Volume 67 — Issue 1 (March 2002)

Post-Disturbance Changes in the Understory of an Oak Forest in Southwestern Virginia

ABSTRACT An Appalachian oak forest, dominated by scarlet and chestnut oaks in 1971, was sampled in 1994 and again in 1999 to determine changes in density and basal area of overstory trees, changes in density and composition of understory vegetation, height growth of seedlings and saplings after disturbance by single tree gaps, primarily of scarlet oak, and general ice damage to the canopy. From 1971 to 1994, 82% of scarlet oaks died, so by 1994 the stand was dominated by chestnut oak and red maple. Changes in overstory tree density and basal area were not significant, but decline of scarlet oak was significant. This suggests that the stand is in a state of flux. Post-disturbance increases in total densities of shrubs and saplings, including white pine, were significant, as well as the increase in red maple seedlings and decline of flowering dogwood seedlings. Relative increase in height growth of white

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Environmental Correlates of Oak Decline and Red Maple Increase in the North Carolina Piedmont

ABSTRACT We examine the decline of oaks (Quercus spp.) in eastern forests and the concomitant increase in red maple (Acer rubrum) abundance using data collected over 75 years near Durham, North Carolina. Oaks declined in abundance on all hardwood-dominated sites, while early-successional pine stands showed a slight increase in oak abundance. Red maple has increased in density 6-fold over the last 75 years in all stands. Diameter distribution data from mapped stands suggest that oak decline results from a lack of recruitment. An analysis of environmental characteristics influencing the rate of increase in red maple density shows that the rate is slowest on sites with wet, sandy, high pH soils. Oak decline occurs faster on sites with higher initial oak abundance, and appears unrelated to changes in red maple abundance. Overall, the rate of transition from oak to red maple dominance is influence by both local site and landscape characteristics.

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Noteworthy Botanical Collections from the Fire-Maintained Pineland and Wetland Communities of the Coastal Plain of the Carolinas and Georgia

ABSTRACT During a survey of residual fire-maintained pineland vegetation of the Atlantic Coastal Plain Province, we discovered occurrences of numerous rare species. Here we report 27 taxa as new or historically reported without known documentation for South Carolina and one as new to North Carolina. Two species are identified as having been incorrectly attributed to South Carolina. In addition, the known ranges of 20 other regionally rare taxa are significantly expanded. The additions to the South Carolina flora include primarily species more common farther to the south and species formerly thought to display range disjunctions between southeastern North Carolina and Florida or southwestern Georgia.

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Vascular Plants of Glacial Drift Prairies in Macoupin County, Illinois

ABSTRACT Four small prairies located on Illinoian till in Macoupin County, Illinois were studied to determine their floristic composition. All of the prairies were less than 1 ha in size. Big bluestem (Andropogongerardii) and little bluestem (Schizachyrium scoparium) were the dominant grasses, while common forbs included Echinacea pallida (pale coneflower), Ratibida pinnata (dropping coneflower), Solidago nemoralis (field goldenrod), and Dalea purpurea (purple prairie clover). The prairie flora consisted of 159 taxa in 45 families. Exotic species accounted for 14 species, while eight woody species were found. Perennial grasses accounted for about 25% of the total cover and importance value. One of the prairies is protected, the Roderick Prairie Nature Preserve.

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The Aizoaceae and Molluginaceae of the Southeastern United States

ABSTRACT Keys and descriptions are presented for the Molluginaceae and the Aizoaceae, sensu stricto, of the southeastern United States. Two genera and four species (1 native) are documented for Molluginaceae; for the Aizoaceae, sensu stricto, seven genera and ten species (3 native) are documented. Two taxa formerly attributed to either the Aizoaceae, sensu lato, or Molluginaceae (Gisekia pharnacioides and Geocarpon minimum) are excluded from the Molluginaceae and Aizoaceae, sensu stricto, but are described herein and included in the keys for the purpose of cross-reference and historical perspective. An additional six species (one species in Molluginaceae and five species in three genera of Aizoaceae, sensu stricto) which occur in areas adjacent to the southeastern states are also included.

