Changes in beta diversity and species functional traits differ between saplings and mature trees in an old growth forest

1. Invasion by generalist tree species can cause biotic homogenization and such community impoverishment is likely more important in rare forest types.  We quantified changes in tree diversity within Carolinian (range in Central Hardwoods), northern (range reached Northern hardwood-conifer/Boreal-spruce-fir) and central species (range in Central Hardwood region and Northern hardwood-conifer) in an old forest in southern Canada at points surveyed 24 years apart.

2. We asked: How did mature tree and sapling composition and abundance change for the 3 species’ groups? Did those changes lead to biotic homogenization? Can species’ changes be explained by community traits? We tested for differences in temporal and spatial tree β-diversity, as well as forest composition and structure, using univariate/multivariate analyses and a community trait-based approach to identify drivers-of-change.

3. Major increases occurred in abundance for mature Acer rubrum (northern), while others decreased (...