Volume 64 – Issue 4 (Dec 1999)

The High Terrace Rolling Uplands include the majority of Louisiana’s Kisatchie National Forest and contain some of the most extensive longleaf pine communities remaining on the western gulf coastal plain. Forty-seven mature stands from this region were sampled. Occurrences of ground layer and overstory species were recorded. Soils and physiography were described and topsoil samples collected. Data were subjected to Two Way Indicator Species Analysis (TWINSPAN) classification and Detrended Correspondence Analysis (DCA) ordination. Ordination scores corresponded to a primary gradient of topographic position and fire frequency and to secondary gradients of wetness among stream floodplains and soil texture among upland sites. Ordination and classification results were used to describe eight natural community types ranging from moist-mesic floodplains to upland longleaf pine communities on sandy soils.

The vegetation, structure, and composition of a mature mixed-hardwood forest in western Maryland was sampled to determine its similarity to old-growth forests characteristic of the mid-Atlantic region. Size class distribution, maximum tree age, basal area, stem density, and coarse woody debris (CWD) volume were consistent with those recorded for other eastern old-growth forests. Betula lenta and Acer rubrum account for almost two-thirds of the overstory stems but only one-fifth of the basal area. Quercus spp. account for over two-thirds of the overstory basal area and about one-quarter of the stems. Betula lenta, A. rubrum, and Prunus virginiana were the most abundant saplings. No Quercus spp. were found in the sapling layer. Most downed debris were in advanced stages of decay and oriented in a southerly direction. Standing snags were primarily in advanced stages of decay, with Robinia pseudoacacia having the highest frequency. Volume of CWD averaged 54.16 m³/ha.

Flowering pattern, flowering phenology, and mating system of the closely-related, interfertile species Penstemon tenuiflorus and P. hirsutus are the same. Flowers are protandrous, but there is some overlap of anther dehiscence and stigma receptivity. Additionally, flowers of different sexual phases are scattered throughout an inflorescence. Primary pollinators of both species were Bombus pennsylvanicus and B. bimaculatus. Outcrossed plants of P. tenuiflorus (studied in both field and greenhouse) and of P. hirsutus (studied in greenhouse only) produced significantly more seeds than selfed plants. In a greenhouse study, bagged, self-pollinated plants of both species produced significantly more seeds than bagged, nonmanipulated ones. However, although number of seeds produced by bagged, self-pollinated plants of P. tenuiflorus in a field study (P. hirsutus not studied) was greater than that produced by bagged, nonmanipulated plants, the differences were not significant. In both species, there was little or no difference in weight or in percent viability in outcrossed vs. selfed seeds, and very few or no seeds were produced by bagged, emasculated flowers. In the field, number of seeds produced by nonbagged, nonmanipulated and by nonbagged, cross-pollinated (by hand) plants of P. tenuiflorus did not differ significantly (P. hirsutus not studied). Neither percent seed germination nor seedling-juvenile growth parameters differed between selfed vs. outcrossed progeny of P. tenuiflorus (P. hirsutus not studied). These results suggest that both species use a mixed mating system consisting of xenogamy, geitonogamy, and autogamy; agamospermy is unimportant. Further, seed set in P. tenuiflorus is not pollinator limited (P. hirsutus not studied), and the species does not appear to exhibit inbreeding depression in seed weight, in seed germination, or in several growth parameters. However, in both species, selfed flowers produced significantly fewer seeds than outcrossed flowers.

