摘要
以Landsat/TM为数据源,在桌面GIS支持下解译出研究区各景观类型,根据植被的生长周期,结合植被指数NDVI作为研究因子,采用目前较为流行的主成分变换法(PCA),结合景观类型图和数字高程模型(DEM),参考相关地理基础图件,对石羊河流域海拔和植被覆盖进行分级分类。运用叠置分析法研究了不同海拔高度和不同植被覆盖下NDVI变化情况;同时分析了各景观类型与海拔和植被覆盖三者之间的空间关系。结果表明:研究区各景观类型大体依海拔呈垂直性分布,各自然要素组成垂直分异性特征亦较为明显。植被覆盖、景观类型与海拔之间呈垂直型分布规律,低海拔区景观类型单一,主要为荒漠系统,且与植被覆盖关系密切,相关度也最高;高海拔区景观类型较为复杂并交错分布,与植被覆盖关系不大,拟合效果不理想。此次研究目的在于对石羊河流域景观格局特征和格局优化研究提供参考思路,对流域生态规划和治理提供依据,对干旱内陆河流域植被及生态环境变化研究具有深远意义。
With the support of GIS technology, and taking the Landsat/TM images as the data source, 14 types of landscapes in Shiyang River basin were obtained in the study by employing the artificial interpretation method. A series of other data such as DEM, vegetation maps, and landscape maps were used. Besides, principal component a- nalysis as well as regression methods were adopted to analyze the landscape changes in different atitude and vegeta- tion cover, also the spatial relationship between NDVI, DEM and landscpe types were researched. The results showed that the landscape types were vertical distribution in terms of elevation, and the vertical-specific characteristics of natural elements were more obvious. In low-altitude area,landscape distribution was more single, and the relation- ship between NDVI and elevation were closely associated. Relatively, in high-altitude area, the distribution of land- scape was staggered. Besides, the distribution of landscape types has evident altitudinal regularity from Qilian mountains in south to desert region in north, and the distribution order is approximately as follows ： glacier and snow - cold desert - water area - marsh land - grassland - woodland - farmland - residential area - overflow land - salinized land - bare soil - bare rock - sandy desert - gobi from valley to mountain top for the big verti- cal space of the height above the sea level. This shows that the influenced areas which are disturbed by human be-ings are in the low altitude. From advanced study,we find residential area is mainly distributed under 2 500 m, a- bout 84.5 % city and town residents live in the range of 1 200 - 3 000 m, but in the range of 3 000 and 4 000 m, residential area only occupies 16. 455%. In thealtitude of 4 500 m above, there is no residential distribution. Through further research ,we find the distribution boundaries and characteristics presented unbalanced. Hence the relaiontship among landscape types,NDVI and DEM were very complex,and the regression result about them were not very perfect. Seen from the whole study area, the landscape developed to the heterogeneous direction, this indi- cated that the proportional difference among various landscapes types was increasing, this kind of change has reflec- ted the human activity＇s influence to the whole landscape to a certain extent. However, the study provides a refer- ence to the landscape pattern and its optimization as well as ecological planning and management. The thoughtway and results were significant for vegetation and ecological environment changes in the arid inland revier basin. Using RS and GIS technology, we can understand the spatial relationship betwwen elevation, vegetation cover and land- scape Types through quantitative analysis in spatial patterns. This technology can explore idiographic landscape structures and related problems of the study area. However, the analysis data is not very ideal. For example, RS im- ages scan cycle is long and its spatial resolution is poor. So it is difficult to get better images of grassland in the growing season under the interferential condition. The data is too complex to analyze one by one. Some results have shortages in calculating and analyzing precision. It will be ameliorated in the future study.
出处
《干旱区地理》
CSCD
北大核心
2012年第1期91-98,共8页
Arid Land Geography
基金
国家自然科学基金项目(40971078)
甘肃省青年科技基金计划项目(1107RJYA077)
西北师范大学青年教师科研能力提升计划项目(SKQNYB10034)资助
