Constraints on Evergreen Broad-Leaved Forests in the Southeastern United States

Abstract

AbstractIn a humid, mild-winter warm-temperate climate, as occurs across most of the southeastern US coastal plain, one would normally expect to find “laurel forests” dominated by temperate-zone evergreen tree taxa, as in other warm-temperate regions. Instead, on the sandy uplands of the geologically young coastal plain, one finds a topogenic, landscape-scale mosaic of wetlands, forests, open woodlands and scrub, some of it maintained by recurring fires. As a result, the potential over the coastal plain is not extensive forest but rather, where soil, topography and fire permit, a slow progression to woods dominated by coriaceous or harder-leaved evergreen broad-leaved trees, with somewhat open canopies and a greater role for deciduous trees, even at maturity. Colder winters to the north constrain most evergreen forest types, but there are also subtler, non-climatic constraints. The purpose of this paper is to describe briefly the main evergreen broad-leaved forest types and their dynamics, and to evaluate the climatic and non-climatic factors that constrain their distributions, especially within the context of local climatic warming and drying.KeywordsWarm-temperate climateHumic sandTopogenic vegetationLimiting temperaturesLaurophyllSclerophyllEvergreen forest successionFire cycle