A forested wetland type unusual for the Piedmont was discovered in northern Wake County, North Carolina in May 1997. The 3.0 ha wetland existed on Wehadkee silt loam that was continuously saturated by groundwater seepage from surrounding slopes. The wetland plant community was best described as either a Nyssa biflora-Liriodendron tulipifera-Pinus (serotina, taeda)/Lyonia lucida-Ilex glabra Forest (Sandhill Streamhead Swamp) or an Acer rubrum var. trilobum / Myrica heterophylla-Gaylussacia frondosa / Andropogon glomeratus-(Sarracenia flava) Woodland (Hillside Seepage Bog), community types that are globally rare or imperiled, respectively. Approximately 20% of the N. biflora population in the wetland were older than 200 yr; the oldest individuals were 280 yr old. The sympatric occurrence of N. biflora, Pinus serotina, Magnolia virginiana, Ilex glabra, Lindera subcoriacea, Smilax laurifolia, Woodwardia virginica, Eleocharis tuberculosa, and Lindernia dubia var. anagallidea, taxa with primarily Coastal Plain distributions, was unusual for the Piedmont. Information from herbarium specimens, county soil surveys, National Wetland Inventory maps, Natural Heritage Program files, and site visits suggested that approximately only five other examples of this wetland type, at the most, currently exist in the Piedmont of North Carolina. Unfortunately, the study wetland was destroyed in December 1997 by a road construction project

Federal land managers use prescribed burning to restore degraded yellow pine stands of the southern Appalachian Mountains. When justifying burning decisions, land managers need evidence of past fire occurrences in the selected stands. This research explored using macroscopic charcoal in soils as an indicator of past fire occurrences. Soil cores were extracted in 10-cm increments from seven yellow pine stands. Soil cores were retrieved from erosional (summit, shoulder, backslope) and depositional (footslope and toeslope) slope positions. Each 10-cm soil sample was examined for the presence or absence of charcoal. The mean percentage of soil samples per site containing macroscopic charcoal fragments was 85.0 ±12.5%. The presence or absence of charcoal did not differ with sampling depth or with slope position. These results demonstrated that macroscopic charcoal is present in soils supporting these yellow pine stands and serves as an indicator of past fire events. It is important to remember that the charcoal in each sample may be from multiple fires. Furthermore, these methods do not answer questions of when the fire occurred or historic fire frequencies.

Thirteen populations of Erythronium mesochoreum Knerr, ranging from 15 to 3,940 individuals, were studied in nine northwestern and central Illinois counties. A species of tall-grass prairies and open oak woodlands throughout its midwestern range, it is present in open oak woodlands and forest-prairie borders characterized by acidic, silt loam soils in Illinois, where it was first reported in 1983. Many populations are threatened by mowing, woody invasion, railroad maintenance, or competition with exotic species, causing several colonies to be in danger of extirpation. Field investigations during the spring of 1998 resulted in the discovery of numerous additional populations on dry oak-hickory ridge tops in southwestern Macoupin County, suggesting the potential for other colonies near other known locations in Illinois.

Estimating plant biomass is important in studies of plant community structure and function (Whittaker and Woodwell 1968, Reiners 1972, Skeen 1974, Johnson and Bell 1976, Schlesinger 1978, Ehrenfeld and Gulick 1981, Ehrenfeld 1986, Pavel 1993). Non-destructive methods of tree biomass estimation are becoming more commonly used since destructive methods are no longer permitted in many areas. Dimension analysis (Whittaker and Woodwell 1968) is a non-destructive method that utilizes species-specific regression equations that describe dimension/biomass relationships between plant components. Only a small amount of destructive sampling is required to initially establish these equations; subsequent work utilizing them is non-destructive. Rather than developing equations for each separate study, researchers can use equations published by others if their work is being conducted on the same species, in the same geographic area, and in the same general habitat type as that work which initially led to the equations. Equations for estimating total above ground biomass and biomass of separate plant components have been developed for several important southeastern hardwood tree species (Clark et al. 1985, Clark and Schroeder 1986).

Noteworthy Collections: Alabama And Maryland

Southern Appalachian Botanical Society is thriving, thanks to an earnest and enthusiastic membership. We are pleased to now be affiliated with American Institute of Biological Sciences. Those of you who attend the annual meeting of that organization should look for the SABS table at future meetings. It is likely that some new members will discover us there.