J. Bauhus et R. Barthel, MECHANISMS FOR CARBON AND NUTRIENT RELEASE AND RETENTION IN BEECH FOREST GAPS .2. THE ROLE OF SOIL MICROBIAL BIOMASS, Plant and soil, 169, 1995, pp. 585-592
Field levels of soil microbial biomass C and N, determined by the chlo
roform fumigation-extraction method, showed no marked seasonal pattern
in limed and unlimed gaps and the surrounding beech stand; average co
ntents were 530, 532 and 674 kg microbial C ha(-1); and 65, 68 and 87
kg microbial N ha(-1) respectively. Liming increased microbial. biomas
s in the stand but had no influence on the size of the microbial pool
in the gap. The decrease in microbial biomass in gaps was attributed t
o a decline of ectomycorrhizal hyphae. Due to the absence of available
carbon soil microbial biomass was not a significant nutrient sink fol
lowing forest disturbance. In situ N mineralization at these sites cou
ld not be explained by fluctuations in microbial N. Laboratory measure
ments of CO2 evolution from soil samples, which were in good agreement
with field CO2 measurements, indicated a decline in easily decomposab
le soil organic matter during the growing season. High metabolic quoti
ents (mu g CO2-C mg C-mic, (-1) d(-1)) of the microflora in gaps indic
ated inefficient energy use.