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Will Burke

headshot of Will Burke

PhD Graduate

Year Admitted

Year Graduated

Research Areas
Hydrology, water resources, climate change impacts, spatial-temporal variability of fire dynamics

Faculty Advisor
Naomi Tague

James Frew, Scott Jasechko, Max Moritz

Dissertation Title & Abstract

Modeling the Interconnected Effects of Fuel Treatments on Forests, Water, and Fire

Fuel treatments, the reduction of forest biomass through mechanical removal or burning, are a flexible forest management tool used to address a variety of human and environmental concerns. Treatments can be used to reduce high severity fire, improve forest productivity and drought resilience, and increase streamflow. However, the effects of fuel treatments can be inconsistent and uncertain and are sensitive to both the treatment and the biophysical environment in which the treatment is done, and these uncertainties may be exacerbated by climate change. Climate change is already increasing wildfire size and frequency, drought, and strain on water supply in much of the Western US. Given that fuel treatments are likely to play a key role in current and future forest management, it is critical that we understand the full range of fuel treatment interactions with climate and effects on forests, water, and fire. Existing ecohydrologic models are limited in their ability to model fuel treatment effects because they do not account for both the within forest stand ecohydrologic effects of changes in forest structure and the watershed scale variation in radiation, water availability, and other factors. The ability to simulate heterogenous vegetation at fine scales is key to implementing fuel treatments like forest thinning. To address this lack I adapted the Regional Hydro-Ecological Simulation System (RHESSYs) to include a new multiscale routing (MSR) approach, RHESSys-MSR. In addition to allowing modeling of within forest stand heterogeneity, MSR enables an additional layer of hydrologic routing, on top of existing topographic hillslope routing. The first chapter of this thesis describes the implementation of RHESSys-MSR and the second two apply this model to investigate fuel treatment effects in a changing climate. In the first application of these methods, I simulate a large set (13,500) of model scenarios varying treatment type, biophysical and climatic conditions for a Central California Sierra forest stand. Results show that plant accessible water storage capacity and vegetation type are dominant environmental controls on the effects of fuel treatments. More broadly I find that estimating the effect of fuel treatments based on only a single biophysical variable fails to capture the extent of possible treatment effects. In the second application, I investigate the interactions between projected climate change and fuel treatment area on the effects of treatments on forest health, fire risk, and streamflow at the watershed scale. Results show that projected climate change has a nontrivial influence on net treatment effects, even compared to a maximized area treated. Fuel treatments and their effects are complex, spanning the environmental domains of forests, water, fire, and climate. Treatments are further complicated by the wide variety in the treatment itself, varying in how forest structure is affected, where it’s implemented, and how often. Model applications like RHESSys-MSR are critical to reducing this uncertainty and developing place-based estimates of fuel treatment effects that can support forest managers. The persistent challenges in understanding fuel treatments and their effects make any progress all the more essential, and as this research and more contributes to this understanding, we can make better and more informed forest management decisions into the future.

MS, Geography, Indiana University - Bloomington
BS, Environmental Science, Santa Clara University

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