华北土石山区中尺度流域防护林空间格局动态变化研究

Dynamic change of protection forest pattern in middle-scale watershed in rocky mountain areas of northern China

以北京市密云县境内的红门川流域为例,利用该流域1990、1995和2000年3期遥感影像资料,基于3S技术进行图像解析和数据处理,建立了流域空间数据库和属性数据库,并进行流域防护林空间格局动态变化分析。从防护林面积结构变化、斑块个数变化、斑块面积变化、斑块总边缘长、斑块平均形状指数、防护林变化速率和区域差异等角度,研究中尺度流域防护林空间格局的变化。结果表明:红门川流域自1990年以来,防护林的林种类型为针叶林、阔叶林、混交林、灌木林地和其他林地,而且不同林种所占比例均比较稳定。流域内防护林的斑块数目变化较小,破碎度逐渐缩小并稳定。斑块大小差异很大,形状偏离正方形,曲折度高,不规则。防护林在不同时期的动态变化不明显,红门川流域防护林空间格局呈稳定态势。

Taking the Hongmenchuan Watershed in Miyun County of Beijing as an example,using the image data of remote sensing of 1990,1995 and 2000,the authors established watershed spatial database and attribute database by analyzing images and data using 3S technologies.Then,dynamic changes of protection forest patterns in the middle-scale watershed were discussed,including area structure,number of patches,area of patches,total length of patch edge,mean shape index of patches,dynamic degree and regional difference.The results show that the protection forest in the Hongmenchuan Watershed was composed of coniferous forests,broad-leaved forests,mixed forests,shrubbery and other forestlands.Moreover,the proportion of different forests remained relatively steady.There was little change of number of patches of the protection forest in the watershed.The degree of fragmentation decreased gradually and tended to stable,while the size of patches varied clearly and their shapes presented a deviation from square shape with high tortuosity and irregular arrangement.There were no obvious dynamic changes for the protection forest in different periods.The spatial distribution of the protection forest in the Hongmenchuang Watershed is stable in the future.