Borealization of the New England – Acadian Forest: a review of the evidence

Abstract

The New England – Acadian Forest (NEAF) is an ecoregion spanning 24 million hectares of the northeastern United States and eastern Canada. The region is characterized as a transitional forest naturally composed of both boreal and temperate species. The term “borealization” is sometimes used to describe various processes driving the NEAF toward a more boreal character at the expense of its temperate forest species and ecological communities. That the NEAF has undergone significant landscape-scale change in the last four centuries since European settlement is well understood. The purpose of this manuscript is to review the literature on the forest composition and dynamics of this region to investigate whether past, current, and (or) predicted future processes of change are indeed driving the forest toward a more boreal character. We examine studies on the historical forest composition and impacts of past and current land-use practices, as well as indirect anthropogenic changes that are predicted to influence future forest compositions of the NEAF. We review over 100 peer-reviewed scientific journal articles and government reports related to this issue. We find ample evidence to suggest that, at the landscape scale, there has been widespread replacement of temperate tree species by boreal species since European settlement. Five primary drivers have facilitated borealization across the NEAF: logging and high-grading, natural reforestation of abandoned farmland, industrial clearcutting, anthropogenic fire, and boreal conifer plantations. Furthermore, the borealization of the NEAF has continued to occur in direct contrast to the predicted impacts of climate change. We encourage future scholarship to tackle these aspects of borealization in the NEAF, including its social, economic, and ecological implications.