Overview of Spatially Explicit Timber Supply Modeling

The economy of British Columbia is highly dependent on its forest resources. To effectively manage these resources, the ability to model the time-dependent timber volumes for the Timber Supply Areas (TSAs) of the Province is critical in many ways. These include providing information for setting the annual allowable cut (AAC) for the TSAs, and projecting the effect of forest management practices on sustainability over the course of many centuries. Also, in the presence of extraordinary events such as the current mountain pine beetle epidemic, it is vital to be able to model the devastating effects of this infestation on the timber supply.

Under contract to the BC Ministry of Forests and Range, BCS has designed and implemented a spatially explicit timber supply simulation software system called FSSAM (Forest Service Spatial Analysis Model). FSSAM has been designed to perform timber supply analysis for the forest management units of British Columbia. This system provides for generation of integrated spatial and attribute data for the landscape units of the management unit, modeling of harvesting at annual intervals over a specified number of years, display of the modeling results, and optimization of the harvest profile. It also allows the modeling of the effects of mountain pine beetles on timber supply. The FSSAM software provides all of the following features:

Data integration and preprocessing. This preprocessing module analyzes and transforms attribute data and spatial data into a form where they can be used for modeling. This preprocessing sets up the representation of the data in a hierarchical structure, with the management unit at the top, then landscape units, blocks, stands, and layers within the stands. The preprocessing also performs automated blocking by aggregating similar stands, and automated roading of the blocks, yielding a road network. In addition, this stage sets up the data for modeling the mountain pine beetle infestation and generates age-area biodiversity and generic constraints for the modeling.

Modeling. This module performs the timber harvest and mountain pine beetle modeling. It sets harvest targets for the management unit and runs a simulation to determine the results of attempting to meet these targets while respecting the constraints. This modeling also takes into account the timber killed by the mountain pine beetle infestation and computes estimates for the volumes and decay rates of standing dead timber and products (e.g., wood chips) as well as non-recovered losses. In addition, the modeling also provides a facility for optimizing the harvest flow profile.

Visualization. This module plots the results of an FSSAM modeling run, at both the management unit and landscape unit levels.

Web interface. This module provides a Java-based interface accessible from the Web. This interface allows the user to run the modeling and visualization components from a remote site.

Distributed processing. This component allows modeling to be performed in a distributed computing environment, with one master process and an arbitrary number of slave processes on separate CPUs.

FSSAM is written mainly in the IDL language (plus some C components) and can be run either in a full IDL Development Environment or using the IDL Virtual Machine, which is available at no change from ITTVIS.

Next: Automated Blocking