THE IMPACT OF BEAVER ON WATERSHED-SCALE SEDIMENT AND CARBON BUDGETS IN THE ADIRONDACK MOUNTAINS, NEW YORK

Beaver are cited as “ecosystem engineers” for their ability to enter a landscape and quickly adjust how water, sediment, and nutrients are routed through watersheds. Several recent studies have investigated the impact of beaver on the geomorphology and hydrology of landscapes in the western United States, but few have focused on the beaver of eastern North America. This project investigates the role of beaver in the sediment and carbon budgets of small catchments in the central Adirondack Mountains of New York.

We focus on Panther Brook (DA = 3.5 km²), where we first established a topographic baseline by surveying the stream’s longitudinal profile from its base level to within 300 m of the catchment’s drainage divide. At 50 m increments along our profile we surveyed the volume of large woody debris (LWD) both in the channel and along cross-valley transects - we also used an Oakfield auger to measure sediment thickness along these transects. For the five beaver meadows along the length of Panther Brook, we conducted bucket auger transects along the long axis of each meadow and across each meadow’s short axis, collecting sediment at 20 cm depth intervals from each bucket auger station. We used depth to refusal for each auger station to determine the spatial distribution of sediment depths to calculate the volume of sediment in each meadow. For each auger sample, we also determined dry bulk density and organic carbon content (via Loss On Ignition).

Our analyses reveal a range of meadow volumes from ~3000-6000 m³ along Panther Brook, which is significant considering the paucity of sediment storage sites between meadows. Considering a range of 15 m/Myr to of 30 m/Myr for upland erosion rates, we find that the largest meadows could store 400-700 years of upland sediment generation. In total, Panther Brook’s five beaver meadows store approximately 3,500 Mg of organic carbon, while total above ground biomass stores approximately 20,500 Mg of carbon, in-channel and floodplain LWD stores 3.5 Mg carbon, and annual riverine export of dissolved organic carbon averages 15 Mg/yr. Beaver are contributing significantly to sediment and carbon storage in this small upland catchment of the Adirondacks, and these results from Panther Brook inform broader interests in the use of beaver as agents of watershed restoration in northeastern North America.