Drivers of bryophyte community change across the Appalachians

Shershen, Eric

ABSTRACT: Work exploring the drivers of vascular plant community change through time are common throughout the literature. The literature pertaining to their non-vascular relatives, the bryophytes, however, dwarfs in comparison. Despite bryophytes providing key ecosystem functions like providing soil stability, sequestering carbon, and providing habitat for macro and microorganisms, the drivers behind bryophyte community change have been assumed to be akin to those of vascular plants despite literature which demonstrates key differences in how bryophytes respond across gradients of abiotic and biotic factors. As such, this dissertation explores these drivers to understand what drives bryophyte communities through time, using the bryophyte communities of the Appalachians as a case study. I used a longitudinal study, herbarium records, and ecological niche modeling to examine 1) What environmental determinants drive bryophyte community change as well as to identify the current state of bryophyte communities 2) How differing management strategies for an invasive pest have impacted bryophyte communities in the past and 3) How macroclimatic variables may determine suitable habitat for species both now, and in the future. The results from these studies finds that elevation, aspect, slope, and gap fraction all play roles in determining bryophyte abundance and/or richness, that extreme management strategies may have negatively impacted bryophyte richness, that substrate generalists are more likely to persist through time following a disturbance, and that climate change will reduce suitable habitat across all bryophytes, with most species experiencing a range contraction at high elevations within national parks and forests. Results from my dissertation are useful for ecologists, land managers, and policy makers when considering drivers of bryophyte community change and locations of where they will reside in the future. This will allow for the better preservation of bryophyte communities at both the community and species level, and consequently, better protect the ecosystem functions they provide.