南水北调中线北京段大宁水库消落带植被分布特征及多样性研究

为探究南水北调中线北京段大宁水库消落带植被的分布特征及多样性，2019年6月对水库消落带典型区域（水位高程46~61 m）开展植被调查，并基于重要值、多样性指数和线性拟合统计方法，探讨消落带植被物种的组成、分布特征及生活型。结果显示：（1）研究区内共发现植被19科、37属、45种，以菊科、蓼科、藜科、莎草科、萝藦科和禾本科的种类较多，绝大部分是单属单种植物；出现频率35%以上的植物仅有2种，为灰绿藜（Chenopodium glaucum）和小飞蓬（Conyza canadensis），占植物总数53%的植被出现频率低于5%；（2）聚类分析表明，大宁水库消落带群落可划分为绵毛酸模叶蓼+小飞蓬、芦苇+朝天委陵菜、狗尾草+假还阳参共3个群落类型，46~50 m、50~55 m、55~61 m水位区段的主要群落分别为绵毛酸模叶蓼+酸模叶蓼、苘麻+艾蒿、狗尾草+葎草+茵陈蒿；（3）消落带植被的平均株高、总盖度及物种多样性指数（丰富度、Shannon-Wiener多样性、Pielou均匀度、Simpson优势度）均表现为随水位梯度升高而增加；（4）按照3级植物生活型的分类方式，将库区消落带植被分为9种生活型，涵盖3种1级生活型（木本、半木本、草本）和6种2级生活型（乔木、灌木、半灌木、一年生草本、多年生草本、水生植物），草本类（89.19%）>木本类（5.41%）>半木本类（4.05%），说明草本类是消落带植被群落的主要建群种，且一年生草本（58.1%）是主要优势生活型。本研究对大宁水库消落带植被物种多样性保护、修复与重建具有重要意义。

Vegetation Distribution and Diversity in the Water-Level-Fluctuation Zone of Daning Reservoir, Beijing Section, Middle Route of the South-to-North Water Diversion

Daning reservoir serves the important functions of water storage, drinking water supply and flood control, and provides critical support for riparian restoration in the Yongding River basin. In this study, an investigation of vegetation in the water-level-fluctuation zone of Daning reservoir was conducted along water level elevation gradients, focusing on species composition, height, coverage, abundance and type. The characteristics of vegetation composition, distribution and type were then analyzed based on importance value, diversity index using linear fitting statistical methods. In June 2019, samples were collected from a 15 m sampling belt within three water level elevation zones (46-50 m, 50-55 m, 55-61 m) . The primary results were as follows: (1) A total of 45 plant species from 37 genera and 19 families were collected, with most genera represented by a single species and most families by a single genus. Compositae, Polygonaceae, Chenopodiaceae, Cyperaceae, Asclepiadaceae and Gramineae were the dominant families. The occurrence frequency of only two species (Chenopodium glaucum and Conyza canadensis) was above 35%, while the occurrence frequency of 53% species was less than 5%. The dominant species along the three elevation zones were Rumex dentatus (46-50 m), Ixeridium dentatum (50-55 m), and Setaria viridis (55-61 m). (2) Cluster analysis indicated three primary types of plant community in the reservoir water-level-fluctuation zone: Polygonum lapathifolium + Conyza canadensis, Phragmites?australis + Potentilla supina, and Setaria?viridis + Crepidiastrum?lanceolatum. The community types within each elevation gradient were as follows: Polygonum lapathifolium + Polygonum lapathifolium (46-50 m), Abutilon theophrasti + Artemisia argyi (50-55 m), Setaria?viridis + Humulus?scandens + Artemisia?capillaris (55-61 m). (3) The average height, coverage and biodiversity of the plant communities all increased with elevation. (4) According to the method of third-level plant life types, the plants in the water-level-fluctuation zone were divided into nine life types covering three first-level life types (woody, semi-woody, herbaceous) and six second-level life types (arbor, shrub, semi-shrub, annual herb, perennial herb, aquatic plant). Herbaceous plants were the primary group in the vegetation community of the water-fluctuation zone (89.19%), followed by woody plants (5.41%) and semi-woody plants (4.05%). In addition, annual herbaceous plants of the total life types were the dominant life type, accounting 58.11% of the total species. Our findings are crucial for the protection, restoration and reconstruction of vegetation diversity in the water-level-fluctuation zone of Daning reservoir.