Abstrakt
It has been suggested that, in addition to consuming litter and releasing C via respiration, soil fauna may also indirectly increase overall C loss from soil by causing the priming effect. This is based on the assumption that fauna increases the amount of liable C rather than N in litter leachate.
An increase in the labile C would increase soil respiration via the priming effect, while an increase in N in leachates would presumably have the opposite effect (negative priming, decrease of respiration). Here we used a microcosm experiment to study the effects of the presence or absence of two species of soil fauna (the collembolan Folsomia candida and the enchytraeid Enchytraeus crypticus) used alone or in combination, on: 1) the litter respiration of five plants (Alnus glutinosa, Calamagrostis epigejos, Quercus robur, Salix caprea, and Picea omorika), 2) the loss of C and N by leaching from the same litter during a one-year laboratory experiment, and 3) the effect of these leachates on microbial respiration of the soil underlying the litter layer.
Litter-based respiration in microcosms was unaffected by soil fauna. The fauna did not affect the leaching of C, but significantly increased the leaching of N.
These effects were strongest in the early stages of decomposition. Leachates collected from fauna and no fauna treatment were then applied to the soil underlying the litter.
The soil supplied by leachate from fauna treatments showed significantly lower respiration than the soil supplied by no fauna treatments leachates. This suggests that the fauna effect on litter leachate may reduce soil respiration.