Green Blog: The Witness Trees

Reaching into the past, Melissa Thomas-Van Gundy paints a vivid picture of a highlands forest dense with white oak, flaming sugar maple and American beeches, with a scattering of yellow poplar, wild cherry and spruce pine and, here and there, a singular crab apple, elm or soaring sycamore tree.

That?s how the Monongahela National Forest in central West Virginia may have appeared before it was slowly distributed among settlers from 1752 to 1899, Dr. Thomas-Van Gundy suggests in research recently published by the Forest Service.

As the land was divvied up, surveyors documented the trees that rested at the imaginary corners and angles of the parcels to mark their boundaries. They were called ?witness trees? ? an expression also used today for trees that were present at key events in American history like Civil War battles. But in this instance, a witness tree was something humbler and more pragmatic ? ?that which witnesses a corner,? as Dr. Thomas-Van Gundy put it.

In the 1930?s, the staff of Monongahela National Forest translated all of these notes and sketches into maps illustrating the spread of various species. Later, this intricate cartography was revised and digitized in a project completed in 2005.

Using those digital maps, Dr. Thomas-Van Gundy and her co-author, Michael P. Strager, applied a technique called indicator kriging, which takes each tree species and, according to its dominance in the records, ?spreads it out? across the landscape ?based on probability,? as Dr. Thomas-Van Gundy put it. They also analyzed features like elevation and topography to describe likely species composition in specific areas. Finally, they produced maps showing what the landscape might have looked like before logging and farming got under way.

White oak and sugar maple were prolific, they found, while trees like red cedar, willow, and holly were scarce. The researchers have not yet researched or drawn comparisons with what trees dominate the forest today. But Dr. Thomas-Van Gundy said, ?I think I will find that some trees like yellow-poplar and black cherry are more common on the landscape now than before, as these species often are found after disturbances such as logging and grazing.?

By the time the study area became national forestland in 1920, the majority of it was heavily logged and grazed, she wrote in an e-mail. The most aggressive period in logging in the area was 1884 to 1903, when narrow-gauge railroads were built into the higher-elevation forests, she added. Fires often erupted in the wood debris left on the ground.

As with most of the national forests in the East, little thought was given back then to retaining the residual forest or regenerating the forest, she wrote.

For the Monongahela National Forest, of which a third is now protected wilderness and the rest available for grazing and timber harvesting, such tree studies could inform potential restoration efforts. ?The Nature Conservancy considers us a biological source? for wildlife, Dr. Thomas-Van Gundy said. ?We?re kind of a crossroads for some species, and we have some endemics like the Cheat Mountain salamander, and larger tracts of roadless area for black bears.?

Aside from species conservation, knowing where certain species adapted and thrived after fires might point to areas where controlled burns would work best, she added.

Across the globe, such historical data could be useful for all kinds of environmental restoration efforts in decades to come. But Dr. Thomas-Van Gundy cautioned against using witness trees as a prescription for exact reconstructions.

With so many variables to consider, including climate change and its impact on plant ranges, she said, assembling a blueprint remains a challenge. ?These old surveys help build the picture and find the missing pieces,? she said.

Source: http://green.blogs.nytimes.com/2012/09/18/the-witness-trees/?partner=rss&emc=rss

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