Converging forest community composition along an edaphic gradient threatens landscape-level diversity.

摘要: Aim  Plant communities across the temperate zone are changing in response to successional processes and human-induced disturbances. Here, we assess how upland forest under- overstorey community composition has changed along an edaphic gradient. Location  Northern Wisconsin, USA. Methods  Forest sites initially sampled 1950s were resampled for diversity, basal area, understorey diversity. We used clustering methods identify groups of stands based on composition, similarity indices, ordination diversity indices evaluate changes species abundance overall structure. Results  Sites clustered into four gradient: ‘hemlock’ dominated by hemlock 1950, ‘mesic’ northern hardwoods, ‘dry’ with a significant pine inclusion canopy diverse ‘dry-mesic’ middle. Collectively, forests gained maple, ash cherry while losing pines, birches red oaks. The dry-mesic shifted towards more mesic hardwood composition. Only driest have remained relatively stable composition. Main conclusions  These trends reflect both ‘mesification’ homogenization among forests. Highly mid-gradient hemlock-dominated transitioning maple dominance. Fire suppression may be favouring invasions plants historically drier sites, high deer likely limits regeneration. If current continue, maples will dominate majority forests, losses local native richness substantial shifts