The influence of microsite characteristics on whitebark pine (Pinus albicaulis) germination and early survival

Abstract

Abstract Whitebark pine, a hardy high-elevation species distributed throughout northwestern North America, is a keystone species for alpine ecosystems for its seeds, a food source for many wildlife species. It defines the community structure of alpine ecosystems, moderates the harsh climate, and increases ecosystem stability. As it is threatened by many factors, including climate change, facilitated migration may be needed to ensure the species’ survival. Outplanting will rely upon knowledge of the specific environmental microsite characteristics that may support successful germination and survival of the species. A common garden experiment to test emergence rates according to variable site conditions was conducted across northern BC. Seed was collected from 7 source populations, stratified for 4 months, and planted in 8 common garden provenance trials distributed across northern British Columbia. Within-site conditions at the microsite level, including soil type, depth, vegetation influence, and topography, were assessed and related to seedling emergence. Convex microsites were positively related to emergence at a coastal, damp site. Surrounding vegetation with lower height seemed to support higher emergence. Organic soils were related to higher emergence rates at that same site. Microsites with shallow soils also had higher emergence rates. Seed source quality, such as seed maturity and development, as well as stratification techniques, may have a greater effect on the germination and first-year survival of whitebark pine seedlings. If facilitated migration supports whitebark pine growth at increasing latitudes, as climate change scenarios suggest may be necessary for species survival, these results may be used for successful outplanting.