Seed dispersal ability of the invasive perennial vines Vincetoxicum nigrum and Vincetoxicum rossicum

Authors: DITOMMASO, ANTONIO - Cornell University; STOKES, COURTNEY - Cornell University; CORDEAU, STEPHANE - Universite De Bourgogne; Milbrath, Lindsey; WHITLOW, THOMAS - Cornell University

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2018
Publication Date: 4/5/2018
Citation: Ditommaso, A., Stokes, C.A., Cordeau, S., Milbrath, L.R., Whitlow, T.H. 2018. Seed dispersal ability of the invasive perennial vines Vincetoxicum nigrum and Vincetoxicum rossicum. Invasive Plant Science and Management. 11:10-19. https://doi.org/10.1017/inp.2018.8.
DOI: https://doi.org/10.1017/inp.2018.8

Interpretive Summary: The invasive vines pale and black swallow-wort are spread by wind-dispersed seeds. We studied how wind speed, seed characteristics, and the height at which a seed is released contributed to the distance seeds traveled before reaching the ground. Black swallow-wort’s larger seeds fell more quickly and generally traveled shorter distances than those of pale swallow-wort. Greater release height, as well as wind speed in the case of black swallow-wort, promoted long-distance seed dispersal in both species. To reduce large-scale spreading of these invasive plants, land managers should cut climbing vines so that seeds are not released from heights around 2 meters or more. Also, preventing seed production in small, non-climbing patches will help suppress their local expansion because many of the seeds can still disperse up to 20 meters away.

Technical Abstract: Black swallowwort and pale swallowwort are perennial vines of European origin that invade natural areas and perennial cropping systems in the northeastern United States and southeastern Canada. Both species reproduce via wind-dispersed seeds in the form of achenes with a coma, but little is known about the pattern and extent of dispersal of these seeds. We studied the relationship of seed release height (0.75 m, 2 m), wind speed at the time of release, seed mass and settling rate on distance traveled. Black and pale swallowwort traveled up to 72.14 and 79.63 m, respectively. Seeds of both species released from 2 m traveled greater distances than seeds released from 0.75 m, which fell within 20 m of the release point. Quantile regression showed that release height was the most important factor influencing long-distance dispersal events. Wind speed also strongly interacted with release height for long-distance dispersal of black swallowwort. Black swallowwort seed mass and settling rates were greater than those of pale swallowwort. Increasing seed mass generally increased settling rate, which in turn decreased distance traveled, except in pale swallowwort, where longer distance-dispersing seeds had a higher settling rate. Our findings suggest that management efforts focus on reducing climbing vines, such as along fences or forest edges, so that seeds are not released from heights around 2 m or more as these seeds are more likely to travel greater distances and result in establishment of new populations further away from the source population. In addition, preventing seed production in small, non-climbing patches will help suppress their expansion because many of the seeds can still disperse up to 20 m away.