Trends in terrestrial plant communities and landscape health indicate the effects of alternative management strategies in the interior Columbia Riverbasin

Current and potential future conditions of terrestrial plant communities an d landscape health were modeled for three alternative public land managemen t strategies in the interior Columbia River basin. Landscape health was def ined as an integration of the degree to which vegetation and disturbance co nditions resemble native patterns and support levels of human activity. The range of vegetation and disturbance variability for a period before the mi ddle 19th century was used as a basis for comparison of current and future regimes to the "historical" system. Departure from the "historical" regime in wildland environments was found to be related to altered disturbance pat terns, especially changed fire regimes, forest insect and disease levels an d excessive livestock grazing effects. Overall, mid-seral forests are curre ntly more prevalent than they were in the past and old forests, especially single-layer structural types, are less abundant. Non-native plant species and altered plant community composition conditions exist across broad areas of rangelands. Landscape health has declined substantially in many areas. Proposed management strategies that emphasize maintenance and restoration a ctivities in a hierarchical landscape approach should generate improved lan dscape health conditions over the next 100 years. However, the massive scal e of changes to disturbance and vegetation patterns from historical to curr ent times and the cost of implementing restoration activities make dramatic improvement unlikely. Published by Elsevier Science B.V.