Mechanisms of Mesophication: Exploring Positive Feedbacks Between Single Tree Water Use and Forest Flammability
In eastern upland oak forests, anthropogenic suppression of natural fire has led to the establishment of shade-tolerant species (red maple, hickory, ash) which create damp and dark understory conditions. These species outcompete oaks (a process called mesophication), preventing oak regeneration and leading to dramatic change in forest composition across large swathes of the eastern US. My research seeks to understand the fundamental mechanisms that allow mesophytes to alter water resource distribution through their partitioning of water and nutrients by the forest canopy to impact fuel quality and quantity in ways that reduce forest flammability and to quantify the spatial and temporal extent over which these mechanisms occur. Two research sites in upland oak forests have shown that mesophytes redirect rainfall to the forest floor in spatially distinct patterns via differences in throughfall and stemflow dynamics. This research is establishing an empirical framework of these species-specific mechanisms, and will provide new opportunities for effective assessment of stages of mesophication and directive for restoration activities using fire, thus ensuring the long-term health and economic benefits of upland oak ecosystems.