Sexual reproduction is an important mechanism shaping plant community composition that will likely be affected by unprecedented rates of climate change in Canada’s North. To anticipate potential changes in plant communities, I aim to understand how changing environmental conditions affect the processes of seed production and seedling emergence, and determine the overall impacts on the reproductive potential of alpine tundra vegetation in Yukon, Canada. I tested the effect of soil warming and nitrogen addition treatments on the timing and success of sexual reproduction of the six tundra species; Dryas octopetala M. Vahl, Salix arctica Pall, Salix reticulata L., Lupinus arcticus L., Carex microchaeta Holm, and Hierochloë alpina (Sw.) R. & S. A summer snow event occurred on 2 July 2012, and I considered the impacts of such an event on the reproductive timing and success of the study species. I also examined the influence of seed availability and soil conditions on initial seedling emergence of three tundra species and three boreal species. I applied seed to natural disturbance sites with bare substrate exposed, and to plots with altered soil temperature and nitrogen availability. Results indicated that reproductive phenology, seed production, and seed viability of tundra species were not affected by increases in soil temperature and/or nitrogen availability but were impacted by the snowfall event. In addition, changes in soil temperature and nitrogen did not affect seedling emergence. Seedling emergence of both boreal and tundra species increased on bare substrates, indicating that surface disturbance creates opportunities for seedling establishment. Overall, my study shows that factors affecting seed production and local disturbance will have greater impact on the success of sexual reproduction in tundra plant communities than changes in soil temperature or nutrients caused by climate change.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2015-04-2063 |
| Date | 2015 April 1900 |
| Contributors | Johnstone, Jill |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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