Three decades of remotely-sensed beaver-driven landscape change at Cranberry Glades Botanical Area, West Virginia, USA

Keywords: beaver, peatland, riparian, geomorphon, Cranberry Glades, remote sensing, Lidar, photography
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 05:20 PM (Eastern Time (US & Canada)) - 2/27/2022 06:40 PM (Eastern Time (US & Canada))
Room: Virtual 32

Abstract

Beaver (Castor spp.) have well-documented roles as ecosystem and landscape engineers. This project remotely monitored beaver activity throughout the Cranberry Glades Botanical Area, a montane perched valley in the Southern High Alleghenies of West Virginia’s Monongahela National Forest. We reconstructed and quantified beaver impoundment dynamics since 1990, presenting the results graphically as both a map and a series of stacked bar charts representing impoundment location (both absolutely and relative to others), site type (primary channel, secondary channel, or ephemeral drainage), presence/absence per decade (related to cycles of construction, maintenance, and neglect), and dam persistence at any given location. Data were optical, aerially acquired, and publicly accessible. Lidar point clouds provided textural context, while photography (color, color-infrared, panchromatic) provided spectral information, with the Lidar/photo combination enabling more-robust analysis.

We calculated the density of detected impoundments and from that a lower-bound estimation of the carrying capacity for beaver over the past three decades. Geomorphon analysis, a machine vision-based terrain classifier algorithm, allowed identification of the scales at which various topographic features were most recognizable. In total, we identified over three dozen beaver impoundments during 1990—2020, giving a lower bound of approximately one per three hectares of suitable habitat. More impoundments were detected during 2001—2020 than during the previous decade, and relatively few impoundments persisted during all three decades. These trends may be confounded by changes in remote-sensing technology across the study period. Geomorphon analysis revealed elements ranging from small-scale beaver-driven microtopography up to larger peatland, erosional, and geological features.