Fuel Treatment Effectiveness
Date: Oct 12, 2012
Prison Wildfire
Fuel Treatment Effectiveness
Location Information
Region: Pacific
Southwest, R5
Forest:
Lassen NF
District:
Eagle Lake
Unit: Champs Project Area,
Harvey DFPZ and
Bugle DFPZ (Proposed)
Wildfire Information (consistent with 5100-29)
Fire Number: CA-LNF-3857
Fire Name: Prison Fire/E-27
Date of Fire Start mm/dd/yr: 08/01/2009
Final Fire Size (acres): 175
Date When Fire Entered Treatment: 08/02/09
Treated Area Burned (acres): 31
Date Fire Contained: 08/25/2009
Project Area Background and Fuel Treatment Information
The Prison Fire Area is located in the northern portion of the Eagle Lake Ranger
District on the Lassen National Forest. The Harvey Defensible Fuel Profile Zone
(DFPZ) and the proposed Bugle DFPZ portion of the Champs project area are
both within the Prison Fire area. In relation to the Prison Fire, the Harvey DFPZ
is located on the north side of Forest Road 33N06, which bisects the fire, and
the proposed Bugle DFPZ is located directly south of the Harvey DFPZ, on the
south side of the road (Figures 1 and 2). The Champs project has been through
litigation several times, resulting in the cancellation of a contracted timber
sale in the Bugle DFPZ; no treatment occurred in this DFPZ. The Harvey DFPZ
was thinned via timber sale in 2003 as part of an earlier project covered under
a different environmental document. Thirty-one acres of the Harvey DFPZ are
located within the fire perimeter, all of which had been thinned prior to the
fire. An underburn was planned for the Harvey DFPZ to complete the fuels
treatment, which had not yet taken place. A portion of a Northern Goshawk
Protected Activity Center (PAC), which is located north of the Harvey DFPZ,
was also burned over. Overall, the Prison Fire burned a total of 175 acres, of
which 31 acres had been previously thinned. The attached maps of the fire
show areas where high severity and high vegetation mortality occurred. The
majority of the high severity areas are located within the untreated Bugle
Prison Fire, Region 5, Lassen National Forest
1
Fuel Treatment Effectiveness
DFPZ, the goshawk PAC, the untreated leave islands within the Harvey DFPZ,
and in the untreated stands adjacent to the Harvey DFPZ.
Existing vegetative cover within the Prison Fire area is primarily eastside pine
and mixed conifer, interspersed with meadow and sagebrush flats. Vegetation
in the untreated portion of the fire area is relatively homogenous in respect to
species composition and age, but there is a wide range of variability in stocking
density and stand structure. Stocking density is moderate to heavy, with
average basal areas ranging between 140 to 220 square feet per acre. To
maintain within-stand diversity, approximately 10 percent of each silvicultural
treatment unit within the DFPZs would be left unthinned in patches (untreated
leave islands), generally ranging in size from ¼ to five acres, and generally
located in the secondary zone of DFPZs.
The Harvey DFPZ residual (post-thinning) basal area was approximately 80 – 100
square feet per acre and also contained the untreated leave islands described
above. All the data gathered from the untreated areas surrounding the Harvey
DFPZ, which also represents the condition of the untreated leave islands,
represents an existing condition basal area of 140 – 220 square feet per acre.
Treatment Type and Acres
Harvey DFPZ
Bugle DFPZ (Proposed)
Mechanically
Thinned
Underburn
Acres
1,143
N/A
Acres
989
Date
Completed
11/2003
Planned for
Fall 2009
Date
Completed
Postponed due to
litigation
Acres in
Prison Fire
Perimeter
32
Acres in
Prison Fire
Perimeter
31
Prison Fire, Region 5, Lassen National Forest
Mechanically
Thinned
Underburn
N/A
Postponed
due to
litigation
2
Fuel Treatment Effectiveness
Narrative of Fire Interaction with Fuel Treatment
On the evening of August 1, 2009, a wide-spread lightning storm passed over
the Lassen National Forest, igniting approximately 35 wildfires on the Eagle
Lake Ranger District. The largest of these fires grew to 175 acres and was
labeled E-27, also known as the Prison Fire. The fire originated at T33N, R9E,
section 32, and was called in at 0800 hours on August 2, 2009 by the Antelope
Mountain lookout. Due to the storm’s expansiveness and the large number of
fires started from all the lightning downstrikes, suppression forces at all three
Lassen National Forest ranger districts were stretched thin responding to initial
attack orders. Additional resources were ordered through dispatch to assist the
forest with its suppression needs.
