title: Contribution of carbonate weathering to the CO2efflux from temperate forest soils.
abstract: Temperate forests provide favorable conditions for carbonate bedrock weathering as the soil CO2partial pressure is high and soil water is regularly available. As a result of weathering, abiotic CO2can be released and contribute to the soil CO2efflux. We used the distinct isotopic signature of the abiotic CO2to estimate its contribution to the total soil CO2efflux. Soil cores were sampled from forests on dolomite and limestone and were incubated under the exclusion of atmospheric CO2. Efflux and isotopic signatures of CO2were repeatedly measured of cores containing the whole mineral soil and bedrock material (heterotrophic respiration + CO2from weathering) and of cores containing only the mineral top-soil layer (A-horizon; heterotrophic respiration). An aliquot of the cores were let dry out during incubation to assess effects of soil moisture. Although the δ13C values of the CO2efflux from the dolomite soil cores were within a narrow range (A-horizon -26.2 ± 0.1 ‰; whole soil profile wet -25.8 ± 0.1 ‰; whole soil profile dry -25.5 ± 0.1 ‰) the CO2efflux from the separated A-horizons was significantly depleted in13C when compared to the whole soil profiles (p = 0.015). The abiotic contribution to the total CO2efflux from the dolomite soil cores was 2.0 ± 0.5 % under wet and 3.4 ± 0.5 % under dry conditions. No abiotic CO2efflux was traceable from the limestone soil cores. An overall low contribution of CO2from weathering was affirmed by the amount and13C signature of the leached dissolved inorganic carbon (DIC) and the radiocarbon signature of the soil CO2efflux in the field. Together, our data point towards no more than 1-2 % contribution of abiotic CO2to the growing season soil CO2efflux in the field.
authors.affiliation: Department of Forest Ecology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape - BFW, Seckendorff-GudentWeg 8, 1131 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schindlbacher
authors.affiliation: Department of Soil Ecology, University of Bayreuth, Bayreuth, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Borken
authors.affiliation: Department of Forest Ecology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape - BFW, Seckendorff-GudentWeg 8, 1131 Vienna, Austria.
authors.forename: Ika
authors.initials: I
authors.lastname: Djukic
authors.affiliation: Department of Forest Ecology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape - BFW, Seckendorff-GudentWeg 8, 1131 Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Brandstätter
authors.affiliation: Institute of Geology, University of Innsbruck, Innsbruck, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Spötl
authors.affiliation: Department of Microbiology and Ecosystem Science, Faculty of Life Sciences, University of Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wanek
keywords: 13C; Carbonate weathering; Soil respiration; Temperate forest