石羊河下游河岸带的景观结构及变化

Landscape Structure and Changes of Riparian Zone in the Lower Reaches of Shiyang River

应用景观生态学和空间对比分析方法,探讨石羊河下游流水和断流河段的河岸带景观,对其绿洲形成、分布及其结构调控和生态环境改善具有参考意义。结果表明：景观要素发生和分布受到河流地貌约束,顺直型河道区域的景观丰富度约为分汊型和漫流型的2倍,在漫流型河道区域以农田为优势斑块。流水和断流河段的景观结构分别呈带状水平结构和镶嵌结构,而斑块丰富度逐渐降低,均匀度增大。地下水位深度达7~8 m引发景观组成和结构变化,距离河床约200 m是河岸带景观发生转变的区域。石羊河下游河岸带景观变化时间与河流改道及水利改造时间相一致,因人类土地利用方式增减景观要素,区域水资源变化促进景观演变。河岸带景观结构是区域绿洲结构的基础。

Using landscape ecology and spatial analysis, the authors studied the riparian landscape in riverand dry stream segment of the lower reaches of Shiyang River, which could provide references for the oasisformation, distribution and the structure regulation and ecological environment improvement. The resultsshowed that： the occurrence and distribution of landscape elements were constrained by fluvial geomorphology;the richness of straight river channel was 2 times as much as that of branch and sheetflood; the farmland was adominant plaque at sheetflood region; the landscape structure of water and dry stream segment was horizontalstrip structure and mosaic structure, respectively, and patch richness gradually decreased, evenness increased;the landscape composition and structure changes caused by groundwater depth of 7- 8 m, the riparianlandscape change area was about 200 m away from the riverbed; the landscape change time of the riparian zonein the lower reaches of Shiyang River was consistent with the time of river diversions and water conservancy,the landscape elements changed due to human land use patterns, and the regional water changes promoted thelandscape evolution. The riparian landscape structure is the foundation of regional oasis structure.