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Each sub-system of SYLVER operates independently with information provided
by the user or by other elements of the system which are:
- the Tree And Stand Simulator (TASS)
that grows the stand and applies silvicultural treatments;
- the Bucking (BUCK) and Sawmill Simulation (SAWSIM)
programs that produce logs and lumber from trees grown by TASS;
- the grading routine (GRADE) that classifies the logs and
lumber according to quality; and
- the Financial Analysis System (FAN$Y) that determines the
discounted net revenue recovered from tending, harvesting and processing
the stand.
Figure 1: Components and Operation of
SYLVER
See Future Development
The growth relationships that drive the development of individual trees
in SYLVER are described in the TASS
web site.
The coastal Douglas-fir
version of SYLVER is based on data from six 50-year-old stands representative
of managed forests located on Vancouver Island (Kellogg, 1989). The
number of trees sampled for each project is outlined below.
- 300 trees were converted
to lumber, and evaluated to estimate the log and lumber yield and
grade recovery (Middleton and Munro, 1989), kiln drying degrade (Mackay,
1989), strength and stiffness of dimensional lumber (Barrett and Kellogg,
1989), and heartwood treatability (Ruddick, 1989);
- 60 trees to study
the relative density distribution (Jozsa et all., 1989), chemical
properties (Swan et al., 1989) and longitudinal shrinkage (Nault,
1989);
- 24 trees to study
the juvenile-mature wood transition (Di Lucca, 1989);
- 17 trees to study
fibre length (Hamm, 1989); and
- 9 trees to study
density and chemical properties of juvenile, mature and top wood (Hatton
and Hunt, 1989a), unbleached Kraft pulp properties (Hatton and Hunt,
1989b), and refiner mechanical pulp properties (Hatton and Johal,
1989).
The input parameters
for the SYLVER components shown in Figure
1 are listed below.
- TASS input parameters are described in the TASS
web site.
- BUCK uses TASS generated tree heights, diameters (inside
and outside bark for the knotty and juvenile wood core), and average
knot size over the length of the stem. This program bucks each tree
according to specifications (i.e., log length, diameter and taper)
that maximize the value of the logs or lumber.
- SAWSIM applies a series of predefined cutting patterns to
log information generated by BUCK and selects the one that maximizes
value based on average market prices. SAWSIM input parameters include
the mill configuration (i.e., type of machine and kerf) and lumber
specifications (i.e., thickness, width and length). It is a
proprietary program developed by Halco
Software Systems Ltd.
- GRADE characterizes logs and lumber by quality
class. The grading criteria for logs are: minimum length, average
small-end diameter, average knot diameter and number of growth rings
per 2 cm. The grading criteria for clear and knotty lumber are:
knot content and juvenile wood percent length, width and thickness.
- FAN$Y uses stand, treatment and product information to evaluate
the impact of selected silvicultural treatments on the discounted
value returned by end products. Some input parameters are:
- land manager (i.e., crown or private); land ownership (i.e.,
crown or private); and market type (i.e., log or lumber);
- forestry costs (e.g., survey, land rent, brushing and weeding,
spacing, fertilization, root rot control, site preparation, planting,
pruning, etc.);
- harvesting costs (e.g., infrastructure development, operation
and administration overhead, tree-to-truck, hauling, etc.);
- manufacturing costs (e.g., milling, drying, machine stress rating,
etc.);
- market prices for logs, lumber and wood chips; and
- financial parameters (e.g., discount rate, U.S. dollar exchange
rate, inflation rate, taxes, adjustments factors for future costs
and prices, lumber premiums, appraisal data, etc.).
SYLVER output integrates
the yield information, product recovery and financial return from a
variety of management regimes. SYLVER is not distributed as stand-alone
package because it is complicated and must be operated by specialists.
Furthermore, SAWSIM is proprietary software.
To provide access to
SYLVER, the Forest Productivity Section
divided the operating responsibilities between the user support service
and the forest manager as illustrated in Figure
1. Both formulate a series of relevant management regimes
and the specifications for bucking, sawing and grading. User support
processes all regimes through to the generation of product files, which
are forwarded to the forest manager for use with FAN$Y on a personal
computer. Then the forest manager can perform sensitivity analyses on
the economic specifications to determine the most suitable prescription
for local conditions. For user support, contact Mario
Di Lucca.
SYLVER is mainly used
for:
- stand level planning
and economic analysis (e.g., silvicultural prescriptions for espacement,
fertilization, pruning, pre-commercial and commercial thinning);
- forest level planning
(e.g., long term timber supply projections for managed stands);
- predicting pest
impact (e.g., laminated root rot and spruce weevil);
- studies of tree
and stand dynamics, wood quality and product value; and
- education and teaching.
Link
to Recent Applications Using SYLVER
Some of the limitations
of SYLVER are:
- it cannot be distributed
as an integrated stand-alone software package;
- it cannot predict
yield of complex stands (i.e., mixed-species and/or uneven-aged stands);
and
- the lumber grade
data required to grade lumber is available only for coastal Douglas-fir.
Work is in progress on other species.
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