A Comparison of Structural Characteristics between Old-Growth and Second-Growth Hemlock-Hardwood Forests in Adirondack Park, New York

This study compares the structural characteristics of 12 old-growth and six postfire second-growth hemlock-northern hardwood stands in north central Adirondack Park, New York, in order to test the null hypothesis that there are no differences in species composition, size structure, age structure and attributes such as dead wood and canopy gaps between old-growth stands and this type of second-growth forest. 2 The second-growth forests of this study regenerated following widespread logging-related fires in either 1903 or 1908; the old growth and second growth have similar environmental settings. 3 Estimates of stand ages, derived from an increment core of the oldest tree in each stand, range from 88 to 390 years. 4 Structural attributes are related to stand age (i.e. stage of development). In comparison with the second-growth forests of this study, older stands are characterized as (a) a larger average diameter of canopy trees; (b) a greater basal area of trees; (c) a lower density of canopy trees and of all trees ≥10 cm d.b.h.; (d) a higher density of eastern hemlock (Tsuga canadensis (L.) Carriere) trees; (e) a higher density of large trees (≥50 cm d.b.h.); (f) larger canopy gaps; and (g) a greater volume of coarse woody debris (both logs ≥20 cm d.b.h. and snags ≥10 cm d.b.h.). 5 Despite differences between old growth and second growth, especially in species composition, it appears from observations of the 18 stands that second-growth forests are developing some structural characteristics of old growth. 6 Structural attributes of the old-growth forests are similar to characteristics of the same forest type in geographically distant areas in eastern USA