The genetic diversity and structure of Quercus rubra L. (Red Oak) in five secondary populations regenerated on old pastures and five paired old-growth populations were compared to determine whether secondary populations may have lost genetic diversity present in the presettlement forest. Old-growth samples had significantly greater nuclear allelic richness than secondary stands at the four microsatellite, simple sequence repeat (SSR), markers tested, but there was no significant difference at three chloroplast SSRs. There was however tenfold greater differentiation (high F_ST) among secondary forests than among old-growth forests for the chloroplast loci, suggesting greater population isolation at the time of their founding. The young age class in secondary stands had significantly greater chloroplast allelic richness than the old age class, suggesting some recovery as the forest cover increased. Forest cover and patch size at peak deforestation was not correlated with allelic richness in secondary stands, but the power of this test was low. The current size of old-growth stands is, however, positively correlated with levels of genetic diversity. Results suggest that deforestation for agriculture may reduce genetic diversity of forest trees, particularly in the first generation after deforestation, but that some recovery of this diversity is likely in these patchy landscapes. Wind dispersed pollen flow may increase in these areas, but animal dispersed seed flow may be reduced.

Platanthera sparsiflora is a variable species to which Limnorchis ensifolia and L. laxiflora have been referred. Recently, authors have adopted L. ensifolia for a group of plants that have also been referred to L. laxiflora and P. sparsiflora. None of these existing names apply to a recently delineated but related group, here described as the new species P. tescamnis. This species is distinguished by a small column with short rostellum lobes that position the viscidia above the orifice of the spur. The species exhibits ecological preferences that are unique in the group, occurring at relatively low elevations and in comparatively dry habitats in a hot, arid region. It occurs across the Great Basin and Colorado Plateau and bordering areas in California, Nevada, Arizona, Utah, and Colorado.

Coastal sandplain heathlands are managed largely by prescribed burning. While it is known that salt spray is an important natural disturbance contributing to the maintenance of coastal heathlands, it is unclear whether fire in coastal areas intensifies the detrimental effects of salt spray on plants growing close to the ocean. We carried out a field experiment to test the interactive effects of fire and salt spray on Martha's Vineyard, Massachusetts. Following a prescribed fire, one-meter-square plots were established in burned and unburned areas and randomly assigned a control or salt spray treatment. After ten weeks of spray treatments we found that burning stimulated new growth and salt spray consistently increased plant water stress, increased leaf necrosis, and inhibited shoot elongation. Burning did not increase the negative effects of salt spray in individual plants; salt spray and control treated plants growing in burned areas showed less water stress and leaf necrosis than those in unburned areas. This may be due to increased water availability in the burned area resulting from lower biomass and therefore lower competition for water and lower evapotranspiration rates. Burning reduced plant canopy height, decreased vascular plant species richness, and stimulated new growth in plants. Our results suggest that fire indirectly reduces the damaging effects of salt spray by increasing soil water availability and decreasing plant water stress.

Introduced species make up about 15% of the flora of the Mount Holyoke Range, Hampshire County, Massachusetts, one of the core natural areas in the state. Geographic Information Systems software was used to compare the distribution of sample locations with introduced invasive species, introduced non-invasive species, or only native species as a function of distance from disturbance corridors that included roads and power-line right-of-ways. Habitat preferences were also analyzed for the two groups of introduced species. Thirty-nine percent of 475 geo-referenced sample locations had introduced species. Of these, twice as many had introduced non-invasive species as had introduced invasive species, with Poa compressa the most common species in the first group and Berberis thunbergii the most common in the second group. A high proportion of sample locations for both groups of introduced species were close to disturbance corridors, with about a third of the sample locations with these groups found within 50 m of disturbance corridors and most of the rest found within 300 m. The distributions of both groups of introduced species differed significantly from the distribution of native species, but not from each other. Disturbed habitats had the highest frequency of both groups of introduced species, but their relative frequency differed in other habitats. Introduced invasive species were common in moister habitats, which may restrict their spread in the range, while introduced non-invasive species tended to occupy drier habitats on upper slopes. These more open habitats may function as a refuge for some species in the introduced non-invasive group. However, high frequencies of both groups in disturbed habitats and the similarity in distribution suggests that human activities associated with disturbance corridors and past land use are of major importance in determining the distribution of both groups of introduced species across the landscape.

Lectotypes are designated for Impatiens fulva Nutt. f. albiflora E.L. Rand & Redfield, and for I. biflora Walter f. immaculata Weath. These are basionyms for two color forms of I. capensis Meerb., indigenous to eastern North America.