Transcript Document

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
www.sciencedirect.com
• Costello, Elizabeth, Schimidt, Steven. “Microbial
Diversity in Alpine Tundra Wet Meadow Soil”.
Environmental Microbiology (2006) 8(8), 14711486. 12/1/07. <www.iternet.edu/sites/>