College of Science
87 Impacts of Wildfire on Xylem Anatomy in Three Tree Species in Southwest Colorado
Lamia Hajdarevic
Faculty Mentor: William Anderegg (Biological Sciences, University of Utah)
Wildfires and drought conditions are a growing concern globally. Exacerbated by climate change and land management practices, increased fuel aridity is fostering increasingly more frequent and severe wildfires in the western United States. Conditions produced during these events can cause an abundance of issues and significant ecological impacts, particularly concerning forest ecosystems. Given the predicted rise in fire frequency and strength due to increasing fuel aridity, understanding the physiological responses of trees to fire events is vital for accurately estimating post-fire ecosystem dynamics, risks, and their interactions with climate-caused disturbances.
This project investigates how wildfire impacts the hydraulic traits and xylem anatomy of three conifer species- ponderosa pine (Pinus ponderosa), engelmann spruce (Picea engelmanni), and subalpine fir (Abies lasiocarpa)- found in southwest Colorado. These species occupy varying habitats; Ponderosa pine grows in lower elevations, while engelmann spruce and subalpine fir grow at higher elevations. To address these questions, I analyzed core samples from three tree species collected by Ph.D. student Annapurna Post-Leon in 2023 and 2024 from both burned and unburned plots in San Juan, Colorado. I sanded and prepared cores until individual tracheids (the water-conducting xylem cells in conifers) were visible before scanning them. Using ImageJ software, I measured tracheid area for each species. Furthermore, I analyzed climate data using TerraClimate to compare anatomical responses to environmental variation.
The results indicate that ponderosa pine exhibits the strongest sensitivity to climate variability, producing smaller tracheids during drier years and larger tracheids during cooler periods. This potentially reflects adaptations to lower-elevation, water-limited habitats. In contrast, engelmann spruce and subalpine fir exhibited weaker correlations with both precipitation and temperature, demonstrating increased resilience to climate fluctuations, likely because they inhabit cooler, wetter environments where moisture availability is more consistent, reducing drought stress. These patterns imply that engelmann spruce and subalpine fir maintain more conservative and stable hydraulic strategies. Additionally, the results indicate that wildfire and corresponding drought years can influence hydraulic traits, though further analysis is needed to determine adaptive responses or cumulative damage within burned species.
Working with Dr. William Anderegg and graduate student Annapurna Post-Leon has allowed me to contribute to a broader investigation into forest resilience and climate stress. Beyond learning technical methods, I have developed critical analytical and problem-solving skills that have extended beyond ecological research into my daily life. On a personal level, this experience has strengthened my scientific curiosity and has demonstrated the importance of exploring the links between climate change, ecosystem health, and ecosystem resilience.
Ultimately, this research contributes to a growing understanding of how forests respond to climate change. As wildfires and drought conditions continue to increase in severity, insights from this work may help inform predictions of forest sensitivity and guide conservation efforts, improving our understanding of resilience in ecological systems.
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