Dynamics and Edge Effect of an Atlantic Forest Fragment in Brazil

ABSTRACT The woody plants in an edge area formed approximately 35 years ago in an Atlantic Forest fragment in northeastern Brazil were examined, and three environments defined: edge, intermediate, and interior. Canopy tree densities and basal areas were found to be similar in all three environments, and also similar to previous published studies in the same region; species richness was greatest at the forest edge. The understory showed greater species richness in the forest interior, but greater diversity and equitability in the intermediate environment. Understory environments close to the forest edge demonstrated larger stem diameters than in the forest interior, although at lesser densities and with smaller total basal areas. Our results indicated the existence of distinct patterns in canopy and understory that most likely reflect differences in the response times of these two vegetation layers, with the understory being more sensitive to alterations in environmental structure.

摘要 本研究对巴西东北部大西洋森林（Atlantic Forest）片段中形成时长约35年的边缘区域内的木本植物展开调查，共划定三类生境：林缘、林内过渡区与林内。研究发现，三类生境的冠层树木密度与胸高断面积均无显著差异，且与该区域此前已发表的相关研究结果相近；林缘生境的物种丰富度最高。林下植被层在林内生境中物种丰富度最高，但在过渡区表现出更高的群落多样性与物种均匀度。靠近林缘的林下生境，其植株茎径大于林内生境，但植株密度更低，总胸高断面积也更小。本研究结果表明，冠层与林下层植被呈现出截然不同的分布格局，这大概率反映了两类植被层响应环境结构变化的时间差异——林下层对环境结构改变的敏感性更强。