Updates to Radiata pine and Douglas fir Forecaster Calculator

The Forecaster Calculator ( “Calculator” ) is a simple web based forest simulation tool for radiata pine and Douglas-fir in New Zealand.  It simulates the tree growth and the log products produced at a single clearfell age on a per hectare basis. From web access statistics the model is being well used. Its target audience is primarily consultants and  small forest owners wishing to calculate estimates of the volume and log product mix on a particular site at a particular age for a given silvicultural regime.

The  Calculator can be accessed from the Forest Growers Research web site at:


The Calculator is built using the same set of models as the Forecaster desktop application which is widely used by the forest industry for yield table generation (i.e. log product volumes by age), regime evaluation and silvicultural scheduling.

The original Calculator had predefined log grades and log prices and user feedback suggested the ability for users to edit log prices to more representative values would make the output from Calculator runs more realistic. The standard log product definitions remain but the ability to use local log price stumpage values that drive the log cutting optimiser is a very useful addition to the Calculator.  The other change is that the cutting strategy and associated log products detail are now user specific so the last edit by the user can be retrieved and used in further simulations.

For Douglas fir the user still has to enter a 500 Index value for their stand as there is no reliable 500 Index layer for Douglas fir. This is because small scale variation in topography, exposure, soil moisture etc appear to have a significant impact on productivity so it is much more difficult to create a useful Douglas fir 500 Index layer. Clarification has been added to the Calculator indicating the user will need to enter specific data through a measurement event to calibrate the model for Douglas fir.

Feedback from users on the Forecaster Calculator is always welcome.