Enchytraeid worm (Oligochaeta) influences on microbial community structure, nutrient dynamics and plant growth in blanket peat subjected to warming

Our aim was to determine whether the response of below-ground feedback processes to atmospheric warming affects nutrient dynamics and primary production in a model peatland ecosystem. Specifically, we examined the interactions between a dominant soil animal of a blanket peat ecosystem (Enchytraeidae. Oligochaeta) and microbes in response to soil warming (to 6degreesC above current mean summer temperatures), and the consequences of these interactions for nutrient mineralisation and the growth of the graminoid Festuca ovina L. Enchytraeids reduced soil microbial biomass (total PLFA) by 23%, but did not affect soil nutrient availability or plant nutrient content. Enchytraeids did, however, increase C mineralisation by 8%, measured as dissolved organic carbon (DOC) release in the soil solution. Atmospheric warming increased plant nutrient uptake (increasing shoot N and P contents by 12 and 11%. respectively). but reduced the function of enchytraeids with respect to their role in DOC release (by 16%). These findings suggest that in the short term, independent of the effects of enchytraeids. warming may have reduced the ability of the soil microbial biomass to immobilise nutrients and may have relaxed the competition for nutrients between plants and microbes in these nutrient poor soils. increasing the ability of plants to act as a nutrient sink. The results suggest that although soil warming may disrupt biological interactions that are presently operating in these ecosystems, this may not necessarily result in detrimental effects on ecosystem function, which we determined by the growth of F. ovina. (C) 2002 Elsevier Science Ltd. All rights reserved.