In response to increasing wildfire severity and extent across the dry forests of the western United States in the last several decades, federal policy initiatives have encouraged joint vegetation management and fuels treatments to restore ecosystem composition, structure and function and reduce the potential for extreme fire behavior (e.g. National Fire Plan, 10-year Implementation Strategy, Healthy Forest Restoration Act of 2003). To meet these broad objectives managers are increasingly emphasizing treatments that simultaneously reduce potential fire behavior and create or maintain complex forest structures. However, our understanding of the effect that complex forest structures have on fire behavior are limited due to non-spatial fire management tools and a lack of well-designed field studies. Consequently there is knowledge gap between the fuels treatment theory and actual management practices which limits manager’s ability to adequately design effective fuel treatments and develop monitoring and assessment strategies that can provide reliable information regarding the long-term efficacy of restoration treatments and support policy and budgetary decisions. The overall objective of this research was to examine the influence of forest restoration treatments on vertical and horizontal fuel heterogeneity and the effect of altered forest heterogeneity on potential fire behavior. To address these overall objectives we used a combination of intensive field-sampling, and numerical modeling to: 1) examine changes in horizontal and vertical heterogeneity following restoration treatments in the southern Rocky Mountains; 2) characterize changes in surface fuel variability and the scale of spatial autocorrelation in surface fuels following restoration treatments; 3) simulate changes in potential fire behavior following restoration treatments using the Wildland Urban Interface Fire Dynamics Simulator and operational fire behavior models; and 4) develop and refine methods of quantifying forest complexity and surface fuel load in dry western forests.

This study highlights several key findings: 1) current restoration treatments in the southern Rocky Mountains are not meeting all non-spatial principles of fuels reduction treatments but are still effective in reducing potential fire behavior, 2) restoration treatments are resulting in an aggregated spatial pattern of trees consisting of a matrix of individual trees, clumps and similar to descriptions of historical dry, 3) Restoration treatment longevity in the southern Rocky Mountains is dependent upon the magnitude and timing of regeneration, 3) WFDS was capable of reproducing reasonable predictions for crown fires 4) Surface fuel are highly variable and have small scales of spatial autocorrelation. This variability was altered following thinned and thin-and-burned treatments however, this effect varied by fuel component.