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In northeastern North America, alpine snowbank communities are rare plant assemblages that form in sheltered sites above treeline where late-lying snow provides insulation from late-season frosts and a longer-lasting source of water. We measured snowpack and studied community composition and plant traits at the species and community scales across the snowmelt gradient at snowbank sites on Mt. Washington, New Hampshire. We used nonmetric multidimensional scaling ordination and analysis of similarity to examine community composition across the snowmelt gradient and measured plant traits (height, leaf dry matter content, leaf area, and specific leaf area) of four focal species (Carex bigelowii, Chamaepericlymenum canadense, Clintonia borealis, and Maianthemum canadense). We assessed trait variability of the four focal species across the snowmelt gradient and evaluated community-weighted mean trait values and phenotypic plasticity between snowbank core and edge habitats. Analysis of similarity indicated that vascular plant diversity increased (p < 0.001), lichen and bryophyte cover decreased (p < 0.001; p < 0.025), and community-weighted mean leaf area increased (p < 0.001) in the core of snowbank communities where melting dates were later. Analysis of similarity indicated that vascular plant communities varied significantly across the snowmelt gradient. The transition in community composition and trait values across the snowmelt gradient are indicative of changing environmental conditions and ecosystem functions, though more research is needed to determine the extent to which phenotypic plasticity and ecotypic uniqueness influence trait expression of snowbank species. Genetic analysis may be necessary to evaluate population dynamics among isolated alpine communities, which may be vulnerable to climate change or displacement by exotic or lowland species. [ABSTRACT FROM AUTHOR]

Included in information on the status of 50 bird species and five mammal species in the Melon River valley, Northwest recorded in the Thelon Wildlife Sanctuary. Thirty of the bird species, along with Red Squirrel (Tamiasciurus hudsonicus), Moose (Alces alces), Porcupine (Erethizon dorsatum), River Otter (Lutra canadensis), and Beaver (Castor canadensis) were not reported by either J. C. Critchell-Bullock or C.H. D. Clarke during reconnaisances of the Thelon River area during the 1920s and 1930s. Although recent, increased search effort may explain many of these differences, it is likely that the Common Loon (Gavia immer), Mallard (Anas platyrhynchos), American Widgeon (Anas americana), Surf Scoter (Melanitta perspicillata), Gyrfalcon (Falco rusticolus), Yellow-rumped Warbler (Dendroica coronata), Rusty Blackbird (Euphagus carolinus), Moose, and Red Squirrel have established breedingpopulations in the Thelon River area since the 1930s. Several hypotheses may explain northward range expansions, including a recent warming trend at the northern treeline during the 1970s and 1980s. Although apparent changes in the mammalian and avian faunas are consistent with an hypothesis linked to climate change, correlational studies areprobably inadequate to link climate change causally with changes in species distribution. [ABSTRACT FROM AUTHOR]

Abstract: Deuterium-labeled water (2H2O) has emerged as a novel isotope tracer. Following the administration of 2H2O, it is possible to study the dynamics of carbohydrate, protein, lipid, and DNA and to determine body composition. Those studies require reliable measurements of the 2H labeling of water. Although simple gas chromatography–mass spectrometry (GC–MS) methods have been developed for measuring the 2H enrichment of biological fluids, investigators have not reported on the intra- and/or interdaily variability of the measurements. We have experimentally examined the reproducibility of one GC–MS method for measuring the 2H labeling of water. Briefly, hydrogen (deuterium) atoms in water were exchanged with those bound to acetone, and the 2H labeling of acetone was then determined under electron impact ionization. We found that the coefficient of variation is generally less than 0.5% when water is labeled between 0 and 2.8 mole percentage excess 2H. We demonstrated that this highly reproducible result allows one to use 2H2O and the “acetone method” to measure physiological parameters such as body composition in mice. [Copyright &y& Elsevier]