Habitat types – What they can tell us now and in the future

Habitat classification systems utilize the relationship between the herbaceous layer and potential climax vegetation to classify forest vegetation. Habitat classification systems have been developed throughout the United States including Michigan. In 2010, ten years after the first sampling, 30 of the original 200 plots throughout the Western Upper Peninsula were resampled twice during the growing season. Exotic earthworm populations were also sampled in early September at all 30 plots. Nonmetric multidimensional scaling (NMS) ordination was used to discern differences in habitat types between years (2000 vs. 2010) and between seasons in 2010 (spring vs. summer). Overstory trees per hectare (TPH) decreased from 2000 to 2010, likely the result of forest management activities. A greater number of herbaceous species were observed in 2010; however, the majority of these new species were weedy or invasive. Exotic European earthworms were observed in all habitat types; earthworm densities generally increased with increasing soil richness and site quality, with herbaceous plant cover negatively associated with earthworm biomass. Continual monitoring of these plots will allow scientists and managers to assess how herbaceous community change through time and observe the effects of invasive species and changing climatic patterns on forest ecosystems of the Great Lakes region.