富营养化湿地生境本地菟丝子偏好寄生外来入侵种的机理研究

Compared with terrestrial ecosystem, wetland ecosystem is more vulnerable to interference, more sensitive to alien invasive species, with more wide-spread eutrophication pollution. Thus, it frequently suffers from exotic invasions, and the control of alien invasive species in wetland ecosystem is characterized with higher requirements and more difficulties. Because of their co-evolution with local communities but slight negative ecological effects on ecosystem, the native species are considered to be the effective and environmentally benign enemies of alien invasive species. Therefore, with the objects of two kinds of native dodders (i.e., Cuscuta chinensis and Cuscuta australis) and the alien invasive plants in wetland ecosystem, this project attempts to detect the following questions: (1) By comparison on the parasitism extents and growth status of two dodders on the alien invasive plants and their congeneric native species, it aims to select the target dodder with higher host preference and more inhibition effects. (2) To compare the growth status and control effects of target dodder under different nutrient treatments (i.e., high N, high P, high N and P), it illuminates the impacts by eutrophication on the control effects and host preference of target dodder to the alien invasive plants in wetland ecosystem. (3) By testing the parasitism extents and control effects of target dodder on the different alien invasive plants in wetland ecosystem with different nutrient treatments, it implicates the correlations between the host preference of target dodder and the contents of nutrients and parasitic signal substance (i.e., flavonoids) of the alien invasive plants in wetland ecosystem. This project provides with the direct scientific basis and important theoretical support for the risk assessment and feasibility analysis on the control of alien invasive plants in wetland ecosystem by native dodders.

与陆地生态系统相比，湿地生态系统可入侵性强、抗干扰能力弱、富营养化污染广，遭受外来入侵种危害严重，且防治要求高、难度大。本地种与当地生态系统协同进化、负面生态效应小，被认为是外来入侵种高效无污染的天敌。为此，本项目以本地种(菟丝子和南方菟丝子)寄生防治湿地外来入侵种为例：(1)比较两种菟丝子对湿地外来入侵种及其同属本地种的寄生抑制情况，筛选寄主偏好性强、防治作用效果好的目标菟丝子；(2)对比不同养分处理(高N、高P、高N与P)目标菟丝子寄生湿地外来入侵种的生长状况与防治效果，揭示湿地富营养化对目标菟丝子防治湿地外来入侵种的寄主选择与防治效果的影响；(3)比较目标菟丝子在不同养分处理、不同湿地外来入侵种的寄生情况和防治效果，阐述目标菟丝子的寄主偏好性与湿地外来入侵种的养分含量、寄生信号物质黄酮之间的相关性，为本地菟丝子防治湿地外来入侵种的风险评估与可行性分析提供直接科学依据与重要理论支持。

与陆地生态系统相比，湿地生态系统可入侵性强、抗干扰能力弱、富营养化污染广，遭受外来入侵植物危害严重且防治要求高、难度大。本地种与当地生态系统协同进化、负面生态效应小，被认为是外来入侵种高效无污染的天敌。为此，本项目以本地种防治湿地外来入侵种为主旨，通过野外群落调查、种子萌发实验和温室栽培实验开展了以下研究：..(1)通过群落调查本地种防治湿地外来入侵种对被入侵群落结构的影响，发现本地种防治策略使被入侵生境的土壤微生物的结构发生改变，有利于被入侵植物群落的恢复与生物多样性的提高。本研究为评价以本地种抵御湿地外来入侵种的生物防治措施的生态安全评价提供重要理论参考。..(2)通过探讨养分水平和化感作用对湿地外来入侵种及其同属本地种的种间关系影响，发现本地种芦苇对湿地外来入侵种互花米草具有化感作用缓解效应，且养分浓度高有利于增强本地种对外来入侵种的竞争优势。本研究为评价以本地种抵御湿地外来入侵种的可行性提供直接科学证据。..(3)对比不同湿地外来入侵种及其同属本地种的化感浸提液对不同菟丝子种子萌发的影响，发现菊科的加拿大一枝黄花对菟丝子种子萌发具有显著促进作用。在应试的几种菟丝子中，以(中国)菟丝子的萌发效果最好。本研究为筛选寄主选择性强且抑制效果好的目标菟丝子提供了直接科学依据。..(4)探讨菟丝子和富营养处理对湿地外来入侵种及其同属本地种的生长以及种间关系的影响，发现菟丝子对湿地外来入侵种的化感作用具有显著影响，且高养分条件有利于提高本地种抵御湿地外来入侵种的竞争优势。本研究为探讨本地种抵御湿地外来入侵种的作用机理提供了重要理论参考。..综上，本项目以菟丝子为例，系统地探讨了以本地种抵御湿地外来入侵种防治方法的生态安全、影响因素、作用机理以及可行性分析，为湿地外来入侵种的高效且环境友好的生物防治措施的制定提供直接科学依据和重要理论参考。