Elevated atmospheric carbon dioxide increases soil carbon

Jastrow, Julie D.; Miller, R. M.; Matamala, Roser; Norby, Richard J.; Boutton, Thomas W.; Rice, Charles W.; Owensby, Clenton E.

doi:10.1111/j.1365-2486.2005.01077.x

Cited by 227 publications

(209 citation statements)

References 33 publications

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“…In our sweetgum forest, annual sequestration of N into wood (20) and soil organic matter (18) exceeded the input of exogenous N into this ecosystem, implying a drawing down of the soil N capital (25). Mechanisms have been proposed whereby eCO 2 could increase N availability and compensate for increased N demand, such as stimulation of N mineralization by increased labile C inputs (29) and increased allocation to mycorrhizal fungi (11).…”

Section: Discussionmentioning

confidence: 99%

“…2); the bulk of the NPP increase occurred as increased fine-root production, especially in the deeper soil profile (16). Increased NPP was associated with greater C input to soil (17) and a gain in soil C (18), and it was this 6-y dataset that was used in a synthesis of NPP responses in FACE experiments (7). Now, with 11 y of data, our analysis must be revised.…”

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confidence: 99%

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CO ₂ enhancement of forest productivity constrained by limited nitrogen availability

Norby

Warren

Iversen

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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858

572

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Stimulation of terrestrial plant production by rising CO 2 concentration is projected to reduce the airborne fraction of anthropogenic CO 2 emissions. Coupled climate-carbon cycle models are sensitive to this negative feedback on atmospheric CO 2 , but model projections are uncertain because of the expectation that feedbacks through the nitrogen (N) cycle will reduce this so-called CO 2 fertilization effect. We assessed whether N limitation caused a reduced stimulation of net primary productivity (NPP) by elevated atmospheric CO 2 concentration over 11 y in a free-air CO 2 enrichment (FACE) experiment in a deciduous Liquidambar styraciflua (sweetgum) forest stand in Tennessee. During the first 6 y of the experiment, NPP was significantly enhanced in forest plots exposed to 550 ppm CO 2 compared with NPP in plots in current ambient CO 2 , and this was a consistent and sustained response. However, the enhancement of NPP under elevated CO 2 declined from 24% in 2001-2003 to 9% in 2008. Global analyses that assume a sustained CO 2 fertilization effect are no longer supported by this FACE experiment. N budget analysis supports the premise that N availability was limiting to tree growth and declining over time -an expected consequence of stand development, which was exacerbated by elevated CO 2 . Leaf-and stand-level observations provide mechanistic evidence that declining N availability constrained the tree response to elevated CO 2 ; these observations are consistent with stand-level model projections. This FACE experiment provides strong rationale and process understanding for incorporating N limitation and N feedback effects in ecosystem and global models used in climate change assessments.CO 2 fertilization | free air CO 2 enrichment | global carbon cycle | sweetgum | coupled climate-carbon cycle models P olicy decisions to mitigate climate change require dependable predictions of the forcings and feedbacks between the terrestrial biosphere and the climate (1). Currently, climate models that are coupled to terrestrial and oceanic carbon (C)-cycle models simulate a positive feedback to climate change such that the airborne fraction of anthropogenic CO 2 emissions increases with, and amplifies, climatic warming (1). However, the uncertainty in these projections is high, largely because of uncertainty in the offsetting negative feedback that may occur if stimulation of terrestrial plant production by rising CO 2 concentration increases land C storage and thereby reduces the airborne fraction of anthropogenic CO 2 emissions. Coupled climate-C-cycle models, including those used in the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) (2), are sensitive to this negative feedback on atmospheric CO 2 (3). For example, dynamic global vegetation models (4) simulate an increased terrestrial C sink resulting from the physiological responses of plants to elevated atmospheric CO 2 concentration (eCO 2 ), and when coupled to climate models, inclusion of the CO 2 fertilization effect slows the increase in...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

CO ₂ enhancement of forest productivity constrained by limited nitrogen availability

