Differential Resistance to Tree Species Loss between Two Dominant Communities in a Resilient Southeastern Landscape

Abstract

The southern Cumberland Plateau is a resilient landscape, meaning one that can resist or rebound from a suite of interacting disturbances such as climate change, herbivore release, introduced pathogens, and fire suppression. This region possesses several attributes that contribute to landscape resilience, including topographic variability, high species diversity, geological heterogeneity, and landscape connectivity. However, individual communities within the region may have different levels of resiliency. We used a 19-year study of forest change in two adjacent Cumberland Plateau communities to test for differences in ecological resistance to species loss. We found that the study area experienced a net loss of 7 species, with more species disappearing from the cove (–9 species) than the upland (–3 species). In the cove forest, the smallest size classes experienced significant species loss, with a mean loss of 4.8 and 6.0 species for sapling size classes, leading to a skewed size distribution with the majority of woody species represented by large adults. Upland communities maintained their structure, possibly due to a greater prevalence of stem and root sprouting species. From these results, we conclude that the upland community was more resistant to species loss and better maintained its structure compared to the cove community. Differential change between two adjacent communities highlights that the purported landscape resilience of the southern Cumberland Plateau may vary between its two most dominant communities.