Reduced functionality of soil food webs in burnt boreal forests: a case study in Central Russia

Abstract

© 2017, Pleiades Publishing, Ltd. Abstract: Functionality of soil food webs after forest fires remains generally unexplored. We address this question by studying both burnt and unburnt spruce forests in Central European Russia (Tver Region). In August 2014 we sampled two spatially distant blocks consisting of forest areas burnt in 2010 and the respective unburnt controls. We analyzed biomass and structure of soil food webs as well as carbon mobilization with respect to carbon stocks in the dead wood, litter and soil after burning. The biomass of soil fauna was moderately reduced in the burnt plots. For some groups like testate amoebae and enchytraeids, however, this decrease was highly significant and corresponded with the decreased C-stock in litter. For the other taxa changes in biomass were insignificant. At the same time C-flow through the soil food web after fire was strongly reduced mainly due to the reduction of biomass of active fungi and secondary decomposers. The overall consumption rate of detritus by the soil food web strongly decreased in the burnt forests and was maintained predominantly by the decomposition activity of bacteria instead of fungi. This resulted in the reduction of the total soil food web functionality related with C-mobilization in the forests four years after a fire event. Brief Summary: We compared rates of carbon mobilization by soil food webs in burnt and unburnt boreal forests in Central Russia. Despite of only slight decrease in soil animal biomass, consumption rate of carbon in the soil food webs after fire was considerably lower and mainly associated with soil bacteria instead of fungi.