Differences in Plant Community Composition with Increasing Height on Rock Faces Compared to the Top and Bottom Communities

Authors: Alison Kryger, Eliza Grames

SUNY Campus: Binghamton University

Presentation Type: Poster

Location: Old Union Hall

Presentation #: 33

Timeslot: Session A 9:00-10:00 AM

Abstract: Natural rock walls provide habitat patches for many plant species, offering protection from competition, predation, and anthropogenic disturbance. We investigated how plants assemble on rock walls, whether plants are primarily filtered from top or bottom communities, and how dispersal methods affect colonization success. Plant species abundance and richness were sampled at six locations across New York State using quadrats at the top and bottom of rock walls and transects on the walls ranging from 0-18 meters above the ground. Of the 97 genera identified across all sites, 15 (15.5%) were found exclusively on the rock wall. As height on the rock wall increased, the dissimilarity to top communities decreased (p = 0.005) by 10% for every one meter increase in height. There was no significant effect of height on dissimilarity to the bottom communities. Additionally, as slope increased, dissimilarity to both the top (β = 0.009, p < 0.001) and bottom (β = 0.015, p < 0.001) communities increased indicating that colonization was more successful on shallower slopes. There was a significant effect of wall micro-features (i.e. crack, face, or ledge) on observed variation in dissimilarity (p = 0.013, df=2). Of the genera sampled, 48% were dispersed by wind, 7% by gravity, 3% by ballistic mechanisms, 6% by myrmecochory, and 36% by other animals. These results suggest that communities are primarily filtered from top communities and provide insight into the persistence of plant communities in this extreme environment.