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Flagstaff
Interface Treatment Prescription
Results
in the Wildland/Urban Interface
Slash
Treatment
Hand
Piles: This
is the typical method of handling slash.
Hand piles should be teepee-shaped and a minimum
of six feet tall and six feet wide.
Pile placement needs to be carefully considered.
Piles should be located in openings to avoid
scorching leave trees when the piles are later burned.
Likewise, placing piles on top of old stumps
or logs should be avoided to reduce both the amount
of smoke and the chance for "creep" when the piles are
later burned. We have found that to the public, a scorched
tree is worse than a cut tree and "creep" is an "escaped
controlled burn."
Machine
Piles: This
method is sometimes feasible in more open areas. We have had the most success with the windrow
piling method perfected on the Mormon Lake Ranger District. This requires directional falling into a windrow
that can then be pushed into large piles by a dozer
during a single pass.
Because the dozer is not constantly spinning
and turning, few ruts are made. The larger piles result in fewer piles per acre, speed production
by an estimated 30%, and can be ignited under snowier
or wetter conditions than traditional hand piles.
At first, some were skeptical of this method,
but once the process and results have been observed,
comments have been favorable.
We have also employed whole tree skidding.
Chip
or Grind: Although,
occasionally used this technique is comparatively expensive
and chips decompose slowly in our area.
If future underburning is anticipated for the
site, chips may add to smoke management problems.
The material can, however, be used for mulch
or decorative landscaping. Hauling chips to a disposal site is expensive.
Lop-and-Scatter:
The decision to utilize this method should receive
careful consideration.
If the amount of slash is light and the manager
can complete a broadcast burn soon after cutting, it
may be effective. However,
we seldom use this method.
Due to the increased fire hazard, dried lopped-and-scattered
slash should never be left in-place adjacent to homes.
Pile
Burning
Piles
should be burned only when consumption will be greater
than 90%. A
test pile may need to be burned to ensure this is achievable.
All pile burns should be conducted under conditions
intended to reduce scorch, minimize smoke issues, and
lessen potential control problems. Quality is the number one concern, not acres
treated per day. This
is the case regardless if the material is hand or machine
piled.
Because
we intend to broadcast burn most, if not all, sites
we work on, we often pile some of the existing dead-and-downed
material. These
piles are then burned when the slash piles resulting
from thinning are burned, which aids in smoke reduction
during the following broadcast burn.
Some material is left onsite for wildlife cover.
Hand
Piles: As a standard practice, we wait for either snow
cover or an extended wet weather episode.
On burn day, the crew will ignite a reasonable
number of piles. As they burn-down, the crew goes back through
the area and consolidates each pile 2-3 times to ensure
complete, and timely consumption.
The work pace is governed by the intent to have
all piles burned-down by nightfall.
Machine
Piles: When burning this type of pile, we wait for snow.
As the piles are burned, a small dozer is ideally
on-hand to shape up the piles and landings. While the dozer is working, seed can be spread
and worked into the ground.
This results in faster site recovery, less likelihood
of noxious weeds becoming established, and reduced visual
impact.
Broadcast
Burning
Treating
ground fuels is a critical component of our stand enhancement
and fuel reduction effort.
Once an area has been thinned and the slash has
been treated, the site should be broadcast burned (Figure
5). As our prevailing
wind is from the southwest, burn blocks, where possible,
are burned starting in the northeast and working toward
the southwest. Fireline is usually constructed by hand or
with a drag pulled by an ATV.
As
a standard practice, standing dead trees are either
hand lined or otherwise excluded from the burn block. The same is true for cultural or archaeological sites or other features
important to the manager that might be degraded by fire.
Figure 5.
This parcel at the Brannen Homes development
was broadcast burned following
selective thinning, pruning, and slash disposal.
Photo by Larry McCoy USFS
Once
ignited, deep duff and needle accumulation at the base
of the larger older trees will often smolder for days. This essentially bakes the cambium layer and
death can occur 1-2 years or more after the burn. To avoid such damage, the duff and needle material is routinely
raked away from high-risk trees.
Usually raking to a distance of one foot from
the bole is sufficient.
We do the same for downed logs we wish to preserve
for wildlife cover.
The
preferred season for broadcast burning is normally during
breaks in the summer monsoon season, during the transition
from the monsoon season to drier fall weather or during
the fall and early winter. While spring burning is sometimes used, it
must be balanced against resource availability, training
commitments, and the normally escalating fire danger
indices prevailing at this time of year. However, if the planned burn is small, of short
duration, and anchored to a recent burn or fuel break,
spring burning can be done with reasonable safety.
Our
ultimate goal is to shift more burns into the summer
months to recreate the historical fire regime.
This will become easier once a site has been
previously burned to remove excessive accumulations
of fuel.
The
underburning prescription generally calls for strip-head
fires along with a combination of backing fires (used
at starting points and on steep slopes) with target
flame lengths of 1 to 3 ft. Ignition by hand with drip torches or with
ATV-mounted torches is preferred.
Ignition is usually begun at mid-morning following
the break-up of the night time temperature inversion
and the establishment of the day time wind pattern. Every effort is made to complete ignition by
early afternoon, with burn blocks generally kept small
to achieve this objective.
Although
each burn block may have specific objectives, we generally
have two overall objectives for the operation:
1.
Reduce 1 and 10 hour fuels by a minimum of 60%, and
2.
Keep tree mortality to less than 5% of the existing
stand.
Intense
public notification is an essential element of the program.
This is achieved by posting signs in the area
announcing the proposed burn, news releases, and in
many cases, door to door contact throughout the nearby
neighborhood(s). Any concerns receive immediate attention, either
by a phone call or personal visit.
If these concerns surface on the day the site
is being burned, we often detail the project manager
or a crewmember to visit the person while the fire is
still underway. We
also conduct a continuing education program through
talks to civic groups, environmental organizations,
and others to inform the community of the importance
and benefits of the program.
Our
experience has shown that a previously notified neighborhood
is willing to tolerate smoke for a day, but after 2-3
days, patience wears thin.
A particular log, stump, or site within a burn
unit may be extinguished the first night if it becomes
a major concern to a nearby resident.
We
attempt to design our burns so they can be dispersed
throughout the community so as to not constantly impact
the same neighborhood(s).
The Flagstaff Fire Department has offered to
relocate smoke sensitive people: to-date, however, no
one has taken advantage of the offer.
Neighborhood air sheds, indicated by diurnal
smoke flows, are routinely mapped so we can plan future
smoke management efforts.
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