Abstract:

Lhasa is at the forefront and is central to the construction of the national ecological security barrier. Datura stramonium has become a serious invasion trend in Lhasa, posing significant bioecological safety risks to urban environments. This study selected the D. stramonium communities in the urban area of Lhasa as the research subject, and used the typical plot survey method to analyze the species composition, community similarity coefficient, importance value, and other quantitative characteristics of the plant communities in the D. stramonium invasion areas in Lhasa, as well as the preliminary impact on the diversity of the invaded plant communities. This provides data for the study of the diversity of invasive plant communities within urban areas using Lhasa as a case study. The results showed that 1) the plant community species composition in the D. stramonium invasion areas in Lhasa totaled 74 species across 62 genera and 22 families, among which the Asteraceae, Poaceae, and Amaranthaceae families had the most species, with as many as 23 species of alien plants. The annual herbaceous plants accounted for 47.30% of the total number of plants. 2) There are 4 plant species with a high frequency of occurrence (91%-100%) in the D. stramonium communities, accounting for 5.41% of the total number of species, which is a very small proportion, indicating a clear dominance of certain species; the native plants Dysphania schraderiana and Chenopodium album, along with D. stramonium, have the highest co-occurrence frequency, while Kali monopterum and Taraxacum grypodon also have significant frequencies. Among the invasive plants, the highest co-occurrence frequencies with D. stramonium were found in Galinsoga parviflora and Amaranthus retroflexus, and the Bray-Curtis similarity coefficient of the community quadrats was generally low, indicating significant variation in the species diversity composition of the D. stramonium communities and a wide ecological niche breadth. 3) The Pearson correlation analysis results indicated that the species richness of the quadrats was negatively correlated with the importance value of D. stramonium, meaning that as the coverage of D. stramonium increased, the species richness significantly decreased. D. stramonium plant communities in Lhasa contain a considerable number of invasive companion species. Future efforts should focus on conducting a comprehensive baseline survey of alien invasive plants throughout the urban area of Lhasa, and on strengthening basic research related to the invasion mechanisms of D. stramonium in high-altitude areas. The results of this study provide plant ecology data for the invasion and prevention of D. stramonium in built-up areas of Lhasa.

Key words: invasive plants, Datura stramonium, Lhasa, plant community, community similarity, diversity

摘要：

拉萨市是国家生态安全屏障建设的前沿中心阵地。曼陀罗（Datura stramonium）在拉萨市已形成严重入侵趋势，对城市人居环境有很大的生物生态安全风险。选择拉萨市区曼陀罗群落为研究对象，采用典型样地调查法对拉萨市曼陀罗入侵地植物群落物种组成、群落相似系数、重要值等数量特征及初步对入侵地植物多样性的影响进行分析，为城市范围入侵植物群落多样性的研究提供拉萨市的数据。研究结果表明，1）拉萨市曼陀罗入侵地植物群落物种组成共计22科62属74种，其中菊科、禾本科与苋科的种类居多，且外来植物多达23种，另外一年生草本植物占47.30%。2）曼陀罗群落中出现频率较高（91%—100%）的植物种有4种，占总物种数的5.41%，优势种的优势度现象明显；本土植物菊叶香藜（Dysphania schraderiana）与藜（Chenopodium album）和曼陀罗伴生频率最高，单翅猪毛菜（Kali monopterum）与反苞蒲公英（Taraxacum grypodon）次之，入侵植物中的牛膝菊（Galinsoga parviflora）与反枝苋（Amaranthus retroflexus）和曼陀罗伴生的频率最高；群落样方的Bray-Curtis相似系数普遍较低，说明曼陀罗群落物种多样性组成变化明显，生态位幅度较宽。3）Pearson相关性分析结果表明，样方物种丰富度与曼陀罗的重要值显著负相关，即随着曼陀罗盖度的增加物种丰富度显著减少。拉萨市曼陀罗植物群落中存在较多具有入侵性质的伴生种，建议下一步加大对整个拉萨市区外来入侵植物的全面本底调查，加强曼陀罗在高海拔地区入侵机制相关方面的基础研究。研究结果可为拉萨建成区曼陀罗的入侵性及其预防控制提供植物生态学数据参考。

关键词: 入侵植物, 曼陀罗, 拉萨, 植物群落, 群落相似性, 多样性