Abstract Detail

Biogeography

Long, Jim [1], Schenk, John J. [2].

Comparative Floristic Studies of Georgian Sandhill Ecosystems Reveals a Dynamic Composition of Endemics and Generalists.

Sandhill habitats are characterized by sandy, xeric soils that contain a unique assemblage of plants and animals. Similar to the broader long-leaf pine (Pinus palustris) and wire grass (Aristida stricta) ecosystem that sandhills are a subset of, agriculture, development, and habitat modifications have caused sandhill ecosystems to become degraded and fragmented, putting many species at risk of extinction. Previous studies have focused on species diversity within individual sandhill sites, leaving us with an incomplete understanding of how these communities form, what species are sandhill endemics, whether endemic species are widespread across sandhills, and how species have evolved and adapted to these communities. To gain a more comprehensive understanding of how these ecosystems assembled, we sampled four Georgian Coastal Plain sandhills and compared species occurrences as well as life history patterns. We identified 301 species from 70 families that occurred on sandhills, and as expected, species diversity was positively correlated with sandhill area size. The proportion of endemic taxa, however, was not influenced by area, as all four sites contained approximately the same number of endemics regardless of size. Endemic species differed from generalists in that the majority of species were herbaceous perennials. Sandhill generalists were seldomly widespread across sites and mostly occurred on one or two sites. The majority of species that occurred on sandhills were non-endemic species that opportunistically colonized these habitats from the surrounding areas. Colonization occurred at a rate that was proportional to the habitat area, but species composition did not significantly correlate with the distance between sites (P = 0.57). Despite the large number of generalists, we identified only a small proportion of non-native species. Taken together, our results provide the first opportunity to observe the dynamic nature of sandhill ecosystems. The Georgian sandhills we investigated were quite different from one another due to endemic and generalist species turnover, but were consistent in being inhabited by a subset of taxa. Among the 27 species that occur on all sites, the sandhill endemics Eriogonum tomentosum, Liatris tenuifolia, Licania michauxii, Paronychia herniarioides, Polygonum pinicola, Quercus laevis, Quercus margarettae, and Sabulina caroliniana are particularly abundant taxa that help define these habitats. Given the area effects to species diversity, our results also suggest that additional decreases in sandhill habitats will have a negative effect on plant species diversity, which could lead to the loss of the small, but important endemic sandhill community.

1 - Georgia Southern University, Biology, P.O. Box 8042-1, Statesboro, GA - Georgia, 30460, USA
2 - Georgia Southern University, Department of Biology, 4324 Old Register Road, Biological Sciences Building, Statesboro, GA, 30458, United States

Keywords:
species composition
biogeography
Ecology
endangered
endemic
floristic
Plant community analysis.

Presentation Type: Oral Paper
Session: 13, Biogeography
Location: Sundance 3/Omni Hotel
Date: Monday, June 26th, 2017
Time: 2:45 PM
Number: 13006
Abstract ID:237
Candidate for Awards:None