Hemlock woolly adelgid, Adelges tsugae, is spreading throughout the northeastern United States, causing large-scale dieback of the eastern hemlock, Tsuga canadensis. This study examined soil nitrogen transformations and stream water nitrogen content at five hemlock-dominated stands in southern Pennsylvania, spanning a spectrum of hemlock mortality, from no mortality to total A. tsugae–induced mortality with subsequent regrowth. Organic content, extractable nitrate, and net nitrification and mineralization rates, as well as nitrate and ammonium movement through the soil were significantly higher at sites with high mortality. Our results suggest that stand-level hemlock mortality is leading to increased nitrogen inputs to stream water. Stream water nitrate concentrations were lowest at the site with little to no mortality (0.035 mg/L NO₃⁻) and highest at the site with intermediate mortality (0.69 mg/L NO₃⁻). In the sites with the longest time since infestation and highest mineralization and nitrification rates, regenerative seedling growth (Betula spp. in particular) is leading to increased uptake of nitrate, likely reducing nitrate leaching rates once substantial regeneration occurs. However, for a period of several years after infestation, hemlock dieback may be a significant source of nitrate in headwater streams, potentially altering headwater aquatic community composition and increasing downstream nutrient pollution.

Three sites with populations of federally endangered golden sedge (Carex lutea LeBlond) were sampled to investigate whether circumneutral soil conditions were associated with a species distribution restricted to 208 km² within two adjacent counties of the lower North Carolina Coastal Plain. Populations were selected to include different soil series found in a state-owned natural area. Observed golden sedge rhizome and root depths among three specimens, one per site, ranged from 6 to 8 cm below the soil surface, which suggested primarily topsoil influence. A total of 96 soil samples, 48 topsoil and 48 subsoil, were collected in transects and analyzed. Mean pH values within populations were very strongly (4.7) to moderately (5.7) acid for topsoils and moderately (5.8) to slightly (6.5) acid for subsoils. These values did not differ significantly inside versus immediately outside each population, but varied among topsoils and subsoils between populations. Other soil variables associated with marl and limestone parent material influence (i.e., cation exchange capacity, base saturation, calcium, and magnesium) did not exhibit any consistent trends either inside versus outside, or between populations. A prior study found a mean soil pH of 6.7 within golden sedge populations, but choices of sample sites and analysis techniques were questionable. Lack of soil specificity for this species encourages both searches for golden sedge populations outside the known range and restoration or enhancement of local populations.

Harperella (Harperella nodosum) is the only federally listed endangered plant species in the Chesapeake and Ohio Canal National Historical Park (C&O Canal NHP) in the National Park Service in Maryland and one of four federally listed endangered plant species in West Virginia. This paper contrasts unsuccessful and successful efforts to reintroduce harperella seedlings in the main stem of the flood-prone Potomac River and on opposite sides of the river in damp sites in western Maryland and in streams in northeastern West Virginia. The reintroduction efforts in Maryland unsuccessfully transplanted seedlings on cobble bars on the Maryland side of the Potomac River and in artificial sites in the prism of the C&O Canal where harperella had never been found; the reintroduction efforts in West Virginia successfully transplanted seedlings on cobble bars in two tributaries of the Potomac River in West Virginia where harperella populations once flourished but in the last decade or so had been decimated by floods and ice damage. This investigation has contributed to defining harperella's life-cycle characteristics and ecological requirements. The data and observations presented can be used as a guide for reintroducing harperella seedlings and, by extension, other semiaquatic plant species into appropriate sites.

A comprehensive survey of the vascular flora of a constructed wetland in Grady County, Georgia was conducted at monthly intervals between August 2004 and May 2006. The constructed wetland is used as a part of a nutrient remediation system to improve the sustainability of plant nursery water-handling practices. The survey evaluated vegetation in a 3.1 ha, two-stage constructed wetland consisting of two deep cells (Stage 1; mean depth 0.75 m) totaling 1.8 ha that drain into two shallow cells (Stage 2; mean depth 0.2 m) totaling 1.3 ha. Each cell was band planted in 1997 with seedlings or liners of six wetland plant species. During the 2-yr survey, 141 distinct species were collected from the 3.1 ha constructed wetland; of the taxa collected, there were 101 genera from 51 families. Native taxa made up 76.6% of the species recorded, and 24.1% of the taxa were introduced. Hydrophytic plants accounted for 68.1% of the plants collected and the remainder (31.9%) were classified as nonhydrophytes. Because 57.4% of the taxa surveyed were perennial, it is likely that plant propagules introduced by wildlife (waterfowl, reptiles, and amphibians) were the dominant method of plant introduction rather than primary succession. Vascular plant community diversity increased 24-fold during the 9-yr period after constructed wetland installation.

North American Castanea consists of three morphologically variable species: Castanea dentata, Castanea pumila, and Castanea ozarkensis. Taxonomy of these species has been complicated by intermediate morphology, similarity in growth habit due, in part, to the chestnut blight, and putative naturally occurring hybridization in the southern Appalachians. The primary goal of this study was to determine if chloroplast DNA (cpDNA) distribution reflects the morphological variation observed in North American Castanea. To that end, we sequenced a single cpDNA gene region for 233 accessions collected from much of the range of the genus in North America. Once samples were grouped into haplotypes, we sequenced additional cpDNA regions to ensure that the observed haplotypic relationships were robust. We identified four main lineages and observed that for three of these, leaf and twig morphology are reliable predictors of haplotype identity (especially outside of the southern Appalachians). Haplotypes of the fourth lineage are shared among accessions of C. dentata and C. pumila, and trees with intermediate morphology. Geographic mapping of the haplotypes showed that they are largely found in separate geographic ranges but overlap in the southern Appalachians. While three clades closely correspond to the morphology of North American Castanea, it appears that the fourth lineage may have been recognized in the past as the hybrid taxon Castanea × neglecta because of its morphology that is intermediate between C. dentata and C. pumila.