26 Mega-Traces: Advances in Ichnology and Zoogeomorphology (Posters)

Friday, 20 March 2020
1:30 PM - 5:30 PM
Lake Anne

RIPARIAN COMEBACK: RECENT BEAVER COLONIZATION OF A VERNAL WELAND, TYLER STATE PARK (BUCKS COUNTY, PENNSYLVANIA)

Paper number: 26-6
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Low banks and steep slopes surrounding a vernal wetland, which occupies a meander bend of Neshaminy Creek (Tyler State Park, Pennsylvania), were surveyed in the fall of 2019 for evidence of increasing beaver (Castor canadensis) activity in response to concern by the park officials. The study area was housed a new beaver lodge and showed various evidence of impact by this ecosystem engineer, whose populations started to rebound in recent years. The accessible area on the east side of he wetland was surveyed for felled trees and evidence of bark chewing. At nine locations, slope angle (mean: 7.2°), distance to wetland, azimuth of tree fall (azimuth and height of bark chew for un-felled trees), height and circumference (mean: 23.1 cm), of remaining tree stump and width of beaver incisor marks were measured. Most vegetation was removed immediately landward of the lodge, which was located ~10 m from the water line during surveys. In addition, some gnawed stumps of small trees were visible in the flooded parts of the wetland. Four samples of pointed stumps were sawed off and taken for further analysis and to reduce potential danger to park visitors. Beavers showed strong preference in removing lodge-building material at a consistent distance from the water line (4.2-5.1 m), which is likely due to a water position during the activity period. Because trees play a crucial role in wetland health by stabilizing steep banks and providing shade to the habitat, this peripheral damage may exacerbate the impact of future flooding events. On the other hand, relict stumps may serve as helpful indicators of both proximity to former watercourses and paleo-shoreline trends.

Geological Society of America Abstracts with Programs. Vol. 52, No. 2

doi: 10.1130/abs/2020SE-343267

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