BIOGEOCHEMICAL CONSEQUENCES OF WILDFIRE IN MOUNTAIN LAKES OF THE WESTERN UNITED STATES

Author

• Brooke Genevieve Bain-White

Year of Award

2026

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Systems Ecology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Ashley P. Ballantyne

Commitee Members

Robert O. Hall, Jr., Philip E. Higuera, K. Arthur Endsley, Jill S. Baron

Keywords

algae, lakes, nutrients, paleolimnology, wildfire

Abstract

Wildfire activity has increased in lake watersheds across the western United States but predicting lake responses to wildfire and post-fire dynamics is challenging due to the small number of empirical studies examining wildfire–lake interactions. Based on findings from relatively few studies, a conceptual model has emerged suggesting that wildfire reduces lake water clarity through increased loading of light-absorbing molecules and particles, including growth-limiting nutrients, which may in turn increase primary producer biomass. In this dissertation, I use both conventional and emerging limnological approaches to examine the ecological consequences of wildfire in mountain lakes. In Chapter 1, I developed a new framework for generating comprehensive, predictive lake nutrient budgets and applied it to Lake McDonald, Glacier National Park, Montana, USA, showing that a wildfire in 2017 was the most plausible cause of nutrient enrichment detected in 2018. Next, I show that a series of wildfires over the last century did not leave a clear imprint on the sediment archives of the three largest and deepest lakes in Glacier National Park. Algal dynamics were instead more responsive to climatic variability. Finally, I show that wildfire events have subtle and short-term effects on optical water quality conditions using optically active water quality parameters inferred from remotely sensed data. Specifically, wildfires do not consistently reduce water clarity; however, concentrations of chlorophyll-a and dissolved organic carbon are consistently elevated during the first ice-free season post-fire, after which they return to pre-fire levels. Future work should focus on compensatory responses within primary producer assemblages following wildfire, as well as the interactive effects of increasing wildfire frequency and other environmental stressors, including climate change and anthropogenically enriched atmospheric deposition, on primary producer community composition and abundance.

Recommended Citation

Bain-White, Brooke Genevieve, "BIOGEOCHEMICAL CONSEQUENCES OF WILDFIRE IN MOUNTAIN LAKES OF THE WESTERN UNITED STATES" (2026). Graduate Student Theses, Dissertations, & Professional Papers. 12679.
https://scholarworks.umt.edu/etd/12679