Influence of fire disturbance and biophysical heterogeneity on pre‐settlement ponderosa pine and mixed conifer forests

摘要: Fire frequency is assumed to have exerted a strong influence on historical forest communities in the inland Pacific Northwest. This study reconstructs structure and composition year 1890 fire from 1760 at 10 sites spanning broad productivity gradient southern Blue Mountains of eastern Oregon. We tested for relative frequency, climate, soils, topography by fitting variables ordinations structural compositional configurations. also built formal statistical models using non-parametric permutational multivariate analysis variance. Because disturbance biophysical influences may vary depending scale which relationships are examined, we 4- 12-ha three equal-sized areas within each site. The proportion fire-intolerant species basal area reconstructed ranged 0% 43%. 75%. Despite significant differences between sites, frequencies were relatively similar. Mean return intervals (MFRIs) calculated 10.6 21.2 yr. MFRIs 28.8 yr. Fitting model building with perMANOVA showed that topographic position index vapor pressure deficit had stronger site-scale than metrics. Available soil water was most important sites. Relatively frequent across range types Blues appears been uniform dynamics modulated fine-scale heterogeneity. If conditions goal management, treatments reduce fuel restore appropriate Blues.