Disturbance dynamics influence Carex pensylvanica abundance in a northern hardwood forest

We examined relationships involving the abundance of Carex pensylvanica Lam., a native sedge that can form dense mats in northern hardwood understories, and three types of disturbances: forest management, deer herbivory, and exotic earthworm activity. Stands managed using even-aged silvicultural systems in areas with high deer densities (> 20 deer km^-2) had greater C. pensylvanica cover than stands managed using even-aged silvicultural systems in areas with lower deer densities (10-20 deer km^-2), or unharvested second-growth communities. Stands managed using uneven-aged silvicultural systems were not significantly different from any other treatment group, regardless of deer density. There was a significant management × deer × earthworm interaction, and earthworm density had a positive relationship with C. pensylvanica cover in most management history × deer density combinations. High levels of disturbance associated with at least two of the three factors considered in this study were associated with high C. pensylvanica cover, but patterns across any single variable were inconsistent. These results elucidate the intricate nature of invasive plant dynamics, and provide a baseline for more detailed studies of the causal mechanisms underlying sedge mat formation in northern hardwood forests.