Adams D FEMC2007

PNWPrivate: A Nested System of Regional Private Timber Supply Models for Oregon and Washington with Extension Mill and Resource Detail

Darius Adams, Department of Forest Resources, Oregon State University, Corvallis, OR, 97331, USA, darius.adams@oregonstate.edu
Gregory Latta, Department of Forest Resources, Oregon State University, Corvallis, OR, 97331, USA, greg.latta@oregonstate.edu

PNWPrivate is a system of market-based timber supply models used to project log use, timber harvest and silvicultural investment on private lands in Oregon and Washington. The key objective in developing the system was to retain detail-detail on timber resource characteristics by avoiding aggregation into resource strata and detail on timber users by modeling log consumption decisions at the finest possible user scale. Basic resource data derive from plots taken as part of the standard federal forest inventory process. The timber resource is modeled at the sub-plot level and future stand development projected using individual tree models under an array of possible silvicultural regimes. Projected future tree lists are stored, facilitating detailed descriptions of future stands and potential harvest. Private owners are viewed as land value maximizers given current and future log prices and management costs. Selection of silvicultural regime is endogenous. Log demand is modeled at the processing center level (individual mills or milling clusters) in a process where capacity addition or contraction is endogenous as well as the volume of logs demanded. Oregon and Washington log markets are linked to national and international log and product trade via econometric models of these higher level markets. Within Oregon and Washington, the market area under analysis can be expanded from the half-state (e.g., western Washington) to the full two-state region with appropriate intra-regional log trade endogenous. System solutions are found via linear or mixed integer programming depending on the desired model configuration using high-capacity solvers.

In example applications, the capabilities of the system to provide resource details have been exploited to project the potential future harvest from private lands by log diameter, species, and owner group at the county level. For mills and log buyers planning future wood acquisition strategies, this provides a picture of potential future harvest in a degree of detail heretofore unavailable. With the basic resource unit at the sub-plot level, and given standard plot data on proximity to stream courses by stream class, the model has also been used to simulate the timber harvest impacts of alternative riparian protection policies. Since the model works with tree lists rather than aggregates, fairly complex and realistic requirements on leave tree sizes and species can be examined.

As computational and data storage capabilities continue to improve in the future, we believe PNWPrivate will be a prototype for expanded and still more detailed future resource analysis and planning systems. The basic approach can also be linked to data derived from satellite imagery to reduce the effective plot size or expansion factor through “nearest neighbor” methods. Expansion to areas beyond the PNW is underway.