fire prevention as a ghg mitigation strategy presented by robert beach, rti international brent...
TRANSCRIPT
Fire Prevention as a GHG Mitigation Strategy
Presented by Robert Beach, RTI International
Brent Sohngen, The Ohio State University
Presented atForestry and Agriculture Greenhouse Gas Modeling Forum
March 6-8, 2007Shepherdstown, West Virginia
RTI International is a trade name of Research Triangle Institute
3040 Cornwallis Road ■ P.O. Box 12194 ■ Research Triangle Park, NC 27709Phone 919-485-5579 e-mail [email protected] 919-541-6683
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Introduction
Heightened concern in recent years that intensive human intervention may have made forests more susceptible to negative effects of wildfires
Evidence that fire management interventions such as prescribed burning and thinning can reduce potential hazards related to wildland fires by removing smaller materials that can act as ladders for fires
Healthy Forests Restoration Act called for widespread thinning in US forests in order to help make them less susceptible to the negative effects of fires
Potential for reduction in the impacts of fires suggests that additional short-term carbon emissions could lead to smaller emissions in the future if large fires are reduced Implications for carbon sequestration in fire-prone stands
This is an exploratory study to examine the net carbon effects (accounting for time) of thinning using the Forest Vegetation Simulator-Fire and Fuels Extension (FVS-FFE) model
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Study Region and Plots
Representative ponderosa pine stands in the Eastern Cascades region of OregonRegion has been identified as having high build-up
of fuels in forests, that could potentially lead to large-scale consequences if fires break out
Ponderosa pine is the dominant species in the Eastern Cascades
Plot data obtained from the US Department of Agriculture, Forest Service, Forest Inventory and Analysis
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Models
Used FVS-FFE model to assess biomass stocks, thinning options, and simulated fire effects
FVS models stand dynamics, including growth of forests, mortality, and other attributes
The Fire and Fuels Extension can be used to model changes in biomass in different pools over time and to simulate the effects of a fire on these pools as well as modeling residual stand growth. FFE can be used to simulate the effects of fires under
different weather conditions
Examined carbon storage and emission profile over a 100-year period with and without thinning and with and without a fire
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Models (2)
Fuel Reduction Cost Simulator (Fight et al., 2006) was used to estimate costs of extracting materials from thinning operations
Used cut list from FVS to identify the trees that were thinned
Benefits of extracting marketable materials were estimated using price data from the OR Dept of Forestry
Estimated non-CO2 emissions (methane, nitrous oxide) from wildfire using EPA emission factors
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Assumptions
Thinning from below until 50 sq ft basal area
Material in the range of 5"-7" is used for pulp and material >7" dbh is used for sawtimber
All remaining material is assumed to be chipped and burned onsite, leading to an immediate emission
Calculate carbon stock in standing biomass using factors from Smith et al (2003)
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Representative Stand
Stand Identifier =>
4120040202990513
Stand "90513" Latitude; Longitude 42.4100; 122.5800
Sampling Weight 15,968
Month/Year Measured 07/2004
Elevation (ft)/Slope 2105/40%
Age 70
ft3 per acre /site class
1792/20 – 50 ft3/acre/year
Trees per acre 319
Crowning Index (MPH)
47.5
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Change in Carbon Stock with Thinning
0
10
20
30
40
50
60
70
80
90
100
2000 2020 2040 2060 2080 2100
tC/h
a
No Thinning Thinning w/o Products Thinning w/Products
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Unthinned Stand with Fire in 2010
0
10
20
30
40
50
60
70
80
90
100
2004 2014 2024 2034 2044 2054 2064 2074 2084 2094
t C
/ha
Base Forest w/o Fire Small Fire Larger Fire
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Change in C Storage from Thinning Relative to Baseline
-0.40
-0.35
-0.30
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
2004 2014 2024 2034 2044 2054 2064 2074 2084 2094
Year
ton
ne
s/h
a/y
ea
r
Thinning w/o fire
Thinning w/ fire
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Thinning without Fire
Immediate release of carbon from thinning
Thinned stand slowly begins to approach carbon storage of unthinned stand over time
PV of carbon change over 100 years from case study stand is -4.12 tC/ha without fire
PV of carbon change with fire is actually even more negative in this case at -4.95 tC/ha
Harvesting operation cost: $678/acre
Value of wood harvested: $498/acre
Net value: -$180/acre
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Other Stands
Across the 487 ponderosa pine stands in the Eastern Cascades of OR available from FIA dataOver half had lower carbon emissions from fires
when they had been thinnedHowever, only in a minority of cases (<20%) were
the lower emissions from fire sufficient to offset the higher emissions from thinning
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Timing of Thinning and Fires
We also examined a number of scenarios that varied the timing between thinning and the fire
Initially we thought that the findings may be related to the fire occurring shortly after thinningHowever, it made relatively little qualitative
difference in changes in carbon storage
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Conclusions
Based on our simulations and assumptions, thinning tended to result in lower discounted net carbon storage In the absence of wildfires, carbon storage is
reduced relative to baseline due to the removal of carbon during thinning
With wildfires, the majority of plots examined did have lower emissions if they had been thinned, but not sufficiently lower to offset the emissions from thinning
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Future Research/Extensions
Alternative fire models FOFEM, CONSUME, others
Accounting for interactions with other stands
Prescribed burning
Quantify factors impacting effectiveness of thinning in reducing emissions
Include harvesting
Stochastic wildfires
Examination of climate effects