NLCD tree canopy cover is a 30 m raster geospatial dataset that is available for the conterminous United States, coastal Alaska, Hawaii, and Puerto Rico. These data contain percent tree canopy estimates, as a continuous variable, for each pixel across all land covers and types and are generated by the United States Forest Service (USFS). The USFS derives tree canopy cover from multi-spectral Landsat imagery and other available ground and ancillary information. 2011 and 2016 Forest canopy products are available for the Continental United States, coastal Alaska, Hawaii, and Puerto Rico.
For additional information regarding creation of NLCD percent tree canopy products:
Coulston, J. W., Jacobs, D. M., King, C. R., and Elmore, I. C. 2013. The influence of multi-season imagery on models of canopy cover: a case study. Photogrammetric Engineering & Remote Sensing79(5):469-477.
Coulston, J. W., Moisen, G. G., Wilson, B. T., Finco, M. V., Cohen, W. B., and Brewer, C. K. 2012. Modeling percent tree canopy cover: a pilot study. Photogrammetric Engineering & Remote Sensing78(7): 715-727.
Click here for additional USFS Tree Canopy Cover Datasets