Year of Award
2026
Document Type
Thesis
Degree Type
Master of Science (MS)
Degree Name
Systems Ecology
Department or School/College
W.A. Franke College of Forestry and Conservation
Committee Chair
Scott Ferrenberg
Commitee Members
Sharon Hood, Philip Higuera
Keywords
Pinus ponderosa, climate-growth relationships, dendrochronology, prescribed burning, fuel-reduction treatment, carbon
Subject Categories
Forest Management | Other Forestry and Forest Sciences
Abstract
Over a century of fire suppression in western North American forests has increased surface fuels and tree density, particularly in low-elevation, frequent-fire forests, enabling higher-severity fire when these forests burn. Fuel-reduction treatments are widely used to restore historical forest structure and mitigate wildfire risk, but their long-term effects on individual tree vigor and climate resilience remain poorly quantified. Using dendrochronology, I analyzed annual growth increments in ponderosa pine (Pinus ponderosa) trees within a 20+ year study of prescribed fire and mechanical thinning at the Lubrecht Experimental Forest in western Montana, USA. Across 12 experimental units, I cored 236 trees and modeled basal area increment (BAI) as a function of tree size and age, a dynamic neighborhood competition index, and climate variables including growing season precipitation and vapor pressure deficit. Tree size and age explained 75% of the annual BAI variation. Competition and climate also significantly influenced growth. Mechanical thinning increased tree growth by reducing average levels of competition, while prescribed fire alone did not significantly alter growth, likely because the low-severity burns left the overstory largely intact. Mechanical thinning altered tree sensitivity to climate with a significant treatment × precipitation interaction indicating that trees were buffered against interannual precipitation variability, maintaining higher growth rates and experiencing smaller relative reductions in growth during drought compared to controls. My results demonstrate that fuel-reduction treatments can provide multiple benefits including reduced wildfire risk, enhanced tree vigor, and increased resilience to climate variability. These co-benefits have important implications for adaptive management and carbon sequestration under a warming and drying climate.
Recommended Citation
Blankenship, Gibson Brown, "QUANTIFYING THE INFLUENCES OF PRESCRIBED FIRE AND THINNING ON TREE CLIMATE-GROWTH RELATIONSHIPS IN PONDEROSA PINE" (2026). Graduate Student Theses, Dissertations, & Professional Papers. 12674.
https://scholarworks.umt.edu/etd/12674
© Copyright 2026 Gibson Brown Blankenship