DISSERTATION RESEARCH: Physiological mechanisms in climate-induced forest mortality

Carnegie Institution Of Washington, Washington DC

Investigators

Abstract

In western United States, massive mortality events have occurred recently across many tree species, often linked to severe drought and temperature, and are expected to increase with climate change in the next century. Trembling aspen forests recently experienced a severe and rapid drought-driven mortality across several western states, affecting up to a fifth of aspen forests. Despite the prevalence and impact of these events, there is relatively little known about exactly how forests die from drought and temperature stress. The proposed research would help illuminate the physiological mechanisms of how aspen forests succumb to drought stress over multiple years. Understanding the long term effects of severe drought on water uptake and use by trees is critical to informing pathways and thresholds of such mortality events. This research will shed light on the response of forests to climate change, currently a large uncertainty. Tree death can transform regional landscapes and have severe effects on how forests function and on the services they provide to humans, such as timber, tourism, and wildlife habitat. Furthermore, forest diebacks can lead to dramatic decreases in forest uptake of carbon, resulting in an positive feedback to climate warming. Thus, understanding how and where forests could die in the future would greatly benefit local stakeholders in the western United States. This research will aid in projecting which regions, tree species, and forests could be most vulnerable to drought and climate. Additionally, the research will involve students from local communities in field research and will communicate the results to a broad array of land managers and stakeholders, greatly increasing the impact of the findings.