Ley, R Lipson, D
Mark W Williams Schmidt, S
Department of Envrionmental, Population and Organsimic Biology.
University of Colorado. Boulder, CO 80309-334
Department of Envrionmental, Population and Organsimic Biology.
University of Colorado. Boulder, CO 80309-334
Department of Geography and
Institute of Arctic and Alpine Research
University of Colorado, Boulder
Department of Envrionmental, Population and Organsimic Biology.
University of Colorado. Boulder, CO 80309-334
Abstract
The cold, wind-swept summits of mountains in mid-latitude areas of the world are among the
most inhospitable habitats on Earth. Little is known about life under the snow and in the rocky
world of these extreme environments. Here we report preliminary data on microbial
communities, growth rates, and biogeochemical diversity from samples collected near the
continental divide in the Colorado Rocky Mountains at an elevation of about 4000 m. These
soils have less than 1\% organic matter and are snow covered 9-10 months of the year. By
monitoring the physical conditions in the soil continuously over the past year, we have found
that during the snow covered period, the soils show very stable temperature (-1 deg C) and
moisture conditions. The microbial community in these soils can carry out basic
biogeochemical functions found in vegetated soils. The population sizes of sulphur-oxidizing
bacteria in mid-winter is 2000 cells/g soil, and ammonia-oxidizing bacteria is 200 cells/g soil.
These autotrophic bacteria are fixing CO2 and could be an important C source for these soils.
We have measured the biomass of heterotrophic microbes capable of mineralizing phenolic
compounds which ranges from 1,000 to 500,000 cells/g soil. In preliminary laboratory studies,
we have found that these heterotrophic microbes are capable of growing in soil temperatures of
-2 deg C, and are metabolically active at -6 deg C.