Baseline to novel ecosystems in Michigan, USA, with a quantitative and qualitative assessment

Abstract

ABSTRACT Pre-Euro-American settlement vegetation provides information about historical ecology. I evaluated baseline conditions and novel status of current forests in Michigan using historical (1836 to 1858) and current (2010–2015) surveys and assessed quantitative and qualitative measures of novel status. Aspen (increased from 2% to 11% of all trees) and red maple (<2% to 12.5%) replaced eastern hemlock (15% to 2%) and American beech (8% to <1%) as most abundant species. Density was similar between surveys but mean diameter (trees ≥12.7 cm) decreased from 39 to 22 cm. The emerging forest type is a mix of early- to mid-successional species, particularly red maple, from eastern broadleaf forests of the central-eastern US.Openlands in southern Michigan have been replaced by agriculture and closed forests. Historical forests dominated by few tree species have transitioned to diverse eastern broadleaf forests throughout the eastern US, conforming to quantitative and qualitative measures of novel ecosystem status. Besides exceeding a quantitative threshold (e.g., squared chord distance), current forests meet novel status because they are ubiquitous, constitute a new normal, arise predictably, and unavoidably in response to disturbance or land-use change, auto-organize, and retain novelty after crossing thresholds challenging to reverse.