互花米草入侵对鸟类的生态影响

生物入侵威胁本地物种生存,破坏生态系统的结构和功能,是导致全球生物多样性丧失的重要原因之一。外来植物是入侵生物中的重要一类,可以显著改变本地植被群落,并影响其他生物类群。鸟类作为生态系统中的较高营养级,对由入侵植物引起的栖息地变化十分敏感。互花米草自引入中国沿海以来,其分布区域不断扩散,多数研究认为互花米草入侵造成本地生物多样性降低和生态系统退化。系统梳理了互花米草入侵对鸟类栖息地、食物资源、繁殖、群落等方面的生态影响。主要负面影响有:(1)植被群落结构不利于鸟类栖息、筑巢、觅食;(2)鸟类食物资源丰度和多样性下降;(3)本地鸟类种群数量和物种多样性显著下降。在我国东部沿海湿地,互花米草入侵已经显著改变了植被与鸟类分布格局。但随着入侵历史的增长,少数小型雀形目鸟类却可以逐渐适应互花米草生境。互花米草入侵为某些非本地鸟类提供了空白生态位,在一定程度上丰富了本地物种多样性,对互花米草的快速清除反而可能不利于已适应并依赖互花米草生境的鸟类。综上,认为互花米草入侵对鸟类群落甚至整个生态系统的影响可能需要更多研究进行综合评价,应开展长期、大尺度、多因子的监测研究和多物种比较研究,建立生态评价模型并制定科学有效的互花米草管理对策。

Ecological effects of invasion by the smooth cordgrass Spartina alterniflora on birds

As one of the leading causes of the loss of global biodiversity, biological invasion severely threatens the existence of native species and destroys the structure and function of the original ecosystem. Alien plants,an important category of invasive species, can significantly change the local vegetation communities, and have a major effect on other related biological groups. Birds, which are positioned at the higher trophic levels in ecosystems, are particularly sensitive to changes in habitats caused by invasive plants. The typical smooth cordgrass (Spartina alterniflora) continued to spread since it was introduced to China''s coastal regions, which provided the impression that the smooth cordgrass might decrease biodiversity and degenerate the ecosystem. In this study, we systematically elaborated the ecological effects of the invasive smooth cordgrass on avian habitats, food resources, reproduction, and communities. The negative effects of the invasion mainly included:(1) the unsuitability of the altered vegetation community structure for avian roosting, nesting, and foraging; (2) the decrease in richness and diversity of avian food resources; (3) the remarkable decline in the number of populations and species diversity of native birds. The invasion of smooth cordgrass in China''s eastern coastal wetlands had changed the distribution pattern of native vegetation and birds drastically. However, some small passerines could adapt to the habitat of long time invasion by the smooth cordgrass gradually. Indeed, several non-native birds have adapted to the newly formed ecological environment, which provided free ecological niches for them, and consequently enriched the diversity of native species in some extent. Therefore,the rapid weeding of smooth cordgrass might be detrimental to those birds, which have already adapted to the smooth cordgrass and become dependent on it. In summary,further research focusing on long-term, large-scale, and multifactorial monitoring, and multi-species comparisons, are necessary for comprehensively evaluating the effect of invading smooth cordgrass on the avian community and the entire ecosystem, with the aim of establishing ecological evaluation models and adopting scientific and efficient management countermeasures against the invasion.