富营养化湖泊沉水植物对附生群落遮荫效应的响应机制研究

Submerged macrophytes and its epiphytic community are key components of aquatic ecosystem. Nowadays, the negative correlation between these two components is a hot spot in studying aquatic ecology, especially in eutrophicated lake ecosystems. Based on the shading effect of epiphytic community on sumerged macrophyte in eutrophicated lake ecosystem, this proposal studies how endogenous hormones regulates the trade-off between growth and defense of submerged macrophytes in response to the shading effect of epiphytic community; how endogenous hormones regulates the response of submerged macrophytes in response to the shading effect in high ammonia condition; and how the interaction between high ammonia and shading effect influences the germination of asexual propagules and the colonization of seedlings of submerged macrophytes，using methods of field and experimental ecology, physiology and physiological ecology. The purpose of this proposal is to reveal the mechanism of the response of submerged macrophytes to the shading effect of epiphytic community in eutrophic lake ecosystems. The research will deepen our understanding of the reduce of aquatic plants, especially submerged macrophytes,caused by eutrophication,and further improve theories of the aquatic plant ecology. The research will also help to explain the transformation between grass-dominated and algae-dominated lake ecosystems and provide important theoretical basis for lake eutrophication control and ecological restoration.

沉水植物与其表面的附生群落是水生生态系统的重要组成部分。而这两者之间存在此消彼长的负相互作用也是当今水生态系统，特别是富营养化湖泊生态系统的研究热点之一。本项目将以富营养化湖泊中附生群落对沉水植物的遮荫效应为切入点，运用野外生态学、实验生态学和生理生态学等研究技术和手段，研究内源激素调控沉水植物生长与防御权衡利弊响应附生群落遮荫效应途径；高氨环境中沉水植物响应附生群落遮荫效应的内源激素调控途径；高氨与附生群落遮荫效应影响沉水植物无性繁殖体萌发与幼苗建群能力。以期揭示富营养化湖泊生态系统中沉水植物对附生群落遮荫效应的响应机制。其研究结果必将有益于深化我们对富营养化导致水生植物特别是沉水植物消失原因的了解，研究结果必将进一步丰富水生植物生态学的理论成果；也将有利于从理论上解释草型湖泊与藻型湖泊之间的转换机理,也能为湖泊富营养化治理与生态修复提供重要理论依据。

沉水植物是水生生态系统的重要组成部分。沉水植物与其表面的附生群落存在此消彼长的负相互作用，是富营养化水生态系统的研究热点之一。但是，目前国内外相关研究数量较少，特别是富营养化水环境下附生群落与沉水植物之间的相互作用模式还需进一步深入研究。本基金主要从沉水植物浸提液组分对附生藻类生长的影响；附生群落影响外来沉水植物的入侵能力；沉水植物无性繁殖体对富营养化条件的响应等方面，研究富营养化水体中，沉水植物与附生群落之间的相互作用及沉水植物生长、萌发与幼苗建群能力。本基金研究结果显示：复杂的叶形态沉水植物更有利于附生藻类群落的附着；沉水植物叶片浸提液中具有特定物质有较强的抑藻效应，并且在低浓度条件下具有更好的抑藻效应。外来种沉水植物对本地附生藻类群落的响应不显著，这是造成外来水生植物成功入侵的重要原因。同时，本基金结果还显示了沉水植物菹草石芽响应富营养化水体出现小型化趋势；首次发现了并报道了菹草石芽的两种生态类型，并研究了它们的生态适应性。本基金成果将会对沉水植物资源利用，水生生态环境保护和水生生态系统的科学管理发挥积极的现实作用，对目前我国退化湿地生态系统的恢复也能提供科学依据。