Abstract Detail


Szakacs, Alexandria [1], Krings, Alexander [2], Wentworth, Thomas [3].

Shade-tolerance classification of the upland herbaceous flora of the Carolina and Virginia Piedmont (U.S.A.).

In the absence of disturbance, uplands of the southeastern United States Piedmont become dominated by closed-canopy forest. However, historical accounts describe savanna-like conditions over at least portions of the region dating as far back as the 1500s. These open habitats are thought to have declined because of development, fire suppression, and loss of native grazing animals, but their legacy is evident in the rich diversity of persisting heliophytes in areas of primarily human-maintained open habitats, such as power-line rights-of-way and roadsides. Conservation practices required to restore and sustain Piedmont savanna are hampered by rudimentary understanding of community assembly and maintenance dynamics. Such understanding would be facilitated by a robust classification of species into specialist and generalist guilds related to canopy openness, a classification that is currently unavailable on a broad scale. Our objective was to develop a shade-tolerance classification for the upland Piedmont herbaceous flora of the Carolinas and Virginia, based on quantitative plot data from the region. A dataset of plot records (representing natural and semi-natural vegetation of the Piedmont region of the Carolinas and Virginia) was obtained from the Carolina Vegetation Survey database. Following quality control, the dataset contained 1743 plots and 1727 species (including 1147 native herbaceous species), with species’ abundances in plots reported in cover classes. We estimated the canopy coverage of each plot from the cover codes of its tree species. We assigned each plot to open (<25% canopy cover; n = 97), semi-open (25-75% canopy cover; n = 166), or closed (>75% canopy cover; n = 1480) habitat classes. We calculated biserial correlation coefficients, which provide a positive or negative value for each species, dependent on the species’ abundance and habitat association. We assessed species-habitat associations for native herbaceous species by: (1) single habitat classes (i.e., open, semi-open, and closed), and (2) habitat class combinations (e.g., open, open-semi-open, open-closed, etc.). A permutation test was employed to test the significance of the association between each species and the habitat class (or combination of classes) for which it had the largest coefficient. Species with p-values < 0.05 were considered specialists of that habitat class and those with no significant association to any habitat class were considered generalists or infrequent species. Of the 1147 native herbaceous species in the dataset, 264 (23%) were open and/or semi-open habitat specialists, 129 (11%) were closed or closed-semi-open habitat specialists, and 753 (66%) were generalist or infrequent.

1 - North Carolina State University, Department Of Plant And Microbial Biology, 100 Derieux Pl., Campus Box 7612, Gardner Hall 2115, Raleigh, NC, 27695, United States
2 - Department Of Plant And Microbial Biology, North Carolina State University, Raleigh, NC, 27695, United States
3 - North Carolina State University, Department of Plant and Microbial Biology, 100 Derieux Pl, Campus Box 7612, Raleigh, North Carolina, 27695, United States

eastern Piedmont
biserial correlation.

Presentation Type: Oral Paper
Number: 0002
Abstract ID:655
Candidate for Awards:Ecological Section Best Graduate Student Paper

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