The Interior Northwest Landscape Analysis System: A step toward understanding integrated landscape analysis

Abstract

The Interior Northwest Landscape Analysis System (INLAS) project demonstrated a method for assembling teams of scientists to conduct integrated landscape analyses at the mid- or subbasin scale in the interior Northwestern United States. A state and transition modeling system (STM) with transition probabilities calibrated by using a stand-level silvicultural model to estimate rates of vegetative change was used as a central vegetative “modeling engine.” It connected to a variety of resource-related models including: wildlife habitat quantity, insect activity, grazing by ungulates, timber management, and wood utilization potential. Where appropriate, the study team examined other vegetation modeling approaches including an optimization approach based on heuristic methods and modifications to an existing stand-level projection tool, which was integrated with existing fire and insect behavior models. The STM approach provided a relatively simple interface for most resource models. These were connected to examine the influence of vegetative succession, natural disturbances, and management over a 100–200-year horizon under three management scenarios: (1) background natural disturbance, (2) fire suppression only, and (3) active fuel management. Taken all together, the results suggest to us: (1) maintaining abundant large-tree multistoried structure in cool, moist forest conditions is likely to be difficult, (2) both active fuel treatment and passive management scenarios increased the proportion of large-tree single-story forests in dry forest conditions, and (3) fire suppression only was least effective in producing and maintaining these “legacy” structures in either dry or moist forest conditions.