Population Dynamics of Alpine Tundra Soil Bacteria, Niwot Ridge, Colorado Front Range, U.S.A.

Abstract

Seasonal fluctuations of the alpine tundra soil bacterial populations have been measured within Kobresia-Deschampsia meadows and bare ground on Niwot Ridge, Colorado Front Range. Bacterial population densities of both bare-ground and meadow sites were greatest during fall and lowest during winter. The percentage of soil bacterial population having the ability to produce extracellular proteases, amylases, lipases, and pectinases was highest during the fall and lowest during winter. The total number of bacteria and the diversity of bacterial genera were consistently lower in the bare-ground site than in meadow sites. Members of the genera Pseudomonas and Bacillus were isolated with the greatest frequency during all seasons from all sites. Bacillus species were dominant during the winter season. Total numbers of nitrifying and denitrifying bacteria were high during summer and spring and lowest during winter.