ABSTRACT A statistical analysis of characteristics of Carex retroflexa Willd. and Carex texensis (Torr.) L. H. Bailey is provided. This analysis confirms the distinctiveness of these two species, which some authors have considered as a single taxon in the past. Analysis reveals Carex texensis perigynia average less than 1.3 mm wide, with a spongy portion length of less than 1.1 mm. Carex retroflexa perigynia average 1.3 mm or more wide, with a spongy portion 1.1 mm long or longer.
ABSTRACT Amaranthus pumilus, a federally threatened species that inhabits the transient and highly variable barrier beach environment of the United States, has been extirpated from nearly three-fourths of its historic range. This study ascertained habitat requirements and determined how certain biotic and abiotic factors influence A. pumilus | populations on Figure Eight Island, North Carolina. Data obtained were then compared to findings of Cakile edentula studies (C. edentula is common throughout the range of A. pumilus) in an effort to explain differences in range and abundance. Scarification and temperatures of 35?C enhanced seed germination. The majority of A. pumilus plants were found on overwash fans. Mortality was greatest following storm periods that inundated seedlings through four tidal cycles. Density of seedlings had no affect on mortality rate. No evidence was found for biological control of A. pumilus populations. Maximum seedling emergence from burial by sand was less than 1 cm.
ABSTRACT Recent collections document a state record for this rare, endemic species, bringing the known range of this taxon to 12 counties in four states (West Virginia, Virginia, North Carolina, and Tennessee). Habitat affinities and identification clues are provided, along with a county map of the species range.
ABSTRACT Quantitative data on composition and structure of the tree stratum were collected from fifty forest communities in eastern, western, and southwestern Virginia, eastern West Virginia and the western part of the Great Smoky Mountains having American beech (Fagus grandifolia) as a major [IV > 17.5 (of 100)] component. Forty-eight different species of trees were tallied in these communities. Basal area of trees (m2/ ha) ranged from 16.3 to 58.2, whereas density of trees (N/ha) ranged from 198 to 1,820. Average density was lowest in eastern Virginia (369) and highest in western Virginia (680). Beech was the leading dominant in most of the communities sampled in all regions except for western Virginia, but its most important canopy associates varied among regions. Results of DECORANA ordination separated the fifty communities along the regional lines studied and would seem to parallel the distributional pattern of the three “races” sometimes recognized for beech.
ABSTRACT Age and structural characteristics were measured in two frequently burned old-growth mountain longleaf pine (Pinus palustris Mill.) communities along Choccolocco Mountain in northeastern Alabama. Stands studied were open-canopied and park-like (8.3 to 13 m2 ha-1 basal area; 282-297 trees ha-1), fitting historical descriptions of the now endangered communities. Maximum pine ages in the two stands exceeded 240 years. Both stands underwent continuous pine recruitment over the past 145 years, with all 5-year age classes represented. Congregations of even-aged pine patches were found throughout both stands. Multiple tree patches ranged from 15 to 170 years old. Large even-aged patches were present in both stands (up to 2124 m2), though isolated single trees were more common, accounting for about half of all patches. Continued work on pristine remnant forests and savannas is necessary due to their increasing rarity and importance as reference models for management and restoration.
ABSTRACT Changing disturbance regimes, particularly decreasing fire frequencies, may result in distributional changes of species across southern Appalachian landscapes. Some researchers have hypothesized that Pinus strobus (eastern white pine) is undergoing a change in site affinity from mesic to xeric sites in southern Appalachian forests, but no studies have evaluated the landscape-level status of P. strobus. We examined the status of P. strobus in a 225-ha old-growth Quercus landscape within the Ellicott Rock Wilderness (ERW) in South Carolina by sampling 80 plots. Pinus strobus exhibited the highest mean density (267 trees ha-1) of all species in the 1-10 cm diameter class, with 96% of the P. strobus currently in these Quercus forests establishing since 1950. Density of P. strobus in the 1-10 cm diameter class was most highly correlated with P. strobus density >10 cm diameter, and was not strongly correlated with other measured vegetation variables such as total Quercus
ABSTRACT We inventoried two 1-ha plots on opposing watersheds (WS2-WS-S, WS18-WS-N) three times (1983, 1989, 1998) over a 16-year period to contrast how differing precipitation (P) regimes affect tree mortality. From 1983 to 1989, annual precipitation averaged 16.5% less than the 64-year mean; from 1989 to 1998, it averaged 12.2% above the mean. In 1989 and 1998, standing crop biomass, aboveground net primary productivity, mortality rates and species composition were determined. In 1989, following the dry period, the highest mortality for canopy tree species was in Carya spp. and Quercus velutina in both watersheds. Following the wet period in 1998, mortality was highest in Cornus florida in both watersheds, presumably due to the Anthracnose fungus; however, net change in stem density due to ingrowth was positive for this species in the WS-S watershed (+34%) and negative in the WS-N watershed (-18%). Estimated ANPP for WS-S was 10 and 1,076 kg