北京市湿地植物多样性及旱生植物入侵对生物多样性的影响

通过研究北京市湿地植物群落的结构，群落植物物种的组成、分布等情况，对湿地植物物种的重要值和湿地的生物多样性进行了分析。结果表明北京市主要湿地的物种组成和群落结构存在很大的差异，湿地内主要物种的重要值有季节性的变化。决定湿地群落中植物组成的主要因素是：旱生植物入侵、人为活动的干扰强度和湿地的水资源状况。因为连年降雨的减少导致了北京市湿地面积的下降和旱生植物的入侵问题日益加重。如汉石桥湿地保护区，捧草等入侵植物的群落盖度达到90％以上，有些形成单优势的群落，抑制了芦苇等湿地植物的生长。使湿地在整体上呈退化的趋势，湿地的景观价值、生态价值、湿地功能和湿地的生物多样性均严重损坏。因此，必须采取措施解决北京市湿地的水资源短缺问题，减少人类活动干扰，以恢复北京市郊县湿地和城市建成区湿地的活力，保护湿地的生物多样性。

Plant Diversity and Impact by Xerophytes Invasion in Wetland in Beijing

By studying the structure of the plant community, the species composition and it's distribution in plant community, the plant diversity and the important value of some dominant plants in wetlands in Beijing were analyzed. The result shown that there is a significant difference in the species composition and community structure in different wetlands. The important value of wetland plants reveals a seasonal variation. The major factors that impact the species composition in communities were: xerophytes invasion, the intensity of human activities and the water resources status of the wetland. The decrease of precipitation has the problem of wetland loses and xerophytes invasion even worse. As in Hanshiqiao nature reserve, the community coverage of invasive plants like Humulus scandens can even reach 90% or more, they may have formed a community with only one dominant plant, which makes it impossible for the native wetland plants like Phragmites communis to grow. As a result, the wetland shows a tendency of degradation. The landscape valuation, ecological valuation and the function of the wetland were lost significantly. The wetland plant diversity is highly jeopardized and more vulnerable than ever before. It is better that we take immediate actions to solve the problem of water resource shortage, and cut down human activity disturbances, so wetlands at rural area or built-up area of Beijing might be able to regain their vitality. Only with that, it is possible that wetland biodiversity will be protected smoothly and fundamentally.