Give a Dam: Dynamic variations of beaver ponds, their impact on the P cycle, and why we should care

Environmental Engineering Graduate Seminar Kenny Larsen, Ph.D. Candidate in Environmental Engineering, Michigan Tech Bio: Kenny is currently pursuing a Ph.D. in Environmental Engineering at Michigan Technological University. He has a BS In Geology Utah Valley University and a BA in French Studies. He has served as the CEE department representative to the Graduate Student Government and is currently on the GSG Sustainability Committee. He served as an official observer from Michigan Tech at the 2019 COP25 in Madrid, Spain. He was also awarded the Graduate Student Service Award in Spring 2020 as well as the David W Hand Environmental Process Engineering Lab Award in Spring 2019. Abstract: Beavers are some of nature’s most impactful ecosystem engineers and their ponds were once abundant in headwater streams in North America. However, overhunting and conflict with humans has removed them from their role as the prominent ecosystem engineer in streams, fundamentally changing the way our stream networks function. Little is known about the effects that beaver ponds have on phosphorus cycling in headwater streams. Dynamic changes of the physical and chemical environments within ponds affect the amount and form of phosphorus moved downstream of a pond. Identification of pond processes and a quantification of their effects are still questions needing to be answered. Short scale processes play a particularly important role in managing phosphorus available to biologic uptake. Increasing beaver populations highlight the need to understand and model the effects ponds have on phosphorus cycling, from the pond to continent, and hourly to century scales. Beaver ponds shape the way phosphorus transforms, moves, and sequesters in headwater streams. Results from studies of beaver ponds in Michigan’s Upper Peninsula show a complex and dynamic system controlling the levels of phosphorus within ponds and downstream.