ABSTRACT The 24-ha Abrams Creek Wetlands (Winchester City and Frederick County, Virginia) is an array of fen, swamp, and disturbed transitional ecosystems underlain by limestone and dolostone bedrock. Soils of the area are generally characterized by exceptionally high levels of calcium (>10,000 ppm). Floristic data were collected through monthly surveys during the 2012–14 growing seasons and plot sampling in representative locations. We documented 296 vascular plant species during the inventory period; eight species found previously were not relocated. The 304 total species comprised 206 genera in 78 families. Of these, 55 species were graminoids (27 grasses, 21 sedges, 7 rushes). Obligate or facultative wetland species comprised 43% of the list. The 216 native species represented 71% of the total and included 20 listed as rare in Virginia. Plot data revealed that native species represented 72–99% of the total vegetative cover in the communities sampled. Floristic quality of the 12 constituent sites was ...

ABSTRACT Seedling survival and growth in eastern white pines (Pinus strobus L.) might be limited by white-tailed deer (Odocoileus virginianus) browsing. However, most studies have occurred in areas central to the white pine range, making other factors such as seedling microenvironment unimportant. If microenvironment becomes a concern near the edge of the white pine range, then factors such as seedling placement in relation to forest openings could be important, especially given that deer herbivory tends to be most intense near forest edges. We evaluated the relative importance of deer browse and seedling position in openings on seedling survival and growth in central North Carolina at the southern edge of the white pine range. Further, we determined if bud caps and caging improved survival and growth. Seedlings ≤ 10 m from the edge survived at a greater proportion than those > 10 m from the edge (83% and 73%, respectively). Initial height was the most important predictor of survival (R2 = 0.55; p < 0.01...

ABSTRACT In pyrogenic ecosystems, fire often plays an integral part in plant population dynamics. For a subset of plant species in such ecosystems, fire is connected to seed set and/or germination, resulting in postfire recruitment episodes. We investigated the relationship between fire and seed set in the perennial forb Liatris ohlingerae (Asteraceae), one of many species endemic to the pyrogenic Lake Wales Ridge ecosystem of central Florida. Our study focused on comparisons of seed production and invertebrate damage to flowers across L. ohlingerae populations in locations encompassing a range of intervals since fire, between 1 mo and 9 yr prior to the study. We found that the estimated seed set was significantly higher in populations burned less than 1 yr prior to the study than in all other populations. Both low invertebrate damage and high seed production rates contributed to this trend in the populations burned < 1 yr prior to the study. Previous research has demonstrated that germination of L. ohli...

ABSTRACT Sewanee: The University of the South, located in Franklin County, Tennessee, is a 5,263 ha site that encompasses a variety of plateau and cove habitats on the southern Cumberland Plateau in southeastern Tennessee. The vascular flora of the University of the South was documented from 1948–2015 and comprises 1,118 species and lesser taxa in 553 genera and 150 families. We documented 229 exotic taxa, 20.5% of the flora. This flora contains six state records, 74 Franklin County records, and two potential new species. Eighteen taxa are listed as protected either at the state or federal level, including the federally listed endangered Clematis morefieldii and state listed endangered Diamorpha smallii, Silphium brachiatum, and Symphyotrichum pratense. When compared to the five other published floras for the southern Cumberland Plateau in Tennessee, the University of the South flora is the most diverse, capturing 69% of the total taxa at the species level for the region. The high diversity of plant spec...

The Panther Knob Preserve is important in the Central Appalachians because it is the region's largest high-elevation pitch pine (Pinus rigida) community, containing numerous rare and threatened plants and animals. Plant community structure and evidence of fire in 2008 were quantified to (a) document successional changes since 1985, and (b) test the hypothesis of pitch pine regeneration failure without recent fire. Diameter at breast height (dbh) of trees and percent cover of plants within 19 plots, each 20 × 20 m, were measured. Increment borings were used to estimate stand age, and evidence of fire, such as bark charring and soil charcoal, was recorded. Mineral soil from the top 10 cm was collected to evaluate the connection between soil characteristics and plant composition. Cluster analysis of percent cover values identified four plant community types. Diameter distributions, age structure, and the presence of only seven seedlings indicated little recent pine regeneration on the plateau. Comparisons with Fleming's (1985) observations showed that pines are taller but declined in percent cover, that ericaceous shrubs are denser, and that the threatened variable sedge, Carex polymorpha, has declined. Charred woody debris, fire scars, or soil charcoal occurred at 16 of 19 sites. Plant community structure, represented by nonmetric multidimensional scaling (NMS) ordination axes, was not correlated directly with the presence of fire evidence or soil mineral nutrients (principal components analysis [PCA] axes). A new conceptual model of pine dynamics on Panther Knob is introduced. Successional pathways with and without fire are discussed in the context of management.

Cloud immersion experienced by high-elevation rock outcrop plants reduces the leaf-to-air vapor pressure deficit (VPD), decreasing transpirational water loss. Frequent cloud immersion might ameliorate water stress in shallow-soil outcrop communities, increasing water use efficiency and growth. Current climate pattern predictions propose that Southern Appalachian cloud immersion frequency will decrease, potentially increasing water stress in rock outcrop plant populations. In this experiment, outcrop specialists Hydatica petiolaris (cliff saxifrage) and Solidago simulans (granite dome goldenrod) were grown in microcosms simulating current, reduced, and absent cloud immersion. Maximum photosynthetic rates, light saturation point and water use efficiency (WUE) increased, and transpiration decreased with decreasing immersion duration. Root mass, root-to-shoot ratio, and specific leaf mass were greatest in the reduced immersion treatment. Simulating nonimmersed abiotic conditions while measuring gas exchange in a leaf cuvette resulted in higher VPD, photosynthetic rate, transpiration, and lower WUE across treatments. Results indicate acclimation in response to immersion duration for some physiological parameters, suggesting the ability of these plants to adapt to changing climatic conditions. Further experimentation is needed to determine the effects of reduced cloud immersion on plant fitness.

Young mixed hardwood forest communities that colonized abandoned croplands during the late 19th century in northern Florida were typically winter burned annually after pine saplings could survive fire. Hardwood trees persisted as coppice that grew from root crowns within grassy undergrowth. This plant community changed little thereafter, except for the continued growth of pine trees. An 8.64-ha tract of this community was inventoried in 1966, from which fire was permanently excluded thereafter. This tract, called NB66, was reinventoried in 2010 to document maturation of the plant community and to identify the contributing causes that controlled ecological development. Hardwood coppice that was released from fire grew to form a nearly continuous canopy averaging 19.7 m high after 44 years. Many older pines died and disintegrated without causing canopy gaps. Prior to 19th century plantation agriculture, the original vegetation consisted of shortleaf pine-oak-hickory (SPOH) woodland, which intergraded with longleaf pine savanna on sandier soils. These species occur at NB66 but the forest remains dominated by native offsite species, which are aggressively reproducing. These offsite species formerly occurred in less elevated landscape positions in association with magnolia-beech and bottomland hardwood forests. Frequently burned old-field pineland adjacent to NB66 has remained stable indicating that no factors other than fire exclusion caused release of hardwoods from their "fire trap." There was no trend toward recovery of the original SPOH community, and forest development is postulated on the basis of mesophication processes. Recruitment of new species—both woody and herbaceous—since 1966 was modest; most remain uncommon.