Fire has become an increasingly important disturbance to understand due to recent increases in fire size and severity, along with growing human habitation in rural areas. Causes of spatial variation in fire severity across landscapes include daily weather conditions, fire suppression and fuel build up, other past management action, and climate. Fire severity patch location could be stochastic, or fixed in space by topographic influences. However, quantifying the effect of topography on observed patterns of fire severity patches is difficult because fires are stochastic events burning through dynamic and heterogeneous fuel, weather, and historic management conditions. Neutral simulation models will allow this research to hold these confounding factors constant to assess the interaction of topography on predicted fire intensity. This research will address the following questions, using Lassen Volcanic National Park as a case study: 1) What is the distribution of forest surface and canopy fuels and how are those fuels related to the underlying biophysical landscape? 2) What is the effect of topography on fire intensity for a landscape of homogenous fuels burning under constant weather conditions? 3) Do observed patterns of high intensity fire match either the hypothetical neutral model results or the results from fire simulation of real landscape conditions using mapped surface and canopy fuels? Canopy fuels will be mapped by combining field measurements with topographic information and remotely sensed Landsat data within a classification and regression tree model to predict canopy fuel loads across the landscape. A neutral model approach to fire behavior modeling will compare hypothetical landscapes with both real landscapes and historical data on fire severity to assess the strength of topographic controls on fire intensity and the usefulness of this novel approach.
The results of this study will address the role of topography in creating heterogeneity in vegetation community structure and composition across the landscape through its influence on fire intensity. Furthermore, this research will evaluate the impacts of fire suppression on changing the landscape location of high intensity fire-created patches. Some types of vegetation, especially in Lassen Volcanic National Park, but also in other locations throughout California and the US west, require high severity fire that has been vigorously suppressed. Using neutral models to assess the potential for high severity fire to create heterogeneity on the landscape will help both resource managers and fire fighters to make better decisions regarding wildfires, Wildfire Use, prescribed fire, and other fuel treatments in highly altered forests. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.
