June-Wells M.,U.S. Department of Soil and Water |
June-Wells M.,New England Environmental Incorporated |
Gallagher F.,Lipman |
Gibbons J.,U.S. Department of Soil and Water |
Bugbee G.,U.S. Department of Soil and Water
Lake and Reservoir Management | Year: 2013
Our analysis of 156 lakes and 5 nonnative aquatic macrophyte species suggest that 4 water chemistry variables can be used to assess the risk associated with species invasion in Connecticut lakes. Our analysis showed that water chemistry and longitude explained a significant amount of the total data variance (33%). Additionally, individual species logistic regressions suggest that these species' distributions were determined by the specific conductance and pH of the water body. Lakes were then placed into one of the following groups: (1) Cabomba caroliniana/Myriophyllum heterophyllum (CM), (2) Myriophyllum spicatum/Najas minor/Potamogeton crispus (MNP), (3) Mixed (Mixed), or (4) No Invasive (NI). Multivariate analysis of variance suggests that water chemistry of the groups CM and MNP differed significantly (p < 0.001), and the variables that contributed to this difference were specific conductance (F = 22.16), alkalinity (F = 19.40), and pH (F = 18.61). The Mixed and No Invasive groups were not significantly different. Discriminant function analysis was used as a final analytical tool to determine the risk of NI group lakes developing populations of our nonnative species. The results suggest that the 4 abiotic variables could predict the identity of the CM and MNP groups with a high degree of certainty (i.e., 79 and 71% correct, respectively). When the NI group was included in the discriminant analysis, 34% of these lakes were grouped with CM and 14% with MNP. The remaining 52% of NI lakes had water chemistry parameters capable of supporting all species examined in this study. From these findings, water chemistry risk assessment ranges were developed for these common nonnative species in Connecticut. © Copyright by the North American Lake Management Society 2013.
June-Wells M.,New England Environmental Incorporated |
Gallagher F.,Rutgers University |
Holzapfel C.,Rutgers University
Journal of the Torrey Botanical Society | Year: 2014
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. © 2014 Torrey Botanical Club.
Adams J.M.,Seoul National University |
Kang C.,Seoul National University |
June-Wells M.,New England Environmental Incorporated
Ecological Research | Year: 2014
There is a common and long-standing belief that tropical butterflies are more striking in their coloration than those of cooler climates. It has been suggested that this is due to more intense biotic selection or mate selection in the tropics. We tested whether there were differences in coloration by examining the dorsal surface color properties of male butterflies from three regions of the western hemisphere: the Jatun-Satcha Reserve in lowland Ecuador (tropical), the state of Florida, USA (subtropical) and the state of Maine, USA (cool temperate). We digitally photographed the dorsal wing and body surface of male butterfly specimens from Maine, Florida, and Ecuador. For each photograph, we analyzed the mean and variation for the color-parameters that are thought to be related to colorfulness; namely Hue, saturation and intensity. Overall, the Ecuadorian sample exhibited more varied intensity, saturation, and Hue compared to the other regions. These results suggest a more complex assemblage of colors and patterns regionally and on a butterfly-by-butterfly basis in the tropics. The greater complexity of colors within each butterfly in our Ecuadorian sample suggests that tropical butterflies are indeed more 'colorful', at least by some measures. Possible reasons for this include stronger predation pressure selecting for aposematism, greater species diversity selecting for camouflage or warning coloration against potential predators, and easier recognition of potential mates in a species rich environment. © 2014 The Ecological Society of Japan.