Litter decomposition, CO2-release and enzyme activities in a snowbed and on a windswept ridge in an alpine environment.

At two mountain sites in the Austrian Central Alps (Hohe Tauern), a windswept exposed ridge and a snowbed, at altitudes of 2,300 m and 2,550 m above sea level, respectively, microbial activities were investigated by measuring the decomposable organic matter, the CO2-release, the phosphatase, urease, xylanase and cellulase activities and the decomposition of litter.The microbial activities measured in the soil at the exposed ridge were generally lower than those at the flat site above and the slope below. These results may be explained by a deficiency of organic substrates, together with the effect of frequent drought stress during the vegetative growth period. The activities measured in the poorly drained soil of the snowbed were lower than those at the other sites. The highest activities were measured immediately after the thawing of the frozen topsoils at all sites. At this time the bacterial and fungal populations increase simultaneously with the disintegration, by physical action and enzymic activity, of the litter fall from the previous year.