, Volume 43, Issue 1, pp 1–15 | Cite as

Inorganic nitrogen and microbial biomass dynamics before and during spring snowmelt

  • Paul D. Brooks
  • Mark W. Williams
  • Steven K. Schmidt


Recent work in seasonally snow covered ecosystems has identifiedthawed soil and high levels of heterotrophic activity throughout the winterunder consistent snow cover. We performed measurements during the winter of1994 to determine how the depth and timing of seasonal snow cover affectsoil microbial populations, surface water NO\({\text{NO}}_{\text{3}}^{\text{ - }} \) loss during snowmelt, and plant Navailability early in the growing season. Soil under early accumulating,consistent snow cover remained thawed during most of the winter and bothmicrobial biomass and soil inorganic N pools gradually increased under thesnowpack. At the initiation of snowmelt, microbial biomass N pools increasedfrom 3.0 to 5.9 g n m-2,concurrent with a decrease in soil inorganic N pools. During the latterstages of snowmelt, microbial biomass N pools decreased sharply without aconcurrent increase in inorganic N pools or significant leaching losses. Incontrast, soil under inconsistent snow cover remained frozen during most ofthe winter. During snowmelt, microbial biomass initially increased from 1.7to 3.1 g N m-2 and thendecreased as sites became snow-free. In contrast to smaller pool sizes,NO\({\text{NO}}_{\text{3}}^{\text{ - }} \) export during snowmeltfrom the inconsistent snow cover sites of 1.14 (±0.511) g N m-2 was significantly greater (p< 0.001) than the 0.27 (±0.16) g N m-2 exported from sites with consistent snowcover. These data suggest that microbial biomass in consistentlysnow-covered soil provides a significant buffer limiting the export ofinorganic N to surface water during snowmelt. However, this buffer is verysensitive to changes in snowpack regime. Therefore, interannual variabilityin the timing and depth of snowpack accumulation may explain the year toyear variability in inorganic N concentrations in surface water theseecosystems.

