Date of Award

5-2013

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Cynthia Loftin

Second Committee Member

Judith Rhymer

Third Committee Member

Francis Drummond

Abstract

Clayton’s copper butterfly (Lycaena dorcas claytoni) is a Maine state endangered species that relies exclusively on shrubby cinquefoil (Dasiphora fruticosa) as its host plant. This shrub typically is found on the edges of wetlands rich in calcium carbonate or limestone. Calcareous wetland habitats that support large, persistent stands of D. fruticosa are rare in Maine (McCollough et al. 2001). Currently only 21 sites in Maine are known to support large stands of D. fruticosa, and L. d. claytoni populations have been observed at only nine of these. Because nearly the entire global range of this butterfly is in Maine, it is critical that Maine assumes the primary role in the conservation of this rare subspecies.

Conservation of L. d. claytoni depends in part on the ecological integrity of its habitat. Vegetation structure and hydrological conditions in wetlands may affect the distribution and robustness of D. fruticosa, which also may influence its use as a host plant by L. d. claytoni. I conducted field studies in 2009 and 2010 in ten wetlands in Maine with robust stands of D. fruticosa to evaluate pore water nutrients, hydrological conditions, shrub and tree species composition and distribution, and D. fruticosa distribution, structure, age and condition; seven of these wetlands support populations of L. d. claytoni, and three of these wetlands are unoccupied. I identified five hydrological types based on differences in water source and surface and ground water dynamics. Three wetlands were dominated by groundwater discharge, six wetlands were down-flow dominant, and one wetland fluctuated between groundwater discharge and recharge. Pore water analytes reflected hydrogen ion and conductivity gradients among the wetlands and vegetation community distributions within the wetlands, however, these differences did not reflect wetland occupation of L. d. claytoni. Dasiphora fruticosa age ranged from 7 to 37 years. Previously reported Lycaena dorcas claytoni encounter rates were greater in wetlands containing larger D. fruticosa plants of intermediate age and with greater bloom density. Butterflies are able to differentiate among glucose, fructose and sucrose in nectar. I found D. fruticosa produces hexose dominant nectar (sucrose/[glucose + fructose] <0.1), with only trace amounts of sucrose measured in < 3% of the samples. Conservation and recovery of L. d. claytoni depends in part on the quality and distribution of its habitat. Although Maine’s wetlands hosting L. d. claytoni currently support robust stands of D. fruticosa, their isolation likely limits movement of the butterfly. Increased connectivity among wetlands containing shrubby cinquefoil may aid dispersal and improve likelihood of long-term L. d. claytoni population.

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