Transcript Slide 1

Mechanical fuels reduction treatments effects on
fire behavior, fuel loads, and forest ecology
Osceola National Forest
Sept. 28th, 2011
Sponsors: Conserved Forest Ecosystems Outreach and Research (CFEOR);
Southern Fire Exchange (SFE: www.southernfirexchange.org); Joint Fire Science
Program; US Forest Service; University of Florida Fire Science Lab
Hosts:
Jesse Kreye, and David Godwin, PhD Candidates
James Camp and Dawn McKinstry, Research Assistants
Leda Kobziar, Asst. Professor of Fire Science
School of Forest Resources and Conservation, University of Florida
Contact us: [email protected]; (352) 846-0901
Table of Contents
Map of treatment locations………………………………….1
Treatment effects on shrubs & litter……………………..2
Understory composition………………………………….......3
Rank of variables among treatments…………………….4
Photo guide……………………………………………………..…5-8
Fire behavior and effects………………………………….9-11
Soil characteristics……………….………………………...12-13
Synopses………………………………………………………….….14
Driving Directions
Head right (east) on US Hwy-90 approx. 2 miles
•
Turn left (north) on Ocean Pond Rd / CR-250A at the Ocean Pond
Campground sign
•
Cross the RR tracks and continue on Ocean Pond Rd over I-10 for
approx. 7 miles
•
Turn left (south) on Gum Swamp Rd / CR-250 at stop sign
•
Continue approx. 1 mile experimental units on left
•
Park on the right (north) side of Gum Swamp Rd
Ocean Pond Rd / CR-250A
•
Map of Treatment Locations
Walking Path through Site:
Image from ~2 weeks post
burn
p. 1
Osceola NF Fuels Treatment Effects
6 months post-burn & 1 year post-mowing
Compartment 69: As of Sept. 25, 2011
p. 2
Percent Cover and Average Height of Shrubs
80
1.4
Avg. Shrub Ht.
Palmetto
60
1.2
1
0.8
0.4
Palmetto
Palmetto
0.6
Other shrubs
10
Other shrubs
20
Othe r shrubs
30
Other shrubs
40
Palmetto
% Cover
50
Height (m)
70
0
0.2
0
Control
Mow
Burn
Mow+burn
Litter and Duff Depths and Mass
12
12
Duff mass
10
10
Litter mass
Control
Mow
Burn
Duff Depth
Litter Depth
Duff Depth
0
Litter Depth
2
Duff Depth
4
Litter Depth
Mow+burn
4
2
0
Mass (Mg/ha)
6
Duff Depth
6
8
Litter Depth
Depth (cm)
8
Osceola NF Fuels Treatment Effects
p. 3
6 months post-burn & 1 year post-mowing
Percent Cover of Understory, Litter, and
Bare Ground < 0.5 m height
Burn
Control
31
0
42
14
Shrub
Shrub
56
Grass
Grass
Herb
Herb
Litter
Litter
5
Bare Ground
50
0
Bare Ground
0 2
Mow
Mow+Burn
24
0
42
4
Shrub
Shrub
Grass
Grass
Herb
49
Herb
50
Litter
Litter
Bare Ground
6
0
24
3
Bare Ground
Osceola NF Fuels Treatment Effects
6 months post-burn & 1 year post-mowing
p. 4
Rank of Values Among Treatments
(1 = highest value, 4 = lowest value)
Biomass
Control
Mow
Burn
Mow + Burn
Shrubs
1
2
3
4
Litter
1
1
4
3
Duff
1
2
4
3
Palmetto Cover
1
3
2
4
Palmetto Height
1
2
2
3
Other Shrub Cover
2
1
4
3
Other Shrub Height
1
2
4
3
Shrub (<0.5 m ht.)
