基于RS和GIS的贺兰山高山林线初步研究

论文基于RS和GIS方法,运用Landsat 8-OLI影像和DEM数据获取贺兰山高山林线分布信息,并对林线植被NDVI特征和林线分布特征进行研究。结果表明：1）生长季初期山地针叶林和高山灌丛草甸NDVI值差异明显,两种植被NDVI栅格像元的分布及其数量在山地垂直空间的变化指示出贺兰山2 900~3 200 m海拔范围出现高山林线现象。2）贺兰山高山林线主要分布在中部顶峰周边区域,林线上边界平均高度3 106 m,下边界平均高度3 022 m。主山脊两侧区域的东坡和北坡林线的平均高度较高,西坡和南坡低。3）山地针叶林与高山灌丛草甸NDVI栅格数据可以作为影像分类数据的补充,对影像分类方式确定的高山林线分布区域进行修正,能够提高林线提取的准确性。

Primary Study on Alpine Timberline of Helan Mountain Using RS and GIS

The alpine timberline (AT) is an important ecotone of mountain vegetation. Extensive researches have been conducting in this ecotone for its dynamic state of vegetation and sensitivity to climate change. Investigating the location and the distribution of AT in a mountain area is significant for the research of dynamic AT. With the RS data and spatial analysis techniques, it is convenient and efficient to achieve this purpose. The Helan Mountain, which is in the adjacent area of the Yinchuan Plain and the Inner Mongolia Prairie, has a representative altitudinal vegetation-belt spectrum in the arid western part of China. It is a good area for AT research. The AT positions on Helan Mountain were obtained from Landsat 8-OLI and DEM by using RS and GIS methods. The NDVI of major vegetation types and vertical distribution pattern of ATs were analyzed in this study. The results are as follows: 1) The ATs on Helan Mountain appear on the altitudes of 2 900-3 200 m.a.s.l, which is revealed by the vertical distribution pattern of the subalpine conifer forest and alpine scrub, meadow. 2) The mean elevation of AT upper borderline and lower borderline is 3 106 m.a.s.l and 3 022 m.a.s.l respectively. The mean elevations of both AT borderlines are higher on the north and east slopes than on the west and south slopes. 3) The NDVI data is an effective supplement for image classification to detect AT.