10 May 2010, 10:05am
Forestry education Restoring cultural landscapes
by admin

Barbed-wire pitch posts preserve forest history

Note: the following excellent essay is reposted with permission of EPTG editor John Cordsen. There is a surprising amount of history recorded in fence posts, of all things. This is our second fence post/history article. The first is Roger Underwood. 2005. The jam post and plain wire fence: An insight into York’s agricultural, ecological and economic history. Barladong (5) 2005: 16-27 [here].

Old fences reveal lessons

By Ron Gosnell, Special to the Estes Park Trail-Gazette, 05/06/2010 [here]

At old ranches and on some remaining farms near the foothills, one can see old barbed-wire-fence “pitch posts.” These relics of a bygone era artistically reveal some Colorado history and provide an interesting forestry lesson.

Pitch posts were cut and split from the dense and heavy wood of live pitchy trees. Pitch is a resin found in evergreen trees and it forms when trees are injured. When the injury is caused by heat from ground-surface, low-intensity forest fires, and the fire has not killed the tree, more sap is made. This resin then concentrates in outer layers of sap-wood.

Long ago, forest fires were started from lightning and often times by indigenous people. Native Americans knew that a flush of new and tender vegetation that sprouts after fire meant well-nourished game and thus better hunting. With no human effort to suppress forest fires, they were frequent, and trees were often injured by fire.

In those conditions, a “relatively young,” 150-year-old tree may have received fire damage three, four, five or more times in its lifetime. A living tree exposed to that many fires accumulates high concentrations of pitch all the way from its heartwood center out to the bark.

Many fire-injured trees had a portion of their lower bark burned off. Exposed and charcoaled wood made inverted V-shaped black areas called “cat faces,” usually on the uphill side. Often, the cat-faced trees healed over the charred surface with new wood, which can be seen in cross-sections of old pitch posts. Fire events can sometimes be dated by annual tree rings of wood that grew over the black fire scar or surround it.

Still other old forest fires left no definitive trace. Very light intensity fires did not scar trees. Other fires simply killed and then totally consumed tracts of young trees. Later, new forest hides old fire evidence. Unquestionably, though, prior to Colorado`s settlement, frequent fire and pitchy trees were parts of the forest environment.

Back then, many forest fires persisted for months. These long-lasting fires took on a variety of day-to-day behavior, depending upon weather, terrain and fuel conditions in their path. Some fires smoldered underground for a long time as root fires, only to be rekindled with a strong, dry wind. Over centuries of time, subsequent fires affected miles and miles of forest, covering a wide range of aspects and elevations.

Then things changed. Colorado settlers took advantage of an abundant supply of pitchy trees. Pitch wood resists rot. Fence posts cut and split from living pitch trees would seemingly last forever. Miners, farmers and ranchers paid a premium for solid, pitchy logs and wood-cutters soon depleted accessible forests of pitchy trees.

Decades later, encouraged by a forceful conservation movement, forests regenerated naturally or were replanted. Many trees grew, but pitchy trees did not. About the only evidence of pitch trees that we still have are “antique” pitch posts.

Sometimes these pitch posts are found in the darnedest locations. For example, you might find one pitch post standing at a place where you would never expect an old fence-line to have been. These lonely pitch posts actually strengthened a fence-line at critical locations and they remain, while other posts deteriorated long ago.

Some pitch posts are scattered about on local properties, part of previously larger forest tracts, or land that was divided-up for sale. In a few cases, lacking legal survey, pitch posts still serve as property line and corner-markers.

A lack of pitchy trees in existing forest is something to ponder. In spite of an abundance of trees, pitchy trees did not form, because while a “new” forest grew, frequent fire was the missing agent to produce pitch wood.

Original forests had many fewer trees. This is confirmed by personal observation records and by the earliest photographs of uncut forest. What existed was a sustainable forest condition, with frequent fires behaving as a beneficial tool.

Fires killed off much tree regeneration, and especially thin-barked lodgepole and highly flammable young Douglas and subalpine fir. Thick-barked ponderosa pine, however, was able to compete well, and at higher elevations than is generally recognized.

Following fires, a living forest had a plentiful pitch tree component which, incidentally, resisted bark beetles. Forests were sustainable because fires did not burn too fiercely. There simply wasn`t too much fuel accumulation to feed each succeeding fire.

Furthermore, at both low and higher forest elevations, the random nature of individual fires (location, duration, intensity) contributed to a patchwork forest diversity, which interrupted the continuity of vegetation. If a crown fire were burning through treetops, a break in the forest canopy would soon drop the flames to the ground.

Today`s crowded forest condition is the result of preserved forest re-growth and more than 100 years of effective fire suppression. Every year, without any compensating action for accrued growth, more stored solar energy accumulates as excess vegetation.

Excess vegetation includes an uninterrupted blanket of conifer trees. One example can be seen from Colorado Highway 7, about 11 miles south of Estes Park, near Camp Saint Malo. This is a popular tourist stop and photograph location.

Looking west into Rocky Mountain National Park from near St. Catherine Chapel, all the way up Mt. Meeker to timberline, a discerning eye can still differentiate subtle tree needle color and tree shape differences that reveal numerous old fire perimeters. But, these timber-stand differences are disappearing, more so every year. Instead of a previous variety of forest conditions in view, the whole timbered mountainside looks about the same.

Here and at other mountainous areas of public and private land, clearings caused by old fires have regenerated abundantly with trees. Patches of different-age trees now appear uniform, because little trees caught up to big ones in approximate size. Tree crowns now touch each other and aspen has been shaded out. Beneficial forest-structure diversity and associated pitchy trees are gone.

Some tree species that are plentiful now were not favored in previous times. Recent fire history is that most forest fires are contained when small, and in less than one day`s time. Forest absent of fire exposure encourages thin-barked and highly flammable trees to survive and thrive.

For a long time, there has been very effective forest fire control, with insufficient tree-thinning and managed fire. Our culture is motivated by a single-minded desire to save trees. Attempting fire reintroduction now to restore the ecosystem, without first taking away some of the fuel buildup, is risky.

Ironically, instead of our forests being well-protected as expected, they are prone to severe fires and unsustainable. Fires that escape initial attack release extraordinary amounts of stored energy. That heat usually kills all the trees in a fire`s path, rather than just injuring some.

Take a look at recent fire-scarred mountains. Where the forest was too thick with trees, or where there existed miles of uniform timber, almost all trees are dead. Dead trees do not produce pitch wood.

Those pretty, old pitch posts are painted with moss and lichens, wrapped with generations of barbed-wire and hammered with rusty spikes. If they could talk, maybe more people would understand the modern-day care needed to effectively protect our forests.

Author Ron Gosnell is a retired Colorado state forester.



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