It’s clear from the research and case studies that the “Defensible Space” fire protection strategy is valid for Angel Fire home owners but the Village of Angel Fire “Wildfire Protection Plan” may be catastrophically flawed!
With some exceptions, according to a study conducted by the Forest Service’s Rocky Mountain Research Station, the modifications had “little apparent effect on fire severity.”
The accepted wisdom underlying the Healthy Forests Initiative is that poor management has left forests overcrowded, resulting in severe fire seasons in recent years.
An aggressive thinning program is needed, according to this analysis, to reduce the number and severity of western wildfires. Interior Secretary Gale Norton and other senior officials say that some 190 million acres of federal land are at severe risk of fire and must be treated.
But the Hayman fire offers several caveats to that way of thinking:
• The impact of forest thinning projects on fire — what works and what doesn’t under differing conditions — is not well understood. The research record is spotty at best.
• The amount of acres that need thinning in order to protect homes may be far less than commonly thought, and much of it is in private, not federal hands.
• The critical factor in keeping homes safe, according to a Forest Service researcher, is reducing flammable vegetation within 150 feet of homes and using fire resistant building materials.
For example, the recently released Sierra Nevada Forest Plan states that reduction of forest canopy cover actually causes more severe fires by increasing the velocity of “mid-flame winds.” Further, the Fire and Fuels section of the Sierra Plan acknowledges that “in areas where the larger trees have been removed, stand replacing fires are more likely to occur.” This same section, for the purposes of fire and fuels management, defines “large trees” as those over 12 inches in diameter.
There have been few empirical studies looking at the effectiveness of thinning as a treatment for reducing wildfire hazard (Frost 1999). The studies that have been conducted have reported highly variable results. Some studies indicate that thinning treatments designed to reduce fire risk actually increase the risk and severity of the fires (Huff, et al. 1995, van Wegtendonk 1996, Weatherspoon 1996). Although these treatments may reduce the flammable biomass in the area, they also lead to drier forests and higher winds (Countryman 1955, Agee 1997). Additionally, silvicultural treatments, even when conducted carefully, can lead to the following adverse conditions (excerpted from Frost 1999):
- Damage to soil integrity through increased erosion, compaction, and loss of litter layer (Harvey, et al. 1994, Meurisse and Geist 1994).
- Increased mortality of residual trees due to pathogens and mechanical damage to boles and roots (Hagle and Schmitz 1993, Filip 1994)
- Creation of sediment that may eventually be delivered to streams (Beschta 1978, Grant and Wolff 1991)
- Increased levels of fine fuels and near-term fire hazard (Fahnestock 1968, Weatherspoon 1996, Wilson and Dell 1971, Huff, et al. 1995)
- Dependence on roads, which result in numerous adverse effects (Henjum, et al. 1994, Megahan, et al. 1994)
- Reduced habitat quality for sensitive species associated with cool, moist micro-sites or closed-canopy forests (FEMAT 1993, Thomas, et al. 1993)
But when you remove that much canopy shade small trees and brush sprout and grow prolifically. Within 5 years or so the risk of catastrophic wildfire has dramatically increased. Also, immediately after logging the open canopy increases sunlight and wind on the forest floor. Forest fuels dry sooner and this also increases fire risk.
“The evidence suggests that wildland fuel reduction for reducing home losses may be inefficient and ineffective: inefficient because wildland fuel reduction for several 100 meters or more around homes is greater than necessary for reducing ignitions from flames; ineffective because it does not sufficiently reduce firebrand ignitions.”
Yet another study indicating thinning is ineffective or increases wildfire risk!
Effectiveness of Fuel Treatments
for Mitigating Wildfire Severity:
A Manager‐Focused Review and
Dr. Philip N. Omi, Professor Emeritus
P.O. Box 854
Sebastopol, CA 95473
Mr. Erik J. Martinson, Consultant
MarLynn Ecological Consulting
524 Whedbee Street,
Fort Collins, CO 80524
No relationship was found between thinning intensity and subsequent fire response among the thin‐only treatments, suggesting that any benefit from the reduction in canopy fuels is offset by the increase in surface fuels.
However, previous reviews of the literature on fuel treatment effectiveness have noted above all a paucity of empirical data and heavy reliance on anecdote, theory, and modeling (Carey and Schumann 2003, Martinson and Omi 2003, Graham and others 2004, Peterson and others 2005).
One anecdote from such systems suggests that thinning may exacerbate fire behavior (Alexander and Lanoville 2004), but data have not been presented that could be included in our synthesis.
Not just theoretical conjecture but the only actual test:
Alexander and Lanoville 2004
the following can be concluded:
1) an aspen stand after full green-up can serve as a very effective barrier to high-intensity crown fires under certain circumstances;
2) the NFPA 299 Standard was found adequate for a flanking crown fire; and
3) the positive effects of fuel removal–manipulation on potential fire behavior may be offset by the negative effects of decreased fuel moistures and increased in-stand winds, thus enunciating the need for treating the organic layer in order to modify fire behavior. Photographs of all three experimental crown fires associated with the ICFME fuel treatment tri-als carried out to date can be found on the ICFME website (http://fire.cfs.nrcan.gc.ca/research/environment/icfme/icfme_e.htm).