后河自然保护区珍稀植物群落谱系结构的时空变化

群落中所有物种对的亲缘关系程度构成群落的谱系结构。研究群落的谱系结构可以有效地揭示环境过滤、竞争排斥、中性过程三大生态过程对群落构建的相对重要性。本文以湖北后河自然保护区1hm。固定样地的珍稀植物群落为研究对象，分别研究了5m×5m、10m×10m、20m×20m、30m×30m、40m×40m、50m×50m6个空间尺度和在10m×10m、20m×20m、30m×30m、40m×40m、50m×50m5个空间尺度下5cm≤DBH〈10cm、10cm≤DBH〈15cm、15cm≤DBH〈20cm、DBH≥20cm4个径级对亚热带常绿落叶阔叶混交林群落谱系结构的影响。结果发现：随着空间尺度的增加，谱系结构逐渐趋向聚集。随着径级的增大，群落谱系聚集程度越来越小。但当DBHI〉20cm时，群落谱系聚集度较高。在25m。的尺度上群落谱系结构表现为随机，而在100m^2及更大的尺度上群落谱系结构都表现为聚集，说明在亚热带常绿阔叶落叶混交林的群落构建过程中，小尺度上中性过程可能起主导作用，而大尺度上生态位过程可能更重要。

Phylogenetic Structure of a Rare Plant Community in Houhe Nature Reserve over Time and Space

The phylogenetic structure of a community is composed of all genetic relationships between species across the community. Understanding the phylogenetic structure of a community will help reveal the relative importance of habitat filtering, competitive exclusion and the stochastic processes constructing the community. We studied a rare plant community in a 1 hm2 permanent plot in Houhe Nature Reserve, Hubei Province. We examined the effects of spatial scales （5m×5m, 10m×10m, 20m×20m, 30m×30m, 40m×40m, and 50m× 50m） and DBH classes （5cm≤DBH〈10cm, 10cm≤DBH〈15cm, 15 cm≤DBH〈20cm, and DBH≥20 cm） at spatial scales （10 m×10 m, 20 m×20 m, 30 m×30 m, 40 m×40 m, and 50 m × 50 m） on phylogenetic structure of the community in a subtropical evergreen and deciduous broadleaf mixed forest. The results demonstrated that, with increasing spatial scale, the phylogenetic structure tended to cluster. The degree of phylogenetic clustering decreased with increasing DBH classes. However, the degree of phylogenetic clustering was very high at the scale of DBH≥20 cm. The phylogenetic structures of the communities were random at the scale of 25 m2 and clustered at scales of 100 m^2 and larQer, indicatina that neutralitv mav Dlav a leading role at small scales and niche processes may be more important at large scales for community assembly in subtropical evergreen and deciduous broadleaf mixed forest in this case.