Shifting disturbance regimes altered the vegetation of the Central Appalachian Ridge and Valley region during the past two centuries. The objective of this research was to use repeated public land surveys to characterize early Euro-American settlement vegetation and identify the nature and timing of post-Euro-American settlement vegetation change in an agricultural watershed in southwestern Virginia, USA. Land surveys (N  =  297) from 1786 to 2000 were compared for temporal shifts in tree species, shrubs, stumps, snags, and non-vegetative markers. Tree species used in the land surveys were further classified by sprouting capability, shade tolerance, and seed type, and tested for temporal shifts in frequency. To identify potential topographic sampling bias in the surveys, the distribution of landform references recorded in the deeds was compared to the distribution of landforms classified from a digital elevation model (DEM). Landform references noted in conjunction with witness trees were used to further test for species associations with particular landforms. The pre-Euro-American settlement forest was dominated by Quercus alba L. and Castanea dentata (Marshall) Borkh. Quercus alba and C. dentata were relatively evenly distributed across all landforms, while Quercus montana Willd. and Quercus velutina Lam. were strongly associated with upland landforms. Post-Euro-American settlement landscapes experienced a decline in Q. alba, Q. velutina, and Quercus rubra L. and an increase in Q. montana and C. dentata. Vigorous sprouting and shade intolerance were silvical characteristics that dominated across all sampled land-use periods.

Arbuscular mycorrhizal fungi (AMF) may promote plant invasion by enhancing plant performance and competitiveness. However, only a small number of studies have considered the interactions between local soil microbial communities and invasive plants, and even fewer have focused on alien trees. Ailanthus altissima (Mill.) Swingle is a serious problem in the Mediterranean Basin, where it has invaded many habitats. We investigated the symbiosis between A. altissima and indigenous AMF in two invaded, ecologically different Mediterranean woodlands. Mycorrhizal infection was high at both sites (> 60% of the root fragments were mycorrhizal), indicating that A. altissima roots may be infected by AMF under different ecological conditions. In a greenhouse experiment, A. altissima seedling growth was evaluated in untreated soil (natural soil containing the entire microbial community except AMF propagules), in sterilized soil, and in sterilized soil containing the entire microbial community except AMF. Seedling growth was greater in the natural soil than in the other two soils. Seedlings in natural soil but not in the other two soils were extensively colonized by AMF, indicating that AMF may have been responsible for the greater growth in the natural soil. Growth was poorer in the sterile soil that had been inoculated with a soil suspension lacking AMF propagules than in the sterile soil, suggesting that the natural soil also contained pathogens and that the AMF countered the effects of these pathogens. Overall, the results indicate that AMF are an important biotic component of Mediterranean woodlands invaded by A. altissima and AMF may facilitate A. altissima's invasion in these woodlands.

Outbreeding depression, a decline in offspring fitness resulting from mating between distantly related individuals, can jeopardize the success of habitat restoration projects. Concern about outbreeding depression has led to the recommendation that restoration projects use seed collected from geographically proximate populations. However, this recommendation assumes that (1) geographically proximate populations are more ecologically similar than distant populations, and (2) offspring of crosses between individuals from ecologically similar populations have higher fitness than offspring of crosses between ecologically dissimilar populations. We tested these assumptions in Lobelia siphilitica, a species commonly used in ecological restoration. We grew F₁ offspring of within- and between-population crosses in the greenhouse and measured four components of performance: seeds per fruit, seed size, germination success, and final aboveground biomass. We found mixed support for the recommendation that restoration projects use seed collected from geographically proximate populations because of concerns about outbreeding depression. Geographically proximate L. siphilitica populations had more similar annual mean temperatures than distant populations, as expected if geographically proximate populations are more ecologically similar. However, there was no relationship between geographic distance and the difference in annual precipitation. We also found that crosses with climatically dissimilar populations decreased the performance of L. siphilitica, as expected if there is outbreeding depression. However, we detected outbreeding depression in only a subset of populations. Consequently, our results support the recommendation that factors other than geographic distance, particularly climatic distance, need to be considered when selecting seed sources for ecological restoration projects.

