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Increased burn severity and simulated climate warming drive shifts in ecosystem function and understory plant traits one year post-fire in northern Arizona

Taber, Ethan Michael (2021) Increased burn severity and simulated climate warming drive shifts in ecosystem function and understory plant traits one year post-fire in northern Arizona. Masters thesis, Northern Arizona University.

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A changing climate and altered fire regimes in the semi-arid southwestern U.S. have led to questions regarding future forest composition and ecosystem processes. Forests that are fire adapted and have been historically shaped by fire are at risk of conversion to non-forest ecosystems by uncharacteristically severe fires. Trait-based plant ecology provides a means of assessing the impacts of varying levels of disturbance on community composition and ecosystem function and can be used to predict community trajectories. The aim of this study was to quantify the effects of increasing burn severity and simulated climate warming on two ecosystem functions and three plant functional traits, approximately one year post-fire in a northern Arizona Pinus ponderosa forest understory. Plots were established along a burn severity gradient including unburned, low, and high burn severity areas. Open-top warming chambers were employed to produce just over 1°C of warming. We found that the interaction of high burn severity and simulated climate warming significantly increased decomposition rates, decreased community weighted mean (CWM) trait values for leaf dry matter content, and increased specific leaf area of a dominant C4 bunchgrass (Muhlenbergia montana). Additional significant effects were observed according to severity alone. Our results indicate potential for divergent community composition, structure, and ecosystem functioning over time in response to disturbance and warming. Our results indicate that herbaceous and shrub understory communities after future high severity fires may be on novel successional trajectories. Our conclusions support ongoing efforts to reduce the likelihood of high severity fires in this region, and provide information on trait expressions and species that may prove useful in future post-fire restoration efforts. Given the projected increase of high severity fires in the southwestern U.S., understanding the combined effects of climate warming and high burn severity will be critical for successful proactive land management.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: Ecology; Fire; Function; Severity; Traits; Warming; Pinus pondeerosa; Plant succession; Forest recovery; Southwest (U.S.); Climate change
Subjects: S Agriculture > SD Forestry
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of the Environment, Forestry, and Natural Sciences > School of Earth Sciences and Environmental Sustainability
Date Deposited: 13 Jul 2022 16:46
Last Modified: 13 Jul 2022 16:46
URI: https://openknowledge.nau.edu/id/eprint/5825

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