Initial attack resources responding to the Prison Fire on August 2, 2009 were a
Type 4 Incident Commander (ICT4) and a Type 3 dozer. The initial size-up of
the fire showed it to be approximately one acre in Fuel Model 2 (Ponderosa
Pine stands with grass and shrub understory), on the south side of Forest Road
33N06. Because there was little to no wind, generally flat terrain, and easy
access for the dozer, the fire was quickly contained and put into patrol status.
Due to the number of fires on the district which required the attention of all
the district’s suppression resources, the fire was put into patrol status. A
contract engine that arrived with the initial order for more resources was
assigned to patrol the Prison Fire.
Later that afternoon around 1430 hours, the winds began switching from WNW
to SW, and increased to 20-25 mph. Prior to the increased wind speeds, the
patrol resources report having walked the fireline thoroughly several times
without seeing any threats to the line. However, once the wind increased and
changed directions, a snag (standing dead tree) which had previously been
smoldering undetected next to the dozer line fell across the fireline and flared
up, igniting the grass and receptive fuels on the north side of the fireline. Using
Forest Road 33N06 as a control line, a burnout attempt was made to “get out in
front” of the rapidly growing spot, but with the limited number of resources
on-scene, gusty winds, and lack of available resources nearby, the resources
were unable to safely burnout ahead of the flaming front. The ICT4 then made
the decision to order helicopters and other resources, with the knowledge that
they may not arrive for some time.
The Fuels Officer and the District Fire Management Officer (DFMO) arrived onscene shortly thereafter and informed the ICT4 of the Harvey DFPZ location.
The DFMO asked the Fuels Officer to scout the fire, to see if the Harvey DFPZ
could be utilized to aid fire suppression activities. The Fuels Officer later
remarked that while he did not see the flaming front as he was scouting, he
Prison Fire, Region 5, Lassen National Forest
3
Fuel Treatment Effectiveness
observed plume activity indicating that the fire was moving quickly northward,
pushed by the wind. With the wind gusting at high speeds and pushing the
flaming front northward, the untreated areas adjacent to the Harvey DFPZ
experienced group torching and high intensity burning in surface fuels (see
attached map and photos). Resources ordered at the time of blow-up included
four dozers, two Type 2 handcrews, three engines, and two air tankers. At
approximately 2300 hours that evening, wind speeds began decreasing,
ultimately allowing suppression forces to contain the fire.
The Harvey DFPZ could not be utilized to stop the forward spread of the Prison
Fire, due to the erratic, wind-driven fire behavior resulting from the
thunderstorm activity and the lack of resources available when the fire crossed
the original control line. However, the Harvey DFPZ provided suppression
resources with an anchor point on the west flank of the fire. Also, post-fire
monitoring data demonstrates that the Harvey DFPZ treatment was effective in
reducing fire severity and contributed to improving landscape resiliency.
In providing information for this report, the ICT4 stated that with the status of
the winds, dry conditions, lack of local resource availability, and cured,
abundant fuels in the area, the Prison Fire could very easily have grown to
become a major wildfire, spanning many more operational periods and
increasing suppression costs. The Fuels Officer commented that because the
Bugle DFPZ was untreated, a high volume of surface fuel loading and dense
pockets of timber were available near the fire’s ignition point, likely aiding the
fire’s growth, intensity, and movement into the crowns. He believes that if the
Harvey DFPZ had been left untreated, there would probably have been more
spotting and crowning as the fire moved north, with greater intensity and
spread along its flanks. The Fuels Officer further added that while he was on
his scouting mission, the only torching he observed within the Harvey DFPZ was
in the untreated leave islands.
