Radial and longitudinal variation in stem diameter increment of lodgepole pine, white spruce, and black spruce: species and crown class differences
Radial and longitudinal variation in stem diameter increment were examined in lodgepole pine (Pinuscontorta var. latifolia Engelm.), white spruce (Piceaglauca (Moench) Voss), and black spruce (Piceamariana (Mill.) B.S.P.) in Alberta using graphical techniques. Three-dimensional surfaces of diameter increment at various heights and ages differed among the three species and dominant, codominant, and intermediate crown classes within each species. Relative to the maximum growth rate, black spruce and white spruce maintain higher and more constant levels of diameter increment over time than lodgepole pine. Variation among species probably reflects differences in shade tolerance, while differences among crown classes within a species are probably related to shading and wind stress effects. There were more similarities among the diameter increment surfaces for the three crown classes in lodgepole pine than in the two spruces. The stem diameter increment surfaces help explain the development of differences in stem form among the three species.