Conventional wood supply simulation models have been found inadequate in both calculating true assessments of wood supply and in translating management strategies into on-the-ground management design. These models treat forests as aspatial entities and are unable to include economic and wildlife considerations in management design and calculation of wood supply. This paper presents and discusses the design and construction of a GIS-based (geographic information system) spatial wood supply model. The model uses geographic distribution of stand development types and stages and their change over time to control harvesting and calculate wood supply based on extraction economics ($/m3) and wildlife habitat values (opening size and green-up). The paper points out that: a spatial model is capable of producing harvest schedules and forest performance indicators that reflect geographic context as well as condition of stands; a GIS database is more important in spatial modelling than GIS technology; harvest blocks are the basic geographic element in spatial modelling; a spatial model provides a truer assessment of wood supply; and stand topology makes it relatively easy to integrate wildlife and timber management.