Hazard risk assessment of alien plants in roadside ecosystem in Maoershan National Forest Park.
Roadside ecosystems are common places susceptible to alien plant invasion. It is, therefore, of important significance to conduct hazard risk assessment of alien plants in the ecosystem. A list of alien plants in the roadside ecosystem of the Maoershan National Forest Park was worked out based on data consultation, field surveys and the 9 criteria set by Webb and Presten for determination of native or alien plants. The roadside ecosystem was divided into three levels, high, moderate and low, in terms of disturbance in the light of nature of the road, volume of traffic, width of the road and pavement of the road. The analytic hierarchy process (AHP) was adopted to build a risk assessment index system, which was then used to assess hazard risks of all the alien plants in the list. Results show that there were a total of 39 species of alien plants detected in the roadside ecosystem of the national forest park. However, compared with roadside ecosystems in areas lower in latitude, the roadside ecosystem in the national forest park was lower in number of alien species and hazard risk. The alien plants are mostly herbs from America and now widely distributed in China because of their outstanding uses. Plants of compositae make up the biggest proportion. Among the alien plants in the ecosystem, there are five species high in risk, i. e. Oenothera biennis, Bidens bipinnata, Erigeron annuus, Amaranthus retroflexus and Senecio vulgaris. In the zones, high and moderate in disturbance level, of the roadside ecosystem, the alien plants were rated higher in risk than those in the zone low in disturbance level. A. retroflexus, S. vulgaris, B. bipinnata were rated higher in risk in the zone moderate in disturbance level than in the zone high in disturbance level. To ensure ecological safety of the national forest park, it is essential to mitigate as much as possible the damage to the original environment caused by road construction in the park and pay high attention to post-construction ecological rehabilitation and at the same time to intensify the enforcement of quarantine and removal of alien plants.