MICROBIAL COMMUNITY STRUCTURE AND PH RESPONSE IN RELATION TO SOIL ORGANIC-MATTER QUALITY IN WOOD-ASH FERTILIZED, CLEAR-CUT OR BURNED CONIFEROUS FOREST SOILS
E. Baath et al., MICROBIAL COMMUNITY STRUCTURE AND PH RESPONSE IN RELATION TO SOIL ORGANIC-MATTER QUALITY IN WOOD-ASH FERTILIZED, CLEAR-CUT OR BURNED CONIFEROUS FOREST SOILS, Soil biology & biochemistry, 27(2), 1995, pp. 229-240
Humus phospholipid fatty acid (PLFA) analysis was used in clear-cut, w
ood-ash fertilized (amounts applied: 1000, 2500, and 5000 kg ha-1), or
prescribed burned (both in standing and clear-cut) coniferous forests
to study the effects of treatments on microbial biomass and community
structure. The microbial biomass (total PLFAs) decreased significantl
y due to the highest rate of wood-ash fertilization, clear-cutting and
the two different fire treatments when compared to control amounts. F
ungi appeared more seriously reduced by these treatments than bacteria
, as revealed by a decreased index of fungal:bacterial PLFAs when comp
ared to the controls. The community structure was evaluated using the
PLFA pattern. The largest treatment effect was due to burning in both
areas studied, which resulted in increases in 16:1 omega5 and proporti
onal decreases in 18:2omega6. Clear-cutting and the different amounts
of ash application resulted in similar changes in the PLFA pattern to
the burning treatments, but these were less pronounced. Attempts to co
rrelate the changes in the PLFA pattern to soil pH, bacterial pH respo
nse patterns (measured using thymidine incorporation), or substrate qu
ality (measured using IR spectroscopy) were only partly successful. In
stead, we hypothesize that the changes in the PLFA pattern of the soil
organisms were related to an altered substrate quantity, that is the
availabilty of substrates after the treatments.