地形对贺兰山高山林线分布高度的影响

Effect of topography on alpine timberline altitude of Mountain Helan

运用遥感数据和空间分析技术提取贺兰山高山林线,并结合DEM数据计算相关地形因子,采用相关分析和多元回归分析定量研究不同地形因子对高山林线分布高度的影响.结果表明,贺兰山高山林线上、下边界平均高度分别为3 106和3 022m,主山脊西侧山地高山林线上、下边界分布高度范围和平均高度比东侧略高.在山地两侧影响高山林线上边界高度的地形因子及其贡献率具有差异.南北朝向指数和地形指数对山地西侧高山林线上边界高度变化的相对贡献率分别为56.7%和43.3%;南北朝向指数、地形指数和坡度对东侧高山林线上边界高度变化的相对贡献率分别为50.9%、31.0%和18.1%.坡向是影响贺兰山高山林线分布高度的重要地形因素,而坡面凹凸程度和坡度对高山林线分布高度的影响与其他地形因素具有一定关系.

Alpine timberline （AT） positions on Mountain Helan were obtained from RS data by spatial analysis, topographic data were used to quantify effect of topography on AT altitude with correlation analysis and multiple linear regression analysis. The mean altitude of AT upper and lower borderline was found to be 3 106 m. a. s. 1 and 3 022 m. a. s. 1, respectively. The range and mean altitude of both AT borderlines was found to be higher on the west side of Mountain Helan. The contribution of South-North Contrast Index （SNCI） and Topographic Index （TI） to the altitude of AT upper borderline on west side was 56.7% and 43.3%, respectively. Contribution of SNCI, TI and Slope to the upper borderline of AT altitude on east side was found to be 50.9%, 31.0% and 18. 1%, respectively. Therefore aspect is a significant factor regulating AT altitude.