BC Ministry of Forests - Research Branch - Forest Productivity Section

Online Presentations: SYLVER Demo/Volume vs Value

Person pruning a tree.

SYLVER is designed to help foresters choose defensible silvicultural prescriptions.
For example, how would you weigh the future value of clear lumber against the current cost of pruning?
We'll address this question later under a separate topic.
But first, let's look at the broader issue of value.


Conventional analysis in B.C. maximizes volume production.
But economic recessions and other market forces are forcing us to think about maximizing the value of the resource we will be harvesting, ... and that will affect management decisions.
Take rotation length, for example.

VOLUME/AGE GRAPH (with trees)

Here we've plotted volume against plantation age.
To manage for volume, ...

VOLUME/AGE GRAPH (with tangent)

... we draw a line tangent to the volume curve ...
and achieve maximum volume production by harvesting each crop at age 80.

DOUBLE GRAPH (volume/age - value/age)

Now watch this age change from 80 to 70 years when we introduce value.
Costs, revenues and interest rates shorten the rotation, and increase the value of the stand.
We know this because of SYLVER ...

User working on PC

... which our Stand Modelling Group has been developing since 1985, with input from Forintek and others (PAPRICAN, UBC & industry) because our volume prediction systems need wood properties and product quality before they can address value. That is ...


Quality links volume to value.
We upgraded a volume-oriented growth model (TASS), linked it to models that capture quality (BUCK, SAWSIM & GRADE), and added a financial analysis system (FAN$Y) to assess value.
We use TASS, the Tree And Stand Simulator, ...

TASS: Grows Managed Stands (physical models)

... because it has sufficient tree detail to incorporate wood properties.
TASS also simulates the dynamics of stand development with high resolution as you can see in the following simulation:


We'll plant 1110 trees/ha 3m apart and grow them to age 15.
Notice the wide variation in tree size.
Let's thin out the weaker trees ...
leaving 500 well-spaced trees of relatively high vigour.
Next we'll grow the stand until the canopy closes.
Notice the increasing shade on the forest floor.
Very little light reaches the ground after age 40.
Let's continue to age 100. Keep one eye on the volume and DBH and watch how they increase over time.
These scenes are a series of frames captured from an actual run.
Every branch and every stem corresponds to equivalent elements in TASS.
With such detail, we can capture the effects of planting density, thinning, fertilizing, pruning, bridge-tree removal for control of root rot, and other silvicultural techniques.
The growth relationships and stand dynamics are derived from permanent sample plots remeasured for up to 60 years.
Let's take a brief look at the other modules in SYLVER.

BUCK: Cuts Trees into Logs

BUCK "cuts the trees into logs" of optimum length.

SAWSIM: Saws Logs into Lumber

SAWSIM selects the cutting pattern that will yield the greatest lumber value ...

SAWSIM: Calculates Lumber Yield

... and also "calculates lumber yield" tables which show the range of lumber dimensions and volume at potential harvest ages (40 - 100 years).
To assess the revenue from the 66,000 board feet of 2 x 4s produced at age 100, for example, we have to call GRADE which ...

GRADE: Determines Quality & Value

... categorizes lumber volume by grade, and applies market prices (of your choice) to determine lumber revenue ...
In this example, clear visually appealing lumber is worth 3 times that of the common #2 grade.
It has an impact on stand value out of all proportion to its volume.

FAN$Y: Analyzes Value

FAN$Y uses lumber volume, hauling distance, discount rate, costs (tend, harv, manuf), and revenue (lbr, chips) to prepare financial statements including the Net Present Value [which will be explained later].


In summary, SYLVER consists of five closely linked modules which were developed under the umbrella of the Douglas-fir Task Force. [Lodgepole and hemlock are in progress. Work on other species will likely follow.]


This concludes our introduction to SYLVER and the issues of volume and value. We hope you or your staff will take advantage of this powerful tool to help manage your forests for volume, quality and value. Please contact Research Branch if you'd like more information about SYLVER.

Learn about:

Link to Research Branch.