mechanical fuels reduction treatments effects on fire behavior, fuel loads, and forest ecology...
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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 FloridaContact 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
Ocean Pond Rd / CR-250A
Gum Swam
p Rd / CR-250
US HWY-90
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
Map of Treatment Locations p. 1
Walking Path through Site: Image from ~2 weeks post
burn
Osceola NF Fuels Treatment Effects6 months post-burn & 1 year post-mowing
Compartment 69: As of Sept. 25, 2011
Control Mow Burn Mow+burn0
10
20
30
40
50
60
70
80
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Other shrubsOthe r shrubs
Other shrubs
Other shrubs
Palm
etto
Palm
etto
Palm
etto
Palm
etto
Percent Cover and Average Height of Shrubs
Avg. Shrub Ht.
% C
over
Hei
ght (
m)
Control Mow Burn Mow+burn0
2
4
6
8
10
12
0
2
4
6
8
10
12
Litter
Dep
th
Litter
Dep
th
Litter
Dep
th
Litter
Dep
th
Duff
Dept
h
Duff
Dept
h
Duff
Dept
h
Duff
Dept
h
Litter and Duff Depths and Mass
Litter mass
Duff mass
Dep
th (c
m)
Mas
s (M
g/ha
)
p. 2
Osceola NF Fuels Treatment Effects6 months post-burn & 1 year post-mowing p. 3
Percent Cover of Understory, Litter, and Bare Ground < 0.5 m height
24
24
3
50
Mow
ShrubGrassHerbLitterBare Ground
42
2
56
Control
ShrubGrassHerbLitterBare Ground
31
5
50
14
Burn
Shrub
Grass
Herb
Litter
Bare Ground
42
6
49
4
Mow+Burn
ShrubGrassHerbLitterBare Ground
Osceola NF Fuels Treatment Effects6 months post-burn & 1 year post-mowing p. 4
Biomass Control Mow Burn Mow + Burn
Shrubs 1 2 3 4
Litter 1 1 4 3
Duff 1 2 4 3
Understory
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
Percent Cover
Shrub (<0.5 m ht.) 1 4 3 2
Grass 4 1 3 2
Herb 0 1 0 0
Ranking1=highest value4=lowest value
0=actual value is zero*Underline indicates a relatively larger difference from other values
Rank of Values Among Treatments(1 = highest value, 4 = lowest value)
Osceola NF Fuels Treatment EffectsPhoto Guide- CONTROL p. 5
Treatment: ControlPhoto Date: May 2011
Location: Osceola National Forest Columbia County, Florida30.2657, -82.4919
Fuel LoadingTreatment Control
N 7mean sd
1h (Mg·ha-1) 0.39 0.51
10h (Mg·ha-1) 1.60 1.24
100h (Mg·ha-1) 0 0
1000h S (Mg·ha-1) 0.25 0.65
1000h R (Mg·ha-1) 0 0
Litter (Mg·ha-1) 9.49 2.42
Duff (Mg·ha-1) 14.60 3.39
Shrub H-A (Mg·ha-1) 9.6
Litter Depth (cm) 8.2 2.1
Duff Depth (cm) 5.7 1.8
Palmetto Cover (%) 62 24
Palmetto Height (m) 1.0 0.2
BA (m2·ha-1) 19.4 6.0
0 3 6 9 120
5
10
15
20
25
30
0
0.5
1
1.5
2
2.5
3
3.5Control
Rate of spread
Flame length
Windspeed (km/h)
Rate
of S
prea
d (m
/min
)
Flam
e Le
ngth
(m)
Osceola NF Fuels Treatment EffectsPhoto Guide- BURN TREATMENT p. 6
Fuel LoadingTreatment Burn
N 11mean sd
1h (Mg·ha-1) 0.09 0.11
10h (Mg·ha-1) 1.56 1.64
100h (Mg·ha-1) 0.27 0.60
1000h S (Mg·ha-1) 4.89 11.82
1000h R (Mg·ha-1) 0 0
Litter (Mg·ha-1) 2.22 0.62
Duff (Mg·ha-1) 11.15 2.51
Shrub H-A (Mg·ha-1) 0.30
Litter Depth (cm) 1.9 0.5
Duff Depth (cm) 4.0 1.3
Palmetto Cover (%) 18 11
Palmetto Height (m) 0.5 0.1
BA (m2·ha-1) 18.6 8.3
Treatment: Burn OnlyTreatment Date: February 2011Photo Date: March 2011
Location: Osceola National Forest Columbia County, Florida30.2653, -82.4929
0 3 6 9 120
0.5
1
1.5
2
2.5
3
3.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7Burn
Rate of spread
Flame length
Windspeed (km/h)
Rate
of S
prea
d (m
/min
)
Flam
e Le
ngth
(m)
Osceola NF Fuels Treatment EffectsPhoto Guide- MOW TREATMENT p. 7
Fuel Loading
Treatment: Mow OnlyTreatment Date: August 2010Photo Date: October 2010
Location: Osceola National Forest Columbia County, Florida30.2642, -82.4920
Treatment MowN 9
mean sd1h (Mg·ha-1) 0.97 0.45
