珠穆朗玛峰国家级自然保护区密叶红豆杉所在群落的特征及区系分析

基于野外15个群落样方物种调查,对珠穆朗玛峰国家级自然保护区密叶红豆杉(Taxus contorta Griffith)所在群落的结构、物种多样性、区系地理成分及密叶红豆杉的年龄结构进行研究。结果显示:(1)调查样地内共有维管植物53科116属154种,以蔷薇科、毛茛科、菊科、百合科等占优势;在科、属级区系分析中,热带成分分别占46.2%、18.0%,温带成分分别占53.8%、82.0%。(2)密叶红豆杉所在群落的建群种分别为乔松(Pinus wallichiana A.B.Jackson)、云南铁杉(Tsuga dumosa(D.Don)Eichler)和喜马拉雅冷杉(Abies spectabilis(D.Don)Spach),密叶红豆杉为下层乔木的重要伴生成分或优势成分。(3)从各群落内部比较来看,草本层的Margalef指数和Simpson指数在3个群落中都最高,说明群落的草本层物种多样性最丰富,数量也最多;从群落间比较来看,乔松林灌木层和草本层的Margalef指数最高,乔木层的最低。(4)在3种群落中密叶红豆杉数量都呈增长趋势,且幼苗库较充足,在云南铁杉林和喜马拉雅冷杉林中,密叶红豆杉从幼苗到幼树的生长过程经历了较强的环境筛选。

Analysis of the characteristics and floristic elements of communities containing Taxus contorta Griffith in Zhumulangmafeng National Nature Reserve,Tibet

Based on a survey of 15 community sample species, we studied the age structure, community structure, species diversity, and floristic elements of communities containing Taxus contorta Griffith in Zhumulangmafeng National Nature Reserve, Tibet. Results showed that: (1) There were 154 vascular species belonging to 116 genera and 53 families in all plots. Families such as Rosaceae, Ranunculaceae, Asteraceae, and Liliaceae dominated in the communities. Furthermore, based on analysis of family and genus, tropical components accounted for 46.2% and 18.0% and temperate components accounted for 53.8% and 82.0%, respectively. (2) The dominant species in the communities included Pinus wallichiana A.B. Jackson, Tsuga dumosa (D. Don) Eichler, and Abies spectabilis (D. Don) Spach. Taxus contorta was the accompanying or dominant species in the secondary arbor layer. (3) The Margalef and Simpson indices were the highest in the herb layer, indicating that herbaceous plants were dominant in terms of diversity and quantity in all communities. The Margalef index values were the highest for the shrub and herb layers but the lowest for the arbor layer in the Pinus wallichiana communities. (4) Taxus contorta showed abundant seedlings in the three communities. However, the development of young seedlings into young trees was impacted by the environmental pressures experienced in the Tsuga dumosa and Abies spectabilis communities.