An unmanaged forest understory in New Quarter Park, York County, provides a wide range of community and ecosystem health benefits to the Chesapeake Bay watershed. (Photo by Evan Visconti/Virginia Mercury)
Approximately 60% of Virginia is located inside the Chesapeake Bay watershed, and those communities now have access to an updated map that shows precisely how their landscapes are changing over time.
The Chesapeake Bay Program’s land use and land cover change mapping project compares the landscape across three different snapshots in time, offering a detailed view of the watershed up to as recently as 2021.
The research shows Virginia has lost nearly 50,000 acres of tree canopy in its portion of the watershed to development over just seven years.
The publically-available mapping project “empowers people with information that they can use to make longer term and more sustainable land-use decisions,” said Peter Claggett, research geographer with the U.S. Geological Survey and lead for the Chesapeake Bay Program land data team.
“Overall, it enables you, down to a community level, to identify opportunities for restoration and conservation and for everyone to gain a perspective about how their community is changing over time,” Claggett said.
The most significant change to the landscape between 2014 and 2021 that researchers hope to highlight with the data was a rapid loss of tree canopy and forests due to human development.
Tree cover status and change fact sheets were created as part of the project to provide county or municipality-level analysis of tree canopy and a summary of the local benefits those trees provide.
Experts quantified several of the benefits trees provide with a tool called iTree Landscape, which estimates how much air pollution, stormwater runoff and carbon are removed from the environment by the trees in communities.
The estimates provide a more concrete way for people to understand what tree canopy is worth, because “talking about acres of tree canopy between time periods is a little abstract in some ways,” said Elliott Kurtz, geospatial data engineer for the Chesapeake Conservancy’s Conservation Innovation Center, a contributor to the mapping project.
The iTree estimates show that “we’re not just doing this to protect the trees for the trees’ own sake; this is also providing real benefits to people in the community,” said Kurtz.
In addition to the watershed-wide mapping project, the Virginia Department of Forestry (DOF) is currently working on creating its own map as part of a 2024 General Assembly bill that requires the agency to create a “Forestland and Urban Tree Canopy Conservation Plan” for the entire state by November 2026.
The statewide data mapping project will compare how the landscape has changed between 2018 and 2023 through the use of aerial imagery and DOF’s “boots on the ground” knowledge of every timber harvest operation in the Commonwealth, Johnson said.
This will ideally provide an even more accurate look at how Virginia’s landscape is changing, and identify precisely which tree canopy losses are temporary as a result of rotational timber harvests and which are permanent as a result of development.
“The concern from the Chesapeake Bay Foundation is that when the land use changes completely to something other than forest, pasture or agriculture, then you lose the infiltration ability of the land,” said Ann Jurczyk, the Chesapeake Bay Foundation’s Virginia manager of urban restoration.
“Generally, that’s when you have increased storm water runoff and increased heat and the other things that are detrimental to both the people and the critters that live in the Bay,” Jurczyk said.
Claggett said one of the major benefits of landscape mapping is that it allows communities to zoom in or out and ask, “‘are we on a trajectory that we want to continue, or are we headed to become a place that we don’t want to become?’”
Emerging threats to tree canopy
A plot of land is cleared of trees for development in Charles City County. (Photo by Evan Visconti/Virginia Mercury)
The watershed as a whole lost just over 100,000 acres of tree cover to development over the seven-year course of the study so far, with nearly half of those losses occurring in Virginia, according to data from the project.
Researchers also analyzed losses of what they termed forested extent. These are lands that not only contained tree canopy with an unmanaged, natural understory when the images were taken, but also lands that were in the early stages of regenerating back into natural forest after being logged prior to imaging.
Taking these lands into account, data shows the watershed as a whole lost about 177,000 acres of forested extent to development, with Virginia contributing a loss of over 70,000 acres.
(Graphic courtesy of the Chesapeake Bay Program and the State of Chesapeake Forests storymap)
The research uncovered several emerging threats to tree canopy in Virginia, which include the construction of utility scale solar arrays, warehouses, road expansions and electrical transmission lines.
Landscape changes like these are considered permanent, whereas harvesting land for timber and then allowing it to regenerate, an industry that statewide adds over $20 billion to Virginia’s economy annually, is viewed as a temporary change to tree canopy and the forest structure.
Virginia’s portion of the watershed is seeing more development as a result of its emerging land uses, “and it’s very much along these sort of growth corridors from D.C. southward to Richmond and then from Richmond east to Hampton Roads,” said Jurczyk. “We’re growing by leaps and bounds; Charlottesville, Staunton, Harrisonburg all lost tree canopy as well.”
The timing of the mapping project allowed researchers to capture “the initiation of utility scale solar in the region,” said Claggett. The growing source of energy has major implications on how communities are making use of their land, particularly in Virginia where 54% of all solar panels that the project mapped throughout the watershed were found.
Between 2014 and 2018, the project mapped just over 600 acres of solar panel arrays in the Commonwealth. Then between 2018 and 2021, that number jumped to over 3,200 acres of solar panel arrays mapped.
“Unlike other states, in Virginia for the first time period, 74% of (land containing solar arrays) came from forested extent, and the second time period saw 68% come from forested extent,” Claggett said.
These percentages signify yet another competing land use in Virginia’s forestlands.
