Microbial community dynamics and enzyme activity of an Antarctic fellfield soil during the austral summer

Microbial and enzymatic activities were measured during the 49-day austral summer of 1991 in two fellfield soil polygons (WW-5 and WW-18) at Signy I. In 0-2.5 cm cores, microbial counts of bacteria and yeasts increased 100-fold during the summer in both polygons, but fungal numbers increased only in WW-18. The phosphatase activity of both polygons increased but there was no consistent trend in other enzyme activities. In a second experiment, 0-8 cm soil cores collected at day 14 were divided into 0-4 cm and 4-8 cm fractions. Phosphatase activity in the 0-4 cm fraction of WW-18 was twice that in the 4-8 cm fraction. β-D-Galactosidase was detected in the 4-8 cm fraction of both WW-5 and WW-18 but not in the 0-4 cm fraction whilst β-D-Glucosidase activity was only detected in the 0-4 cm fraction of WW-5. In both polygons carbohydrate carbon was 1.5 x greater in the 0-4 cm fraction compared with the 4-8 cm fraction. The bacteria and yeast populations of WW-18 were approximately 1000 x greater in the 0-4 cm than in the 4-8 cm fraction. There was no change in the fungal population of WW-18 with depth but populations in WW-5 were approximately 165 x greater in the 4-8 cm fraction compared with the 0-4 cm fraction.