Seed dormancy in high elevation plants: implications for ecology and restoration

Seed germination is a crucial event in the life of every sexually reproduced higher plant. A portion of the seeds of many species are dormant; they do not germinate unless specific environmental signals or events occur. The objective of this research was to determine the extent of seed dormancy in 28 species of grasses and forbs from alpine-subalpine areas of the Olympic Mountains, Clallam Co., Washington. Five species were non-dormant. After-ripening improved germination of eight species, five required cold stratification, scarification benefitted four, and some seeds of 11 species required light. Four others failed to germinate at all under the given treatments. At least one species may have possessed more than one dormancy mechanism. Results from this study support recommendations for shallow or surface sowing of seeds to satisfy light requirements and fall-planting to increase the likelihood of natural scarification and cold stratification. The diversity and extent of dormancy mechanisms encountered here suggests that under harsh and uncertain alpine growing conditions, natural selection may favor seeds with a genetic system for dormancy and delayed germination. After-ripening occurred even while seeds were in cold-dry storage, suggesting that ecological studies should not use cold-stored seeds and assume they will behave as though they are freshly matured. Seed dormancy may control germination timing and rate, which in turn effect plant establishment and competitive ability, and ultimately population, successional, and community patterns of high-elevation vegetation. Successful germination protocols improve propagation success and aid efforts to revegetate disturbed areas in Olympic National Park and other high-elevation areas in the Pacific Northwest.