1
4
3
2
Grass
4
1
3
2
Herb
0
1
0
0
Understory
Percent Cover
Ranking
1=highest value
4=lowest value
0=actual value
is zero
*Underline indicates a relatively larger difference from other values
Osceola NF Fuels Treatment Effects
p. 5
Photo Guide- CONTROL
Location: Osceola National Forest
Columbia County, Florida
30.2657, -82.4919
Treatment: Control
Photo Date: May 2011
Fuel Loading
Treatment
N
Control
7
mean
sd
1h (Mg·ha-1)
10h (Mg·ha-1)
100h (Mg·ha-1)
1000h S (Mg·ha-1)
1000h R (Mg·ha-1)
Litter (Mg·ha-1)
Duff (Mg·ha-1)
Shrub H-A (Mg·ha-1)
Litter Depth (cm)
Duff Depth (cm)
Palmetto Cover (%)
Palmetto Height (m)
BA (m2·ha-1)
0.39
0.51
1.60
1.24
0
0
0.25
0.65
0
0
9.49
2.42
14.60
3.39
9.6
8.2
2.1
5.7
1.8
62
24
1.0
0.2
19.4
6.0
Control
30
3.5
Rate of spread
3
Flame length
2.5
20
2
15
1.5
10
1
5
0.5
0
0
0
3
6
9
Windspeed (km/h)
12
Flame Length (m)
Rate of Spread (m/min)
25
Osceola NF Fuels Treatment Effects
p. 6
Photo Guide- BURN TREATMENT
Location: Osceola National Forest
Columbia County, Florida
30.2653, -82.4929
Fuel Loading
Treatment
N
Burn
11
1h (Mg·ha-1)
10h (Mg·ha-1)
100h (Mg·ha-1)
1000h S (Mg·ha-1)
1000h R (Mg·ha-1)
Litter (Mg·ha-1)
Duff (Mg·ha-1)
Shrub H-A (Mg·ha-1)
Litter Depth (cm)
Duff Depth (cm)
Palmetto Cover (%)
Palmetto Height (m)
BA (m2·ha-1)
mean
sd
0.09
0.11
1.56
1.64
0.27
0.60
4.89
11.82
0
0
2.22
0.62
11.15
2.51
0.30
1.9
0.5
4.0
1.3
18
11
0.5
0.1
18.6
8.3
Burn
3.5
0.7
Rate of spread
3
0.6
Flame length
2.5
0.5
2
0.4
1.5
0.3
1
0.2
0.5
0.1
0
0
0
3
6
9
Windspeed (km/h)
12
Flame Length (m)
Rate of Spread (m/min)
Treatment: Burn Only
Treatment Date: February 2011
Photo Date: March 2011
Osceola NF Fuels Treatment Effects
p. 7
Photo Guide- MOW TREATMENT
Location: Osceola National Forest
Columbia County, Florida
30.2642, -82.4920
Fuel Loading
Treatment
N
Mow
9
1h (Mg·ha-1)
10h (Mg·ha-1)
100h (Mg·ha-1)
1000h S (Mg·ha-1)
1000h R (Mg·ha-1)
Litter (Mg·ha-1)
Duff (Mg·ha-1)
Shrub H-A (Mg·ha-1)
Litter Depth (cm)
Duff Depth (cm)
Palmetto Cover (%)
Palmetto Height (m)
BA (m2·ha-1)
mean
sd
0.97
0.45
2.29
1.97
1.16
1.63
0.43
0.84
0
0
12.88
2.40
12.06
2.08
1.2
5.3
1.2
4.4
1.1
11
8
0.7
0.3
20.0
7.3
Mow
25
2.5
Rate of spread
20
2
Flame length
15
1.5
10
1
5
0.5
0
0
0
3
6
9
Windspeed (km/h)
12
Flame Length (m)
Rate of Spread (m/min)
Treatment: Mow Only
Treatment Date: August 2010
Photo Date: October 2010
Osceola NF Fuels Treatment Effects
p. 8
Photo Guide- MOW + BURN TREATMENT
Location: Osceola National Forest
Columbia County, Florida
30.2660, -82.4909
Fuel Loading
Treatment
N
Mow+burn
9
mean
sd
1h (Mg·ha-1)
10h (Mg·ha-1)
100h (Mg·ha-1)
1000h S (Mg·ha-1)
1000h R (Mg·ha-1)
Litter (Mg·ha-1)
Duff (Mg·ha-1)
Shrub H-A (Mg·ha-1)
Litter Depth (cm)
Duff Depth (cm)
Palmetto Cover (%)
Palmetto Height (m)
BA (m2·ha-1)
0.21
0.11
1.35
0.66
0.17
0.50
0.80
1.60
0.06
0.18
1.74
0.58
10.67
3.29
0.0
1.5
0.5
3.7
1.7
4
3
0.3
0.2
22.5
10.3
Mow + Burn
3.5
0.7
Rate of spread
3
0.6
Flame length
2.5
0.5
2
0.4
1.5
0.3
1
0.2
0.5
0.1
0
0
0
3
6
9
Windspeed (km/h)
12
Flame Length (m)
Rate of Spread (m/min)
Treatment: Mow & Burn
Date: Mow: August 2010
Burn: February 2011
Photo Date: March 2011
Fuels Treatment Effects on Fire Behavior
p. 9
*Immediate Post-Treatment Conditions
Potential Fire Behavior – Immediate Post Treatment
(Behave: customized FM9 for post-burned, Hough-Albini for others;
actual Rx fire conditions)
30
Predicted Rate of Spread
Control
25
Meters/ minute
Mow
20
Burn and Mow + Burn
15
X observed (Burned
10
Control)
5
X observed (Mow)
0
0
3
6 (km/h)
Wind speed
X
3.5
Control
3
12
Predicted Flame Length
observed (Burned Control)
Mow
2.5
Flame Length (m)
9
Burn
MowBurn
2
1.5
1
X observed (Mow)
0.5
0
0
3
6
Wind speed (km/h)
9
12
Fuels Treatment Effects on Fire Behavior
*6 months post-burn & 12 mo. post-mowing
p. 10
Potential Fire Behavior – Present Day
(Behave H-A model; 90th % wildfire conditions)
Predicted Rate of Spread
45
Control
40
Mow
Meters/ minute
35
Burn
30
MowBurn
25
20
15
10
5
0
0
3
6
Wind speed (km/h)
9
12
Predicted Flame Length
5
Flame Length (m)
4.5
Control
4
Mow
3.5
Burn
MowBurn
3
2.5
2
1.5
1
0.5
0
0
3
6
Wind speed (km/h)
9
12
Actual Fire Effects on Trees
Burn Only and Mow + Burn (burned Feb. 26, 2011) p. 11
Burn Only: Total Crown Damage (%)
Percent Damage (% of crown)
120
y = -3.3125x + 140.2
R² = 0.5983
100
80
60
40
20
0
0.0
20.0
30.0
DBH (cm)
40.0
50.0
Mow + Burn: Total Crown Damage (%)
120
Percent Damage (% of crown)
10.0
100
80
60
40
y = -1.4559x + 79.181
R² = 0.1128
20
0
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
DBH (cm)
No. Trees with % Crown Scorch
12
Burn Only
Number of Trees
10
Mow + Burn
8
6
4
2
0
0-10
11-20
21-30
31-40
41-50
51-60
61-70
Percent of Crown Volume Scorched
71-80
81-90
91-100
Fuels Treatment Effects on Soil T & MC%
p. 12
Soil Temperature
• Burning increased soil T throughout the study period.
