城市化影响下北京市外来入侵植物特征及其分布

通过文献资料分析和实地调查相结合的方法,对北京市外来入侵植物的种类、生活型、起源地、引入途径和分布等特征进行了分析,结果表明:该地区共有48种外来入侵植物,隶属39属19科,其中菊科、禾本科、苋科和大戟科植物为优势科,占到了所有入侵植物总数的60.4%.除火炬树外,其余47种植物均为草本植物,以起源于美洲的居多(70.8%),多为伴随种子苗木运输无意引进.入侵植物分布受城市化水平和人口密度影响显著,城市功能扩展区分布有最多的入侵植物,就入侵种分布密度而言,城市功能拓展区和城市核心区均明显高于近郊区和远郊区.目前北京入侵植物主要分布于农田、绿地、花圃等半人工生态系统,尚处于可控范围之内,但北京的自然地理条件及城市化进程使其仍存在较高的入侵风险,在将来的防治工作中应采取更加严格的检疫措施.

Ecological characters and distribution of invasive plants under the influence of urbanization in Beijing, China

Based on the field survey and literature review, the species composition, life form, origin, invasion track and distribution of alien invasive plants under the influence of urbanization in Beijing were studied. The results showed that there were 49 species of alien plants in this region, belonging to 39 genera and 19 families. Compositae, Gramineae, Amaranthaceae and Euphorbiaceae were the dominant families, which occupied 60.4% of total invasive plants. All invasive plants were herbs except Rhus typhina. Most of these species were originated from America (70.8%), and many of them were accidentally introduced accompanied with introduc-tion of seeds or ornamentals. Urbanization level and human density significantly influenced the distribution pattern of the invasive plants. The extended urban area had the maximum number of invasive plants; as far as the density was concerned, core urban area and extended urban area were remarkably higher than the suburban and the exurban. To date the invasive plants in Beijing region were mainly distributed in the semi-manmade ecosystem, such as farmland, green-space and nursery, which made them under control yet. However, Beijing region still has a high risk of biological invasion due to its complex geological and geomorphological condi-tions and its rapid urbanization. More rigorous quarantine solutions should be taken to prevent further invasion.