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Vegetation Disturbance and Maintenance of Diversity in Intermittently Flooded Carolina Bays in South Carolina
Author(s) -
Kirkman L. K.,
Sharitz R. R.
Publication year - 1994
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.2307/1942127
Subject(s) - species richness , species evenness , ecology , vegetation (pathology) , dominance (genetics) , species diversity , perennial plant , forb , plant community , wetland , biology , grassland , medicine , biochemistry , pathology , gene
We manipulated the fire regime and soil disturbance in four grass—dominated Carolina bay wetlands during a prolonged drought period and examined vegetation composition and cover within dominant vegetation types prior to and after treatments. We used the seedling emergence technique to determine the role of the seed bank in the recovery process. Burning did not affect richness, evenness, or diversity (all vegetation types combined); however, soil tillage increased diversity, including both evenness and richness. Percent similarity of the vegetation before and after disturbance was greater in the burning treatment than in the tillage treatment, probably due to greater disruption of the rhizomes of the perennial vegetation by tillage. Vegetation types varied in degree of recovery, although dominance was not altered by either treatment. Several native fugitive species increased following disturbance, indicating that species coexistence in these Carolina bay wetlands depends on the life history characteristics of residual vegetation, as well as that of seed bank species. The seed bank (72 600 seedlings/m 2 ) was larger and species richness (108 species) was greater than reported for most other freshwater wetlands. No differences in species richness, evenness, or diversity were detectable among the seed banks associated with different vegetation types in the bays. The floristic composition of the seed bank did not resemble the standing vegetation in patches dominated by large perennial grasses (Panicum hemitomon, Leersia hexandra, and Andropogon virginicus). In contrast, seed bank samples associated with vegetation dominated by an annual forb (Iva microcephala) or the small perennial grasses Panicum wrightianum or P. acuminatum var. unciphyllum more closely reflected the standing vegetation. Species appear to persist with recurring and multiple disturbances because of seed banks, rhizomes, morphological plasticity during inundation, sexual reproduction following inundation, and perenniality coupled with early sexual maturity. Conservation management of intermittently inundated wetlands should incorporate techniques to foster maintenance of endemic species richness and the recruitment of rare species. During periods of drought, it may be desirable to disturb the aggressive perennial vegetation to allow recruitment of less common species.