HETEROGENEITY OF FOREST CHARACTERISTICS IN PRIMARY AND SECONDARY FOREST STANDS ON THE 3RD CHICKASAW LOESS BLUFF, TENNESSEE

In this study, non-spatial and spatial components of heterogeneity wer e contrasted for a mid-successional forest (55 years old) and an adjac ent primary forest in western Tennessee. Analyses of size-class freque ncies showed that whereas all size classes were well represented in th e primary forest, the second-growth stand was marked by a greater numb er of canopy/subcanopy-level (10 to 50 cm dbh) trees but fewer underst ory individuals, especially in the 2 to 4 cm dbh size class. Variabili ty of basal area, maximum tree size, and understory diversity was grea ter for the primary stand, whereas variability of overstory (>10 cm db h) 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 pa cking of canopy individuals in the second-growth stand. Furthermore, t he second-growth stand displayed no evidence that gap replacement proc esses, the dominant successional process in old-growth forests in west ern Tennessee, have resumed; instead, the second-growth stand apparent ly is still dominated by maturation of the canopy coupled with thinnin g of understory and subcanopy individuals.