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Abstract
Casual observations have suggested that intermediate size and age gaps may exist in the eastern hemlock (
Tsuga canadensis (L.)Carr.) populations of Algonquin Provincial Park, Ontario. This was confirmed in vegetation surveys reported here. Several hypotheses, involving mortality risks at different points in the life cycle of hemlock, are proposed to explain the age gap. The hypotheses include seed predation (a period of intense seed predation), seedling establishment (a period of environmental or climatic changes limiting seedling establishment), hare browsing (a period of high snowshoe hare populations and intense browsing), ungulate browsing (a period of heavy ungulate browsing limiting hemlock recruitment), stem exclusion (normal stem dynamics), and canopy suppression (long-lived canopy stretching tolerance limits of hemlock seedlings).
Parent Publication
Citation
Vasiliauskas, S. A.; Aarssen, L. W. 2000. Interpretation of age-structure gaps in hemlock (
Tsuga canadensis) populations of Algonquin Provincial Park, Ontario, Canada. In: McManus, Katherine A.; Shields, Kathleen S.; Souto, Dennis R., eds. Proceedings: Symposium on sustainable management of hemlock ecosystems in eastern North America. Gen. Tech. Rep. NE-267. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 205.
