Vegetation patterns in eastern Oregon and Washington are largcly a result of environmental condilions, plant ecology, and disturbances operating at multiple scales and in ditterent environments. In tum, vegelative patterns strongly influence the amount, severity, and distribulion of disturbances generated by various agents. This paper focuses on the latter -- the relations hetween vegetation patiem, disturbance, and forest health and productivity. At all scales, vulnerability io disturbance appears to increase when vegetation condition and pattern differs from the historical or expected range for a given environment. Generally, forests that are older composed of larger trees, denser, more homogeneous, or more contiguous than would be expected under natural or historical disturbance regimes are nore vulnerable to) mortality from insects and disease. Factors related to vulnerability include site potential, host abundance, canopy slructurc, host size, patch vigor, patch density, patch connectivity, topography. and logging disturbance. Morlality from insecls and disease contributes ro diverse habitat, but current levels of tree motality from insects and disease are ofien outside the historical of expected range given site enliromerl. High levels ol mortality may continue because many forests have become more homogeneous, contiguous, and dominated by shade-tolerant species owing to fire suppression and managment. Uncharacteristically, severe fires will likely increase in the nert 100 years even with restoration management because of changed vegetation patterns and other factors. Information at stand or site scales is relatively abundant ln the scientific and rnanagement literature. Much broad-scale information is based on models and expert opion. Research at broad scales is scanty and difficult. © 2001 by the Northwest Scientific Association. All rights reserved.