Torres, Gabriel, Ecology, Susquehanna University, 500 W Sassafras St, Selinsgrove, Pennsylvania, 17870, torresg@susqu.edu; Thomas, Shannon, Chesapeake Conservancy, 1250 W Sassafras St, Selinsgrove, Pennsylvania, 17870, sthomas@chesapeakeconservancy.org; Wilson, Matthew, Freshwater Research Institute Susquehanna University 1250 W Sassafras St Selinsgrove Pennsylvania, 17870, wilsonmatt@susqu.edu.
Riparian buffers are one of the most effective strategies for improving stream water quality, stabilizing streambanks, and supporting wildlife. Yet many restored sites experience inconsistent maintenance and invasive plant species succession, leading to reduced native vegetation diversity and loss of function over time. Herbicide is a common management tool for restored riparian buffer maintenance. This study examines how invasive plant populations respond to herbicide application rates and methods — which influence the success of riparian buffer restoration. We collected data on different types of herbicide treatments and compared target invasive plant relative density over a three-year period (2023-2025) across 16 restoration sites in Lycoming, Synder, and Union Counties, Pennsylvania. Our results indicate herbicide management helps mitigate some invasive plant populations. For example, callery pear (Pyrus calleryana) populations declined from 0.05 occupancy rate across all sites from 2024 to <0.01 in 2025 (p = 0.01698, R2 = 0.1581). However, this trend is not the case for all species, such as reed canary grass (Phalaris arundinacea; p = 0.0877, R2= 0.066). These findings suggest that moderate herbicide use paired with consistent monitoring may gradually improve restoration outcomes by limiting invasive plant densities and promoting native plant biodiversity to recover. Next steps will involve returning to 5 sites that overlap across three years to measure diameter breast height of tree species to determine which specific tree species are showing significant growth.
restoration effectiveness, buffer maintenance, riparian, invasive species