alpine nitrogen cycling nitrogen saturation snowmelt tundra 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Baron JS (1991) Biogeochemistry of a Subalpine Ecosystem: Loch Vale Watershed, Ecological Studies Ser. 90. Springer-VerlagGoogle Scholar
  2. Baron JS, Ojima DS, Holland EA & Parton WJ (1994) Analysis of nitrogen saturation potential in Rocky Mountain tundra and forest: Implications for aquatic systems. Biogeochemistry 27: 61–82Google Scholar
  3. Bowman WD, TA Theodose, JC Schardt & RT Conant (1993) Constraints of nutrient availability on primary production in two alpine communities. Ecology 74: 2085–2097Google Scholar
  4. Bowman WD (1992) Inputs and storage of nitrogen in winter snowpack in an alpine ecosystem. Arctic and Alpine Res. 24: 211–215Google Scholar
  5. Brookes PC, Landman A, Pruden G & Jenkinson DS (1985) Chloroform fumigation and the release of soil nitrogen: A rapid direct extraction method to measure microbial biomass nitrogen in soil. Soil Biol. Biochem. 17: 837–842Google Scholar
  6. Brooks PD, SK Schmidt & MW Williams (1995a) Snowpack controls on soil nitrogen dynamics in the Colorado alpine. In: Tonnessen K, Williams M & Tranter M (Eds) Biogeochemistry of Snow-Covered Catchments (pp 283–292). International Association of Hydrological Sciences Publication 228, Wallingford, UKGoogle Scholar
  7. Brooks PD, Schmidt SK, Walker, DA & Williams MW (1995b) The Niwot Ridge snow fence experiment: Biogeochemical responses to changes in the seasonal snowpack. In: Tonnessen K, Williams M & Tranter M (Eds) Biogeochemistry of Snow-Covered Catchments (pp 293–302). International Association of Hydrological Sciences Publication 228, Wallingford, UKGoogle Scholar
  8. Brooks PD, Williams MW & Schmidt SK (1996) Microbial activity under alpine snow packs, Niwot Ridge, CO. Biogeochemistry 32: 93–113Google Scholar
  9. Brooks PD, Schmidt SK & Williams MW (1997) Winter production of CO2 and N2O from alpine tundra; environmental controls and relationship to intersystem C and N fluxes. Oecologia 110: 403–413Google Scholar
  10. Burns SF (1980) Alpine Soil Distribution and Development, Indian Peaks, Colorado Front Range. PhD Dissertation, University of Colorado, Boulder, COGoogle Scholar
  11. Cline D (1995) Snow surface energy exchanges and snowmelt at a continental alpine site. In: Tonnessen K, Williams M & Tranter M (Eds) Biogeochemistry of Snow-covered Catchments (pp 157–166). International Association of Hydrological Sciences Publication 228, Wallingford, UKGoogle Scholar
  12. Creed IF, Band LE, Foster NW, Morrison IK, Nicholson JA, Semkin RS & Jeffries DS (1996) Regulation of nitrate-N release from temperate forests: A test of the N flushing hypothesis. Water Resour. Res. 32: 3337–3354Google Scholar
  13. Davidson EA, Eckert RW, Hart SC & Firestone MK (1989) Direct extraction of microbial biomass nitrogen from forest and grassland soils of California. Soil Biol. Biochem. 21: 773–778Google Scholar
  14. DiStephano JF & Gholz HL (1986) A proposed use of ion exchange resins to measure nitrogen mineralization and nitrification in intact soil cores. Comm. Soil Sci. Plant Anal. 17: 989–998Google Scholar
  15. Fisk, MC (1995) Nitrogen dynamics in an alpine landscape. PhD Dissertation, University of Colorado, Boulder, COGoogle Scholar
  16. Fisk MC & Schmidt SK (1995) Nitrogen mineralization and microbial biomass N dynamics in three alpine tundra communities. Soil Sci. Soc. Am. J. 59: 1036–1043Google Scholar
  17. Grant MC & Lewis WM (1982) Chemical loading rates from precipitation in the Colorado Rockies. Tellus 34: 74–88Google Scholar
  18. Greenland D (1989) The climate of Niwot Ridge, Front Range, Colorado. Arctic and Alpine Research 21: 380–391Google Scholar
  19. Hart SC & Gunther AT (1989) In situ estimates of annual net mineralization and nitrification in a subarctic watershed. Oecologia. 80: 284–288Google Scholar
  20. Kendall C, Campbell DH, Burns DA, Shanley JB, Silva RA & Chang CC (1995) Tracing sources of nitrate in snowmelt runoff using the oxygen and nitrogen isotopic concentrations of nitrate: Pilot studies at three catchments. In: Tonnessen K, Williams M & Tranter M (Eds) Biogeochemistry of Snow-covered Catchments (pp 339–348). International Association of Hydrological Sciences Publication 228, Wallingford, UKGoogle Scholar
  21. Lewis WM & Grant MC (1980) Relationship between snow cover and winter losses of dissolved substances from a mountain watershed. Arctic and Alpine Research 12: 11–17Google Scholar
  22. Lewis WM Jr, Grant MC & Saunders JF III (1984) Chemical patterns of bulk atmospheric deposition in the State of Colorado. Water Resour. Res. 20: 1691–1704Google Scholar
  23. Mullen RB & Schmidt SK (1993) Mycorrhizal infection, phosphorus uptake, and phenology in Ranunculus adoneus: Implications for the functioning of mycorrhizae in alpine systems. Oecologia 94: 229–234Google Scholar
  24. Oberbauer S & Billings WD (1981) Drought tolerance and water use by plants along an alpine topographical gradient. Oecologia 50: 325–331Google Scholar
  25. Rascher CM, Driscoll CT & Peters NE (1987) Concentration and flux of solutes from snow and forest floor during snowmelt in the West-Central Adirondack region of New York. Biogeochemistry 3: 209–224Google Scholar
  26. Schimel JP, Kielland K & Chapin FS III (1994) Nutrient Availability and Uptake by Tundra Plants. In: Reynolds JF & Tenhunen JD (Eds) Landscape Function: Implications for Ecosystem Response to Disturbance: A Case Study in Arctic Tundra (pp 203–221). Springer-VerlagGoogle Scholar
  27. Sievering H, Burton D & Caine N (1992) Atmospheric loading of nitrogen to alpine tundra in the Colorado Front Range. Global Biogeochemical Cycles. 6: 339–346Google Scholar
  28. Sommerfeld RA, Musselman RC, Ruess JO & Mosier AR (1991) Preliminary measurements of CO2 in melting snow. Geophysical Research Letters 18: 1225–1228Google Scholar
  29. Sommerfeld RA, Mosier AR & Musselman RC (1993) CO2, CH4, and N2O flux through a Wyoming snowpack. Nature 361: 140–143CrossRefGoogle Scholar
  30. Sommerfeld RA, Massman WJ & Musselman RC (1996) Diffusional flux of CO2 through snow: Spatial and temporal variability among alpine-subalpine sites. Global Biogeochemical Cycles 10: 473–482Google Scholar
  31. Walker DA, Halfpenny JC, Walker MD & Wessman CA (1993) Long-Term studies on snowvegetation interactions. Bioscience 43: 287–301Google Scholar
  32. Walker MD, Webber PJ, Arnold EH & Ebert-May D (1994) Effects of inter-annual climate variation on above ground phytomass in alpine vegetation. Ecology 75: 393–408Google Scholar
  33. Williams MW & Melack JM (1991) Solute chemistry of snowmelt and runoff in an alpine basin, Sierra Nevada. Water Resources Research. 27: 1575–1588Google Scholar
  34. Williams MW, Caine N, Baron J, Sommerfeld RA & Sanford RL (1993) Regional assessment of nitrogen saturation in the Rocky Mountains. EOS, Transactions of the American Geophysical Meeting, 1993 Fall Meeting 74(Supplement): 257Google Scholar
  35. Williams MW, Bales RC, Brown AD & Melack JM (1995) Fluxes and transformations of nitrogen in a high-elevation catchmen, Sierra Nevada. Biogeochemistry 28: 1–31Google Scholar
  36. Williams MW, Brooks PD, Mosier AR & Tonnessen KA (1996a) Mineral N transformations in and under seasonal snow in a high-elevation catchment, Rocky Mountains, USA. Water Resources Research 32: 3175–3185Google Scholar
  37. Williams MW, Losleben M, Caine N & Greenland D (1996b) Changes in climate and hydrochemical responses in a high elevation catchment, Rocky Mountains. Limnol. Oceanogr. 41: 939–946Google Scholar
  38. Zak DR, Groffman PM, Pregitzer KS, Chreistensen S & Tiedje JM (1990) The vernal dam: Plant-microbe competition for nitrogen in northern hardwood forests. Ecology 7: 651–656Google Scholar

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • Paul D. Brooks
    • 1
  • Mark W. Williams
    • 2
  • Steven K. Schmidt
    • 3
  1. 1.Water Resources DivisionU.S. Geological Survey –BoulderUSA
  2. 2.Department of Geography and Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderUSA
  3. 3.Department of EPO BiologyUniversity of ColoradoBoulderUSA

Personalised recommendations