The latest edition of the National Land Cover Dataset (NLCD 2011) for Alaska is now publicly available.
The extensive NLCD database continues to add to our understanding of where land cover change has occurred across the Nation over time. Derived from carefully calibrated, long-term observations of Landsat satellites, NLCD data are used for thousands of applications such as best practices in land management, indications of climate change, determining ecosystem status and health, and assessing spatial patterns of biodiversity.
“Recognizing that land cover is changing rapidly in the high latitudes of the Arctic, it is vital that we have the clearest view of the spatial and temporal patterns associated with those changes,” said Suzette Kimball, acting Director of the U.S. Geological Survey. “As the Arctic becomes more accessible to human endeavors, understanding changes in land cover becomes critical in both using and preserving Alaska’s precious resources.”
For Alaska, this database is designed to provide ten-year cyclical updating of the state's land cover and associated changes. Based on Landsat satellite imagery taken in 2011, the data describe the land cover of each 30-meter cell of land in Alaska and identifies which ones have changed since the year 2001. Nearly six such cells - each 98 feet long and wide - would fit on a football field.
The updated information tells an objective 10-year land cover change story for Alaska. With a decade of change information available, resource managers, researchers, planners in government and industry —anyone who wishes to investigate the topic — can better understand the trajectory of land cover change patterns and gain insight about land cover change processes.
By far the greatest Alaska change across this decade has been the conversion of forests to shrub and grasslands, primarily as a result of wild land fire. Other land cover categories that have experienced losses from 2001-2011 include perennial ice and snow and wetlands.
NLCD is constructed by the 10-member federal interagency Multi‑Resolution Land Characteristics Consortium (MRLC). This on-going 20 year collaboration of MRLC demonstrates an exemplary model of cooperation among government entities that combine resources to efficiently provide digital land cover for the Nation. Their teamwork in producing the NLCD not only significantly advances land cover science and data, but saves taxpayer money.
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 products provide 20 classes of land cover in Alaska and also define the degree of surface imperviousness in urban areas (usually composed of concrete, asphalt, stone, and metal — widely recognized as a key indicator of environmental quality in urban areas).
The range and spatial accuracy of this information have made it essential to thousands of users, enabling managers of public and private lands, urban planners, agricultural experts, and scientists with many different interests (for instance, climate, invasive species or hydrogeography) to identify critical characteristics of the land and patterns of land cover change. The data informs many fields of environmental investigation, from monitoring forests to modeling water runoff in urban areas.
NLCD 2011 products were released for the conterminous U.S. last year; products for Hawaii and Puerto Rico will be released later this year. NLCD data can be downloaded free of charge at the MRLC website.