Growth and reproductive potential of the invasive exotic vine Vincetoxicum rossicum in northern New York State

Abstract

The alien invasive vine Vincetoxicum rossicum (Kleopow) Barbar. is problematic in the Lower Great Lakes Basin of North America. The lack of effective control strategies exacerbates the need for a better understanding of the growth and reproductive potential of V. rossicum. Thus, a 2-year field experiment was performed in a field site in 2003 and 2004 that was densely colonized by V. rossicum. Mean height of V. rossicum stems was 20% and 45% greater in naturally shaded plots compared with plots receiving full sun in 2003 and 2004, respectively. During the 2-year study, the density of stems 10 cm or taller averaged 134 stems·m–2, substantially greater than reported in previous field studies for this species. The high densities of stems and seedlings indicate that this field site may be near or at carrying capacity. Each stem produced, on average, 17 mature follicles with some stems producing as many as 100 follicles. Each follicle yielded an average of 15 seeds, each composed of an average of two viable embryos. A typical V. rossicum stand in this site produced as many as 54 000 seedlings·m–2 annually. More flowers (2400 flowers·m–2), follicles (2250 follicles·m–2), and total seeds (32 000 seeds·m–2) were produced in plots receiving intermediate light compared with plants in full sun (1650 flowers·m–2, 1600 follicles·m–2, and 25 000 seeds·m–2) or shaded (1600 flowers·m–2, 2000 follicles·m–2, and 28 000 seeds·m–2) plots. Seeds harvested from follicles in the low light plots were 41% more likely to be dormant than seeds collected from follicles in full sun plots. Seeds collected from plants in full sun plots had the lowest frequency (∼36%) of single embryo seeds and the highest frequency (∼64%) of multiple embryo seeds. These findings suggest that V. rossicum growth and reproductive output is influenced by light environment. While competitive strategies differ between the light environments, the decrease in viability and germination in shaded sites may not be large enough to affect population growth over multiple generations. The substantially greater growth and reproduction of V. rossicum reported in this study relative to previous research may explain the increasing abundance and range expansion of this species in many Lower Great Lakes regions of Ontario and New York State.

Phytotoxicity of Antofine from Invasive Swallow-Worts

“…Swallow-wort vines can grow 1-2 m or more during the growing season, producing dense, tangled masses of vines that climb up and over supporting vegetation (Christensen, 1998;Douglass et al, 2009). Stand densities can average 134 stems per m 2 and 1800 seedlings per m 2 (Smith et al, 2006). Large stands reportedly exclude most other vegetation, including the related milkweeds, and are encroaching on at least five threatened or endangered species in New York and New England and on the globally-rare alvar communities in Ontario and New York (Haribal and Renwick, 1998;Lawler, 2000;Tewksbury et al, 2002;Douglass et al, 2009).…”

“…Denis and Cappuccino, 2004). Seed production can be prolific in high-light environmentsaround 32,000 seeds per m 2 for high density stands of pale swallow-wort, and seeds are polyembryonic, containing 1-8 embryos (Cappuccino, 2004;DiTommaso et al, 2005a;Smith et al, 2006). Polyembryony may contribute to enhanced seedling establishment and survival rates, which can be over 50% for pale swallow-wort (DiTommaso et al, 2005a;Ladd and Cappuccino, 2005;Hotchkiss et al, 2008).…”

“…Both species are drought tolerant and can grow in soils of a wide range of pH (DiTommaso et al, 2005b;Magidow et al, 2008). Pale swallow-wort also is shade tolerant, although in heavily shaded areas, little reproduction by seed occurs (Smith et al, 2006;Hotchkiss et al, 2008).…”

Impact of herbivory on performance of Vincetoxicum spp., invasive weeds in North America

“…This slow establishment phase followed by exponential growth may be due to density-dependant responses (Miller et al 2008;Cappuccino 2004;Cappuccino et al 2002), and such responses may explain why this group has successfully invaded a variety of disturbed and undisturbed habitats (Averill et al 2008). Vincetoxicum rossicum tends to be shade-tolerant, and is found further into forest understories, while V. nigrum tends to be limited to habitat edge and open areas (Milbrath et al 2006) where its densities can approach 180 shoots/m 2 and 2,500 seedlings/m 2 (Smith et al 2006). Although somewhat less in closed canopied habitats, swallow-wort densities can still reach as high as 117 shoots/m 2 and dominate ground cover up to 70% (Miller et al 2008;DiTommaso et al 2005).…”

The exotic invasive plant Vincetoxicum rossicum is a strong competitor even outside its current realized climatic temperature range

“…Cynanchum rossicum (Kleopow) Borhidi) is an alien invasive plant species from the Ukraine and southwestern Russia that has established in the north-eastern United States and southern Ontario. Vincetoxicum rossicum was first found in Toronto in 1889 (Smith et al 2006). It is a perennial self-pollinating vine that produces pods filled with comose seeds that are wind-dispersed.…”