Bark beetle induced tree mortality has resulted in visually stunning and unprecedented swaths of dead trees throughout mountainous regions globally. Exacerbated by a changing climate, this large-scale ecosystem disruption has implications for forest health, fire, climatic feedbacks, and water resources – including water quality. Notably, shifts in the form of dissolved organic carbon export can lead to increased formation of carcinogenic disinfection byproducts during water treatment. While the magnitude of this response is varied, we have established correlations to the percentage of trees impacted within a giving watershed. In exploring this association and underlying biogeochemical shifts, we adopted an interdisciplinary approach combining terrestrial microbiology, hydrology, and geochemistry at the tree scale. A mitigating effect was discerned in Rocky Mountain forests where a sufficient density of actively respiring trees scavenged the release of inorganic nitrogen from proximal bark beetle-impacted trees. The terrestrial microbial community under beetle-impacted trees mirrored this trend suggesting a threshold value of tree mortality where ecosystem buffering was surpassed. Collectively, our research has implications for forest recovery in this nitrogen-limited montane ecosystem and could aid in the prediction of and preparation for water resource challenges.
About the Speaker: Dr. Jonathan O. (Josh) Sharp, Associate Professor, Civil and Environmental Engineering Colorado School of Mines
Jonathan (Josh) Sharp is an Associate Professor in the Department of Civil and Environmental Engineering and Director Elect for the Hydrology Program at Colorado School of Mines. His work in environmental engineering microbiology focuses on the implications of biological processes on water quality and reuse in both natural and engineered settings. It is grounded in a multidisciplinary approach that combines molecular, microbiological, and geochemical tools to address questions important to the disciplines of environmental engineering and hydrology. Dr. Sharp received his BA from Princeton University, PhD from UC Berkeley and conducted postdoctoral training at EPFL, Switzerland. His research has been sponsored by a number of agencies including NSF, DOE, EPA, DoD, and USGS. Josh has received numerous teaching and research accolades including Kavli Fellow and National Science Foundation CAREER awards.
Host: Zhao Hao