极小种群博罗红豆的群落物种组成和空间分布格局

为保护博罗红豆(Ormosia boluoensis)资源,基于广东象头山国家级自然保护区建立的0.6 hm2固定样地,研究了博罗红豆所在群落的物种组成、径阶结构、空间格局、种内关联及其与群落优势种的种间关联。结果表明,样地内共调查到胸径≥1 cm的木本植物4503株,隶属于38科57属84种。优势种有甜槠(Castanopsis eyrei)、密花树(Rapanea neriifolia)、密花山矾(Symplocos congesta)、深山含笑(Michelia maudiae)和赤楠(Syzygium buxifolium)等,博罗红豆的重要值仅为1.84%,径阶结构呈倒“J”型,空间分布格局在0~22.1 m的尺度上呈现聚集分布,在22.2~30.0 m的尺度上呈随机分布。博罗红豆与甜槠无关联性,与赤楠在个别尺度上有微弱的负相关性,与密花山矾主要呈负关联性,与密花树、深山含笑主要呈正关联性。博罗红豆的成树和幼苗在0~3.7 m的空间尺度上呈现强正关联,小树和幼苗在0~5.9 m的尺度上呈正关联性,而成树与小树的关联性较弱。因此,推测博罗红豆的空间分布格局受负密度制约、种子扩散限制和生境异质性的作用,在后期的管理中可以适当移植幼苗和对群落中的灌木及小乔木进行适度的疏伐。

Species Composition and Spatial Distribution Pattern of Ormosia boluoensis with Extremely Small Population

In order to protect Ormosia boluoensis resources,the community characteristics,including species composition,population structure,spatial pattern,intraspecific association and interspecific relation with dominant species were studied based on 0.6 hm2 fixed plot in Xiangtoushan National Nature Reserve in Guangdong Province,which is the concentrated distribution area of O.boluoensis.The results showed that there were 4503 individuals with DBH(diameter at breast height)≥1,belonging to 84 species,57 genera and 38 families.The dominant species of the community were Castanopsis eyrei,Rapanea neriifolia,Symplocos congesta,Michelia maudiae and Syzygium buxifolium.The importance value of O.boluoensis was only 1.84,and its diameter class structure showed an inverse‘J’type.For spatial pattern,Ormosia boluoensis showed an aggregated distribution at scale of 0-22.1 m and a random distribution at scale of 22.2-30.0 m.As for interspecies relationship,there was no obvious association between O.boluoensis and Castanopsis eyrei and only a weak negative correlation with Syzygium buxifolium on some scales.There was a negative correlation with Symplocos congesta,while a positive association with Rapanea neriifolia and Michelia maudiae.There was positively strong associated between seedlings and adult trees of O.boluoensis at scale of 0-3.7 m,and positively associated between young trees and seedlings at scale of 0-5.9 m,but the association between adult and young trees was weak.Therefore,the spatial distribution pattern of O.boluoensis was affected by negative density restriction,seed diffusion limitation and habitat heterogeneity.So,proper seedlings transplantation and thinning in the community could be implemented in the later management.