Tuesday, September 20, 2011

Arizona Wildfire Not As Damaging As First Reported


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A new GIS analysis of burn severity demonstrates less harm to forests than commonly reported.

The record setting fires of 2011 in the Southwest were widely reported as disastrous, yet new analysis by WildEarth Guardians shows the fires burned mostly as would be expected and may have long-term beneficial effects, with appropriate follow-up. Unfortunately, people lost homes and other structures in these fires.

Though the size of the individual fires broke all records for New Mexico and Arizona and fire behaved uncharacteristically in ponderosa pine – the fires mostly burned as expected. Where it burned unexpectedly hot highlights the need to focus scare resources on forest restoration in these vegetation types.

The results, based on preliminary data, reinforce the facts that fire is a natural process in southwestern forests and will present challenges for communities that live in and nearby these forests. In addition, where the fires did burn abnormally, attention is needed on those particular forest types in the form of thinning and controlled burns.

Key findings:

· Wildfires in Arizona and New Mexico account for 17% of all acres burned in 2011 and that figure jumps to 37% if Texas is excluded.
· New Mexico and Arizona had 1,445 wildland fires to date, burning a total of 1,310,861 acres.
· The Wallow Fire (AZ): Over 64% of the area within the fire perimeter burned at low severity or not at all, while just 16% burned at high severity and 20% at moderate severity.
· The Horseshoe II Fire (AZ): Nearly 58% of the area within the burn perimeter burned at low severity or not at all, while just 12% burned at high severity.
· The Las Conchas Fire (NM): Nearly 20% of the fire area burned at high severity, 29% at moderate severity and 39% at low severity.
· The Pacheco Fire (NM): Almost 37% of the burn area burned at high severity and another 27% at moderate severity.
· Of the 11 western states, New Mexico has the 8th and Arizona the10th largest area of undeveloped, forested private land bordering fire-prone public lands.
· New Mexico has 600 square miles of undeveloped, forested private lands adjacent to fire-prone public lands and Arizona 400 square miles.
· New Mexico is 7th and Arizona 8th among western states in the amount of forested land where homes have already been built next to public lands.

Fire is a natural and inevitable force of nature. Though the fires of 2011 were big, they behaved mostly as we would expect. Forests are flammable and we must learn to live safely with this awesome force of nature.
The GIS analysis, performed by Bird’s Eye View GIS, demonstrates that four fires, each very different in region and the vegetation types burned were large, making up almost 40% of all the wildland acreage burned in 2011 outside of Texas. The 7.5 million acres burned in wildfires this year is above the 10-year average of 6 million acres, but still far below the 145 million acres that burned on average prior to 1800.


Fire in the vegetation types that typically experience long return intervals, but high severity behaved normally, for example the spruce-fir forest types and wetter mixed conifer forests. In drier, forest types that typically experience short fire return intervals and low to moderate severity, the fires behaved mostly as expected with one exception: ponderosa pine forest that experienced uncharacteristic “hotter” fire. Larger, hotter fires in this dry forest type are predicted by scientists and result from forest management practices such as livestock grazing and fire suppression in combination with drought and climate change. Restoration and fuel management will be a high priority in the future for these dry forests.

With limited financial resources, national forests must be managed strategically. We know how to fire proof homes but we cannot fireproof forests in the West. Therefore, we need to spend money on a reasonable combination of controlled burning and thinning immediately around human communities.

The report concludes that the fires likely did more good than harm in controlling fuels built up over years of fire suppression, but that maintaining the lower fuel conditions with controlled burns and other management will be critical. It also concludes that development of housing in the wildland urban interface must be more tightly controlled in states like Arizona and New Mexico that still have significant development potential in fire-prone ecosystems.

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