Soil characteristics of North American sites colonized by the non-native, invasive vines black swallow-wort and pale swallow-wort

Authors: MAGIDOW, LILLIAN - Cornell University; DITOMMASO, ANTONIO - Cornell University; WESTBROOK, ANNA - Cornell University; KWOK, MATTHEW - Cornell University; KETTERINGS, QUIRINE - Cornell University; Milbrath, Lindsey

Submitted to: Northeastern Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: 3/25/2022
Citation: Magidow, L., Ditommaso, A., Westbrook, A.S., Kwok, M.J., Ketterings, Q.M., Milbrath, L.R. 2022. Soil characteristics of North American sites colonized by the non-native, invasive vines black swallow-wort and pale swallow-wort. Northeastern Naturalist. 29(1):108-132. https://doi.org/10.1656/045.029.0111.
DOI: https://doi.org/10.1656/045.029.0111

Interpretive Summary: Black and pale swallow-wort have become an invasive weed problem in northeastern North America, although the two species show little overlap at local field sites. Black swallow-wort was expected to occur primarily on lower pH, low-fertility soils and pale swallow-wort on higher pH, high-fertility soils. Soil collections from six states and one Canadian province showed that both species were found on soils that varied widely in pH (4.7–7.9) and soil type. However, black swallow-wort tended to be found on lower-fertility soils and pale swallow-wort on higher-fertility soils. Our findings suggest that diverse soils are susceptible to invasion by swallow-worts, and therefore sites near existing swallow-wort populations must be monitored to avoid new infestations.

Technical Abstract: Vincetoxicum nigrum (Black Swallow-wort) and V. rossicum (Pale Swallowwort) are non-native, perennial vines that are spreading across North America. We collected soil samples from invaded sites in the northeastern United States and southeastern Canada. We also performed GIS analyses using the site locations, locations from iMapInvasives, and soil data from SSURGO. We found that Black Swallow-wort tended to occupy Inceptisols while Pale Swallow-wort occupied soils with more silt and clay, including Alfisols. Mean soil pH was lower at Black Swallow-wort sites compared to Pale Swallow-wort sites. However, both species colonized soils that varied widely in pH, fertility, texture, and taxonomy. We conclude that abiotic soil characteristics do not strongly constrain swallow-wort distributions in North America.