The basal fern genus Botrychium presents both taxonomic challenges and issues related to conserving rare species. To track how individuals may vary morphologically and to improve our understanding of the demographic dynamics of this genus, we tracked the presence, size, and shape of 818 Botrychium sensu stricto individuals distributed over 23 sites in the Upper Peninsula of Michigan from 2008 to 2010. This is the first study we know of that tracks morphological change in the genus. Around 45% of the total number of plants observed in 2008 appeared in 2009 and 2010. About 20% of the individuals that did not reappear in 2009 subsequently re-emerged in 2010, confirming vegetative dormancy. Taller plants were likelier to emerge in subsequent years. However, height was uncorrelated with age so younger plants were as likely as older plants to reappear. New recruitment in 2010 was ~5.5%. Plant size and morphology were generally stable within seasons but changed between years, complicating efforts to delineate confusing species like Botrychium matricariifolium (Döll) A. Braun ex W. D. J. Koch. Species identity and traits in the previous year often predicted morphology but not consistently across all years and traits. Habitat differences among sites did not strongly affect reappearance or morphological change. However, height, morphology, and emergence may respond to variation in rainfall, herbivory, and/or interactions with mycorrhizal fungi or surrounding plants among years. Future studies should strive to estimate recruitment and survival over many years in order to distinguish dormancy from mortality, estimate longevity, track demographic fluctuations, and estimate long-term population viability.

Eight peat bogs and wetlands near Steuben, ME were sampled in July 2005 to assess local diversity of freshwater algae. A surprising number of conjugating green algae, especially from the order Desmidiales, was seen even in this small local sample, summing up to 130 species and subspecific taxa. We present an overview of past floristic literature pertaining to desmid species distribution in New England and enrich the current checklist by 65 new records for the state of Maine. Additionally, eight taxa could not be confidently matched to known species, suggesting they may represent heretofore undescribed taxonomic entities. This, coupled with the fact that desmids can serve as water quality indicators, suggests that the desmid diversity in northern New England merits further attention and research.

Fomitopsis feei (Fr.) Kreisel and F. lilacinogilva (Berk.) J. E. Wright & J. R. Deschamps are reported as new to the Brazilian Amazonia and the State of Pernambuco, F. feei to the Brazilian semi-arid, F. cupreorosea (Berk.) J. Carranza & Gilb. to the States of Amazonas, Pará and Pernambuco, and F. nivosa (Berk.) Gilb. & Ryvarden to the Brazilian semi-arid, to Northeast Brazil and to the States of Acre, Rondônia and Roraima. A key to the species of Fomitopsis reported for the Neotropics are provided.

This species belongs to Eleocharis subg. Eleocharis section. Eleocharis ser. Eleocharis subser. Truncatae Svenson and it is similar to Eleocharis subarticulata (Nees) Boeck., E. montevidensis Kunth and E. albibracteata Nees & Meyen ex. Kunth. The new species differs from other species of the genus Eleocharis by its cylindrical, spongy, not septate culms; emucronated sheaths with oblique apex; pauciflorus spikelets; sterile lower glume; upper glumes stramineous to light brown, membranous, smooth, with inconspicuous veins, with or without a submarginal dark brown band, hyaline margin developed and gradual from the rest of the scale; achenes plano-convex, reticulate, with pyramidal stylopodium with up to half the wide of the achene. Morphological description, illustration, data on habitat, and comparison with the similar species are presented.

Repeated measurements of permanent plots in northeastern U.S. forests provide an opportunity to assess how stand-level changes impact carbon storage in aboveground biomass over time. We used 42 years of census data for >6000 individual trees in a 2.9- ha permanent plot at the Harvard Forest (Petersham, MA, USA) to determine how changes in stand age, structure, and species composition affect carbon storage in aboveground biomass in a Quercus-Acer forest. From 1969 to 2011, the biomass of live trees increased linearly (R²  =  0.99, p  =  0.0002), from 150 Mg ha⁻¹ to 268 Mg ha⁻¹, confirming that this ca. 110-year-old stand is still in the aggradation phase of stand development. Over time, a higher proportion of the stand's biomass occurs in large trees. Quercus rubra L. (red oak) accounts for >80 percent of the increase in aboveground biomass due to the rapid growth of dominant stems and low canopy mortality rates. Changes in the biomass of live Acer rubrum L. (red maple) stagnated after 1991, in contrast with region-wide increases, while the proportion of total biomass in subordinate Betula alleghaniensis Britton (yellow birch), Betula lenta L. (black birch), Fagus grandifolia Ehrh. (American beech), and Castanea dentata (Marshall) Borkh. (American chestnut) increased. In the absence of major canopy disturbance we predict that Q. rubra dominance will continue to increase and the stand will steadily accrue carbon for the next century.