Prison Fire, Region 5, Lassen National Forest
4
Fuel Treatment Effectiveness
Weather Observations and Trends
According to data from the Gordon Remote Automated Weather Station
(RAWS), the weather trends during the week prior to the lightning storm (July
24, 2009 at 10:46 through August 2, 2009 at 09:46) indicated daytime
temperatures in the upper 80s and lower 90s with overnight low temperatures
dipping only into the mid-50s. Relative humidity (RH) routinely dipped into the
low teens during the day, with several days showing lows in the single digits.
RH recovery overnight was poor throughout the week, staying primarily within
the 40 - 60 percentiles. The 10-hr. fuel moisture trends show daily fuel stick
lows in the 4-7 range; in fact, there were several days during this time frame
where the fuel stick readings never increased beyond single digits. Gusty winds
had been recorded every afternoon for the week leading up to the Prison Fire,
which likely contributed to drying out the 1-hr. fuels and making them
receptive to ignitions from dry lightning during the wide-spread thunderstorms.
Conditions When Fire Entered Treatment
Date and Source of Observations: 15:46 on 02 Aug 2009, Gordon RAWS
(WIMS data obtained from ROMAN website)
ERC (value): 51
Windspeed and Direction: 6 mph with
gusts to 9 mph, WNW
Temperature: 80 degrees F
RH: 33%
Fuel Moistures
1 hr:
N/A
10 hr: 11%
Live Fuel Moisture: N/A
Prison Fire, Region 5, Lassen National Forest
100 hr: N/A
1000 hr: N/A
Measured or Estimated? 10 hr. fuels were
measured by the Gordon RAWS at 15:46.
No on-site data for the other fuel
moisture classes is available.
5
Fuel Treatment Effectiveness
Fuel Treatment and Fire Area Maps
Figure 1. Shows areas of high severity over the burn area and the Champs project treatment locations.
Prison Fire, Region 5, Lassen National Forest
6
Fuel Treatment Effectiveness
Figure 2. Shows areas of high vegetation mortality and the completed Harvey DFPZ treatment locations, as well as the untreated proposed Bugle DFPZ portion of the Champs project. The drop points and controlled area points are irrelevant in this report. Prison Fire, Region 5, Lassen National Forest
7
Fuel Treatment Effectiveness
Post-burn Monitoring Data (2011)
In September of 2011, two years after the Prison Fire, the Eagle Lake District
ecology crew returned to the area to gather information. Their objectives were
to quantify fire severity attributes in a treated DFPZ and adjacent untreated
forest stands that were burned during the wildfire. They sampled vegetation
data from the four distinct forest management areas that were burned within
or adjacent to the Prison Fire. The comprehensive vegetation monitoring
document, Prison Fire Monitoring, contains detailed results from the monitoring
and is referenced at the end of this report. Selected tables, graphs and photos
were pulled from this document to show the effects of the Prison Fire in four
different stand types (Figure 3).
Figure 3. Approximate monitoring transect locations for each treatment area.
Prison Fire, Region 5, Lassen National Forest
8
Fuel Treatment Effectiveness
Fire severity attributes were evaluated in four treatment areas: Prison Fire:
Burn, an area within the fire perimeter that was burned over but was not
thinned; Prison Fire: Control (No Treatment), an area the fire did not enter and
was not thinned; Prison Fire: Harvey DFPZ, an area within the fire perimeter
that was burned over and was mechanically thinned prior to the wildfire; and
Prison Fire: Leave Island (No Treatment), an area located within the Harvey
DFPZ which was burned over but was excluded from thinning . Figure 3 shows
the approximate locations where vegetation monitoring transect data and
photos were collected. The following photo series displays the differences in
burn severity in the four treatment areas.
