Volume 65 — Issue 1 (March 2000)

Canopy, woody understory, and herbaceous strata of headwater wetlands were quantitatively sampled in the inner coastal plain of Virginia and Maryland. Canopy species distribution patterns were then compared with field indicators of hydrologic regime using Detrended Correspondence Analysis (DCA). Sixteen canopy species, 21 subcanopy species, 9 vine species, and 40 herbaceous species were encountered in the 18 sampled stands. One third of sampled sites were overwhelmingly dominated (IV > 50) by Acer rubrum L., while Liquidambar styraciflua L. was important (IV > 15) in half of the stands. The DCA ordination separated stands dominated by Nyssa biflora Walter and Fraxinus spp. from stands dominated by Liriodendron tulipifera L. along a moisture gradient measured by a field indicator of microtopographic depressional storage.

Sapling strata of most sites were overwhelmingly dominated by Liquidambar styraciflua L., although Acer rubrum L. and Fraxinus spp. were also important in many sites. In the subcanopy stratum, Carpinus caroliniana Walter, Lindera benzoin (L.) Blume, and Ilex opaca Aiton occurred in 60-70% of the sites sampled. In the herb layer, Boehmeria cylindrica (L.) Swartz, Glyceria striata (Lam.) Hitchcock, and Thelyptris palustris Schott occurred in 40-60% of sampled sites. The subcanopy and herb layers differed substantially in composition from headwater wetlands in North Carolina, perhaps a reflection of differences in climatic conditions and site histories relative to past logging and/or fire frequencies.

Alnus maritima (Marsh.) Nutt. (seaside alder) is a rare North American species known to occur naturally in only three very small, disjunct populations in northwestern Georgia, the Delmarva Peninsula, and south-central Oklahoma. The most plausible explanation for this disjunction is the reduction of a once-larger range, but factors governing the size of the three existing populations have not been determined. This study examined the possible reproductive limitations of A. maritima caused by its autumnal fruit ripening and corresponding seed dispersal habit. We found that most (65.7%) of the seeds were dispersed during winter months, and a model simulating their fate showed a reduction in total germination percentage from 63.3% to 19.5% after exposure of seeds to winter temperatures typical of native habitats. The total germination percentage declined from 57.9% to 39.7% for seeds overwintered on trees. Based on this evidence, we propose that timing of seed dispersal reduces seed germinability, thereby limiting the natural distribution of A. maritima.

This paper describes methods used to investigate the effects of post-European settlement land-use on the structure and species composition of a central Pennsylvania woodlot. Historical accounts and witness tree analysis used to reconstruct the pre-settlement landscape describe a prairie/savanna occupying the Penns Valley region of central Pennsylvania. The historical information suggests the woodlot originated following European settlement, when land uses such as farming, grazing, and eventual land abandonment altered the original landscape, allowing development of closed canopy woodlots on hilly areas with poorer soil quality. Dendroecological analysis of the woodlot also supports post-settlement origin. The oldest tree individuals established around forty years after settlement indicating the woodlot is not a pre-settlement origin remnant but a result of post-settlement land-use patterns. In addition, subsequent land-use in the woodlot was recorded in the tree ring record. Numerous growth increases in residual trees correspond with multiple selective removals of timber from the stand since settlement. These small gap openings fostered regeneration of more shade tolerant red maple. Due to fire suppression and selective harvesting of dominant oaks the stand is currently undergoing oak replacement by red maple.

Emery Woods is a Quercus-Acer saccharum-Carya forest that meets criteria for old growth. Ordination analysis indicates that variation in tree composition is related to slope exposure. Size class analysis indicates that the current canopy composition has a high potential for change, as Acer saccharum is expected to gain in importance while without larger-scale disturbance most Quercus spp. and Carya spp. may be lost from the canopy, resulting in a lower tree diversity. We collected 219 vascular plant species from 69 families.

Noteworthy Collections: From Herbarium NCU, Arkansas, Louisiana, North Carolina, Oklahoma, Tennessee, Virginia, West Virginia, and New Jersey

Carolina hemlock is a southern Appalachian endemic that occurs from northeastern Georgia to southwestern Virginia. It is typically found on dry, exposed, and nutrient poor slopes; although not abundant, it may sometimes occur in nearly pure stands. The importance values (IV) of Carolina hemlock at this site were 49.2, 89.7, and 38.5 in the tree, small tree, and sapling strata (total possible = 100). Oaks (Quercus spp.) were present in the canopy but do not appear to be self-sustaining, and maples (Acer spp.) appear to be limited to the lower canopy levels. The absence of Carolina hemlock seedlings at this site, and gaps in the age distribution of stems >5 cm DBH suggest that recruitment may be episodic. The dominance of the species may be attributable to the elimination of American chestnut (Castanea dentata) during the 1930s and 1940s. The growth rate of Carolina hemlock at this site was faster than those reported by Humphrey on more productive sites in North Carolina. This confirms Humphrey’s findings that Carolina hemlock exhibits a stress-tolerant life history strategy.

The Flomaton Natural Area is a virgin stand of longleaf pine located in Escambia County, Alabama. Fire has been absent for at least the past 45 years from the stand. Efforts are underway to restore this fire-dependent ecosystem through the re-introduction of fire. This paper presents data collected in advance of the re-introduction of fire. A substantial hardwood understory and midstory have developed and a thick litter layer has accumulated in the absence of fire. Longleaf pine (Pinus palustris) regeneration and her baceous vegetation are almost nonexistent. Considering all trees >1.25 cm DBH, longleaf pine averages 309 stems/ha and 19 m²/ha, or 65% of total stand basal area. The predominant hardwood species are water oak (Quercus nigra), laurel oak (Q. laurifolia), southern red oak (Q. falcata), and black cherry (Prunus serotina). Together these hardwoods average 929 stems/ha and 6.5 m²/ha, or 22% of the total stand basal area. Other pines and hardwoods comprise 8% and 5% of total stand basal area, respectively. Considering only saplings (1.25 to 12.7 cm DBH), longleaf accounts for only 11% and the four major hardwoods 64% of total sapling basal area.

The fern, Botrychium lunarioides, has been considered not only one of Alabama’s rarest ferns, but also one of the Southeast’s. We report the current distribution and 13 new county records of this fern in Alabama. It is now apparent that B. lunarioides is more common in Alabama than previously thought.

A recent report (Ward and Taylor 1999) of the discovery on Merritt Island, Brevard County, Florida, of a small population of tree-form gopher apple (Licania michauxii), was accompanied by brief mention of other woody species believed to have evolved from an arboreous habit in accommodation to the frequent fire regime of the xeric southern woodlands. Though the evolutionary derivation of these species pairs-one in mesic woodlands, the other in xeric sand pine scrub or high pine-may be intuitively obvious to many Florida observers, there appears to be no published statement calling attention to these relationships and to the implication they cast as to the origin of the coastal plain flora. It is apparent that a somewhat fuller commentary addressing these other species pairs is needed.