Rethinking Climate, Forests, Wildfires, & Biodiversity

Rethinking Climate, Forests, Wildfires, & Biodiversity
George Wuerthner

I attended the 88 fires: Yellowstone and Beyond fire conference in  Jackson,
Wyoming. The conference went on for five days and had many  simultaneous
presentations, featuring some of the latest insights  into wildfire ecology and fire
behavior. The following are some of  the highlights.

Weather and climate figured into many presentations for a variety of  reasons.
Speakers like Tony Westerling of the University of
California and Tom Swetnam of Arizona State University spoke about  long term global
climate change which will likely increase the
severity and number of large wildfires in the future.

Many speakers from agency managers to wildfire ecologists emphasized  over and over
again the influence of drought, low humidity and wind  on fire spread and behavior.
The conclusion of speakers is that under  severe weather conditions, some fires are
unstoppable and we are
already seeing such a trend in fires today.

For instance, Yellowstone researcher Roy Renkin emphasized that fuel  moisture is
the primary determinant of fire severity. His research  suggests that wind and
drought must exceed the 97^th percentile
before one gets a stand replacement fire, and if it exceeds the 99^th  percentile
nothing will stop a fire and it will burn through all fuel  types, including thinned
forest stands. In other words there are very  predictable thresholds in fuel
moisture and wind speed that creates  the ideal conditions for fire spread. When
these conditions are met,
wildfires are large and unstoppable.

Other speakers talked about the effect of wind on fire spread. Even  in a dry year
like 1988, the majority of fires are small without wind  to drive them. For
instance, Bob Mutch retired from the Missoula Fire  Lab, found that out of 249 fires
that started in the Greater
Yellowstone Ecosystem in 1988, the majority or 81% burned ten acres  or less. Huge
acreages of the forest were consumed during the few  days when high winds prevailed.

For instance, the 1988 Canyon Fire that burned through the Bob
Marshall Wilderness was propelled by high winds of the Jet Stream  which dipped down
to the surface above the fire. With the Jet Stream  pushing it, the fire raced
across 190,000 acres in a single day.
Researchers emphasized that wind was a major factor in all large
fires including historic blazes like the 1910 Burn that charred more  than 3 million
acres of the Northern Rockies. While the few days when  high winds prevailed, while
the few days when high winds prevailed,  While the few days when high winds

During a field trip, I talked to Penny Morgan of the U of Idaho who  recently
published a couple of papers on the fire history of the
Northern Rockies. She found that a strong connection between climatic  conditions
and fire years. Of 11 years with significant acreage
burned by wildfire between 1900 and 2003, six occurred prior to the  1940s and five
have occurred since 1988. All were correlated with dry  springs and hot summers. The
years between 1940 and the 1980s were  wetter and cooler than the years before and
after calling into
question whether fire suppression has been as effective as previously  assumed. Yet
it is these post war years that forms the basis for our  views about what is
“normal” behavior for wildfires.

This is where other speakers’ research fit into the mix. Cathy
Whitlock of Montana State University has looked at long term fire  histories
throughout the West, including a 17,000 year fire history  for Yellowstone. Her
conclusions are that the recent past climatic  conditions no longer exist. In other
words, trying to “manage” for  past vegetation patterns is not going to work because
we now have a  new climatic regime that is has warmer temperatures, a longer drying
season, and generally higher winds than the recent past. Thus
thinning forests to “restore” a “historic” appearance to the
landscape may be pointless. We are now into a new climate model that  will change
fire behavior as well as vegetation response.

Proposed treatments like thinning, logging and other prescriptions  are ineffective
for many forest types under the new climatic
conditions. For instance, Ronald Wakimoto of the U of Montana
Forestry School suggested that thinning of lodgepole pine forests as  is now
occurring on Forest Service lands in the Northern Rockies is  “fool management” not
fuel management. Thinning, as Wakimoto noted,  simply makes the forest floor hotter,
drier and windier-all
ingredients that increase fire spread and severity.

