Anthropogenic Ties to Late-Successional Structure and Composition in Four New England Hemlock Stands

Abstract

Abstract. The pace and magnitude of long-term change in the forests of eastern North America is poorly understood. The current study examines the developmental history of primary Tsuga canadensis stands in central Massachusetts from before European settlement to the present. Through an integrated reconstructive approach employing stand-level pollen stratigraphies, tree ring chronologies, and long-term archival records, we show how the characteristic structure and composition of old-growth forests in southern New England developed in four stands through a history of anthropogenic and natural disturbance, rather than through the gradual process of autogenic succession. Forest composition during presettlement times was distinct at each site and included a variety of successional stages ranging from late-successional northern hardwood-Tsuga assemblages to assemblages dominated by early successional to mid-successional taxa such as Castanea, Quercus, and Pinus. Anthropogenic disturbance during the 18th and 19th centuries resulted in novel assemblages dominated by Castanea or Betula. Composition at the four sites converged on the current assemblage dominated by large, late-successional Tsuga, in response to altered patterns of disturbance in the 20th century. The age of the dominant trees (100-200 yr) and apparent stability of the current forests masks the extent to which their origin is a product of the cultural landscape and is in no way representative of pre-European forests at these sites.

Managing for late-successional/old-growth characteristics in northern hardwood-conifer forests

“…Group-selection treatments are modified to approximate the average canopy opening size associated with fine-scale natural disturbance events in New England, based on the findings of Seymour et al (2002).Research over almost three decades has described the characteristics and dynamics of oldgrowth northern hardwood and mixed northern hardwoodconifer forests across a range of geographic settings and disturbance histories (e.g. Whitney, 1984;Gore and Patterson, 1985;Foster, 1988;Hunter, 1989;Woods and Cogbill, 1994;Tyrrell and Crow, 1994a,b;Dahir and Lorimer, 1996;Hunter and White, 1997;Lorimer, 1998, 1999;McGee et al, 1999;Hale et al, 1999;McLachlan et al, 2000;Ziegler, 2000;Crow et al, 2002;Angers et al, 2005;Keeton et al, in review). Structural objectives for SCE are derived from this body of research.…”

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

“…The structural characterization of formerly managed stands would be more useful to anticipate the future forest changes than other approaches based on long-term processes of autogenic succession (McLachlan et al 2000). The study of both natural and managed stands with spatial analytical methods is essential to generate theories about stand developmental processes in human-inXuenced forests (Penttinen et al 1992).…”

Forest remnants in the Long Point region, Southern Ontario: Tree species diversity and size structure

“…Management that restricts human intervention in protected natural areas is often based on a perception of inherent stability in long-undisturbed forests and assumes that pre-settlement conditions in North American ecosystems will persist if human activity, including management intervention, is minimized. This perception has recently been criticized as evidence accumulates to indicate that many ecosystems require repeated natural or human disturbances for some species to be sustained, especially those that are opportunistic, shadeintolerant or adapted to disturbance (e.g., fire) (Weaver and Kellman, 1981;Lorimer, 1984;Abrams and Nowacki, 1992;Botkin, 1992;Ziegler, 1995;McLachlan et al, 2000). The recent reintroduction of fire to a number of North American systems follows from this discovery.…”