Aging beaver impoundments using growth rates of standing softwoods

Authors: Kendal Massey, Emily Arsenault, Abby Hullihen, John Donnelly

SUNY Campus: SUNY ESF

Presentation Type: Poster

Location: Old Union Hall

Presentation #: 14

Timeslot: Session A 9:00-10:00 AM

Abstract: The North American Beaver (Castor canadensis) changes its landscape by felling hardwood trees, creating impoundments to water and decreasing the growth rates of impacted trees. These impacts are episodic and cyclical. Therefore, reconstructing the history of beaver influence in a system over time can be important for understanding long-term ecosystem function. Commonly used methods to age beaver impoundments are destructive and not possible in sensitive systems. Here, we propose and test a non-invasive way to estimate timing of flood events by aging beaver impoundments using dendrochronology on standing softwood trees. In an Adirondack forest where beaver activity has been tracked for over 70 years, we sampled three beaver ponds over an age gradient, from intact dams to breached dams, to historically dammed reaches. We then estimated flood timing for one stream with a breached dam of unknown age. At 150-meter increments, transects were surveyed to obtain tree species and crown class information (n=45). In these riparian zones, softwoods were cored along both high- and low-energy segments of stream. Skeleton plotting was used to determine years of decreased growth. There was a statistically significant difference in the proportion of softwood trees between low-energy (71% softwood) and high-energy (37% softwood) reaches (p=0.004). A distinct pattern was seen when comparing skeleton plots from high-energy to low-energy sections of the stream with unknown beaver impoundment ages, implying two major damming events. Preliminary results indicate a new potential method for determining the hydrological his