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Evaluating population border dynamics among Artemisia vulgaris and community constituents in an urban successional plant assemblage1

June-Wells, Mark, Gallagher, Frank, Holzapfel, Claus
Journal of the Torrey Botanical Society 2014 v.141 no.1 pp. 14-28
Artemisia vulgaris, community structure, forbs, grasses, introduced species, plant communities, population dynamics, shrubs
Assessing border properties within vegetative assemblages is critical to the understanding of plant community dynamics and to the development of non-native species management protocols. Population border zones are the most dynamic part of a plant community and can be evaluated to determine population dynamics, management necessity, or species/species interactions. From a management perspective, changes in these borders can be used to evaluate the overall trajectory for populations in a community, the effects of disturbance, and/or non-native species on the community structure. We examined the trends of Artemisia vulgaris (L.) borders that were adjacent to other species populations in a mixed urban plant community in an effort to determine the future community identity and how interactions may vary among species of differing guilds. We analyzed trends in border properties, which were developed specifically for this study, over a four-year period. Our design included all co-dominant species bordering A. vulgaris from the following guilds: (1) Forbs, (2) Grasses, and (3) Shrubs resulting in a complete assessment of guild interactions (forb/forb, forb/grass, and forb/shrub). We found that interactions among species varied considerably and were not directly related to the guild membership. Instead, interactions and the dynamic nature of population borders varied on a species by species basis. Our results also suggest that population dynamics of differing life form guilds (i.e., forb/shrub) were not necessarily related to direct competitive interactions; rather, they may be a result of yearly fluctuations in the larger species' (shrub) population. Finally, we found that A. vulgaris did not necessarily exclude all species; in fact, A. vulgaris was thwarted by some species and co-mingled with others.