Thursday, 18 December 2014
Christopher E Soulard1, William Acevedo1, Kristi L Sayler2 and Janis L Taylor2, (1)US Geological Survey, Menlo Park, CA, United States, (2)US Geological Survey, Sioux Falls, SD, United States
Land-use/land-cover (LULC) change information for the entire conterminous United States is becoming more common, yet existing national-scale LULC datasets may provide an incomplete story of change or may contain questionable land change statistics. In order to evaluate these datasets appropriately, the overall quality, accuracy, or precision of LULC products needs be determined independently. To this end, the USGS Land Change Research Project manually collected LULC change for 676 sample blocks for the 2001-2006 and 2006-2011 time periods. The team identified 29 of 84 Level III EPA Ecoregions that underwent specific types and amounts of land change between 1973 and 2000, and updated LULC change information to 2011 in these regions using the same sample block classification procedure as the USGS Land Cover Trends project. Ecoregion specific alterations in the sampling density were made to expedite the completion of manual block interpretations. Results from this study include ecoregion-based statistical estimates of the amount of LULC change per time period, the most common types of conversions, rates of change, and percent composition. Overall estimated amount of change per ecoregion from 2001 to 2011 ranged from a low of 370 km2 in the Northern Basin and Range Ecoregion to a high of 78,782 km2 in the Southeastern Plains Ecoregion. The Southeastern Plains Ecoregion continues to undergo one of the most intense forest harvesting and regrowth cycles in the country, with 16.6% of the ecoregion changing between 2001 and 2011. These manually collected LULC change statistics provide a new, valuable resource that may be used along with other ground truth data and field verified LULC data to independently validate other land change products or used alone to conduct regional land change assessments.