西藏林芝市城区植物种类构成及其分布特征

Species composition and distribution characteristic of plants in the urban area of Nyingchi, Xizang

随着林芝市城市化进程的加快和对内外交流的通畅,给外来植物的引入和扩散提供了更便利的途径,大量外来植物用于城市绿化建设、小区景观配置,外来植物进入的速度不断加快。为了了解外来植物对市区植物多样性的构成造成的影响,野外采用随机抽取样地的方法,近期内对林芝市城区的6种不同城市生态系统类型中进行了调查,共记录了77科199属319种,其中外来植物63科136属185种。分析结果显示:林芝市城区的外来植物比例高达58.13%,其中66.67%的国外外来种来自美洲和亚洲;不同生活型植物中以二年生草本的外来种比例最高,分别高达82.35%。部分国外外来种已对林芝市城区形成了入侵。外来种比例最高的城市生态系统类型是观赏性要求较高的居住区绿地。外来植物属的地理区系分布广泛,其中北温带分布所占比例较大。在快速城市化的进程中,植物物种的生存和在城市环境中建立自我维持种群的生物多样性保护的能力越来越重要。外来植物由更能够适应本地独特条件或更能利用在城市环境中发现机会的物种组成,对城市生态系统可能存在潜在的生物安全风险。

Population flow and commercial trade communication provide faster and more diversified approach for alien plants. A great many of plants have been used to urban greening and landscape pattern. Alien plants have a fast speed to cause the invasion. To understand the influence of alien plants to the plant diversity of urban area, random sample selection was adopted in six types urban ecosystem. In this study, we recorded 319 plant species from 199 genera and 77 families, among which 185 alien plant species from 136 genera and 63 families. The results showed that the percentage of alien plants in the urban area of Nyingchi was as high as 58.13%, and 66.67% of the alien species originated from America and Asia;the source area was largely comprised of America;herbs biennial had a high percentage of alien species among the various life forms present, to 82.35%. Some of alien species became the invasive plant species in the urban ecosystem of the study area. The kind of alien plant species in residential green space was higher than the other urban ecosystem. The highest proportion of herb and shrub was in residential green space;the highest proportion of arbor was in institutional green space. The floristic geographical distribution of the alien plant genera was wide range. The major source was composed of North temperate, no matter on native genera, national alien genera or abroad alien genera. Cosmopolitan and Pantropic had a high proportion as well. In a rapidly urbanization process, the ability of plant species to survive and build self-sustaining populations in urban environments was increasingly important for biodiversity conservation. Alien plants are comprised of species that can adjust the unique conditions or capitalize on the opportunities found in urban environments. It is possible for urban ecosystem has a potential risk.