水文情势变化影响下洪湖湿地植被演变过程与生态机理

The global climate change has become a great challenge to the human beings. It changes the earth's hydrologic cycle and induces extreme hydrological events frequently. The hydrological process is the most important ecological processes in the wetland, and it is also the most important driving factor of wetland plant community evolution. In China, a few studies have been conducted in the effects of water regimes on the vegetation evolution in the coastal and the alpine wetlands. But few of these works has been done in the middle reaches of Yangtze River lacustrine wetlands, though the drought and flooding are of the biggest disasters in this area. It's imperative that the study of hydrological regimes on the wetland vegetation succession should be conducted in this area and would bring forward response strategy to the climate change. This project will take Honghu wetland as the research object. The main research contents are as follows: (1) the effects of hydrological regimes on plants growth, biomass allocation and reproductive strategies, (2) the influence of hydrological processes on the competition effects of plant species, (3) the response of plant communities to hydrological changes, and (4) the response of vegetation evolvement to the hydrological change process. Though calculation of the species importance values, niches of the species, communities similarities and the communities principal component analysis to characterize the communities changes, we will explain the community ecological evolution mechanism by analysis individual response to hydrological change and population competition ability change, and finally we will clarify the mechanism of wetland vegetation evolution to the water regime change in Honghu wetland. The result of the study will allow us to put forward effective measures in coping with climate change, and it will also provide a theoretical basis for water resources rational utilization and biodiversity protection in the Honghu wetland.

气候变化已成为人类面临的重大挑战，它改变水文循环过程，导致旱涝灾害频发。而水文过程是湿地最重要的生态过程，是湿地植物群落演变最重要的驱动机制。我国在高寒湿地和滨海湿地水文过程变化对植被演变过程和机理的影响研究较多，但在长江中游湖泊湿地研究缺乏，而旱涝是长江中游最大的灾害之一，在此开展水文情势变化对湿地植被演变影响研究，提出应对气候变化的策略显得尤为迫切。本项目以洪湖湿地为研究对象，通过研究（1）水文过程对植物生长发育、物质分配和繁殖策略的影响、（2）水文过程对物种竞争能力的影响、（3）群落变化对水位变化的响应、（4）植被演变与水文过程变化的应对关系，以物种重要值、种群生态位、群落相似性计算和主成分分析等表征群落变化，从个体响应和种群竞争能力变化阐释群落演变的生态机理，揭示植被演变过程对水文情势变化的响应机制，提出应对气候变化的管理策略，为洪湖湿地水资源合理利用和多样性保护提供理论依据。

全球气候变化已成为人类面临的重大挑战，水文过程急剧变化（旱、涝）是其重要特征。而水文过程是湿地最重要的生态过程，是湿地植物群落演变最重要的驱动力。旱涝是长江中游湖泊最大的灾害之一，在此开展水文情势变化对湿地植被演变影响研究，对于揭示其演变过程对水文情势变化的响应机制、丰富浅水湖泊生态学理论、提出应对气候变化的资源利用和管理策略有着重要的理论和现实意义。. 项目通过模拟实验、模型模拟和原位实验并利用遥感影像数据，研究了2011年以来，水文过程和水环境变化以及围网养殖和入侵种等因素对洪湖植物多样性、优势度和群落结构、类型及分布和演化的影响。研究结果表明：. 水文过程（旱涝）通过控制繁殖体和植物体的多寡与存亡直接影响湿地的多样性和生物量，进而导致物种优势度、群落结构、类型的改变，是影响植物群落分布和演化的主导因素。在长江中下游流域，这种“中度干扰”在自然状态下，都会“自然”恢复，并由此维持植物多样性、控制生物量、减缓沼泽化进程。. 但是，水质、人为扰动和入侵种起到了“环境筛”的作用，与水文过程变化一起，共同决定了植物群落演变的趋势和进程。. 而植物自身的特征，如冬性一年生的菹草，既通过生活史调节、减少了竞争，又能产生高效繁殖的石芽，具有“r-对策”特点，是其在诸多因素影响下，保持优势并扩展分布区的原因。红线草是“天蓬型”（canopy-forming）植被，且繁殖方式多样，是其在水文、水质影响下，保持优势的重要因素。而黄丝草为“k-对策”的“地毯型”（meadow-forming）植被，在旱涝及水质下降共同作用，其分布区逐渐向水质好、干扰小的中南部迁移。. 结论认为，近年来洪湖水生植被结构简单、破碎化且向中南部推移，是上述“干扰”以及环境因素共同作用的结果。基于项目成果，预测了洪湖湿地植被近期可能的演变趋势，提出了洪湖湿地处于发展变化的新时期构想，并据此提出了管理建议和对策。