Megan Walsh of the U of Oregon looked at charcoal remains for the  past 1000 years
to determine the fire history in the Willamette
Valley of Oregon. For decades it was presumed that Native American  fires maintained
the valley grasslands and open oak woodlands. Her  research suggests that valley
fire activity responded primarily to  climatic changes.

The influence of Native Americans on wildfire frequency appears to be  localized,
primarily in and near places where permanent occupation  occurred. The idea that
Native American significantly affected fire  frequency across the larger landscape
is called into question.

Another presentation by Dick Hutto of the U of Montana emphasized the  ecological
importance of dead trees, in particular, burnt trees.
Hutto, like many ecologists, is opposed to salvage logging of burnt  trees,
especially on the assumption that dead trees are a “wasted”  resource. Hutto’s
research focuses on birds, and there are many
species that live and forage primarily in burnt forests. Such an
evolutionary response suggests to Hutto that stand replacement fires  have occurred
in all forest types, not just high elevation forests  like those found in
Yellowstone. Despite assertions by the ill
informed to the contrary, we may be experiencing a deficit of
wildfires. In other words, even if it were possible to suppress large  fires-which
clearly it is not–we need more large wildfires, not

Like Hutto other researchers are finding that large blazes have
profound positive effects upon forest ecosystems and associated
species. For instance, Wayne Minshall of Idaho State University has  studied fire
effects on streams for decades. His research found that  stream drainages that
experienced high severity fires rather than  being “destroyed” had the highest
biomass of aquatic insects, which  in turn supported higher densities of cutthroat
trout. But the fire  also had an effect on terrestrial species as well. Minshall
found  that severely burned watersheds also supported higher density of fly
catching birds, bats, and riparian spiders, among other animals.

On a field trip through Jackson and up into Yellowstone with
researchers Monica Turnker, Dan Tinker and Bill Romme, participants  observed a
forest that had been heavily infected by pine beetles in  the 1970s. If Romme had
not mentioned it to us, none of the field  trip participants would have guessed that
the forest had ever
experienced a major beetle outbreak. As Romme explained, beetles,  even under the
most severe infestations, seldom kill all trees. With  the death of some trees, the
remaining trees grow very quickly to  fill in the gaps in the forest canopy.

Furthermore, Romme’s and researchers have found that beetle killed  trees do not
necessarily increase fire hazard. Once a year or two has  passed, and dry needles
and small branches fall off, the forest is  actually less likely to burn than a
green forest under severe fire  conditions. The green forest needles and branches
are loaded with  resins that burn extremely well if the internal moisture of the
trees  dips as occurs during severe droughts. In other words, fire hazard  does not
increase significantly as a result of beetle kill.

Additionally there are many ecological benefits associated with pine  beetle
infestations, including the creation of dead trees for
wildlife use, increased nutrient flows into soils, and other affects.  If
communities and politicians panicking about current beetle
outbreaks could visit the Tetons they would realize there is nothing  to be feared.

The overall conclusions I took away from the conference was that
climate change was going to create climate/weather conditions more  conducive to
large blazes. Management prescriptions like logging
won’t change fire behavior under severe conditions, and in fact, may  improve
conditions for fire spread by opening up the forest to
greater drying and wind penetration. Fortunately, large fires are  ecologically
beneficial and necessary for many ecosystem functions,  including nutrient cycling,
wildlife habitat creation, and other
ecological processes. Therefore, an increase in large burns rather  than being
something to be feared or suppressed should be embraced.  To do this, we need to
change our approach to wildfires from
suppression to co-existence.

The best way to achieve such a relationship is not to fight fires or  log the
landscape in the mistaken believe that we can affect fire  severity or spread,
rather we need to reduce sprawl into the
wildlands urban interface through zoning and planning combined with  greater
attention to making existing structure fire safe. Even
something as a requirement that all buildings in fire prone
ecosystems have metal roofs would go a long ways towards reducing  losses to wildfire.


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