USGS Gap Analysis Project Additional Data: Canopy Cover

Some species respond to the amount of canopy cover within a habitat type. The Percent Canopy Cover dataset was derived from the National Land Cover Dataset. The canopy cover database was compiled from the National Land Cover Dataset, and classifies each pixel into 101 possible values (0% - 100%). The canopy density estimate applies to the forest classes only. For further information on Canopy Cover, see http://landcover.usgs.gov/pdf/canopy_density.pdf. This dataset is a continuous canopy cover percentage and cover the entire U.S. These raster data have a 30 m x 30 m cell resolution. The USGS Gap Analysis Project (GAP) used the best information available to create the elevation ancillary data; however GAP seeks to improve and update these data as new information becomes available.

部分物种会对栖息地内的冠层覆盖度水平做出响应。冠层覆盖百分比数据集（Percent Canopy Cover）源自国家土地覆盖数据集（National Land Cover Dataset）。该冠层覆盖数据库基于国家土地覆盖数据集编制，将每个像素划分为101种可能的取值（0%至100%）。冠层密度估算仅适用于森林类地物。如需了解冠层覆盖的更多详情，请参阅：http://landcover.usgs.gov/pdf/canopy_density.pdf。本数据集为连续型冠层覆盖百分比数据，覆盖美国全境。该栅格数据的像元分辨率为30米×30米。美国地质调查局间隙分析计划（USGS Gap Analysis Project, GAP）采用现有最优信息编制了高程辅助数据；不过GAP计划将在获取新数据后对该数据集进行改进与更新。