外来树种对自然生态系统入侵风险评价指标体系

本指标体系是通过评价外来树种的入侵性(繁殖扩散建群能力)或外来树种的实际扩散程度及其对生态系统的影响来综合评价外来树种对自然生态系统的入侵风险.首先以回答问题的方式进行外来树种的入侵性评价或实际扩散程度评价,及其对生态系统的影响评价,然后通过综合判断表,得出外来树种的入侵风险等级,最后结合外来树种的控制难度等级给出相应的管理对策.入侵性通过植物的繁殖方式、扩散途径和适应能力等3个方面进行评价.实际扩散程度主要考虑外来树种天然更新的方式、扩散进入的植物群落类型和扩散的速度等因素.生态影响评价包括外来树种对生态系统环境因子、植物群落结构组成、当地群体遗传完整性和生态系统营养链等4方面的影响.控制难度考虑影响控制的因素、控制的方法和控制的负面影响等因素.

Indicators for Accessing the Invasion Risk of Alien Woody Plant to Natural Ecosystem

The invasiveness or actual dispersal extent and ecological impacts were emphasized in the system to assess the invasion risk of alien woody plant. The assessing process was designed as follows: First of all,the invasiveness or actual spreading amplitude of alien woody plant and ecological impacts were investigated by answering a questionnaire. Then the invasion risk was evaluated according to a synthetic judgment table. Finally management strategy could be developed according to the invasion risk classes and its difficulty in controlling the invasion. Invasiveness assessment was implemented by evaluating its reproduction,dissemination and adaptation ability. Natural reproduction,the invaded plant community types and dissemination speed were taken into consideration in the evaluation of actual dispersal extent. The influence of alien woody species on environmental factors,structure and function of plant community and on local genetic integrality and nutrition chain in the ecosystem were included in ecological impact indicators. The difficulty in controlling the invasion was related with influencing control factors,control method and the adverse impact on environment.