Lessons in Forest Forensics

 Tom Wessels (above, center) can read the woods the way most of us can read a mystery book -- except he will figure out whodunit long before most of us casual woodswalkers even have a clue about the forest's cast of characters.  An ecologist and professor at Antioch University New England, Wessels is the author of Reading the Forested Landscape, a guide to discerning the history of virtually any piece of wooded land, and on Saturday afternoon, he led a group of interested folks through the forested landscape of the Hennig Preserve up in the Town of Providence at the western edge of Saratoga County.  The experience was offered as a gift to its volunteers by Saratoga PLAN (Preserving Land And Nature), and took place in this land-conservation organization's largest nature preserve, which, as these photos reveal, still lay deep in snow.


The brilliantly sunny afternoon began at the Providence Town Hall with a lecture/slide show in which Wessels illustrated the many ways humans have left their impact on the landscape, including lands that have reverted to mature forest after decades, even centuries, of use as pasture, cropland, or woodlots.  The 604-acre Hennig Preserve offered a splendid example of just such a forest, containing such obvious evidence of human habitation as old stone walls, a pre-Civil-War house foundation and well, and other intriguing features.  Armed with much new information about how to interpret this evidence, we then followed our master sleuth into the forest itself for a fascinating several-hour adventure.

This old stone wall gave Wessels an opportunity to demonstrate how to determine which side of the wall was once used for pasture and which was plowed for crops.  The very level land on the left would indicate a field that was annually plowed and cleared of rocks, while the rockier and more uneven land on the right would suggest that this parcel could have been pastureland, which did not need to be plowed as often, nor cleared of rocks.

Another section of the woods was filled with what Wessels calls "pillows and cradles," humps and depressions that form when living trees are blown over, creating pits in the forest floor that the trees' roots once filled, surmounted by heaps of roots and soil that came up with the fallen tree.  Over time, as the tree roots decay, these pits and mounds smooth out, but the forest floor retains a billowy quality that would have been leveled by plowing or beaten down by the hooves of grazing animals.  A landscape like this, then, was most likely used solely as woodlot and never cleared for agriculture.

This obvious evidence of human habitation, a cellar hole, also includes a clue that the house pre-dated the common use of cast-iron stoves for interior heating.  The rectangular structure in the middle of the far wall is what Wessels called a "basement," a word that was originally used to describe the masonry structures that supported a fireplace and chimney.  This evidence would indicate that the house pre-dated the Civil War of the 1860s.

When we reached a part of the forest that contained a large mound that was mostly clear of trees, Wessels described to us the methods and dangers of burning charcoal in just such mounds, a process that required constant attention by skilled colliers and could take several months.

When we explored areas of the forest that had not been cleared for pasture or cropland but rather left as woodlots for timber and firewood, we could see evidence of old tree stumps long after they had rotted away.   These two little Yellow Birches, for example, did not start to grow in mid-air, as they now appear, but rather began their life as seedlings sprouting on the surface of a stump that has since disappeared with age.

We encountered a good number of well-rotted tree stumps and learned to tell a White Pine from an Eastern Hemlock stump by either the presence or absence of  bark.  Hemlock bark is full of tannin and thus resistant to rot, and so we could find rings of Hemlock bark containing nothing but crumbles of what had been the wood.  In the case of White Pines, its bark drops off after about 25 years, but this conifer containes whorls of branches resistant to rot, as in the case of this stump with the whorl still intact. According to Wessel, it would take at least 70 years for a pine stump to achieve this degree of decomposition.

These are just a few of the fascinating lessons we learned on this afternoon's walk in a beautiful woods with a friendly group of folks committed to preserving such remarkable woodlands as the Hennig Preserve.  Or any of the other tracts in Saratoga County preserved by Saratoga PLAN.  Tom Wessels provided far more information than I could retain at first hearing, so I was happy to be able to purchase Forest Forensics, a clearly illustrated field guide that accompanies his even more comprehensive Reading the Forested Landscape (www.countrymanpress.com). 

It will be fun to see if I can apply this information as I move through all my favorite woodlands.  I'm sure I won't always be able to deduce the meaning of every feature I find, since even Wessels himself can't always explain the mysteries he encounters.  Near the end of our walk on Saturday, we came across several piles of rocks in the woods that by Wessel's own admission didn't conform to any of the theories he had posited.  But that's okay.  I like to think that some mysteries remain that have yet to be explained.