濒危植物藤枣的生境与种群结构特征

Habitat and Population Structure Characteristics of Eleutharrhena macrocarpa

[目的]探索藤枣生境及其种群数量、分布、结构及更新等特征。[方法]在藤枣主要分布地设置5块20 m×20m的调查样地,记录样地中所有胸径(DBH)≥1 cm的植物的物种名称、高度、胸径、及样地的郁闭度、海拔、坡度、裸岩覆盖率、距河流距离、土壤等环境因子,同时在样地中调查藤枣种群特征,分析藤枣藤枣生境地的林分因子、群落特征、生境特征及种群数量与更新。[结果]表明:藤枣生境地林分平均高、平均胸径、平均胸高断面积、林分密度分别为11.98 m、15.13 cm、41.42 m2·hm-2和1 205株·hm-2。群落平均物种丰富度为35.2,群落类型为热带雨林和季风常绿阔叶林;在大小级结构上,不同高度级和径级内物种丰富度和个体多度均呈单峰曲线,最高值均出现在第Ⅱ高度级和径级内,但第Ⅴ(H≥30 m)高度级和第Ⅵ(DBH≥100 cm)径级均有物种和个体分布。藤枣生境地平均海拔高度为1 107 m,坡度为陡坡,坡向则多数为阴坡,处坡下位置;林分郁闭度仅为76%,但距河流较近(31 m),并伴有一定的裸露岩石;土壤接近中性(p H=6.2),养分条件较好。在5块调查样地(面积20 m×20 m)中,共有藤枣28株,分布于19个样方,多数为单方单株分布。28株藤枣平均长度2.39 m,平均基径仅为0.74 cm,平均胸径为0.41 cm。其中,更新幼苗(H<33 cm)为3株,占藤枣总株数的10.71%。[结论]藤枣分布地植物群落类型主要为热带雨林和季风常绿阔叶林,树木较高,树体较大,单峰曲线是其物种丰富度和个体多度在不同高度级和径级内的分布形式。生境地环境以高温高湿为主,土壤养分条件较好。28株藤枣分布于19个样方,多数为单方单株分布。藤枣幼苗数量较少,自然更新受限。

[Objective]To study the habitat and population structure of Eleutharrhena macrocarpa,an endangered plant species in China. [Method]The stand parameters,community characteristics,habitat characteristics,population and regeneration of Eleutharrhena macrocarpa were investigated on five plots（ 20 m × 20 m）. On each plot,the species,height,and DBH（ diameter at breast height） of all individuals with the height（ or length） ≥1. 3 mwere recorded. [Result]The mean height,mean DBH,basal areas,and density of E. macrocarpa community were11. 98 m,15. 13 cm,41. 42 m^2·hm^- 2,and 1 205 stem·hm^- 2,respectively. The species richness was 35. 2 and the community types were tropical rainforest and monsoon evergreen broad- leaved forest. The species richness and abundance showed a single peak curve with DBH and height increasing. The maximum values of species richness and abundance all appeared in the second DBH and height classes. In the same time,it was also found that the species and stems distributed in the fifth height classes and the sixth DBH classes. The E. macrocarpa mainly distributed at 1 107 m m a. s. l.,abrupt slope,shady slope and the bottom part of slope. The canopy density was only 76%and some naked rocks and the neutral and rich nutrient soil existed in the habitat of E. macrocarpa. The position of E. macrocarpa habitat was very near to the river（ only 31 m）. Twenty-eight stems were found in five plots and distributed in nineteen subplots,only one stem existed in most of subplots. The mean length,mean basal diameter,mean DBH were 2. 39 m,0. 74 cm,and 0. 41 cm,respectively. Only three seedlings,about 10. 71% of total E.macrocarpa stems,were found in all plots. [Conclusion]The community types are tropical rainforest and monsoon evergreen broad-leaved forest in the habitat of E. macrocarpa,which have the higher and bigger trees. Single peak curve is the mainly distribution type of species richness and abundance among different DBH and height classes.The environment is characterized by high temperature and high humidity. The soil nutrient is also high. Twentyeight stems of E. macrocarpa distributed in nineteen subplots,one stem in one subplot is the mainly distribution type. The amount of E. macrocarpa seedling is low and regeneration is limited.