自然滩地型湖滨带陆向辐射带宽度界定研究

自然滩地型湖滨带是湖滨带修复的基本参照类型.自然滩地型湖滨带的陆向辐射带是其重要组成部分，是由湖泊最高水位线向陆域延伸一定范围的区域.陆向辐射带有水陆生态交错带的复杂性、过渡性，致使其宽度难以界定.为了探索自然滩地型湖滨带陆向辐射带宽度的界定方法，以太湖、长潭水库和下渚湖为例，基于对湖滨带空间结构特征的理解，以湿生草本植物的重要值计算平方欧氏距离（SED），采用移动分割窗技术（MSWT），界定上述湖泊自然滩地型湖滨带陆向辐射带宽度，并对影响宽度的因素进行分析.结果表明:太湖、长潭水库、下渚湖自然滩地型湖滨带陆向辐射带宽度分别为15~19、19~31、17~21 m.对陆向辐射带宽度与土壤理化性质、植物群落多样性进行相关性分析及冗余分析表明，自然滩地型湖滨带陆向辐射带宽度与土壤营养盐含量无明显相关性，与湖滨带坡度呈显著负相关（P < 0.01），与土壤含水率呈显著正相关（P < 0.05）.研究显示:移动分割窗技术可用于界定自然滩地型湖滨带陆向辐射带宽度；土壤含水率是影响自然滩地型湖滨带陆向辐射带宽度的主要因素，陆向辐射带坡度通过影响土壤含水率，进而影响湿生草本植物分布，是自然滩地型陆向辐射带宽度的次要影响因素. 

Delimiting Radiant Belt Toward Land of Lake-Terrestrial Ecotone with Natural-Wetland Type

The lake-terrestrial ecotone of the natural-wetland type is the basic reference type for lake-terrestrial ecotone restoration. As an important part of the lake-terrestrial ecotone of natural-wetland type, the radiation belt toward land delimited from the annual average highest water level toward land to some extent. The complexity and transitivity shared by lake-terrestrial ecotone makes it hard to delimit. In order to study the method of delimiting the range of terrestrial radiation zone in natural lake-terrestrial ecotone, took Taihu Lake, Changtan Reservoir and Xiazhu Lake as examples, based on the understanding of the spatial structure characteristics of lake-terrestrial ecotone, calculated the squared euclidean distance (SED) with the important value of hygrophic herbaceous plant, used the moving split-window technology (MSWT) to delimit the range of the terrestrial radiation zone in the lakeside zone, and analyzed the factors affecting the width. The results showed that the widths of the radiant belt toward land of lake-terrestrial ecotone of natural-wetland type of Taihu Lake, Changtan Reservoir and Xiazhu Lake were 15-19 m, 19-31 m, and 17-21 m, respectively. The correlation analysis and redundancy analysis were used to determine the relationship between width, soil physicochemical properties and plants community diversity. The results showed that this range had no significant correlation with soil nutrient content, and was significantly negatively correlated with slope (P < 0.01), and positively correlated with soil moisture (P < 0.05). This study shows that moving split-window technology can accurately delimit the range of terrestrial radiation zone in natural lake-terrestrial ecotone. Soil moisture content is the most important factor affecting the width of the radiant belt toward land of lake-terrestrial ecotone of natural-wetland type. The slope of the radiation belt toward land affects the soil moisture content, drives the distribution of hygrophic herbaceous plants, and is the indirect factor.