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Differences in Bark Thickness Among Populations of Baldcypress [Taxodium distichum (L.) Rich. var. distichum] and Pondcypress [T distichum var. imbricarium (Nuttall) Croom]

ABSTRACT This study examines the variation of bark thickness within and among populations of baldcypress [Taxodium distichum (L.) Rich. var. distichum] and pondcypress [T. distichum var. imbricarium (Nuttall) Croom] to determine its usefulness as a taxonomic character. Baldcypress from 14 populations and pond- cypress from eight populations were sampled for bark thickness and trunk diameter. Significant difference was observed in the relation of bark thickness to diameter between the two taxa. When bark thickness to diameter (BT/D) ratios were analyzed, the ratios for baldcypress ranged from 1.2 x 10-2 to 8.9 X 10-2 with a mean of 3.2 x 10-2, while the BT/D ratios for pondcypress ranged from 3.7 x 10-2 to 12.5 x 10-2 with a mean of 6.6 x 10-2. Bark thickness ratio may be a useful diagnostic character when classifying populations when used in conjunction with other characteristics, but it should not be used exclusively for classifying

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Seasonal Changes in the Spectral Properties of Mountain Laurel (Kalmia latifolia L., Ericaceae) in North East Alabama

ABSTRACT Absorptance of visible light (400-700 nm) by mountain laurel (Kalmia latifolia L.) was highest during May followed by April. Compared to May and April, light absorptance decreased 19 and 25% during June and August, respectively. The same results were obtained for light absorptance during December with the exception that during June and August the percentage of light absorptance in the range 562-594 nm was reduced to 56%. Near-infrared light (750-800 nm) absorptance decreased sharply in comparison to the absorption of visible light each sampling time. The lowest absorptance value for the near-infrared light was obtained during June and August (39%), followed in increasing order by December (53%), May (71%) and April (75%). Chlorophyll concentrations gradually increased starting in February and continued through August. In general, reflectance for the visible and near-infrared ranges was lower than 10% for all the sampling period with an exception in April when a sharp

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Helianthus verticillatus Small (Asteraceae) Rediscovered and Redescribed

ABSTRACT Helianthus verticillatus Small was first collected in western Tennessee by S.M. Bain in 1892. J.K. Small described it as a new species in 1898. The species was not seen again in the century following the original collection. It has had varied treatments over the years, as a species or as a hybrid. Between 1994 and 1997, several subpopulations were found and studied in northwestern Georgia and northeastern Alabama. In 1998 it was rediscovered in western Tennessee, near the original site, but apparently not at the same site. Analyses of the morphology of the H. verticillatus, along with a determination of the chromosome number, have permitted an updated morphological description and the conclusion that this taxon is not a hybrid, but a good diploid species of sunflower.

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Vascular Flora of Piedmont Prairies: Evidence from Several Prairie Remnants

ABSTRACT Once scattered throughout the Piedmont region of the Southeast, the Piedmont prairie ecosystem is now relegated to disturbed sites such as roadsides and power line rights-of-way. Unlike the megafauna, the flora of this nearly extinct ecosystem persists in habitat fragments with uncertain futures. The purpose of this paper is to document the results of a five-year study of the vascular flora of six sites, including two that could be considered remnant Piedmont prairies. We collected 548 species and discarded those with no association to the Piedmont prairie ecosystem: nonnative, woodland, and wetland species. The remaining 277 species form a species list for the historic Piedmont prairie community. Four species are Federally- listed: Echinacea laevigata (Asteraceae), Helianthus schweinitzii (Asteracaeae), Lotus helleri (Fabaceae), and Symphiotrichum georgianum (Asteraceae). While no one knows the floral composition of historic Pied- mont prairies, this species list can be used to identify and evaluate prairie remnants

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