Abstract Detail

Ecology

Baruzzi, Carolina [1], Crandall, Rae [1].

Two morphologically and functionally similar bunchgrass species have different effects on plant assemblages.

Local plant community assembly from the larger regional species pool can result in species occurring together more often than expected by chance. Understanding patterns of plant associations in natural communities could help identify species that enhance species coexistence and biodiversity, and are thereby important to reestablish during restoration. Longleaf pine (Pinus palustris) savannas of the southeastern U.S.A. are often targeted for restoration because their historical area has been greatly reduced and they have high economic and environmental value owing to their high biodiversity and ecosystem function. In xeric longleaf pine savannas, two bunchgrasses, wiregrass (Aristida beyrichiana) and dropseed (Sporobolus junceus), are dominant components in the understory and nearly identical in appearance except when flowering. These species also function similarly by promoting the spread of fire across the landscape (i.e., grass-fire feedback), which is essential to maintain the open canopy characteristic of pine savannas. Although both species are frequent and functionally similar, wiregrass is preferentially seeded for restoration, which could affect community assemblages in longleaf pine savannas. We predict that although wiregrass and dropseed are morphologically and functionally similar, they could associate with different plant species and/or alter the abundance of other species. Thus, the codominance of these two species could be one of the mechanisms promoting the high biodiversity typical of pine savannas. Information on species associations in pine savannas is, however, largely unavailable so that understanding interactions between dominant bunchgrasses and other plant species should be considered a priority to inform the restoration of these communities. As such, we explored patterns of associations between dominant bunchgrasses and other understory plant species. We conducted our experiment in a xeric pine savanna at the Ordway Swisher Biological Station, Melrose, FL. To sample understory plant species, we selected 15 wiregrass and 15 dropseed as focal individuals and used a 0.3m x 0.3m plot centered on each bunchgrass individual and recorded number of stems for each plant species present. We also measured bunchgrass basal area and canopy cover. We found preliminary evidence that the two bunchgrass species have different associations in xeric pine savannas. For instance, turkey oak (Quercus laevis) occurred in more than 30% of the dropseed quadrats but was never detected near wiregrass. Although species richness and diversity were not affected by bunchgrass species, dropseed did increase the total number of stems. These results indicate that a more diverse bunchgrass understory should promote a more diverse plant community in pine savannas.

1 - University of Florida, School of Forest, Fisheries, and Geomatics Sciences, 136 Newins-Ziegler Hall, PO Box 110410, Gainesville, FL, 32611, USA

Keywords:
plant community ecology
Plant diversity
Bunchgrass
Pine savannas
Plant associations
Wiregrass.

Presentation Type: Oral Paper
Session: ECO4, Ecology: Community Assemblages, Succession and Marcescence
Location: /
Date: Thursday, July 22nd, 2021
Time: 11:30 AM(EDT)
Number: ECO4007
Abstract ID:705
Candidate for Awards:None