Harvesting Early
Good or Bad?
Eleanor McWilliams, MSc, RPF
J&E McWilliams & Associates Ltd.
Associated Strategic Consulting Experts Inc.
February 27, 2014
It depends on…
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Objectives
Timber supply constraints
Market conditions
Age class distribution
Species composition
Climate change strategies
Accuracy of managed stand yield projections
…
Climate Change…
14,000,000
AAC
12,000,000
Forecasted Harvest (m3/yr)
10,000,000
8,000,000
6,000,000
Base case
4,000,000
Lower Minimum Harvest
Criteria
2,000,000
0
0
50
100
Years from now
150
200
250
Managed Stand Growth
• With the harvest history on the coast and the MPB infestation
in the interior, timber supply forecasting is increasingly
sensitive to estimates of current and future managed stand
growth.
• This in turn has focused the spotlight on the details of
predicting managed stand growth. For example:
• Early height growth
• OAFs
• Forest health impacts
Early height growth
• Improvements are required to:
• Resolve inconsistent joins
between height growth above
and below breast height.
• Provide models users the ability
to input local height growth
information.
Early Height Growth
0.5
Height growth m/year
Lodgepole SI 20
0.4
0.3
0.2
0.1
0
0
2
4
6
8 10
Total Age
12
14
Years to Breast Height
• Intent is to allow users to directly enter years to breast height
if local information is known.
• Currently can get at this in TIPSY by “playing” with the stock
height option, but this is clumsy and potentially misleading.
• Adjustments have been made to site index functions to allow
the input of fractional years to breast height (e.g. 4.2).
• In the future, surveys could include a measurement of where
1.3 m falls between whorls.
OAFs
• Used to net down the potential yields predicted by TASS/TIPSY
• TASS/TIPSY predict regular (self-thinning) mortality, not
irregular mortality due to pests or abiotic damage.
• Special runs can be done to mimic pests or abiotic damage
and some disease modules have been developed (e.g.
Rotsim).
• Default OAF values come from comparison of research plot
data to inventory data.
• Default OAF values were chosen to get best estimates of yields
at rotation.
OAFs
1000
Merchantable Volume
900
800
700
600
500
100/100
400
50/100
300
100/50
200
100
0
15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Age
Monitoring Required
• We need better (in many cases any!) information on how our
regenerated stands are actually growing.
• Need it to adjust our predictions and fine tune our
understanding of stand development to improve management
for timber production and other values.
• Options include:
• Mid-rotation surveys
• Network of permanent plots
• In the ideal world, both.
Why monitoring is required
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To demonstrate sustainability and fulfill responsibilities
To provide critical information for AAC determinations
To check site productivity estimates
To provide forest health incident and impact information
To continually improve basic silviculture
To provide feedback on stocking standards
To ensure wise investments in incremental silviculture
To ensure projected gains from tree improvement are realized
To provide baseline data for climate change studies
To ensure accurate carbon accounting
To realize the full value from our research
Monitoring in other Jurisdictions
• USDA Forest Inventory & Analysis program maintains an
approximately 5 km grid across forest land in the U.S. (both
private and public).
• Approximately 125,000 PSPs, of which 20% are measured each
year.
• If BC was to become a US State, assuming about 2/3 of BC is
forested, USDA FIA would establish about 25,000 PSPs across
the province.
• If we adopted the Swedish model we would establish about
10,000 PSP on a grid across the province.
Most forest management decisions,
including when to harvest,
are based in part on assumptions of
future stand growth.