Herbaceous-layer community dynamics along a harvest-intensity gradient after 50 years of consistent management

In 1958, a demonstrational cutting trial totaling 22.2 ha was established in a northern hardwood forest in Alberta, MI. Eight different treatments were installed, including four diameter-limit treatments (56 cm, 41 cm, 30 cm, and 13 cm), three single-tree selection treatments with residual basal areas of 21 m2·ha–1, 16 m2·ha–1, and 11 m2·ha–1, and an uncut control. Within each treatment, a 0.4-ha permanent plot was established and subdivided into 0.04-ha square subplots. Harvests have been implemented every ten years with the most recent harvest occurring during the winter of 2008 - 2009. We quantified ground layer vegetation response before and after the most recent harvest. Nonmetric multidimensional scaling (NMS) ordination showed a very distinct separation between the most intensive management treatment (13-cm diameter-limit treatment) and the uncut control. Compositionally, the diameter-limit treatments moved with greater directionality and magnitude towards the 13-cm diameter-limit treatment following harvest, while compositional change in the residual basal area treatments was less pronounced and lacked strong directionality. Herbaceous species percent cover generally decreased with increasing residual overstory basal area across treatments. Weedy and early successional species were most abundant under lower residual basal area and diameter-limit treatments. Results based on 50 years of continuous management suggest that diameter-limit harvests likely have a greater impact on the herbaceous community than single-tree selection or no management.