03147nas a2200241 4500008004100000245006800041210006800109260001200177300001400189490000800203520239000211653001102601100002202612700002302634700001702657700002402674700002102698700002402719700002002743700002402763700002102787856009702808 2007 eng d00aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems0 aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems c02/2007 aG01010+120 v1123 a

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–106 years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aLyons, Berry1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aFountain, Andrew, G1 aWall, Diana, H.1 aMoorhead, Daryl, L.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/biogeochemical-stoichiometry-antarctic-dry-valley-ecosystems00760nas a2200229 4500008004100000245012700041210006900168260001200237300001000249490000700259653001100266100002500277700002200302700002100324700002400345700001700369700002400386700001800410700002300428700002000451856005900471 2002 eng d00aSnow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica0 aSnow patch influence on soil biogeochemical processes and invert c02/2003 a91-990 v3510aBiggie1 aGooseff, Michael, N.1 aBarrett, John, E.1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry1 aParsons, Andrew, N.1 aPorazinska, D1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/r086455ju7213711/03551nas a2200217 4500008004100000245009000041210006900131260001200200300001400212490000800226520282700234653001103061100002103072700002703093700001903120700002003139700002403159700002203183700001703205856011103222 2002 eng d00aValley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-20000 aValley floor climate observations from the McMurdo Dry Valleys A c12/2002 a4772-47840 v1073 a

Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from −14.8°C to −30.0°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2 = 0.992) of increasing potential temperature with distance from the coast (0.09°C km−1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites.

10aBiggie1 aDoran, Peter, T.1 aMcKay, Christopher, P.1 aClow, Gary, D.1 aDana, Gayle, L.1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aLyons, Berry uhttps://mcm.lternet.edu/content/valley-floor-climate-observations-mcmurdo-dry-valleys-antarctica-1986-200000603nas a2200169 4500008004100000245014000041210006900181260001200250300001400262490000700276653001100283100002500294700002400319700001700343700001200360856006100372 2002 eng d00aWeathering reactions and hyporheic exchange controls on stream water chemistry in a glacial meltwater stream in the McMurdo Dry Valleys0 aWeathering reactions and hyporheic exchange controls on stream w c12/2002 a1279-12960 v3810aBiggie1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aLyons, Berry1 aBlum, A uhttp://www.agu.org/pubs/crossref/2002/2001WR000834.shtml