Forest Succession in the Glacier Park Cedar‐Hemlock Forests

A gradient analysis and description was made of forest succession among the Thuja plicata—Tsuga heterophylla communities in the vicinity of Lake McDonald in Glacier National Park Montana. Thirty—three pioneer, seral, and climax communities located on well—drained slopes at elevations between 3,200 and 3,500 ft (1,050—1,150 m) were sampled. Through the calculation of indices of community similarity and dissimilarity, the stands were objectively arranged along a unidimensional gradient. The data summarized along the resulting ordination gradient provide a quantitative description of the basic successional pattern existing among these cedar—hemlock communities. Typically, following burning Pinus contorta communities become established, and these in turn are gradually replaced by Pinus monticola and Pseudotsuga menziesii in various proportions. Climax communities on the upland sites become dominated by Tsuga heterophylla, with smaller, but self—reproducing populations of Thuja plicata also persisting.