Stand development in whitebark pine woodlands

Abstract

Analysis of density data from stands in the Northern Rocky Mountains shows that, while seedlings establish at the rate of over 1,000 I ha x year in whitebark pine-grouse whortleberry (Pinus albicaulis-Vaccinium scoparium) forests of all ages, stem numbers in the canopy thin to 400 at 30 years, 150 at 200 years, and 100 at 300 to 600 years. Indices of productive potential, cover, and total circumference rise to an asymptote at about 100 years. Total basal area rises from 0 to 60 m21 ha at about 200 years, the aggregate basal area of trees with diameters over 20 em rises from 0 to 40 m21 ha at about 250 years, and tree height maximizes (12 m) at 200 years. It is hypothesized that further growth in productive potential (that is leaf and I or root area) is prevented by limited supplies of water or a nutrient, further growth in basal area is prevented by lack of a nutrient (probably not carbon, hydrogen, oxygen, or nitrogen) and further growth in height is prevented by scarcity of water.