|DITOMMASO, ANTONIO - Cornell University - New York|
|MORRIS, SCOTT - Cornell University - New York|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2015
Publication Date: 2/9/2015
Citation: Milbrath, L.R., Ditommaso, A., Biazzo, J., Morris, S.H. 2015. Performance of invasive swallowwort juveniles (Vincetoxicum spp.) across a habitat gradient after 7 years. Weed Science Society of America Meeting Abstracts. Volume 53. http://wssaabstracts.com/public/30/proceedings.html.
Technical Abstract: Vincetoxicum rossicum, pale swallowwort [PSW], and V. nigrum, black swallowwort [BSW] are two non-native perennial vines that are increasingly problematic in many regions of the northeastern U.S. and southern Canada. The two species can grow in full sun or shaded forest understories, and infest a variety of habitats from agricultural to natural areas. Establishment and growth of vegetative juveniles may be an especially critical phase in the life cycle of plants and may be targeted for control of invasive species if this stage is important for population growth. We established a long-term field experiment in fall of 2007 to assess survival and growth of early-stage swallowworts in three different habitat types: an old field [high light], a forest edge [transition zone] and forest understory [low light] at a central New York State location where both species are present in the region although not at the experimental site. The two swallowwort species were established from seed in a split plot design with habitat type as the whole plot treatment, swallowwort species as the subplot treatment, and 10 blocks for a total of 60 subplots. From an initial cohort of 40 seedlings per subplot, survival and growth (i.e. height, time to first flower and pods, pod and seed production) of these plants have been monitored annually. From an initial 96 percent survival after one season of growth (2008), percentage survival of juvenile swallowworts decreased by 51-78 percent in the different habitats after two seasons. By the seventh year (2014), the survival rate of juveniles was 8.2 +/- 2.4 percent (field), 6.5 +/- 2.1 percent (ecotone), and 0.6 +/- 0.7 percent (forest). Apart from the first year, BSW survival was greater than PSW every year, averaged across habitats. Also, juvenile BSW plants generally remained at least two times taller than PSW in all habitats. However, the two species were more similar in height after the fourth year in the forest and forest edge habitats. A few BSW plants in the field flowered without producing seed in their second and third year of growth, but subsequently most plants flowered and produced seed within the same season. To date, BSW plants (field only) have required 5.0 +/- 0.4 and 5.3 +/- 0.5 years post-establishment to flower and produce seed, respectively (n= 85). Reproductive BSW had 105.3 +/- 20.4 cm long stems, a root dry mass of 4.5 +/- 1.0 g, and 3.3 +/- 1.4 pods with 7.5 +/- 1.0 viable seed per pod (several samples still being processed). Only three PSW plants from the field habitat have become reproductive in their sixth or seventh year. Reproductive PSW had 88.3 +/- 15.0 cm long stems and 7.7 +/- 5.1 pods (samples still being processed). The low survival observed in this study may be due to both a dense cover of resident vegetation in the old field and leaf litter in the forest as well as wetter conditions than swallowwort tolerates. Also, this research confirms that BSW can reproduce earlier compared with the relatively longer juvenile phase for PSW.