10h (Mg·ha-1) 2.29 1.97
100h (Mg·ha-1) 1.16 1.63
1000h S (Mg·ha-1) 0.43 0.84
1000h R (Mg·ha-1) 0 0
Litter (Mg·ha-1) 12.88 2.40
Duff (Mg·ha-1) 12.06 2.08
Shrub H-A (Mg·ha-1) 1.2
Litter Depth (cm) 5.3 1.2
Duff Depth (cm) 4.4 1.1
Palmetto Cover (%) 11 8
Palmetto Height (m) 0.7 0.3
BA (m2·ha-1) 20.0 7.3
0 3 6 9 120
5
10
15
20
25
0
0.5
1
1.5
2
2.5Mow
Rate of spread
Flame length
Windspeed (km/h)
Rate
of S
prea
d (m
/min
)
Flam
e Le
ngth
(m)
Osceola NF Fuels Treatment EffectsPhoto Guide- MOW + BURN TREATMENT p. 8
Fuel LoadingTreatment Mow+burn
N 9mean sd
1h (Mg·ha-1) 0.21 0.11
10h (Mg·ha-1) 1.35 0.66
100h (Mg·ha-1) 0.17 0.50
1000h S (Mg·ha-1) 0.80 1.60
1000h R (Mg·ha-1) 0.06 0.18
Litter (Mg·ha-1) 1.74 0.58
Duff (Mg·ha-1) 10.67 3.29
Shrub H-A (Mg·ha-1) 0.0
Litter Depth (cm) 1.5 0.5
Duff Depth (cm) 3.7 1.7
Palmetto Cover (%) 4 3
Palmetto Height (m) 0.3 0.2
BA (m2·ha-1) 22.5 10.3
Treatment: Mow & BurnDate: Mow: August 2010 Burn: February 2011Photo Date: March 2011
Location: Osceola National Forest Columbia County, Florida30.2660, -82.4909
0 3 6 9 120
0.5
1
1.5
2
2.5
3
3.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7Mow + Burn
Rate of spread
Flame length
Windspeed (km/h)
Rate
of S
prea
d (m
/min
)
Flam
e Le
ngth
(m)
Fuels Treatment Effects on Fire Behavior*Immediate Post-Treatment Conditions p. 9
Potential Fire Behavior – Immediate Post Treatment(Behave: customized FM9 for post-burned, Hough-Albini for others;
actual Rx fire conditions)
0 3 6 9 120
5
10
15
20
25
30
Predicted Rate of SpreadControl
Mow
Burn and Mow + Burn
Wind speed (km/h)
Met
ers/
min
ute
0 3 6 9 120
0.5
1
1.5
2
2.5
3
3.5Predicted Flame Length
Control
Mow
Burn
MowBurn
Wind speed (km/h)
Flam
e Le
ngth
(m)
X observed (Burned Control)
X observed (Mow)
X
X observed (Mow)
observed (Burned Control)
Fuels Treatment Effects on Fire Behavior*6 months post-burn & 12 mo. post-mowing p. 10
0 3 6 9 120
5
10
15
20
25
30
35
40
45
Predicted Rate of Spread
Control
Mow
Burn
MowBurn
Wind speed (km/h)
Met
ers/
min
ute
0 3 6 9 120
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Predicted Flame Length
Control
Mow
Burn
MowBurn
Wind speed (km/h)
Flam
e Le
ngth
(m)
Potential Fire Behavior – Present Day(Behave H-A model; 90th % wildfire conditions)
Actual Fire Effects on TreesBurn Only and Mow + Burn (burned Feb. 26, 2011) p. 11
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.00
20
40
60
80
100
120f(x) = − 3.31253255101032 x + 140.199059564228R² = 0.598311947538507
Burn Only: Total Crown Damage (%)
DBH (cm)
Perc
ent D
amag
e (%
of c
row
n)
5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.00
20
40
60
80
100
120
f(x) = − 1.45593614913667 x + 79.1809324946272R² = 0.112839449625242
Mow + Burn: Total Crown Damage (%)
DBH (cm)
Perc
ent D
amag
e (%
of c
row
n)
0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-1000
2
4
6
8
10
12 No. Trees with % Crown Scorch
Burn OnlyMow + Burn
Percent of Crown Volume Scorched
Num
ber
of T
rees
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.
Dec Jan Mar Apr May Jun Jul Aug0.00
0.05
0.10
0.15
0.20
0.25Burn
Control
Mow
Mow+Burn
Est.
Soil
Volu
met
ric M
oist
ure
Cont
ent (
m3/
m3)
Plots Burned
B B A A
BC C AB AC D B A A B A A
AB B B A
Soil Moisture
• 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 Carbonp. 13
DEC JAN MAR APR MAY JUN Jul Aug1.00
2.00
3.00
4.00
5.00
6.00
7.00
Burn
Control
Mow
Mow+Burn
2010-2011
Soil
C02
Resp
iratio
n Ra
te μ
mol
CO
2 m
2 se
c-1
A A B AB
B A A AB
B B A B
Plots Burned
C BC A AB
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.
Soil Carbon Respiration Rates
Synopses & Take Home Messagesp. 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.