鄱阳湖湿地维管束植物景观对湖泊水位变化的响应研究

The relationship between wetland ecosystem structure, processes and functions is the leading edge and hot spot of research. The uncertainty remains about how water level affect landscape of plants in the study on the structure, function and process of wetlands ecosystem, yet the multi-scale is the effective measure to resolve related complex system as well as landscape evolving. Consequently, this project will take the Poyang Lake (the largest freshwater lake in China) wetlands in Jiangxi Province as an example. One major aspect will be to apply and compare various scales of mapping which has been identified as a bottleneck in landscape ecology. We will investigate the effects between the water level changes and the range and performance of landscape of vascular plants in the wetlands. The project proposes to evaluate measured water level data, with typical sample spot and localization investigations on landscape of vascular plants, including species, population, community and their habitats, and the application of remote sensing and geographic information system with high precision remote sensing image data and DEM data. It is expected to get an insight on species biodiversity, population dynamics, community succession, and the habitats (microclimate, soil and water) of vascular plants. In methodological terms, the project proposed will apply different scaling methods in order to identify a suitable analytical method. The relation of cause and effect between the changing water levels and the landscape of vascular plants, the characteristics of landscape of vascular plants in the micro-middle-macro scales, and the coupling relationship among water levels, landscape of vascular plants, and the entire vascular plants ecosystem（mainly habitats） are probed in the project. We will conceptualise the characteristics representing the causal connection between the water level and landscape of vascular plants to analyze, predicate and evaluate the evolving regularity of landscape of vascular plants corresponding with water level changes based on the data and information of hydrology, geography, habitats, and vegetation. Finally, the project explores how the ecosystem of hydrophytes responds to global natural abnormal changes as well as human activities' disturbance.

湿地生态系统结构、过程和功能的关系是研究的前沿和热点，水位对湿地植物景观结构及其功能的影响具有不确定性，而多尺度分析是剖析复杂景观变化的有效工具。 以鄱阳湖水位变化和湿地维管束植物景观为对象，拟采用典型样地调查和定位观察方法、实验室分析测试方法以及遥感与地理信息技术的应用，利用湿地水文数据、野外调查获取的湿地维管束植物物种、种群和群落及生境数据、湿地维管植物景观高精度遥感影像数据、湿地高精度的DEM数据等，通过多尺度的比较研究，获取最优的湿地维管束植物景观分析尺度，探究水位变化环境下湿地维管束植物景观特征，探索湖泊水位变化与湿地维管束植物景观的响应关系、湿地维管束植物景观在微观-中观-宏观尺度上的表征以及湖泊水位变化、湿地维管束植物景观与湿地维管束植物生境三者之间的耦合关系，分析湿地维管束植物景观-水位响应的生态过程及其演变规律，从而有助于揭示湿地植物生态系统对全球变化和人类活动干扰的响应。

湿地生态系统结构、过程和功能的关系是研究的前沿和热点，水位对湿地植物景观结构及其功能的影响具有不确定性，而多尺度分析是剖析复杂景观变化的有效工具。鄱阳湖是中国最大淡水湖泊，国际重要湿地。鄱阳湖湿地年际水位变化极为显著，近年来，鄱阳湖湿地水位变化更加剧烈，丰水期低水位，水位消退时间提前，水位消退速度加快，涨水时间推迟，水位上涨急剧等现象更加突出，水位异常变化会导致鄱阳湖湿地生态系统的改变，特别是作为湿地初级生产力的维管束植物，异常水位条件下，环境胁迫加大，维管束植物物种多样性、群落演替也可能出现变化。本课题以鄱阳湖水位变化和湿地维管束植物景观为对象，采用典型样地调查和定位观察方法、实验室分析测试方法以及遥感与地理信息技术的应用，利用湿地水文数据、野外调查获取的湿地维管束植物物种、种群和群落及生境数据、湿地维管植物景观高精度遥感影像数据、湿地高精度的DEM数据等，通过多尺度的比较研究，获取最优的湿地维管束植物景观分析尺度，探究水位变化环境下湿地维管束植物景观特征，探索湖泊水位变化与湿地维管束植物景观的响应关系、湿地维管束植物景观在微观-中观-宏观尺度上的表征以及湖泊水位变化、湿地维管束植物景观与湿地维管束植物生境三者之间的耦合关系，分析湿地维管束植物景观-水位响应的生态过程及其演变规律。结果表明，鄱阳湖湿地主要表现为高水位持续下降，退水时间加快，高水位持续时间减少，低水位持续时间延长。表明鄱阳湖湿地水量减少，水量性缺水越来越严重。鄱阳湖湿地中水体、草洲、泥滩、沙地的面积随着水位变化均呈现出一定的规律性：水体面积与水位值呈显著正相关关系；泥滩、草洲、沙地的面积与水位均呈负相关关系，即三者的面积随着水位的升高而降低。鄱阳湖洲滩前缘维管束植物的分布特征由湖岸至湖底依次为假俭草（狗牙根）群落（>15m）、南荻群落/芦苇群落（14~15m）、灰化薹草群落(11~14m)、水田碎米荠群落/虉草群落（<11m）。