Secondary forest succession in New Hampshire, USA

Abstract

Secondary forest succession in the northern hardwood and spruce-hemlock forests of central New Hampshire, USA, was examined by regressing percentage composition of the major species over stand age, using both temporary and remeasured plots in essentially uncut stands ranging in age from 3 to over 190 years. Plots were classified by site: fine till, sandy till, and softwood sites. Successional change varied by site, and five ecological species roles were detected: dominating climax, stable climax, minor climax, persistent successional, and temporary successional species. After heavy cutting, stands on fine till sites move through an abundance of successional species such as pin cherry ( Prunus pensylvanica L.), aspen ( Populus spp), paper birch ( Betula papyrifera Marsh.), and yellow birch ( B. alleghaniensis Britton) toward a predominence of sugar maple ( Acer saccharum Marsh.) and American beech ( Fagus grandifolia Ehrh.). A similar trend occurs on sandy till, although red maple ( A. rubrum L.) — a low nutrient-demanding species — is a more common successional species and American beech is much more aggressive than sugar maple. On softwood sites (shallow, dry, wet, or poorly aerated soils), the successional species, including high proportions of red maple, are succeeded by a predominance of eastern hemlock ( Tsuga canadensis (L.) Carr.) and, especially at higher elevations, red spruce ( Picea rubens Sarg.). On these softwood sites, a persistent representation of successional species is maintained by frequent stand disturbances. On fine and sandy till, exogenous disturbance has a minimal influence on the composition of the climax forest. Minimum time-to-climax was estimated at 170 years and 250 years on fine till and softwood sites, respectively, using the species composition of old-growth forests in the region as standards.