Transcript Document

Research Update
Coastal Douglas-fir Fertilization
Ian R. Cameron, RPF
Kamloops BC
Eleanor R.G. McWilliams, RPF
North Vancouver BC
Outline
History Overview
• Experiments
• Model Development
Current Work
• Data clean-up, consolidation
• Mixed effects modeling
Specific Questions
• Repeat Fertilizer Applications
• Response on High Sites
Next Steps
Experiments
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•
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•
EP703
Shawnigan Lake
Klinka / Carter
RFNRP
SMC
TASS Fd Fertilizer Module
• Developed in late 1980’s, very few
changes made since.
Stone, J. 1994. TASS fertilization module.
Working draft. Ministry of Forests, Research
Branch unpublished report.
TASS Fd Fertilizer Module
• Coefficients were
derived to modify
crown foliar volume,
mimicking increases
in photosynthetic
efficiency and foliage
biomass as observed
at Shawnigan Lake by
Holger Brix.
Brix, H. 1983. Effects of thinning and nitrogen
fertilization on Douglas-fir: Relative contribution of
foliage quantity and efficiency. Can.J.For.Res.
13:167-175
Physiology of the Response
Unfertilized
Fertilized
TASS Fd Fertilizer Module
• Other functions modelled increase in
height growth.
• Predicted increases in foliar volume and
height translate into increases in bole
volume.
• Magnitude of simulated responses were
calibrated to conform to stand-level stats
observed in research trials, primarily
EP703.
TASS Fd Fertilizer Module
Total Volume Responses for SI 30
fertilized at 10 m top height.
Initial
Trees/ha
m3/ha
%
10,000
48
29.5
4,444
48
29.5
2,500
49
30.6
1,600
41
27.0
1,200
32
22.8
1,111
31
22.2
816
22
18.4
625
16
15.2
494
12
12.8
400
9
11.9
Relative response
varies with initial density
TASS Fd Fertilizer Module
• Multiple fertilizer applications are treated
as independent events.
TIPSY Fd Fertilizer Module
• TIPSY fertilization responses are
generated in a different manner than most
other silviculture treatment responses.
• Not obtained by interpolating between
TASS output tables.
• Based on percentage responses
generated from research and TASS
projections of 1200 trees/ha initial density.
TIPSY Fd Fertilizer Module
TASS Total Volume Responses for SI 30
fertilized at 10 m top height.
TIPSY % response used for
all initial densities for SI 30
fertilized at 10 m top height
Initial
Trees/ha
m3/ha
%
10,000
48
29.5
4,444
48
29.5
2,500
49
30.6
1,600
41
27.0
1,200
32
22.8
1,111
31
22.2
816
22
18.4
625
16
15.2
494
12
12.8
400
9
11.9
TIPSY Fd Fertilizer Module
• Like TASS multiple fertilizations are
treated as independent events.
• This does not mean, however, that two
consecutive applications will have the
same level of response.
TIPSY – Two Fertilizer Treatments – Gain dependent on stand age
Stone 1994
1. Site specific differences in fertilization
response are not included. Site index is
only a surrogate for determining how a
site will respond to nitrogen fertilization.
Response prediction may increase with
knowledge of soil nutrient and moisture
regimes.
Stone 1994
2. Limited data for calibration. Responses
estimates were based primarily on
EP703, which resulted in limited data for
calibration of the module on higher sites.
Stone 1994
3. Response predictions are based on a
single application of 225 kg N / ha.
Multiple applications are implemented as
independent events in both TASS and
TIPSY. Data from multiple applications of
fertilizer was limited and has not been
used in module calibration.
Almost 20 years later,
it is time for some improvements!
Especially with 40 years + of measurements.
Shawnigan Lake
1977
What is new?
• Combining data from Canada and US
• Consistent compilation
– Height-dbh curves
– Volume equations
– Plot summaries
• Modelling the complete growth trend of
each plot instead of just two points in time.
What is new?
• Using more of the EP703 data set
– Previous analyses used a subset of
installations with complete designs
• Focusing the analysis on what the
modellers need to improve TASS / TIPSY
• Using mixed-effects modelling which
explicitly recognizes the hierarchical
organization of the data.
Current Work
• Clean, compile and summarize data from
all available sources.
– EP703
– Shawnigan
– SMC / RFNRP
– Misc US trials
Data Available
Current Work
• Use mixed-effects modelling to estimate
heights
• Historically not all heights measured.
• In many instances only measured heights
of dominant or site trees.
Height-Dbh curves
Specific Questions
• Response to multiple fertilizations
• Response on high sites
Multiple Fertilizations
• Published results based on RFNRP and
SMC data indicate diminished responses
with each additional fertilizer application.
Sucre, E.B., Harrison, R.B., Turnblom, E.C., Briggs, D.G. 2008. The
use of various soil and site variables for estimating growth response of
Douglas-fir to multiple applications of urea and determining potential
long-term effects on soil properties. Can. J. For. Res. 38:1458-1469.
Multiple Fertilizations
• The US data contains several installations
with plots that have been fertilized up to 4
times.
• These have been measured up to 8 years
after the 4th fertilization.
Shawnigan Lake
3rd fert
2nd fert
1st fert
Shawnigan Lake
3rd fert
2nd fert
1st fert
TASS / TIPSY
• Multiple fertilizer applications are currently
modelled as independent events.
Response on High Sites
• EP703 has few high sites.
• Shawnigan is SI 25.
• Klinka / Carter trials found some significant
gains on SI > 35.
• These sites were characterized by:
– Absence of growing season water deficits
– Relatively low foliar N
– Adequate foliar P
Response on High Sites
• Models developed in the US based on
RFNRP results show fertilizer responses
on SI as high as 42.
• Wide range of predicted responses.
• Going to determine if soil moisture and
nutrient regime can add any predictive
power to the model.
Next Steps
• Complete analysis of fertilizer response in
unthinned stands.
• Make initial recommendations for changes
to TASS and TIPSY fertilizer modules.
• Complete analysis of fertilizer response in
thinned stands.
• Make further recommendations for change
to TASS and TIPSY fertilizer modules.
Questions?