三江源地区刺柏属植物群落类型特征

三江源地区位于青藏高原的腹地, 是典型的生态脆弱区, 刺柏属(Juniperus)植物群落是该地区天然林资源的重要组分, 在维持生物多样性与水生态安全方面发挥着重要作用。该研究调查了刺柏属植物群落的主要植被类型, 通过对53个样地的样方数据分析, 量化描述了其各个群落类型的主要特征。结果表明: (1)根据生活型和优势度原则, 该区刺柏属植物群落可划分为祁连圆柏(J. przewalskii)林、大果圆柏(J. tibetica)林、密枝圆柏(J. convallium)林、塔枝圆柏(J. komarovii)林、大果圆柏灌丛和密枝圆柏灌丛, 进一步分为15个群丛。(2)调查所得维管植物共有142种, 隶属34科90属, 其中菊科种数最多, 占总种数的16.20%。(3)群落垂直结构明显, 其中乔木层优势种单一, 灌木层优势种主要有鲜黄小檗(Berberis diaphana)、银露梅(Potentilla glabra)及灌木状的大果圆柏, 草本层以薹草属(Carex)和马先蒿属(Pedicularis)占优势。(4)该区种子植物种的地理成分中, 温带成分占总种数的52.59%, 温带亚洲分布、东亚分布和中亚分布等为本区分布占比较大的分布区类型; 中国特有种占47.41%; 区系成分呈现横断山植物区系和唐古特植物区系成分互相交融的特点。

Characteristics of Juniperus community types in the Three-River-Source Region

Aims Juniperus community is an important component of natural forest resources in the Three-River-Source Region, which is significant in maintaining biodiversity and ecological security on the Qingzang Plateau. Yet, the information on the characteristics of the Juniperus community is lacking due to their special geographical location and varied topography. In this study, the main vegetation types of Juniperus community were investigated, and the main characteristics of each community type were described quantitatively by analyzing data from 53 plots. Methods Based on the analysis of forest resources inventory data in the Three-River-Source Region, the representative distribution area of Juniperus was selected to set up 7 sites, a total of 53 plots. Through the investigation of field communities and plot properties, the importance of each species was quantified and calculated. The principle of life form and dominance methods in Vegetation of China were used to determine community types. Important findings (1) The Juniperus plant community in the Three-River-Source Region was divided into 6 alliances, and then further divided into 15 associations. (2) In total, 142 species of seed plants were recorded, which was belonged to 34 families and 90 genera. Among them, Compositae was the major family, accounting for 16.20% of the total species. (3) The vertical structure of the community was obvious, in which the dominant species in the tree layer was single. The dominant species in the shrub layer were Berberis diaphana, Potentilla glabra and shrubby Juniperus tibetica. The herb layer were dominated by Carex and Pedicularis. (4) Among the geographical elements of seed plant species, the Temperate distribution accounted for 52.59% of the total species, while the rest was Chinese endemic species accounting for 47.41%. Temperate Asian, East Asian and Central Asian were the dominated areal-types in the Temperate distribution. Furthermore, the floristic elements of Hengduanshan flora and Tanggut flora were mixed formed the unique characteristic areal-type in the region.