This interactive web map displays a high-resolution tree canopy change-detection layer for Baltimore City, MD. It contains three tree-canopy classes for the period 2007-2015: (Dark Green) No Change; (Light Green) Gain; and (Red) Loss. It was created by extracting tree canopy from existing high-resolution land-cover maps for 2007 and 2015 and then comparing the mapped trees directly. 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 2007 and 2015 maps were created using object-based image analysis (OBIA) and included similar source datasets (LiDAR-derived surface models, multispectral imagery, and thematic GIS inputs). OBIA systems work by grouping pixels into meaningful objects based on their spectral and spatial properties, while taking into account boundaries imposed by existing vector datasets. Within the OBIA environment a rule-based expert system was designed to effectively mimic the process of manual image analysis by incorporating the elements of image interpretation (color/tone, texture, pattern, location, size, and shape) into the classification process. A series of morphological procedures were employed to insure that the end product is both accurate and cartographically pleasing. No accuracy assessment was conducted, but the dataset will be subjected to manual review and correction. 2006 LiDAR and 2014 LiDAR data was also used to assist in tree canopy change.
Tree Canopy Change at the Neighborhood Level
The City of Baltimore is made up of roughly 250 neighborhoods. Here is a link to download a poster we created using the same data but broken down by neighborhood. The table on the right summarizes the tree canopy data by percent cover at the neighborhood level for 2007, 2015, and then the percent change over that time frame. Neighborhoods are represented numerically on the map. Some neighborhoods saw an increase in canopy cover while others saw a decrease or little change at all. This data combined with the city’s new tree inventory assists Tree Baltimore and partners in prioritizing tree planting efforts focusing on areas with lower tree canopy cover and/or tree canopy loss.
Click the link below to explore the map: