White spruce (<i>Picea glauca</i> (Moench) Voss), black spruce (<i>P. mariana</i> (Mill.) BSP), and jack pine (<i>Pinus banksiana</i> Lamb.) are dominant conifer trees within the boreal forest. Rising CO2 concentrations may create hotter and drier conditions in the Southern Boreal Forest of Canada, and have negative impacts on germination and regeneration of conifers. Conifers vary in their germination requirements and may have different responses to climate change. Experiments were conducted to access the germination potential, variability among collections, and to predict the ability of these conifers to germinate under future climatic conditions. Twelve collections of white spruce and black spruce and ten collections of jack pine seeds were collected from the Boreal Plain Ecozone of Saskatchewan. Seeds of all collections varied in their dormancy characteristics and dormancy breaking requirements because no single stratification or light treatment stimulated germination in all three species. Seed dormancy was greatest in white spruce and least in black spruce. Germination tests at 5, 10, 12.5, 15, 17.5, 20, 25, 30, and 35°C were used to develop thermal time models. Each species had unique temperatures for optimal germination ranging from 20°C in white spruce, 20-25°C in black spruce, and 25-30°C in jack pine. The speed of germination under similar temperature regimes was fastest for jack pine, intermediate for black spruce, and slowest for white spruce. The base temperature for white spruce decreased (r=0.63, P=0.03) with increasing June precipitation while that of jack pine tended to increase with latitude (r=0.60, P=0.07) and April precipitation (r=0.58, P=0.08). No environmental variables correlated with germination of black spruce. The Canadian Global Climate Model, version 2, with emission scenarios predicted future temperature and precipitation at the sites where seeds were collected. Using the base temperature for germination as a guideline, temperatures suitable for germination in the spring are predicted to advance by a few weeks to a month and a half earlier with increased concentrations of CO2. Moisture availability may, however, control seed germination at these sites. Overall, jack pine and black spruce might better adapt to increasing temperature because of their high germination temperatures (>30°C). Variation in most germination parameters existed among collections, suggesting this variability can be used to select seed sources for reforestation or assisted migration in a changing climate.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-05152008-134225 |
| Date | 27 May 2008 |
| Creators | Qualtiere, Elaine |
| Contributors | Johnston, Mark, Coulman, Bruce E., Belanger, Nicolas, Bai, Yuguang, Romo, James T. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-05152008-134225/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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