Earthworm effects on the use of C sources by microorganisms: non-linear response to temperature alteration
1995
Wolters, V. | Ekschmitt, K.
A microcosm was used to study the effect of a the endogeic earthworm Aporrectodeo caliginosa (Savigny) on the use of C by microorganisms in a calcareous beech forest soil and its dependence on temperature (5-25 degrees C). Inclusion of 14C-labelled beech leaf litter made it possible to differentiate between C use by litter-colonizing microflora and by autochthonous soil microflora. The effect of temperature on the soil microbial biomass 12C was confined to a significant increase at 15 and 20 degrees C. The size of the 14C-labelled microbial biomass, in contrast, was positively correlated with temperature. The 12C mineralization increased exponentially with temperature. The relationship between 14C mineralization and temperature, in contrast, followed a logistic curve. Significant main effects of A. caliginosa were confined to 12C mineralization, reflecting an increase in 12CO2-C production in the earthworm treatments. The earthworm effects on 12CO2-C production and on 14C incorporation of the microflora were not linear. The effect of A. caliginosa on 12CO2-C production was most pronounced at intermediate temperatures. It is concluded that temperature alterations affect the microbial use of different C sources in different ways and that the temperature effects can be significantly modified by endogeic earthworms.
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