Does elevated atmospheric CO 2 affect soil carbon burial and soil weathering in a forest ecosystem?

PeerJ

article

Miquel A. Gonzalez-Meler¹  Armen Poghosyan¹  Yaniria Sanchez-de Leon¹  Eduardo Dias de Olivera¹  Richard J. Norby⁴  Neil C. Sturchio¹ 

[1] Department of Biological Sciences and Department of Earth and Environmental Sciences, University of Illinois at Chicago;Space Center, Skolkovo Institute of Science and Technology;Department of Agro-environmental Sciences, Universidad de Puerto Rico at Mayaguez;Environmental Science Division and Climate Change Science Institute, Oak Ridge National Laboratory;Department of Earth and Environmental Sciences, University of Delaware

关键词: Soil C;    Elevated CO2;    Isotope;    Temperate forest;    Bioturbation;    cesium-137;    lead-210;   

DOI  :  10.7717/peerj.5356

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Most experimental studies measuring the effects of climate change on terrestrial C cycling have focused on processes that occur at relatively short time scales (up to a few years). However, climate-soil C interactions are influenced over much longer time scales by bioturbation and soil weathering affecting soil fertility, ecosystem productivity, and C storage. Elevated CO2can increase belowground C inputs and stimulate soil biota, potentially affecting bioturbation, and can decrease soil pH which could accelerate soil weathering rates. To determine whether we could resolve any changes in bioturbation or C storage, we investigated soil profiles collected from ambient and elevated-CO2plots at the Free-Air Carbon-Dioxide Enrichment (FACE) forest site at Oak Ridge National Laboratory after 11 years of 13C-depleted CO2 release. Profiles of organic carbon concentration, δ13C values, and activities of 137Cs, 210Pb, and 226Ra were measured to ∼30 cm depth in replicated soil cores to evaluate the effects of elevated CO2 on these parameters. Bioturbation models based on fitting advection-diffusion equations to 137Cs and 210Pb profiles showed that ambient and elevated-CO2 plots had indistinguishable ranges of apparent biodiffusion constants, advection rates, and soil mixing times, although apparent biodiffusion constants and advection rates were larger for 137Cs than for 210Pb as is generally observed in soils. Temporal changes in profiles of δ13C values of soil organic carbon (SOC) suggest that addition of new SOC at depth was occurring at a faster rate than that implied by the net advection term of the bioturbation model. Ratios of (210Pb/226Ra) may indicate apparent soil mixing cells that are consistent with biological mechanisms, possibly earthworms and root proliferation, driving C addition and the mixing of soil between ∼4 cm and ∼18 cm depth. Burial of SOC by soil mixing processes could substantially increase the net long-term storage of soil C and should be incorporated in soil-atmosphere interaction models.

【 授权许可】

CC BY