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Soil CO 2 dynamics, acidification, and chemical weathering in a temperate forest with experimental CO 2 enrichment

Soil CO 2 dynamics, acidification, and chemical weathering in a temperate forest with... Soils constitute a major component of the global carbon cycle that will be affected by anthropogenic additions of CO2 to the atmosphere. As part of the Duke Forest Free‐Air CO2 Enrichment (FACE) experiment, we examined how forest growth at elevated (+200 ppmv) atmospheric CO2 concentration affects CO2 dynamics in the soil. Soil respiration and the concentration of CO2 in the soil pore space to a depth of 200 cm were measured over a 3‐year period. Soil CO2 production was linked to soil acidification and mineral weathering by measuring changes in the composition of the soil solution, including alkalinity, Si, and major cations. The total flux of dissolved inorganic carbon to groundwater was then calculated from field measurements. The FACE fumigation gas contained a unique 13C signature that labeled newly fixed carbon, which was monitored in the soil system. As a result of CO2 enrichment, annual soil respiration increased by 27% and was accompanied by higher CO2 concentrations in the soil pore space. These changes to soil CO2 dynamics were most likely the result of increased root and rhizosphere respiration, as suggested by the changes to the δ13C of soil CO2. Increased soil CO2 under FACE accelerated the rates of soil acidification and mineral weathering. Thus an increase of 55% in atmospheric CO2 concentration over 2 years resulted in a 271% increase in soil solution cation concentration, a 162% increase in alkalinity, and a 25% increase in Si concentration at 200–cm depth. The flux of dissolved inorganic carbon to groundwater increased by 33%, indicating a negative feedback to changes in atmospheric CO2 that could regulate the global carbon cycle over geological time. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Global Biogeochemical Cycles Wiley

Soil CO 2 dynamics, acidification, and chemical weathering in a temperate forest with experimental CO 2 enrichment

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References (102)

Publisher
Wiley
Copyright
Copyright © 2001 by the American Geophysical Union.
ISSN
0886-6236
eISSN
1944-9224
DOI
10.1029/2000GB001278
Publisher site
See Article on Publisher Site

Abstract

Soils constitute a major component of the global carbon cycle that will be affected by anthropogenic additions of CO2 to the atmosphere. As part of the Duke Forest Free‐Air CO2 Enrichment (FACE) experiment, we examined how forest growth at elevated (+200 ppmv) atmospheric CO2 concentration affects CO2 dynamics in the soil. Soil respiration and the concentration of CO2 in the soil pore space to a depth of 200 cm were measured over a 3‐year period. Soil CO2 production was linked to soil acidification and mineral weathering by measuring changes in the composition of the soil solution, including alkalinity, Si, and major cations. The total flux of dissolved inorganic carbon to groundwater was then calculated from field measurements. The FACE fumigation gas contained a unique 13C signature that labeled newly fixed carbon, which was monitored in the soil system. As a result of CO2 enrichment, annual soil respiration increased by 27% and was accompanied by higher CO2 concentrations in the soil pore space. These changes to soil CO2 dynamics were most likely the result of increased root and rhizosphere respiration, as suggested by the changes to the δ13C of soil CO2. Increased soil CO2 under FACE accelerated the rates of soil acidification and mineral weathering. Thus an increase of 55% in atmospheric CO2 concentration over 2 years resulted in a 271% increase in soil solution cation concentration, a 162% increase in alkalinity, and a 25% increase in Si concentration at 200–cm depth. The flux of dissolved inorganic carbon to groundwater increased by 33%, indicating a negative feedback to changes in atmospheric CO2 that could regulate the global carbon cycle over geological time.

Journal

Global Biogeochemical Cycles – Wiley

Published: Mar 1, 2001

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