Prison Fire: Burn. Wildfire in untreated area outside the Harvey DFPZ. High fire severity and char height, low rate of tree survival. Prison Fire, Region 5, Lassen National Forest
9
Fuel Treatment Effectiveness
Prison Fire: Control. No Treatment and outside of wildfire perimeter. High stand and shrub density, high volume of basal area per acre. Prison Fire: Harvey DFPZ. Mechanically thinnied prior to the wildfire. Low fire severity and char height. Prison Fire, Region 5, Lassen National Forest
10
Fuel Treatment Effectiveness
Prison Fire: Leave Island. Untreated area retained within the Harvey DFPZ. High fire severity and char height, almost no tree survival. Most surviving trees surveyed were infested with red turpentine beetle. Stand Attributes
Live as well as dead trees were included in the following stand attributes to
describe the existing condition of forest stands prior to the Prison Fire. Mean
density (trees per acre, (TPA)) was calculated for each of the four treatments.
Results show that the DFPZ had the lowest density (106 TPA) and the unburned
Control had the highest density (255 TPA) (Table 1, Figure 4). The Leave Island
(burned in wildfire in untreated area inside of the Harvey DFPZ) and Burn
(burned in wildfire in untreated area outside of the Harvey DFPZ) treatments
had similar tree densities in the middle of the density distributions among the
four treatments.
Table 1 and Figure 5 reports the mean basal area (BA) for the 4 treatment
types. Basal area per acre is used by foresters to determine the amount of
timber in a specific location. The calculation represents an estimate of all
trees because it takes small samples from around the forest to determine the
amount of trees, and here, is represented in square feet of stump per acre.
DFPZ and the Leave Island treatment had the lowest basal area measurements
with 93 and 107 sq.ft./ac respectively; while the Burn and Control treatments
had the highest BA with 128 and 133 sq.ft./ac respectively. When basal area
values are significantly lower compared to density values, it indicates that the
Prison Fire, Region 5, Lassen National Forest
11
Fuel Treatment Effectiveness
basal area is contained in many small trees. This pattern can be seen for the
Burn, Leave Island and Control treatments (Figures 4 and 5).
Mean tree diameter at breast height (DBH) results were calculated for all 4
treatment types. Results show that the DFPZ had the highest mean DBH of
13.7” with the Leave Islands having the lowest mean DBH of 9.0 (Table 1).
Density was calculated for five DBH size classes: 1) 0-5”, 2) 5.1-10”, 3) 10.115”, 4) 15.1-20”, 5) >20.1”. The majority of trees in all treatments were < 20”
dbh (87-96%). The DFPZ had only 4% of the trees in the >0-5” dbh size class
while the remaining treatments had between 13-18% of the trees in this size
class (Table 1).
Figure 4. Mean tree density by treatment. Figure 5. Mean basal area by treatment.
Densit
y TPA Burn 214 DFPZ 106 Control 255 Leave Island 196 Mean BA 128 (60‐180) 93 (20‐130) 133 (70‐250) 107 (70‐140) Mean DBH 0‐5” % of TPA Total 5.1‐10” % of TPA Total 10.1‐15” % of TPA Total 15.1‐20” % of TPA Total >20.1” % of TPA Total 11.7 28 13% 73 34% 51 24% 43 20% 21 10% 13.7 4 4% 25 22% 36 32% 31 29% 14 13% 10.8 46 18% 64 25% 87 34% 51 20% 10 4% 10 33 17% 82 42% 65 33% 0 0% 17 8% Table 1. Summary of stand structure attributes. Density (TPA), Basal Area (BA) and Diameter at Breast Height (DBH), and density of trees by tree size class for each treatment. Basal area ranges indicated in parentheses. Prison Fire, Region 5, Lassen National Forest
12
Fuel Treatment Effectiveness
Severity Measures
The burn severity attributes measured were percent tree mortality, bug
presence, live tree crown, and char. A comparison of severity measures among
the treatments shows that the Burn treatment had the highest percent
mortality, the highest proportion of trees with beetles, the least amount of live
crown, and the lowest proportion of trees with light char. In contrast, for the
treatments that burned, the DFPZ had the lowest burn severity measurements;
with the exception of percent bug presence which was higher than the Leave
Island. The Leave Island had similar percent mortality as the burn and had the
highest number of trees in the high char category (Figures 6 and 7).
