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![Page 1: Predicting Sapling Recruitment Following Partial Cutting in the Acadian Forest: Using Long-Term Data to Assess the Performance of FVS-NE David Ray 1, Chad.](https://reader030.fdocuments.net/reader030/viewer/2022032701/56649c9e5503460f9495eefa/html5/thumbnails/1.jpg)
Predicting Sapling Recruitment Following Partial Predicting Sapling Recruitment Following Partial Cutting in the Acadian Forest: Using Long-Term Cutting in the Acadian Forest: Using Long-Term
Data to Assess the Performance of FVS-NEData to Assess the Performance of FVS-NE
David Ray1, Chad Keyser2, Robert Seymour1 and John Brissette3
1School of Forest Resources, The University of Maine, Orono ME2Forest Management Service Center, USDA-FS, Fort Collins, CO
3Northeastern Research Station, USDA-FS, Durham, NH
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Outline
• Background– Motivation– Findings from past work
• Objectives• Methods
– Dataset– Analysis
• Results• Conclusions
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Creation of Stand Structures Over the Creation of Stand Structures Over the Past 25-yrs in MainePast 25-yrs in Maine
Structure Type
1980 1985 1990 1995 2000 2005
Pro
port
ion
of to
tal h
arve
st a
rea
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Pro
port
ion
clea
rcut
0.0
0.2
0.4
0.6
0.8
1.0
Even-aged (OSR & CC)MultiagedClearcut
FPA
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The Northeastern Variant (FVS-NE)The Northeastern Variant (FVS-NE)
• Covers the 14 Northeastern States– Formerly NE-TWIGS (Teck and Hilt 1991)– Lacks a “full” establishment model
• Newly coded Beta version incorporates some major changes– Small tree height and diameter growth– Background and density dependent mortality– Growth modifier function
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Assessing Recruitment DynamicsAssessing Recruitment Dynamics
• Partial cutting leads to cohort recruitment– Regeneration is prolific in this forest type (Brissette
1996)– Heavy cutting favors intolerant hardwoods; lighter
cuts promote tolerant conifers
• Long-term forecasts require consideration of regeneration/recruitment dynamics
• Compare performance of the production and beta versions of the Northeastern Variant
• Provide feedback that can be used to improve model performance
![Page 6: Predicting Sapling Recruitment Following Partial Cutting in the Acadian Forest: Using Long-Term Data to Assess the Performance of FVS-NE David Ray 1, Chad.](https://reader030.fdocuments.net/reader030/viewer/2022032701/56649c9e5503460f9495eefa/html5/thumbnails/6.jpg)
Findings From Past WorkFindings From Past Work
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Penobscot Experimental Forest (PEF)Penobscot Experimental Forest (PEF)
• US Forest Service Compartment Study– 50 yrs of remeasurement data (numbered
trees since the mid-70s)– Inventoried before and after harvests and at
approximately 5-yr intervals between harvests– 2 reps/treatment (~10 ha units)
• Tolerant Northern Conifers (BF, RS, EH)• Range in silvicultural intensity
– From 5-yr selection to commercial clearcutting
![Page 8: Predicting Sapling Recruitment Following Partial Cutting in the Acadian Forest: Using Long-Term Data to Assess the Performance of FVS-NE David Ray 1, Chad.](https://reader030.fdocuments.net/reader030/viewer/2022032701/56649c9e5503460f9495eefa/html5/thumbnails/8.jpg)
Live BA Following Partial Cutting at the PEFLive BA Following Partial Cutting at the PEFObserved vs. FVS PredictionsObserved vs. FVS Predictions
Ray, Seymour, and Keyser (2006)Proc. ECANUSA Conference
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Diameter class midpoint
Summary of Net Growth Comparison Summary of Net Growth Comparison based on ~25 yr Simulation Runsbased on ~25 yr Simulation Runs
~40% above observed production rates
(0.5 cd/ac/yr)
2.5 10 14 >166
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Methodology
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Code Description Cutting cycle (yrs)
Harvests Plot count
FDL Fixed diameter-limit
20* 3 33
MDL Modified diameter-limit
20 3 32
S05 Single-tree/small groups
5 10 33
S10 Single-tree/small groups
10 5 35
S20 Single-tree/small groups
20 3 37
URH Commercial clearcut
30* 2 41
NAT Untreated control
n/a n/a 20
Characteristics of the Partial-Cut TreatmentsCharacteristics of the Partial-Cut TreatmentsStem density
TP
A
0
2000
4000
6000
8000
10000
Basal area
BA
(ft
2 /ac)
0
50
100
150
200
Stand density index
SD
I
0