“Ideally, we’d like to see solar on reclaimed mine lands, on rooftops, on landfills, on land that can’t be used for agriculture or forestry,” Claggett said.
The biggest solar operations currently in Virginia were installed shortly after the 2021 mapping imagery was captured. Claggett said he expects the next round of imagery to pick up between roughly 10,000 to 15,000 more acres of solar arrays in Virginia.
The next update to the Chesapeake Bay Program’s land cover mapping project will analyze imagery from 2025 and 2026. Researchers expect to publish that data before 2029.
A closer look at our streams
The project also released new high-resolution hydrography data, or mapping of how water moves throughout the landscape, to provide the most comprehensive inventory of the watershed’s stream and ditch network to date, according to researchers.
Without updated mapping, if streams are modified or buried over, then we “lose track of how the landscape drains,” said Matt Baker, professor of geography and environmental systems at the University of Maryland, Baltimore County.
The hydrography data has the ability to pick up tiny streams and channels that exist in the headwaters of large rivers that eventually drain into the Chesapeake Bay.
“It’s quite important for us to know about them in our mapping efforts because they are conduits for both the water, nutrients and other pollutants that might move across the landscape,” said Baker. “So in the context of the Chesapeake Bay Program, it’s really important to understand where the water is flowing and what it might be carrying on its way to the Bay.”
Mapping waterways improves researchers’ understanding of where aquatic habitats may exist and what is restricting the natural movements and migration of different species.
The Virginia Department of Wildlife Resources fish passage program samples small streams that flow into the Chickahominy River for environmental DNA of threatened migratory fishes. (Photo by Evan Visconti/Virginia Mercury)
Possible blockades such as culverts, the drainage pipes beneath roads and other infrastructure, can create a barrier to threatened migratory species such as river herring and American shad that depend on making it upstream to spawn.
Updated mapping also allows researchers to identify streams that are missing from existing maps but could be providing aquatic habitat.
An alewife, a type of river herring, caught and released during a Virginia Department of Wildlife Resources electrofishing survey on the Chickahominy River. (Photo by Evan Visconti/Virginia Mercury)
“We’re finding this data shows a lot more streams that hold fish populations,” especially for species found in the colder headwater streams that the research homed in on, said Mike Evans, deputy director of the Chesapeake Conservancy Conservation Innovation Center.
Community tree planting efforts
Despite the significant loss of tree canopy and forested extent to development, communities throughout the watershed still managed to plant a historic number of trees.
“I know there is some discussion of loss, but we also have hit record numbers of new trees in the ground,” said Lara Johnson, the Virginia Department of Forestry’s urban and community forestry program manager.
In 2024, there were about 5,700 acres of community trees planted throughout the Chesapeake Bay watershed, the highest total reported since tracking began in 2014, according to community tree planting data compiled by the Chesapeake Bay Program.
“We’re so proud of our partner Bay states and also all of our partners in Virginia,” said Johnson, highlighting several of the “grassroots” community planting programs that DOF supports.
Volunteers plant trees at Dudley Mountain, Albemarle County, as part of the James River Buffer Program (Photo courtesy of the James River Association)
The Virginia Trees for Clean Water Grant Program is available to communities looking to fund tree-planting efforts that raise public awareness of the benefits of trees and their impacts on water quality. The Throwing Shade VA Program provides a discount on native trees purchased from a Virginia nursery.
“Both of those programs have planted more than 70,000 trees just last year in Virginia,” Johnson said.
Riparian buffers, a major contributor to the overall health of the Chesapeake Bay, are strips of forest that border waterways and act as a natural filter to remove pollutants from runoff before they enter a stream or river.
The Riparian Forests for Landowners (RFFL) program is unique in that it “establishes buffers on landscapes that we probably wouldn’t typically be able to,” said Patti Nylander, the Virginia Department of Forestry’s watershed program coordinator.
The program is open to small, private landowners, a demographic which normally misses out on riparian buffer funding that typically targets large agricultural lands. The program has already added 110 acres of riparian forest buffer in Virginia, said Nylander.
The James River Buffer Program is also making progress on riparian buffer planting. Since its launch in 2019, the collaboration has installed about 1,300 acres of riparian buffer, equal to over 400,000 native trees.
(Map courtesy of the James River Association.)
In addition to planting new trees, Jurczyk said communities need to “put more emphasis on preservation of existing tree canopy and less emphasis on what we replace.”
“Part of that is just understanding at the locality level just how hamstrung we are on enforcing tree canopy replacement,” said Jurczyk.
In Virginia, localities can only require that up to 10% of trees be replaced after removal for developing a commercial or industrial site and 20% or 30%, depending on the district, be replaced after removal for developing a residential site.
The Chesapeake Bay Foundation has argued year after year that the replacement percentage should be “a floor, not a ceiling” on the amount of trees that a locality can require to be replaced after removal for a development, said Jurczyk.
Del. Patrick Hope, D-Arlington, was chief patron of a bill in this year’s General Assembly session that would have given localities statewide the option to enforce higher tree canopy replacement percentages that are currently available only to Planning District 8 in Northeastern Virginia.
After approval by both the House and Senate, Gov. Glenn Youngkin vetoed the bill.
“The current law on tree canopy ordinances strikes a balance between the ability of a locality to hinder residential and commercial development with increased costs and the ability of a locality to preserve tree canopy,” Youngkin wrote in his veto statement.