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A Professional Forester's
Point of View |
By District Ranger Dave Freeland, Sequoia National Forest
The
public may not be aware that their public forests are in a generally
unnatural condition due to the exclusion of fire playing its natural
role within the ecosystem for the last hundred years. This situation
has created overcrowding of trees, along with other associated
vegetation. Forest Ecologists have determined that in pre-settlement
times, a range of 40 to 70 conifer trees per acre existed in the
western landscape. Low intensity fires, burning on a regular basis,
thinned the forest. In comparison, forested areas today contain as
much as 400 to 500 trees per acre. Over crowded forests create an
environment where individual trees have difficulty competing for
limited sunlight, soil moisture and nutrients. As a result, trees
become stressed and are more susceptible to premature mortality from
extended periods of drought and from attack by insects and other
forest pathogens.
Another unwanted condition from fire exclusion is that more shade
tolerant trees become established on each acre due to tree density.
White fir and incense cedar are two shade tolerant tree species
common in our area. In contrast, Ponderosa and Jeffrey pine are less
tolerant to shade as they grow. The foliage of young fir and cedars
extend close to the forest floor, which creates a ³fuel ladder²
where fire can quickly climb low hanging limbs and become
established in the upper reaches of the tree canopy. What should
have been a low intensity ground fire becomes a crown
fire potentially leading to a stand (forest) replacing event.
A more dramatic consequence from unnatural forests is the abnormal
number of catastrophic fires that have occurred over the past 30
years. Excessive tree density, in combination with abundance of dead
and down vegetation and old, decadent brush fields, has created a
formula for disaster. Catastrophic fires have adversely affected
millions of acres over the last several decades well beyond what
occurred historically. As a recent member of a national incident
management response team, I personally witnessed extreme fire
behavior all over the country that took human life, personal
property and destroyed ecosystems that will not be fully recover for
several life times even under ideal conditions. The Manter (2000)
and McNally (2002) are recent examples of unusually large and
devastating fires. The McNally was the largest recorded fire to
occur on the Sequoia National Forest.
What is the solution? Professional land managers, with the
assistance of researchers, continually identify areas of concern,
assess ecosystem function and health, and implement a number of
management strategies. One common practice is to mechanically thin
selected forested areas to reduce the number of trees to within
acceptable limits. Other management actions within the Foresterıs
tool bag include, but are not limited to, introducing fire back into
the ecosystem where appropriate to reduce density of trees and
brush, promote regeneration and establish younger age classes of
vegetation mixed with the older age classes. Less catastrophic
fires, endemic, rather than epidemic insect and disease intrusions,
more succulent food sources for a variety of wildlife species and
improved cattle grazing are positive outcomes.
There are currently two acceptable methods of introducing fire back
into the ecosystem. One method is prescribed burning, which is the
intentional ignition of fires within selected areas, by highly
skilled fire professionals. Prescribed burning can only be initiated
when air temperature, humidity, fuel moisture, wind speed and
direction, optimum smoke lofting, etc. are within acceptable limits.
A more recent technique being used on public lands is wildland fire
use. When a naturally caused fire starts by lightning, wildland fire
use can be approved within predetermined areas, such as wilderness
areas located on the Kern Plateau. In 2003, approximately 5000 acres
were treated within the South Sierra Wilderness through wildland
fire use. Additional acres were treated in 2004. The U.S. Forest
Service intends to expand wildland fire use as a viable tool to
allow fire to play a more natural role in the ecosystem for a
variety of resource and social benefits.
Through continued and appropriate mechanical thinning, prescribed
burning and wildland fire use, land management professionals have
renewed hope to transition valuable public lands back into an
acceptable natural and healthy condition, more resilient to unwanted
catastrophic events. Though this multi-agency effort will take many
decades to make a noticeable difference, wonıt it be worth the
effort?
Dave Freeland
District Ranger
Cannell Meadow/Greenhorn Ranger Districts
Sequoia National Forest
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