Evaluating the Impact of Stream Restoration Techniques on Bank Erosion, Stream Morphology, and Soil Carbon at an Unnamed Tributary of Pine Creek near Woodward, central Pennsylvania
Live staking is a stream restoration technique in which live cuttings and stems taken from native species of trees and shrubs are placed into stream banks, eventually growing into new plants which aids in riverbank protection by increasing soil cohesion. Live staking is an economically viable and easy technique for stream restoration that is being widely implemented in the Chesapeake Bay watershed. Because of the growing use of live staking in stream restorations, there is a growing need for research on the link between live staking and geomorphic resiliency. Here we investigate the impact of live staking on bank erosion, stream morphology, and soil carbon at an unnamed tributary of Pine Creek near Woodward, Pennsylvania. Restoration efforts of this tributary began in fall 2018 by the Penn’s Valley Conservation Association (PVCA) and live staking began in spring 2019 in the upstream section of the tributary.
In this study, we collected baseline data for a long-term study of the impact of live stakes on the floodplain and channel geomorphology, and we investigated the baseline soil carbon distribution. To do this, we mapped floodplain and channel topography and surveyed the stream channel using a Trimble RTK GPS unit. Floodplain soils were sampled along nine transects perpendicular to the channel to investigate soil properties and measure the spatial distribution of soil carbon (using a CHN analyzer). Results from stream channel surveying indicate undercut banks, channelization, very low stream velocity, and silt and clay on the stream bed. Throughout the field site, the soils are silty loams with thin O-horizons (2-8 cm) and some local variability within transects. Soil carbon analysis shows carbon values between 0.36% and 3.32%, which is low within the expected range of soil carbon for degraded floodplain soils. Although we did not observe significant spatial patterns in soil characteristics or in soil carbon content, we did document small increases in soil carbon near the channel, and high amounts of soil carbon near a protected wetland area. We predict that in future years, as the live stakes vegetate the stream banks at this site, there will be an increase in soil carbon, changes in stream bed character and channel sinuosity, and more soil variability, including a thicker O-horizon and possible changes in grain size.