Official website of the New Zealand Farm Forestry Association

Using Forecaster to maximise your forest investment

Jeremy Snook, New Zealand Tree Grower May 2010.

Forecaster is a software system used to estimate the value of tree crop returns based on predicted log out-turns. It works by modelling the effects of site, silviculture and genetics on tree growth and form, branching and wood properties. It is used by the forestry industry to support the correct planning of silvicultural operations such as pruning and thinning, and is especially useful for intensively pruned regimes for radiata pine. Forecaster is also used to develop yield tables to report the predicted volume availability by log grade at each age and to compare the potential effects on costs and revenue of adopting different silvicultural regimes.

How does it work and how can it help?

Developed by ATLAS Technology, the software development arm of Scion, Forecaster is a modelling system that attempts to account for the large variation in tree characteristics that occur on the average hectare. It can work from a list of detailed stem data if the user already has stem measurements which could be from a post-pruning quality control measurement. The system can also work from basic estimates of summary statistics such as basal area, stocking and mean top height. Future work will allow the user to generate a stem list from their site’s estimated productivity, allowing greenfields analysis.

The growth and form of the modelled stems within the stand are projected using various models. A number of publicly available historic models are available in the system, while newer models are available to forestry companies or consultants who are members of Future Forests Research’s radiata research theme.

Simulated pruning

Silvicultural work such as pruning or thinning can be scheduled to be either at specified dates, or when the modelled state of the stems meets certain targets. Pruning is commonly planned to a target value of the diameter of the stem over pruning stubs – DOS. This restricts the size of the defect core and maximises clearwood volume available in pruned logs. As the trees are grown by the models, a wealth of information on their size and other properties is carried along with them to support the modelling process. This allows simulated pruning to be carried out on only the largest and tallest trees which are more likely to remain healthy and produce larger high-value pruned sawlogs at time of harvest. Similarly thinning operations can target smaller, shorter trees for removal.

The objective is usually to harvest the trees and sell them as logs – and harvesting events can also be modelled. One or more harvest dates can be specified, so that it is possible to determine the optimum time to harvest in order to maximise profit. Harvesting cutting patterns can also be tailored to produce logs for local processing or export market.

Once the harvesting and log merchandising has been simulated, results are provided in a consistent format. They include reports and charts to make comparing different scenarios easy.

The implications for forest management

Forecaster is mainly for new science results from the Intensive Forests Systems programme, through the radiata theme of Future Forests Research. Using computer software is a far more practical method of making science available to end-users such as forest managers or consultants than traditional means, such as producing a report.

Good results

Significant scientific results implemented within Forecaster include −

  • The 300 Index national radiata pine growth model, based on measurement data from long running permanent sample plot measurements
  • A branching model which predicts the size, location and angle of branches on a stem
  • Wood properties models including wood density, acoustic velocity and heartwood

Models available in the next version of Forecaster include a modulus of elasticity model, to predict wood stiffness down to a ring-by-ring level within the stem, and C Change. The latter is a carbon model to support decision making around managing trees to meet the needs of the carbon market.

Density, acoustic velocity, and modulus of elasticity models can be used to predict the suitability of the trees for structural timber. In the diagram a 28-year-old stem has been simulated through a cutting pattern to generate logs for a sawmill producing framing timber.

Making complex science simple

The models and processes underpinning Forecaster make it a complex system. But recently there has been a major focus on simplifying what inputs are required by the user. Some of the models require quite detailed variables to predict growth or wood properties and many of these can be provided by a map-style interface.

For example, the user need only click on their location on the map, and the site’s productivity potential for radiata pine is looked up directly from the map. Similarly, regionally appropriate sets of models are available, so the user need not have a detailed understanding of which models to choose before being able to get started. The full range of options is still accessible, so as your understanding increases you can over-ride values.


Another way that Forecaster has been simplified recently is to tailor the software to the work the user wants to complete. For example, a user who just wants to generate a yield table does not need to be concerned with details reported on pruning operations. Unnecessary options and information such as this can be hidden, while other options may have sensible defaults provided to further simplify the user’s task.

Forecaster is frequently compared with the radiata pine calculator originally developed by the NZFFA. The calculator is excellent for quick analysis of small investments. However the requirement to grow the wood fibre more precisely wanted by end-users requires detailed internal tree modelling. This is not possible within the radiata pine calculator’s simplified structure.

The future of Forecaster

The overall vision is to create a seed-to-market modelling system covering the breadth of the value chain. This will model the effects of decisions made by forest managers on site, genetics and silviculture, through to the end product, such as suitability as framing timber.

Characteristics of the wood will eventually be modelled from the trees, into logs, and then into end-products such as framing timber, appearance-grade mouldings, pulp or biofuel. The forest manager then has the power to model different management actions to reach the desired performance of their target end-product.

Another area where Forecaster will be enhanced in the future is to model alternative species. The focus so far has been on radiata pine. But the software has been developed in such a way that it can suit any species, provided that appropriate models exist. As models continue to develop for other species, these will be built into Forecaster. It will allow forest managers, consultants and land owners to evaluate the suitability of a site for various species, with the focus on end product performance.

Jeremy Snook is from ATLAS Technology


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