Differential Responses of Wetland and Upland Riparian Invasive Species to Forest Restoration and Geomorphology

Alexis Garretson1,2, Samantha Mohney3, Morgan Cahill3, Laurel Griffin4, Rachel Silarszka3, Mohonk Preserve Stream Watch Citizen Scientists, Natalie Feldsine2, Megan Napoli2, Elizabeth Long2 1 Department of Biology, George Mason University, 4400 University Drive, Fairfax, VA 22033 2 Daniel Smiley Research Center, Mohonk Preserve, New Paltz, NY 3 Department of Environmental Science and Policy, George Mason University, 4400 University Drive, Fairfax, VA 22033 4 Schar School of Policy and Government, George Mason University, George Mason University, 4400 University Drive, Fairfax, VA 22033

Introduced vegetation in the riparian zone can negatively affect the characteristics and quality of a watershed. Hydrochory, or water dispersal, of invasive riparian vegetation seeds can facilitate the spread, making the riparian zone a critical corridor for new species colonization. Between 2017 and 2019, citizen scientists repeatedly surveyed 20 sites in the Hudson River Valley in New York for the presence of ten introduced species: purple loosestrife, phragmites, multiflora rose, garlic mustard, Dame’s rocket, Japanese knotweed, wineberry, barberry, and oriental bittersweet. Using these data, we investigate the relationship between land-use and geological variables and the community composition of introduced species. Overall, there was a positive relationship between canopy cover and species richness of introduced vegetation. However, there is some variation in individual species response, as the presence of purple loosestrife (Lythrum salicaria) and phragmites (Phragmites australis) were negatively related to canopy cover. In general, increasing basin slope and associated runoff led to an increased probability of invasive species occurrence. However, as with canopy cover, purple loosestrife and phragmites differed in response from other surveyed species and were negatively related to basin slope. As found in previous studies, elevation was negatively related to species occurrence. This may indicate elevation thresholds, particularly in upland species. Our findings highlight the challenges of invasive species control in the riparian zone, as measures targeting one species may lead to the proliferation of other species.

Additional Abstract Information

Presenters: Morgan Cahill, Rachel Silarszka, Laurel Griffin

Institution: George Mason University

Type: Poster

Subject: Environmental Science & Sustainability

Status: Approved

Time and Location

Session: Poster 7
Date/Time: Tue 3:30pm-4:30pm
Session Number: 5007