Norby

Warren

Iversen

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

858

572

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“…Vegetation exposed to atmospheric CO 2 enrichment responds by substantially increasing belowground C allocation, directed to the root biomass, particularly to the fine roots (King et al, 1996;Crookshanks et al, 1998, Janssens et al, 1998, Matamala & Schlesinger, 2000Jastrow et al, 2005). The within-root biomass allocation, however, varies from species to species.…”

Section: Specific Root Length As a Stress Indicatormentioning

confidence: 99%

Specific root length as an indicator of environmental change

Ostonen

Püttsepp

Biel

et al. 2007

Plant Biosystems - An International Journal Dealing with all As

529

349

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Specific root length (SRL, m g71 ) is probably the most frequently measured morphological parameter of fine roots. It is believed to characterize economic aspects of the root system and to be indicative of environmental changes. The main objectives of this paper were to review and summarize the published SRL data for different tree species throughout Europe and to assess SRL under varying environmental conditions. Meta-analysis was used to summarize the response of SRL to the following manipulated environmental conditions: fertilization, irrigation, elevated temperature, elevated CO 2 , Al-stress, reduced light, heavy metal stress and physical disturbance of soil. SRL was found to be strongly dependent on the fine root classes, i.e. on the ectomycorrhizal short roots (ECM), and on the roots 50.5 mm, 51 mm, 52 mm and 1 -2 mm in diameter SRL was largest for ECM and decreased with increasing diameter. Changes in soil factors influenced most strongly the SRL of ECM and roots 50.5 mm. The variation in the SRL components, root diameter and root tissue density, and their impact on the SRL value were computed. Meta-analyses showed that SRL decreased significantly under fertilization and Al-stress; it responded negatively to reduced light, elevated temperature and CO 2. We suggest that SRL can be used successfully as an indicator of nutrient availability to trees in experimental conditions.

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“…To date, the majority of studies on ecosystem C storage response triggered by climate change have been focused on the role of above-ground tissue chemistry and biomass production 12 , the dynamics of total terrestrial C capacity 13 , and more recently in identifying microbial indices of C utilization and activity that lead to trace gas production [14][15][16][17] . However, little is known about the degree to which soil microbialderived C persists in the soil, and contributes to stable C. Microbial production of recalcitrant organic C lies at the root of two issues of global concern-maintaining soil productivity and controlling greenhouse gas levels 7 .…”

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confidence: 99%

Warming and nitrogen deposition lessen microbial residue contribution to soil carbon pool

2012

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Microorganisms have a role as gatekeepers for terrestrial carbon fluxes, either causing its release to the atmosphere through their decomposition activities or preventing its release by stabilizing the carbon in a form that cannot be easily decomposed. Although research has focused on microbial sources of greenhouse gas production, somewhat limited attention has been paid to the microbial role in carbon sequestration. However, increasing numbers of reports indicate the importance of incorporating microbial-derived carbon into soil stable carbon pools. Here we investigate microbial residues in a California annual grassland after a continuous 9-year manipulation of three environmental factors (elevated CO 2 , warming and nitrogen deposition), singly and in combination. Our results indicate that warming and nitrogen deposition can both alter the fraction of carbon derived from microbes in soils, though for two very different reasons. A reduction in microbial carbon contribution to stable carbon pools may have implications for our predictions of global change impacts on soil stored carbon.

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Elevated atmospheric carbon dioxide increases soil carbon

Cited by 227 publications

References 33 publications

CO ₂ enhancement of forest productivity constrained by limited nitrogen availability

CO ₂ enhancement of forest productivity constrained by limited nitrogen availability

Specific root length as an indicator of environmental change

Warming and nitrogen deposition lessen microbial residue contribution to soil carbon pool

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Elevated atmospheric carbon dioxide increases soil carbon

Cited by 227 publications

References 33 publications

CO 2 enhancement of forest productivity constrained by limited nitrogen availability

CO 2 enhancement of forest productivity constrained by limited nitrogen availability

Specific root length as an indicator of environmental change

Warming and nitrogen deposition lessen microbial residue contribution to soil carbon pool

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CO ₂ enhancement of forest productivity constrained by limited nitrogen availability

CO ₂ enhancement of forest productivity constrained by limited nitrogen availability