Calcareous fens are wetlands fed by calcareous groundwater and with predominantly low (< 1 m) vegetation. They are critical habitat for rare species, and development of tall vegetation alters this habitat. Our purpose was to better understand how human activities influence the fen habitat. In 1997 in eastern New York and northwestern Connecticut we located 25 fens using soil maps and field surveys, and delimited these sites using 73 indicator plants classified a priori as fen species, disturbance species, or non-fen woody species. In three plots in each fen we measured species cover, water table depth, organic matter, total inorganic nitrogen, groundwater pH and conductivity, and described land use on and within 100 m of each fen to identify the conditions that may lead to fen degradation. Total inorganic nitrogen correlated most significantly with plant species composition. Fen-species richness was negatively correlated with nitrogen, whereas non-fen woody species richness and cover were positively correlated with nitrogen, suggesting that nitrogen inputs contribute to dominance of tall vegetation in fens. Richness of disturbance indicator species was negatively correlated with soil organic matter. Thus, fens with mineral soil layers may be more susceptible to dominance by non-fen species. Percent cover of disturbance indicator species was greater in fens near public roads. Cover of Lythrum salicaria, an invasive weed, was positively correlated with land-use intensity and was greater near public roads. The use of soil maps, indicator plant richness and cover, inorganic nitrogen, water table, and soil organic matter may be an efficient method for locating, delimiting, and assessing the ecological status of fens.

The Adirondack Mountains of New York State hold some of the southernmost communities of alpine vegetation in the eastern United States. Containing the greatest concentration of rare and endangered species in New York State, this ∼12,000-year-old ecosystem is important to understanding the ecological history of northeastern North America. In order to monitor floristic and vegetational shifts over time, 11 permanent transects were established in 1984 on four summits (Wright, Algonquin, Boundary, and Iroquois) of the MacIntyre Range in the Adirondack High Peaks region. Using the point-intercept method, all 11 transects were sampled in 1984, 1994, 2002, and 2007. Vegetation composition changed significantly over the 23-year period, with an overall decrease in bryophytes/lichens and an increase in vascular plants, indicating that vascular plants were replacing bryophytes, particularly in areas not disturbed by hikers. Community similarity was high among all transects, and increased with time for vascular plants as they became more abundant, indicating a successional convergence. Compositional shifts may also reflect effects of global warming and atmospheric deposition on alpine plant communities.

Andropogon gerardii (Big Bluestem) is a dominant grass of the North American tallgrass prairie. It is also found in remnant populations in the eastern United States, including North and South Carolina, often in association with other species with prairie affinities. We characterized eight A. gerardii population sites across various physiographic regions of North and South Carolina. A total of 362 quadrats (1 m × 1 m) were sampled during the 2006–2008 growing seasons for species occurrence and site and quadrat frequency. Associated species were assigned a commonness index (CI). A Sørensen's Community Coefficient was used to determine floristic similarities among the sites. In addition, soil samples in three quadrats were sampled at each site at three depths (0–10 cm, 11–20 cm, and 21–30 cm) and analyzed for pH; organic C and N contents; extractable P, K, Ca, Mg, Zn, Mn; and CEC (cation exchange capacity). A total of 306 vascular plant species was identified comprising 64 families, including 99 (32%) graminoids. There were 61 (20%) Poaceae and 63 (20%) Asteraceae. Species per quadrat ranged from 1 to 13 with a mean of 5. Andropogon gerardii had the highest CI value (5900), followed by Rubus spp. (1260). Community Coefficient values were < 0.5 for all pairings between sites, indicating high divergence in species composition among even nearby sites. There were 14 rare or watch-listed species identified, including the federal endangered Helianthus schweinitzii at Troy Prairie. A total of 153 (50%) of the species had been previously described as occurring in prairie-like associations. Soil pH values varied from 4.8 to 6.9 among the sites and depths. Ca and Mg nutrient values were also highly variable. Andropogon gerardii was found at high frequencies across all sites, indicating its broad tolerance for a variety of edaphic conditions.

The seaweed flora from James Bay, Canada is compared with three contiguous northeastern Canadian Arctic areas (Hudson Bay, Hudson Strait, and the Ellesmere-Baffin Islands area extending northward to the Arctic Ocean). A conspicuous reduction pattern was evident with 131 taxa recorded for the Ellesmere-Baffin Islands area, 106 for Hudson Strait, 81 from Hudson Bay, and 44 in James Bay. The Ellesmere-Baffin Islands area has a more rocky open coastal environment and higher salinities than James Bay, which is more highly sedimented and impacted by hydroelectric development and freshwater discharge. The Ellesmere-Baffin Islands area (∼32–30.5‰) has a higher mean number of shared taxa (90.0 ± 18.4 SE) than James Bay (37.6 ± 2.7 SE), while Hudson Strait and Hudson Bay have intermediate values of 78 ± 14.1 SE and 64 ± 9.2 SE, respectively. The combined flora from the four areas consists of 164 taxa, including 49 red, 65 brown, 1 chrysophyte, and 49 green algae. Fifty of these total taxa (31%) were only found in one area, with 25 occurring between Ellesmere Island and Baffin Island, 13 within the Strait proper, and 6 in both Hudson and James Bays. Strong habitat and salinity gradients, as well as the great distances between collection sites and the haphazard nature of collections may have contributed to these restrictive patterns. Cheney's (1977) floristic ratio documents that all four geographies (including their composite flora) have cold water floras. Four new distributional records are documented from James Bay: Chaetomorpha minima, Elachista fucicola, Phyllophora pseudoceranoides, and Spyridia filamentosa. The cryptogenic taxon Spyridia, which has unclear origins, is a warm-water disjunct in the northwestern Atlantic previously known only from one site in Nova Scotia and a few locations in southern Maine/New Hampshire but mostly south of Cape Cod, Massachusetts. A single introduced species (Dumontia contorta from Europe) is recorded from James Bay and the Ellesmere-Baffin Islands area, while none are documented from the other areas.

Puccinellia rupestris, British alkali grass or stiff saltmarsh grass, is a European halophyte that has only been documented in North America between 1867 and 1880 from coastal zones of New Jersey, New York, and Pennsylvania. We documented Puccinellia rupestris from southern Ohio along an annually salted roadside habitat in 2007. Our collection represents the fourth United States record and the first vouchered report of this taxon from North America in 127 years. The stable population of this exotic grass demonstrates its ability to migrate inland from a coastal environment and become a newly established member the Ohio vascular flora.