100
200
300
400
500
Conifer stockingPro
por
tion
of B
A
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Large regeneration density
FDL MDL S05 S10 S20 URH NAT
TP
A
0
4000
8000
12000
16000
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Nested Plot Design
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Simulation Run Details
• Focus on 5-yr runs at the plot level– 250 plots; 1,182 plot/interval combinations
• Calibration of LT diameter growth (≥1-in dbh)• Forest wide SI for balsam fir set at 55-ft• Large regeneration only- issues with SDImax
• Regeneration specified by mid-point of height class interval– Beta model equations used to derive species
specific heights for trees ≥ 4.5-ft tall but <0.5-in dbh• Key in on saplings crossing the 0.5-in dbh
threshold (1-in dbh class)
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Performance Criteria
• Presence absence of new recruits
• Compare diameter distributions
• Rates of sapling recruitment and mortality (BA, ft2/ac/5-yr)
• Correlation analysis between residuals and plot attributes
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Results
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Large TreeLarge Tree Calibration StatisticsCalibration Statistics
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The Nested Plots• Recruitment was observed on 55% (653/1,182)
of the plot/interval combinations– Tall regeneration was present on 68% of plots where
recruitment was observed (‘appeared’ on 32%)
• Simulated recruitment was limited to plots with large regeneration present (n=729)– Recruitment was observed on 61% of these plots– PRODFVS predicted recruitment on 35%– BETAFVS predicted recruitment on 68%
• Agreement between observed and predicted– For PRODFVS was 29%– For BETAFVS was 56%
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more on The Nested Plots
• Backwards extrapolation of observed diameter growth– 10% may have been smaller than large
regeneration (URH- intolerant broadleafs)
• Sufficient abundance of large regeneration– 96% of plot/intervals had more than enough to
account for observed recruitment
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Results- Recruitment Basal Area
PRODFVS = -0.43 + 0.59 (OBS); r2=0.10 BETAFVS = 0.26 + 1.66 (OBS); r2=0.13
Production Code
Observed (BA, ft2/ac/5-yr)
0 2 4 6 8 10 12 14 16
Pro
duct
ion
(BA
, ft
2/a
c/5-
yr)
0
2
4
6
8
10
12
14
16
FDLMDLNATS05S10S20URH
Beta Code
Observed (BA, ft2/ac/5-yr)
0 2 4 6 8 10 12 14 16
Bet
a (B
A,
ft2/a
c/5-
yr)
0
2
4
6
8
10
12
14
16
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Ingrowth Dbh Distribution
Dbh (in)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Pro
port
ion
of t
otal
0.0
0.1
0.2
0.3ObservedBetaProduction
Results- Diameter Distribution
Recruitment
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Results- Recruitment & MortalityResults- Recruitment & Mortality
Ingrowth BA
0
1
2
3
4
5
Mortality BA
Ba
sal a
rea
(ft
2 /ac/
5yr
)
0.0
0.2
0.4
0.6
0.8
1.0
HardwoodsSoftwoods
73% SW90% SW
75% SW
20% SW 73% SW
70% SW
Ingrowth/Mortality
Observed Production Beta
Ra
tio (
%)
0
5
10
15
20
4 X
Recruitment BA
Recruitment/Ingrowth
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Results- Residual Analysis
-0.67***
-0.18***
-0.49***-0.83***
-0.08*-0.18*** 0.14***
-0.16*** 0.10**
Recruitment
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Summary of Findings
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Conclusions I
• Difficult hoop for the model to pass through• Large tree calibration statistics were closer for
BETAFVS than PRODFVS
• Recruitment rates were underestimated by PRODFVS (~50%) and overestimated by BETAFVS (~100%) relative to that observed on partially cut plots at the PEF (~2 ft2/ac/5yr)
• Mortality rates were too high, particularly for BETAFVS
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Conclusions II
• The changes implemented in BETAFVS should improve model performance
• Model biases were related to– Large regeneration density for BETAFVS (strong)– QMD, % SW regen, Harvests for PRODFVS (weak)
• Resetting GMOD to 0.5 (from 0.15), too high?– Shade tolerant saplings can just sit there in the
understory (GMOD by shade tolerance?)• The Northeastern Variant covers a large
geographic range; the Acadian Forest Region represents a relatively small part
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Acknowledgements
• US Forest Service– PEF Dataset– Support with FVS
• Northeastern States Research Cooperative (NSRC)
• UMO School of Forest Resources