Riitters Kurt H, Wickham James D, Coulston John W
Southern Research Station, U.S. Forest Service, Research Triangle Park, North Carolina, USA.
Environ Monit Assess. 2004 Feb;91(1-3):257-76. doi: 10.1023/b:emas.0000009240.65355.92.
As part of the U.S. 2003 National Report on Sustainable Forests, four metrics of forest fragmentation--patch size, edge amount, inter-patch distance, and patch contrast--were measured within 137744 non-overlapping 5625 ha analysis units on land-cover maps derived from satellite imagery for the 48 conterminous States. The perimeter of a typical forest patch is about 100 m from the perimeter of its nearest neighbor, except when there is not much forest, in which case that distance is 200 to 300 m. A typical analysis unit has from 10 to 40% as much forest edge as it could possibly have, given the amount of forest present. Most analysis units contain a large number of patches that are less than one hectare in size, and about 10% contain one or more 2000 to 5000 ha patches. Forest often defines the background landscape, and patch contrast is generally either very high or very low in eastern regions and intermediate in western regions. Many research needs were identified by this experimental analysis of available data and metrics.
作为《美国2003年可持续森林国家报告》的一部分，在从卫星图像得出的48个毗连州的土地覆盖图上，对137744个不重叠的5625公顷分析单元内的四项森林破碎化指标——斑块大小、边缘数量、斑块间距离和斑块对比度进行了测量。一个典型森林斑块的周边与其最近邻域的周边距离约为100米，除非森林面积不多，在这种情况下该距离为200至300米。鉴于现有森林面积，一个典型分析单元的森林边缘面积为其可能达到的边缘面积的10%至40%。大多数分析单元包含大量面积小于一公顷的斑块，约10%的分析单元包含一个或多个面积为2000至5000公顷的斑块。森林常构成背景景观，在东部地区斑块对比度通常要么非常高要么非常低，而在西部地区则处于中等水平。通过对现有数据和指标的实验分析确定了许多研究需求。
