National Land Cover Database (NLCD) Tree Canopy Cover (TCC) Conterminous United States

The USDA Forest Service (USFS) builds two versions of percent tree canopy cover data, in order to serve needs of multiple user communities. These datasets encompass conterminous United States (CONUS), Coastal Alaska, Hawaii, and Puerto Rico and U.S. Virgin Islands (PRUSVI). The two versions of data within the v2023-5 TCC product suite include: The initial model outputs referred to as the Science data; And a modified version built for the National Land Cover Database and referred to as NLCD data. The NLCD product suite includes data for years 1985 through 2023. The NCLD data are processed to mask TCC from non-treed features such as water and non-tree crops, and to reduce interannual noise and smooth the NLCD time series. TCC pixel values range from 0 to 100 percent. The non-processing area is represented by value 254, and the background is represented by the value 255. The Science and NLCD tree canopy cover data are accessible for multiple user communities, through multiple channels and platforms. For information on the Science data and processing steps see the Science metadata. Information on the NLCD data and processing steps are included here. Data Download and Methods Documents: - https://data.fs.usda.gov/geodata/rastergateway/treecanopycover/美国农业部森林服务局（USDA Forest Service, USFS）开发了两款以百分比计量的林木冠层覆盖率数据产品，以满足多类用户群体的使用需求。该数据集覆盖美国本土（conterminous United States, CONUS）、阿拉斯加沿海区域、夏威夷群岛、波多黎各以及美属维尔京群岛（PRUSVI）。在2023年第5版林木冠层覆盖率（Tree Canopy Cover, TCC）产品套件中，包含两类数据版本：其一为初始模型输出成果，即科学版数据；其二为针对国家土地覆盖数据库（National Land Cover Database, NLCD）定制优化的修改版数据，即NLCD版数据。NLCD产品套件涵盖1985年至2023年的全时序数据集。NLCD版数据经过预处理，会将水体、非林木作物等非林木地物的冠层覆盖率值掩膜剔除，同时抑制年际噪声并平滑NLCD时间序列数据。林木冠层覆盖率的像素取值范围为0至100%，非处理区域以像素值254标识，背景区域以像素值255标识。科学版与NLCD版林木冠层覆盖率数据可通过多渠道、多平台向多类用户群体开放获取。如需了解科学版数据及其处理流程，请查阅科学版元数据文档；关于NLCD版数据及其处理流程的说明已包含在本文档中。数据下载与方法文档链接：- https://data.fs.usda.gov/geodata/rastergateway/treecanopycover/