• Mowing reduced soil T in the winter months and
increased soil T during the growing season.
Soil Moisture
Plots
Burned
Est. Soil Volumetric Moisture Content (m3/m3)
0.25
Burn
Control
C D B A
0.20
A B A A
Mow
BC C AB A
Mow+Burn
0.15
B B A A
AB B B A
0.10
0.05
0.00
Dec
Jan
Mar
Apr
May
Jun
Jul
Aug
• Soil MC% was increased in the mowed plots, but less so in
the droughty summer season. Increases are likely due to
decreased evapotranspiration (ET) and interception, &
increased litter cover.
• Burning initially increased soil MC% in the Burn Only units.
• Burning in the mowed plots did not have a clear treatment
effect relative to the Mow units.
Fuels Treatment Effects on Soil Carbon
p. 13
Soil Carbon Respiration Rates
7.00
Burn
Control
Soil C02 Respiration Rate μmol CO2 m2 sec-1
6.00
Plots
Burned
Mow
B B A B
Mow+Burn
5.00
4.00
C BC A AB
3.00
B A A AB
A A B AB
2.00
1.00
DEC
JAN
MAR
APR
MAY
2010-2011
JUN
Jul
Aug
Soil Carbon
• Soil carbon and soil organic matter did not differ among treatments
• Soil carbon respiration (SCR) increased from January through July with a
decline in August. This trend follows seasonal variations in soil T rather
than soil moisture content.
• Burning in unmowed plots reduced SCR for 2 months.
• Mowing followed by burning also showed a trend of reducing SCR.
• Mowing did not show an obvious effect on SCR.
Synopses & Take Home Messages
p. 14
After 6 mo. Post Burn and 12 mo. Post Mow:
• Predictions of fire behavior suggest little difference among treatments for rate of spread
• Predictions suggest greater flame lengths in Control, and slightly greater FL in Mow units.
• Burn and Mow + Burn have virtually indistinguishable fire behavior, suggesting it is similarly
mitigated by both treatment scenarios.
Observed Fire Behavior & Effects on Trees:
•
•
•
•
After 6 mo. regrowth, Mow units had lower flame lengths and rates of spread than Burn Only
Behave underpredicted actual fire behavior in Burn Only units.
Mowing prior to burning effectively reduced percent crown volume scorch and TCD.
Bark beetles and tree mortality are present in the Burn Only, but not the Mow + Burn units.
Vegetation and Ground Cover:
•
•
•
•
6 and 12 mo. post treatments, litter cover was near 50% in all treatments
Burned units had more bare ground and grass than control units
Mow Only units had the highest grass and herbaceous component
Palmetto and other shrub height, cover, and biomass were reduced by all treatments.
Take-Home Messages
1.
Although burning, (either following mowing or alone), mitigates potential fire behavior
immediately post treatment, at six months post-burn fuels and vegetation recovered so
that potential rate of spread would was no longer affected by treatment. However, flame
lengths appear to be greatly reduced by all treatments when compared with controls, even
after this recovery time period.
2.
Mowing increases percent cover of herbaceous and grassy species, increasing functional
diversity and potentially improving wildlife habitat. Mechanical disturbance to soils may
be responsible for these effects.
3.
Burning during the dormant season after Mowing decreases herbaceous and grass
components of the understory, when compared with Mow alone.
4.
Mowing long-unburned sites prior to reintroduction of fire reduces fire behavior,
decreases crown scorch and tree mortality, and results in low fire risk. We found no
evidence of increased bole or fine root damage in Mow + Burn sites.
5.
Soil carbon and soil organic matter are not affected in the short-term by treatments;
however, burning appears to decrease soil carbon loss and increase soil temperatures.
•Caveat: Although we have 113 plots across the forest, the data presented herein were generated from the
demonstration site in compartment 69 for the purpose of this workshop. Our data collection is continuing, and
our ultimate analyses will include data from all of the sampled areas, reflecting trends across the greater
landscape. Conclusions may, therefore, change as the additional data are tested.