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Urban Tree Canopy sees increase in Baltimore

The image shows Washington Boulevard tree canopy in 2007 (top image) and the same view in 2015. Images courtesy of the University of Vermont Baltimore, MD, September 22, 2017 - While most urban communities throughout the U.S. are losing tree canopy cover due to a wide variety of threats – including insects, disease, and storms – Baltimore is bucking the trend. Between 2007 to 2015, the City of Baltimore saw a small increase in its urban tree canopy cover. 

Data analyzed by the U.S. Forest Service in collaboration with the City of Baltimore and the University of Vermont show that the city’s urban tree canopy inched up from 27 percent to 28 percent between 2007 and 2015. Tree canopy is the extent of the outer layers of leaves, or canopy, of a tree or group of trees. Percentage of tree canopy cover measures the portion of an area that has tree coverage when viewed or measured from above. While the increase in tree canopy is not dramatic, it is a meaningful step in the right direction, according to Morgan Grove, a research forester and team leader in the Forest Service’s Baltimore Field Station.

Tree canopy change is more complicated than a single statistic. Over the 2007-2015 time period, areas throughout Baltimore experienced both substantial gains and losses in tree canopy cover. The gains totaled 1,500 acres, while the losses totaled 1,300 acres, for a net gain of 200 acres. Grove and a team that included the University of Vermont and the City of Baltimore assessed tree canopy change in Baltimore using high-resolution aerial imagery and 3D airborne Light Detection and Ranging (LiDAR) data. Change was mapped at the individual tree canopy level for every single tree in the city, overcoming the limitations of other studies that used coarser resolution data or sample-based approaches.

“Tree coverage has immense benefits not only to Baltimore city residents, but also to surrounding communities,” Grove said. “Our research has demonstrated that in addition to helping cool buildings and cleaning the air, there is a whole host of ways that urban trees benefit people. In some cases, research has shown that trees can help deter both violent crime and crimes against property. Trees can also help reduce incidents of asthma and other respiratory illnesses.”     

Grove recently presented research on the city’s urban forest as part of a semi-annual meeting of TreeBaltimore; TreeBaltimore is the city’s program coordinating all tree plantings by city agencies, non‑profit organizations, neighborhoods, and community associations.

The city of Baltimore’s goal is to establish 40 percent tree cover by 2030, an increase that is unlikely to happen in steady increments. “Whether due to human activities or natural events, change in urban tree canopy can be instantaneous and dramatic,” said Erik Dihle, Baltimore’s city forester. “Tree canopy increases resulting from new plantings, natural regeneration, and growth, are slow processes that take time and commitment.”

The Urban Tree Canopy approach and protocols were developed by the U.S. Forest Service in 2006 to map and quantify land cover for Baltimore City and aid decision-makers in understanding their urban forest resources, particularly the amount of tree canopy that currently exists and the amount that could exist at multiple scales. The Urban Tree Canopy assessment protocols have since been applied to dozens of counties, cities, and towns in the United States and Canada.


The mission of the Northern Research Station is to improve people's lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.


The mission of the U.S. Forest Service, an agency of the U.S. Department of Agriculture, is to sustain the health, diversity and productivity of the nation's forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains world-renowned forestry research and wildland fire management organizations. National forests and grasslands contribute more than $30 billion to the American economy annually and support nearly 360,000 jobs. These lands also provide 30 percent of the nation's surface drinking water to cities and rural communities; approximately 60 million Americans rely on drinking water that originated from the National Forest System.


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Last modified: September 22, 2017