Question 5:
What tools (decision-support tools, models etc.) do you use to help you make silvicultural decisions? How could they be improved?
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Rethink Silviculture
Discussion Board for Regeneration Practices
We need a model that allows us to forecast the impacts of stand tending, particularly in multi-aged stands. Prognosis BC is a serviceable model that the Ministry has orphaned without an alternative. Without a model it is very difficult to prepare thoughtful and defensible prescriptions, and also difficult to incorporate the results of treatments into Timber Supply Review.
In addition to Prognosis, two common GY models are used in Timber Supply Review for BC. One of them is VDYP for even-aged stands regenerated after natural stand-replacing disturbances. The other is TIPSY for even-aged stands regenerated artificially. TIPSY can use natural GY curves as well. However, none of these models take into account inter-species interactions. There are also other limitations in terms of silvicultural activities response for most species. For example, Douglas-fir is the only species we have a good idea about fertilization response. Other silvicultural activities such as pre- and commercial thinnings have somewhat sketchy response curves for most species. Using the 3 GY models (VDYP, TIPSY, and Prognosis) has becoming a standard in recent years. And, for the most part, the growth projections we have are probably better than in other parts of the world.
For licensees though, a key aspect of the GY curve is estimating the volume growth by sorts (e.g., pulp, peeler, sawlogs).
Finally, predicted anthropogenic global warming is not helping us either. It will only increase the lag between data and assumptions. We should use the latest technology developments and conduct periodic LiDar flights in order to strengthen the yield estimates…in addition to the forest inventory.
We are using the old version of Prognosis BC for for stand level decision. The US Forest Service is maintaining the model out of the Research Station in Fort Collins. The new versions have many feature to model climate change and different health scenarios, but they are not easy to use with metric measurement. A cooperation between BC and the US Forest service would go a long way to make the model more usable.