城市化过程中森林meta种群结构及动态分析

Analysis of forest meta-population structure and dynamics during the urbanization

采用样地每木调查法，通过丰富度、均匀度、多样性、层次结构复杂性和直径结构复杂性等指数进行分析比较，研究了快速城市化过程中深圳市不同立地等级黄牛木meta种群结构。结果表明：黄牛木群落以黄牛木[Cratoxylum cochinchinense（Lour．）Blume]和豹皮樟[Litsearotundifolia var．oblongifolia（Nees）Allen]两物种紧密组合为基本特征，立地等级越高，物种竞争力越强。立地条件好的黄牛木群落物种丰富度、均匀度和多样性比立地条件差的分别高1．58～1．85倍、0．67～0．87倍和1．34～1．60倍，说明缀块生境变差将导致群落层次结构趋于简单，群落不稳定。受城市化影响，黄牛木meta种群在台湾相思（Acacia confusa Merr．）群落和梅叶冬青[Hex asprella（Hook．et Arn．）Champ．ex Benth．]群落中明显占据优势种地位，群落有逆向演变趋势。今后应着力保护群落上层乔木层物种，改善群落缀块生境。

Based on sample investigation and analysis of richness, evenness, diversity, structure complexity of forest community, the structures of Cratoxylum cochinchinense （ Lour. ） Blume population in different site classes were studied during the fast urbanization of Shenzhen City. The research results showed that C. cochinchinense and Litsea rotundifolia var. oblongifolia （Nees） Allen were closely relative species in C. cochinchinense population, and species competition trended stronger under better site condition. Richness, evenness and diversity of C. cochinchinense population in better site were 1.58 - 1.85, 0.67 -0.87 and 1.34 - 1.60 times higher than those in poor site. It revealed that when patch habitat became poor, community structure would go forward simpleness and unstableness. In the process of urbanization, C. cochinchinense meta population became more dominant in Acacia confusa Merr. community and Ilex asprella （Hook. et Am. ） Champ. ex Benth. community, these would promote regressive succession process of forest communities. Enriching layer structure and improving patch habitat of forest communities are very important measures to control regressive succession process from subtropical evergreen broad-leaves forest to secondary shrub forest. The study of meta population structure could be used to guide conservation and utilization of forest resources.