LE3 .A278 2006

2006

Reekie, Edward

Acadia University

Master of Science

Masters

Biology

Biology

Nova Scotia is home to the northern-most disjunct populations of Atlantic Coastal Plain flora species, 11 of which are listed as species at risk by the Committee on the Status of Endangered Wildlife in Canada. This study examined variables that may be limiting the rare elements of this flora in hopes of establishing why they have not expanded to utilize other lakes that appear to be good habitat, including dam reservoir lakes, and how we might alter the management of water levels at reservoir lakes to improve habitat quality there. Two transplant experiments were conducted to examine environmental variables that may be limiting two of the at risk species, Coreopsis rosea Nutt. and Hydrocotyle umbellata L. The first experiment was to determine the effect of growing season length and involved three treatments: time of planting (June, July or August), depth on the shoreline, and water fluctuation regime (three different lakes). The second experiment examined the effect of environmental variables including substrate, vegetation cover, soil moisture, temperature, and water quality. I found that establishment time, flooding, and soil nutrient holding capacity appear to limit both species. The effect of unseasonable flooding was similar to the effect of later establishment in reducing biomass and flowering. Growth and survival were poor under constant flooding. Earlier establishment resulted in slightly higher survival under poor conditions. C. rosea, the upper shoreline specie, though superior in its cold tolerance, had inferior mechanisms for adjusting to flooded conditions in comparison with H. umbellata, the lower shoreline species. At reservoirs, higher fall water levels would prevent cold damage, earlier spring draw down would reduce flood stress, and opening the dam during periods of high precipitation would avoid plant damage due to unseasonable flooding.

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https://scholar.acadiau.ca/islandora/object/theses:116