US: USGS has made the latest edition of the National Land Cover Database (NLCD 2011) public.
Dividing the lower 48 states into 9 billion geographic cells, the massive database provides information about land conditions at regional to nationwide scales. Collected in repeated five-year cycles, NLCD data is used by resource managers and decision-makers to conduct ecosystem studies, determine spatial patterns of biodiversity, trace indications of climate change, and develop best practices in land management.
Based on Landsat satellite imagery taken in 2011, NLCD 2011 describes the land cover of each 30-meter cell of land in the conterminous United States and identifies which ones have changed since the year 2006. Nearly six such cells are each 98 feet long and wide. Land cover is broadly defined as the biophysical pattern of natural vegetation, agriculture, and urban areas. It is shaped by both natural processes and human influences.
NLCD 2011 updates the previous database version, NLCD 2006. The NLCD program is designed to provide five-year cyclical updating of our nation's land cover, similar to the cyclical population updating done by the U.S. Census.
NLCD 2011 products depict 16 classes of land cover in the lower 48 states, define the degree of surface imperviousness in urban areas (impervious surface extent — concrete, asphalt, etc. — serves as a marker for urban environmental quality), and quantify the amount of tree canopy cover (essential for applications dealing with wildfire, carbon sequestration, wildlife habitat, and biodiversity).
NLCD is constructed by the 10-member federal interagency Multi-Resolution Land Characteristics Consortium (MRLC). Additionally, NLCD editions from 2001 to 2011 have been integrated to provide a 10-year land cover change comparison for our nation at five year intervals. NLCD 2011 products will be also released for Alaska later this year. For more information on NLCD and to download NLCD data free of charge, visit theMLRC website.