Investigation of ectomycorrhizal derived soil respiration and dissolved organic carbon fluxes in forests under field conditions
P 1.8 in Ecosystem Function
Ectomycorrhizal mycelia (ECM) play an important role for belowground C allocation in forest soils. Due to methodological difficulties in root separation and sampling under field conditions, the influence of ECM to dissolved organic carbon (DOC) fluxes remains uncertain. There are many contradictory findings about the contribution of ECM to soil respiration (Rs) in literature, ranging from 8 % to 50 %. The Aim of this study is to explore the relationship between biomass production, respiration and exudation of ECM in one approach. To investigate the contribution of ECM to Rs and DOC in a temperate Norway spruce stand in northern Bavaria, mesh bags with different mesh sizes where used to separate root-, ectomycorrhizal and heterotrophic respiration. Closed tubes provide a control without any root and ECM activity and represent heterotrophic respiration and background DOC-fluxes. Rs were measured with an infrared gas analyser in a closed chamber procedure. A ceramic suction device was installed inside every mesh bag to collect soil solution for DOC analyses. Preliminary results from 2009 indicate that ECM contributes to Rs with 43 % to 87 % and influences DOC-fluxes up to 37 %. In summer and autumn 2010, the mesh bags will be harvested to determine the biomass of roots and ECM by mechanical extraction (ultrasonic bath) and biomarkers (PLFA).