Prison Fire: Burn. Wildfire in untreated area outside the Harvey DFPZ. High fire severity and char height, low rate of tree survival. Prison Fire, Region 5, Lassen National Forest
13
Fuel Treatment Effectiveness
Prison Fire: Harvey DFPZ. Low fire severity and char height, high rate of tree survival and understory species recovery. Burn Severity
100
Burn
percent
90
80
DFPZ
70
Leave Island
60
Control
50
40
30
20
10
0
mortality
bug
attribute measured
live crown
Figure 6. Mean percent value for mortality, bug presence, and live crown for each treatment. Prison Fire, Region 5, Lassen National Forest
14
Fuel Treatment Effectiveness
100
Char Severity
percent
90
80
Burn
70
DFPZ
60
Leave Island
50
40
30
20
10
0
light
moderate
char categories
high
Figure 7. Mean percent of trees in each char class by treatment. Mortality/Survival
Mean percent mortality was calculated for all four treatments. Mortality ranged
from 74% in the Burn to 0% in the Control (Figure 8). Therefore, snag density in
the Burn and Leave Island were 158 and 131 snags/ac respectively. The DFPZ
had the lowest number of snags in treatments that burned (41 snags/ac) and
the Control had zero snags.
No trees were affected by the fire in the Control so it was excluded from the
following calculations. A negative relationship was observed for tree mortality
and dbh. The majority of tree mortality occurred in trees <10” dbh with 100%
mortality in size class >1-5”dbh in all burn treatments. The lowest mortality
occurred for trees > 15” dbh in the DFPZ treatment (Figure 8).
Prison Fire, Region 5, Lassen National Forest
15
Fuel Treatment Effectiveness
Percent Mortality
Burn
DFPZ
Leave Island
100%
90%
80%
percent
70%
60%
50%
40%
30%
20%
10%
0%
>1-5
5.1-10
10.1-15
dbh (in)
15.1-20
>20.1
Figure 8. Percent of dead trees by size class for each burned treatment. (Note‐ the 100% mortality for trees > 20” dbh for the leave island treatment was calculated from a random sample resulting in a small sample size of one tree.) Char
The percent of trees (dead and alive) in each char category was calculated for
each treatment except the Control, which had no char (Figure 9). Moderate
char was the most common category with 83.8% of trees in the Burn, 56.3% in
the DFPZ and 33.3% in the Leave Island. Light char was observed most
frequently in the DFPZ at 39.4%, followed by Leave Island with 33% and the
Burn having 11.3%. The Leave Island had the highest proportion of high charred
trees with 33.3% and the Burn and DFPZ had similar levels of 5.0% and 4.2%
respectively.
Char intensity influences the probability of tree survival. Across all burn
treatments light charred trees had the highest percent survival. The DFPZ had
the highest percent survival in all char categories compared to the other
treatment with the exception of 100% survival for the light char category in the
Leave Island treatment. This may be due to a small sample size of 4 trees in
the Leave Island with light char (Figure 9). Additionally, tree size is associated
with char intensity. Figures 10a and 10b show that high char occurs primarily
on trees that are < 15 inch dbh.
Prison Fire, Region 5, Lassen National Forest
16
Fuel Treatment Effectiveness
Percent Survival
100%
Burn
90%
DFPZ
80%
Leave island
percent
70%
60%
50%
40%
30%
20%
10%
0%
light
moderate
high
Char
Figure 9. Percent tree survival rate by char category for treatments that burned.
Prison Fire: Leave Island (No Treatment) Prison Fire: Harvey DFPZ
Prison Fire, Region 5, Lassen National Forest
17
Fuel Treatment Effectiveness
Distribution of char categories by tree size in the burn
100%
90%
low
80%
mod
percent
70%
high
60%
50%
40%
30%
20%
10%
0%
0-5
5-10
10-15
15-20
20-25
dbh size class (in.)
