Niwot Ridge By: Kate Edwards GEOG 4401/5401 Soils Geography Fall 2007 – Univ of Colorado, Boulder

Location Niwot Ridge is located approximately 35 km west of Boulder, Colorado Lying above 3000 m elevation This region is composed of sub-alpine forests, extensive alpine tundra, a variety of glacial landforms, talus slopes, and permafrost.

Research Site

Niwot Ridge Landscape Talus soils: –Snow-covered and barren Wet meadow tundra soils: –Carex scopulorum Dry meadow tundra Soils: –Tussock-forming sedge Kobresia myosuroides

Talus Slopes and Glaciated Region Wet Meadow Tundra Dry Meadow Tundra

Climate Low temperatures throughout the year Annual mean temperature at -3.7 degrees Celsius Mean annual precipitation is about 930 mm –Most occurs as snow during the Winter and Spring. High solar radiation, high wind velocities, and abbreviated growing seasons

Wrong Assumptions Microbial growth under snow does not ceases at low temperatures Microbial growth is an important contributor to primary productivity during the short alpine tundra growing season.

Microbial Diversity in Alpine Tundra Wet Meadow Soil: The soils are acidic (pH from 4.3 to 5.3) and are classified as loamy-skeletal histic pergalic Cryaquepts.

Soil Characteristics along Seasonal Gradient Spring periods have long-term temperature stability near 0 degrees Celsius. Spring snow melt increases microbial community complexity and diversity. Bacterial and Archaea diversity was amplified from saturated spring soil.

Soil Depth Gradient Bacteria diversity and complexity shifts along depth gradient. Bacterial community profile occurred at the surface to subsurface transition.

Summary Microbial growth does exsist in frozen soils. Snow melt during the Spring increases microbial community complexity and diversity in alpine tundra soils. Bacterial community occurs at the surface to subsurface transition.

References: Costello, Elizabeth, Meyer, Allen, Nemergut, Diana, Pescador, Monte, Schmidt, Steven, Weintraub, Michael. “Structure and Function of Alpine and Arctic Soil Microbial communities”.Science Direct. 12/1/07 Costello, Elizabeth, Schimidt, Steven. “Microbial Diversity in Alpine Tundra Wet Meadow Soil”. Environmental Microbiology (2006) 8(8), /1/07.