The proposed project will quantify the effects of hazardous fuels treatments on suppression costs of subsequent wildfires. Spatial econometric models of daily fire suppression costs will be estimated to determine if and to what spatial and temporal extent hazardous fuels treatments and previous wildfires reduced observed wildfire suppression costs for a sample of recent fires that have interacted with previously treated and burned areas. Effects of different fuel treatment types (including wildfire), sizes, and intensities on suppression costs will be estimated for at least 85 fires sampled across different ecosystems (including underrepresented ecosystems). In addition to considering spatial spillovers (autoregression) of suppression costs, we will investigate how time since treatment interacts with other biophysical and environmental factors to influence suppression costs. We will leverage existing datasets on the location, type and intensity of previously treated areas with observed wildfire suppression costs, and use a combination of geospatial analysis and spatial econometric modeling techniques to better understand how hazardous fuels treatments differentially affect wildfire suppression costs. The study results will be highly relevant to managers for comparing expected suppression-cost savings from different fuel treatment scenarios in various ecosystems. This proposal addresses the following two questions and a statement that were highlighted in the FON: 1. How do the costs of implementing various wildland fire suppression strategies compare to fuel treatment costs? 2. What is the expected decay of effectiveness over time following fuel treatments, by vegetation type, by climate conditions and by fuel treatment method and intensity? 3. Evaluate trade-offs among fuels treatment costs and potentially avoided wildfire suppression costs. To evaluate how fuel treatments (including wildfire) affect daily suppression costs, it is essential to have a good understanding what day any given wildfire intersects with a fuel treatment; this is possible by integrating downscaled daily MODIS satellite data or agency generated fire progression maps with daily expenses as reported in I-Suite. Methods developed by Miller and Parks (JFSP Project #12-1-03-19) for quantifying the effectiveness and longevity of wildfire to act as a fuel treatment will also be applied to other treatment types (e.g., intermediate thin), thereby enhancing our ability to evaluate how all treatment types affect fire suppression costs.