Tree Canopy Change, 2009-2014, Prince George's County, MD

<pre>This layer is a high-resolution tree canopy change-detection layer for Prince Georges County, Maryland. It contains three tree-canopy classes for the period 2009-2014: (1) No Change; (2) Gain; and (3) Loss. It was created by first mapping tree canopy in 2014 using LiDAR and multispectral data and then comparing the new map directly to an existing tree-canopy map for the year 2009. Tree canopy that existed during both time periods was assigned to the No Change category while trees removed by development, storms, or disease were assigned to the Loss class. Trees planted during the interval were assigned to the Gain category, as were the edges of existing trees that expanded noticeably. Direct comparison was possible because both the 2009 and 2014 maps were created using object-based image analysis (OBIA) and included similar source datasets (LiDAR-derived surface models, multispectral imagery, and thematic GIS inputs). No accuracy assessment was conducted, but the dataset was subjected to comprehensive manual review and correction.</pre>