研究;(2)退化群落的种类组成具有自身的特征,同样具有较高的物种多样性,对维持整个地区的物种多样性具有独特的贡献;(3)萌枝更新对退化群落的结构和动态起着重要作用,加强这方面的研究有助于探讨群落退化的机制和植被恢复途径;(4)种子传播方式、传播距离对于退化群落的种类组成具有重要影响,并影响到群落结构、动态和物种多样性,也应是进一步加强的研究领域。希望通过这些问题的研究,有助于明了群落的退化机理,并为其恢复改造提供依据。

Analysis of degraded evergreen broad-leaved forest communities in Eastern China and issues in forest restoration

Evergreen broad-leaved forest (EBLF) is now recognized as an important natural resource that contributes to both the biodiversity and the sustainable development of the subtropical regions of China. However, the extent of the EBLF has decreased very significantly due to long-term anthropogenic disturbance including deforestation, logging and fire, and much of it is now degraded to plantation, secondary forests and shrub and grassland communities. Therefore, close attention needs to be focused on the characteristics of these degraded communities with a view to the possibilities for restoration of EBLF. Following comprehensive investigation of typical degraded EBLF in the Tiantong and Dongqian lake region of eastern China, the community types and their characteristic species composition were defined at the regional scale. The results raise several issues about degraded EBLF vegetation and its potential for restoration, which require further detailed research in order to facilitate the development of EBLF ecosystem restoration in China. These issues are (1) Given the importance of anthropogenic disturbance and land use change in determining the composition of the degraded communities, more emphasis should be placed on the relationships between them, and this should become a major focus for future research; (2) The degraded communities of EBLF contain a comparatively high plant species richness and are also characterized by a specific species composition, which make a significant contribution to the maintenance of both regional and local biodiversity; (3) The importance of sprouting of both trees and shrubs as a mechanism for species persistence and regrowth has not been given sufficient recognition. Sprouting allows species to persist in a site even after a wide range of disturbances over hundreds of years. Sprouting ability therefore can have major impacts on species turnover, changes in community structure and species composition, maintenance of biological diversity and is vital to understanding of the vegetation dynamics of EBLF; (4) Seed dispersal pattern has long been considered an important influence on the regeneration of vegetation, and it should strongly influence the distribution of tree recruits in the degraded communities. Nonetheless, seed dispersal patterns for such species are poorly known, and processes controlling the fate of seeds in the degraded community of EBLF have been little studied. Attention to these research areas is essential to the future conservation and restoration of EBLF in China.