HETEROGENEITY OF FOREST CHARACTERISTICS IN PRIMARY AND SECONDARY FOREST STANDS ON THE THIRD CHICKASAW LOESS BLUFF, TENNESSEE

Abstract

In this study, non-spatial and spatial components of heterogeneity were contrasted for a mid-successional forest (55 years old) and an adjacent primary forest in western Tennessee. Analyses of size-class frequencies showed that whereas all size classes were well represented in the primary forest, the second-growth stand was marked by a greater number of canopy/subcanopy–level (10 to 50 cm dbh) trees but fewer understory individuals, especially in the 2 to 4 cm dbh size class. Variability of basal area, maximum tree size, and understory diversity was greater for the primary stand, whereas variability of overstory (>10 cm dbh) tree density and diversity was higher on the secondary stand. Plot aggregations, species-accumulation curves, and semivariogram analysis indicated differences in the scale of patterns of forest structure and composition between the two stands. These differences apparently are related to the smaller crown sizes of maturing trees and the denser packing of canopy individuals in the second-growth stand. Furthermore, the second-growth stand displayed no evidence that gap replacement processes, the dominant successional process in old-growth forests in western Tennessee, have resumed; instead, the second-growth stand apparently is still dominated by maturation of the canopy coupled with thinning of understory and subcanopy individuals. [Key words: heterogeneity, forest structure, forest composition, variance analysis, loess, Tennessee.]