ecoregion boundaries are used in analysis of Land Use Land Cover (LULC) trends
Source: US Geological Survey, Land Cover Trends Project
Virginia is part of the Eastern Temperate Forest. In Bailey's Ecoregions, Virginia includes the Outer Coastal Plain Mixed Province , Southern Mixed Forest Province , and the Central Appalachian Broadleaf Forest--Coniferous Forest--Meadow Province .
The Environmental Protection Agency has defined "Level III" ecoregions and drawn a map of the Mid-Atlantic ecoregions. Several Federal agencies are trying to adopt a common spatial framework - see the draft map of Common Ecological Regions of the Conterminous United States.
But no matter how you characterize the vegetation, can you identify the outline of the state, or any political boundaries? (Need a hint? See the aquatic ecoregion boundaries as defined by Omernik.)
Look close - can you find a natural distinction between the countries of Mexico, the United States, and Canada? If you were a robin migrating through the Atlantic Flyway, could you separate Virginia from North Carolina, or Quebec from Ontario?
Mother Nature and Father Time shaped the landscape without regard for politics. The reverse, however, is not true. Human behavior, displayed through political decisions, will re-draw the boundaries of natural vegetation and revise the normal range of species. If you fly over the western United States, you can see straight lines 30,000 feet below you. Those lines match the property lines of ranchers and farmers, defined initially by cadastral surveyors laying out townships, ranges, and sections according to the Land Ordinance of 1785.
That's nearly 180 years after the first settlement of Europeans in Virginia. After the Revolutionary War, Thomas Jefferson successfully pushed for the newly-independent but not-very-united states to require boundary surveys be finalized before settlement and sale of the of the Northwest Territory.
Jefferson had experienced (as a lawyer, member of the House of Burgesses, and as Governor) the legal confusion that interfered with settlement of new lands due to unclear property lines. "Metes and bounds" surveys in Virginia ("Starting at the big white oak tree, go 400 feet north...") do not always follow natural boundaries like watershed divides. Still, many modern property lines in Virginia reflect the edges of colonial tracts, parcels whose boundaries were defined by natural features in the 1600's and 1700's rather than an arbitrary rectangular survey system imposed upon the land in the 1800's. The edges between many fields and forests in Virginia reflect ownership changes, but the pattern is nowhere near as clear as in the western states.
This categorizing is not just an intellectual exercise in splitting hairs. By assessing how many acres in Virginia are represented by different communities, the state has determined the most important ones to protect. If you're a landowner in the state, the location of that line between "preserve" vs. "OK to develop" property is very, very important... If you're working with The Nature Conservancy, it's equally important to determine the "last great places" so you get the greatest ecological value for your land acquisition investments.
Those investments can be large. Restoring the Chesapeake Bay is not cheap, but it's not the most expensive restoration project now underway. The largest restoration project in history will cost $8 billion, to restore the Everglades. The Federal government will pay 50%, and Florida will finance the other half. Getting state and local funding was a major challenge, and shows how "ecological restoration" alone will not win political support. Instead, the Majority Leader in the Florida Senate described the investment as follows:
On that basis, local governments and the state are willing to invest in the initiative, since more water (drinking-quality water) will permit more economic growth. It will also improve the quality of life in southern Florida, of course, but that's not the selling point in the Florida business community. Note how rarely you hear that the restoration of the Chesapeake Bay will stimulate economic growth in Virginia - and then ask yourself why Virginia politicians have been reluctant to commit to funding or enforcing the state's share of the initiative to "Restore the Bay.".