Figure 10a. Percent of trees in each char category by dbh size class, burned area with no previous treatment. Distribution of char categories by tree size in the DFPZ
100%
90%
low
percent
80%
70%
mod
60%
high
50%
40%
30%
20%
10%
0%
0-5
5-10
10-15
15-20
dbh size class (in.)
20-25
Figure 10b. Percent of trees in each char category by dbh size class, DFPZ treatment Prison Fire, Region 5, Lassen National Forest
18
Fuel Treatment Effectiveness
Understory Vegetation Cover
The least amount of understory cover occurred in the Leave Island treatment,
while the DFPZ had the highest, followed by the Burn and then the Control.
Annual forb cover was higher in all treatments that burned compared to the
Control. With the exception of annual forbs, all functional group cover was
lower in the Leave Island compared to the other treatments. This may be due
to the intensity of the fire within the Leave Island. The proportion of all
functional group cover was similar for the Burn and DFPZ treatments with both
having the highest cover for perennial graminoids and perennial forbs. The
highest shrub cover occurred in the Control, but the DFPZ had the highest
amount of shrub cover compared to the treatments that burned (Figure 11).
The intensity of the wildland fire was lower in the DFPZ and may have not
killed all the shrubs that were present in this treatment prior to the burn.
Prison Fire: Burn. Little to no understory vegetation response. Prison Fire, Region 5, Lassen National Forest
19
Fuel Treatment Effectiveness
Prison Fire: Control (No Treatment). Low diversity of understory vegetation species. Prison Fire: Harvey DFPZ. Higher diversity and understory vegetation response, little to no duff present.
Prison Fire, Region 5, Lassen National Forest
20
Fuel Treatment Effectiveness
Prison Fire: Leave Island (No Treatment). Little to no understory vegetation response. Functional Group Cover by Treatment
45%
40%
35%
percent
30%
25%
20%
15%
10%
5%
0%
Burn
Shrub
DFPZ
Leave Island
Control
treatment
Perennial Forb
Annual Forb
Perennial Graminoid
Figure 11. Average percent cover of each functional group collectively showing total cover for each treatment. Prison Fire, Region 5, Lassen National Forest
21
Fuel Treatment Effectiveness
Summary
Our data indicates that the probability of trees surviving a wildland fire
depends on both the forest management treatments and tree size. We
observed high mortality for trees <10” dbh regardless of burn treatment and
high char occurred more frequently on trees <15”dbh. However, char intensity,
mortality, and bug presence were lower and percent live crown was higher in
the DFPZ compared to the adjacent untreated burned area, demonstrating that
the DFPZ type of management treatment is effective in reducing fire severity
and contributing to landscape resiliency. Additionally, functional group and
total understory plant cover was higher in the DPFZ compared to the other
treatments showing that ecosystem services, such as those provided by
understory plant communities, are able to recover quickly following a wildland
fire within DFPZ management areas. Leave islands located within the DFPZ had
higher mortality and char intensity and less percent live crown compared to the
surrounding DFPZ. Although we did not have a planned study design to evaluate
the effect of leave islands within a DFPZ, the location of the leave islands may
have contributed to the spread of the Prison Fire due to spotting ahead of the
fire, thereby decreasing the effectiveness of the DFPZ treatment (Figure 3).
Additional Documentation
Recommend Additional Documentation? Yes__X___ No_____
1) Jones, B., Hubert, S., Smith, C. Prison Fire Monitoring. June 5, 2012.
Name and Title of Person Completing the Report
Wendy McCartney
Fuels Technician
Eagle Lake Ranger District
Lassen National Forest
Bobette Jones
District Ecologist
Eagle Lake Ranger District
Lassen National Forest
Chuck Lewis
District Fuels Officer
Eagle Lake Ranger District
Lassen National Forest
E-mail:
wendymccartney@fs.fed.us
bobettejones@fs.fed.us
calewis@fs.fed.us
Prison Fire, Region 5, Lassen National Forest
Telephone:
(530) 252-5833 (McCartney)
(530) 252-5816 (Jones)
(530) 252-5832 (Lewis)
22