These maps illustrate the history of deforestation in the United States by “showing the changes in virgin forest cover in the United States.” I have also tacked together an animated version of these maps in order to put the historical loss of virgin forest into a sense of proportion (there’s a three second delay between frames).

Undoubtedly, these forest resources played an important role in the development of the United States. However, the dramatic decline of virgin forest in the United States has impacted biodiversity. For example, the extreme loss of virgin forests has been attributed to the demise of the ivory-billed woodpecker (Campephilus principalis) — a large species of woodpecker that is most likely extinct or exists in very small, fragmented populations.

Admittedly, it is difficult to determine what first nature looked like or to define virgin forest, because Native Americans certainly impacted the natural landscapes of North America. More via Southern Forests For The Future (emphasis added):

Although definitions vary, a primary (or “virgin”) forest often means a forest of native species where there are no clearly visible indications of human disturbance and where ecological processes are not significantly disturbed. Identifying primary forests with precision is difficult, since Native Americans used fire to manage forests prior to European settlement. Given this limitation, one way to approach a definition of virgin forests in the South is those that have not been cleared since European settlement.

At the time of European settlement in North America, such forests covered nearly all of the East Coast. During the next two centuries, agriculture was the most important driver of forest loss in the South. By 1850, large portions of original forest had been cleared for agriculture, although substantial areas remained. Lands along the Atlantic coastal plain, which were the most densely populated areas of the South, saw the greatest loss of forests over this period. However, western areas of the region were largely unsettled, and land in Florida and the Appalachians was difficult to access, clear, and farm.

After the Civil War ended in 1865, the era of industrial logging began in earnest in the South. New railroads moved workers and heavy equipment and transported cut logs to mills and markets, making logging newly profitable throughout the region. The railroads themselves required vast quantities of lumber for crossties. Between 1870 and 1920, the South lost tens of millions of acres of forest.

By the end of the twentieth century, virtually no substantial tracts of virgin forest remained in the South. Remnants can be found in protected lands in parts of the Great Smoky Mountains and in southwestern Florida, but nearly all the South’s current extensive forested area has been previously logged. The remaining forests are located in areas that were difficult to access due to steep or swampy terrain.

Images were found here, here, here, here, here, and here.

UPDATE 1 (21 Jan. 12):

This map depicts the concentration of biomass within the United States. This map is different than the maps above, because the earlier maps depict virgin forest cover and the subsequent loss of virgin forest cover. More via NOAA:

Trees are one of Earth’s largest banks for storing the carbon that gets emitted by natural processes and human activities. Forests cover about 30 percent of the planet’s surface, and as much as 45 percent of the carbon stored on land is tied up in forests.

But did global forests hold more or less carbon in the past? And could they store more in the future? Does it matter where those trees are growing? Scientists really don’t know. But before they can find out, they’ll need a reliable inventory of what is growing today.

Josef Kellndorfer and Wayne Walker of the Woods Hole Research Center (WHRC) recently worked with colleagues at the U.S. Forest Service and U.S. Geological Survey to create such an inventory for the United States. The map above was built from the National Biomass and Carbon Dataset (NBCD), released in 2011. It depicts the concentration of biomass—a measure of the amount of organic carbon—stored in the trunks, limbs, and leaves of trees. The darkest greens reveal the areas with the densest, tallest, and most robust forest growth.

Over six years, researchers assembled the national forest map from space-based radar, satellite sensors, computer models, and a massive amount of ground-based data. It is possibly the highest resolution and most detailed view of forest structure and carbon storage ever assembled for any country.

Forests in the U.S. were mapped down to a scale of 30 meters, or roughly 10 computer display pixels for every hectare of land (4 pixels per acre). They divided the country into 66 mapping zones and ended up mapping 265 million segments of the American land surface. Kellndorfer estimates that their mapping database includes measurements of about five million trees.

“Forests are a key element for human activity,” says Kellndorfer. “Resource managers need to see forests down to the disturbance resolution—the scale at which parking lots or developments or farms are carved out by deforestation. We have to know how much we have, and where, in order to conduct sound management and harvesting.”