Scaled chrysophytes from several Virginia lakes and ponds were identified using transmission and scanning electron microscopy. The presence of Mallomonas caudata, M. tonsurata var. tonsurata, M. striata var. serrata, M. matvienkoae f. matvienkoae (=Mallomonopsis elliptica), Mallomonas sp. and Synura curtispina was confirmed by detailed study of scales, spines and bristles characteristic of the Mallomonadaceae. All taxa reported are new electron microscope verified records for Virginia.
The decrease in nitrification during succession was investigated in the Piedmont of Maryland. Stands of vegetation identified as early, mid, and late successional stages were monitored for available nitrogen and nitrifying bacteria throughout the growing season. Potential rates of nitrification in soils from the three stands were examined by laboratory incubations. Limitation of nitrification by lack of soil nutrients or by allelochemicals released by late successional species were evaluated. Soils from the early successional stand had higher N03- and lower NH4+pools than soils of the late successional stand. Both forms of available nitrogen were low in the mid-successional stand. Numbers of nitrifying bacteria decreased with successional age. Laboratory soil incubations corroborated the field data. A hypothesis of allelochemical inhibition of nitrification was not supported by laboratory soil incubations. No nutrient limitation to nitrification was apparent. Soil pH appeared related to decreased nitrification potential.
Aster chlorolepis Burgess in Small, a member of Aster section Biotia DC. ex Torrey and Gray, has always been considered to be closely related to A. divaricatus, but its taxonomic status has been disputed. To resolve the controversy, over 4000 specimens belonging to the A. chlorolepis-A. divaricatus complex were identified by comparing them to the type specimens of each taxon. Disjoint principal component analysis (DPCA) of morphological data from identified specimens, the first published chromosome counts for A. chlorolepis, and the geographic ranges of both taxa support the segregation of A. chlorolepis from A. divaricatus at species rank. In addition, DPCA allowed identification of 70% of the specimens that could not be identified positively by the above method. Furthermore, the data suggests that A. chlorolepis arose as an autotetraploid derivative of A. divaricatus. Aster chlorolepis may represent, therefore, the long-missing ploidy link between the diploid species and the hexaploid and octoploid species in Aster section Biotia. A range map of and a taxonomic key to A. chlorolepis and A. divaricatus are presented.
Thirty-four shallow, seasonally flooded ponds associated with sandstone strata overlying limestone strata, have been floristically surveyed in the Ridge and Valley physiographic region of Maryland and West Virginia. Most ponds are typically wet in winter and spring, but dry in summer and early autumn. The ponds are small, muck-bottomed, and usually have less than 50 cm standing water when inundated. Vegetation varies from sparse to aspect-dominated by sedges, grasses, or woody plants. Fifty-seven vascular plant species are reported from these ponds, including several that are considered rare in the two states. The endangered sedge Scirpus ancistrochaetus is reported for the first time from both states. Sizes for the clonal populations of this sedge vary among sites from several hundred to several thousand stems.
A vegetation analysis was made of the Bee Branch Gorge Research Natural Area by Hardin and Lewis in 1977. In 1989 we repeated the vegetation analysis to determine what changes have occurred in this hemlock-beech dominated Research Natural Area. In the 1977 analysis, the two co-dominant tree species as indicated by importance percentage (IP) were Fagus grandifolia (IP=21) and Tsuga canadensis (IP=20). In the 1989 sample, Tsuga canadensis (IP=31) had a higher importance percentage than Fagus grandifolia (IP=21). However, the correlation of the IP percentages of all the trees between 1977 and 1989 was high (r2=.95). The major shrubs in 1977 were: Smilax spp., Vitis rotundifolia and Kalmia latifolia. In 1989, the most common shrubs were: Vitis rotundifolia, Arundinaria gigantea (IP=18) and Smilax spp. The major herbaceous plants in 1977 were: Carex picta and Mitchella repens. In 1989, Carex picta and Mitchella repens were still the major plants.
Although there has been some differences in importance percentages of the plants, the study area has not changed much in 12 years, an indication that this is a fairly stable forest. One difference is the increase in the number of paw paw trees in 1989 as compared to 1977.
Calcium-rich exposed substrates are considered to be uncommon in South Carolina, where low pH readings are also the rule. Field data indicate that the calcium rich substrates can be recognized by calcium-indicator plants. The calcium-rich habitats and plant communities include mountain and piedmont marble outcrops and basic forest, and coastal plain calcareous cliffs and calcareous floodplains. These communities are defined. Nineteen selected calciphiles in the region are suggested for further study for inclusion on the South Carolina Heritage Program’s list of plant species of concern. Sixty-one calcium-indicators are listed for the Calcareous Cliff community, fifty-seven for the Calcareous Floodplain community, and forty-eight for mountain and piedmont calcareous habitats. The occurrence of listed plants can be used to predict calcareous substrate types in the region and may be useful as a guide for the cultivation requirements of these plants.
The state of Florida supports a remarkable variety of natural ecosystems and is home to a biota more diverse than that of any other state east of the Mississippi. The editors and contributors to Ecosystems of Florida provide an excellent overview of these natural resources in a single, highly readable volume. Their stated objective is to provide “breadth and depth of treatment … useful to those seeking technical details as well as to Floridians and visitors interested in general information about the environment. ” The classification of Florida’s natural ecosystems into 13 types is thus a compromise between the few broad classes recognized in small-scale vegetation maps and the 69 community-types used by The Nature Conservancy and the Florida Natural Areas Inventory.
Monk et al. (1990) recently concluded that hickories (Carya spp.) are not important enough in eastern United States forests to justify the Oak-Hickory and Oak-Pine-Hickory names which have been applied to some regions. This conflicts with a finding by Farrell and Ware (1991) that hickories are abundant in forests of the northern Virginia Piedmont. A reanalysis of composition of 75 upland hardwood forest stands from the south, central, and northern Virginia Piedmont revealed that hickories had high structural importance in 15 stands of Triassic substrates in northern Virginia, but were rarely important in 60 stands on the prevailing non-Triassic (Paleozoic and pre-Cambrian) substrates in either northern, central, or southern Virginia. In the 60 stands, Carya importance value ranked behind Quercus, Nyssa, and Acer, even though the latter two genera were represented by only one species each (vs. four species of Carya). There seems to be little quantitative basis for including hickory in the name of the prevailing hardwood forest association of the Virginia Piedmont. Monk et al.’s (1989) proposed names “mixed oak” or “oak” may be more appropriate than the “oak-(pine)-hickory” name used by Oosting (1956), Vankat (1979), and Greller (1988, 1989).
The winners of the 1st annual Richard and Minnie Windler Award are Martha Caroline Easley and Walter S. Judd of the University of Florida, for their paper entitled “Vascular flora of the southern upland property of Paynes Prairie State Preserve, Alachua County, Florida” (Castanea 55(3): 142-186). The paper was derived from a master’s thesis completed by Ms. Easley under the direction of Dr. Judd.
The Richard and Minnie Windler Award, a special SABC merit award, has been established by Dr. Donald Windler of Towson State University as a memorial to his parents. This award will be presented each year at the annual meeting of the SABC to the author(s) of the best systematic botany paper published the preceding year in CASTANEA