title: Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO₂.
abstract: The earth's future climate state is highly dependent upon changes in terrestrial C storage in response to rising concentrations of atmospheric CO₂. Here we show that consistently enhanced rates of net primary production (NPP) are sustained by a C-cascade through the root-microbe-soil system; increases in the flux of C belowground under elevated CO₂ stimulated microbial activity, accelerated the rate of soil organic matter decomposition and stimulated tree uptake of N bound to this SOM. This process set into motion a positive feedback maintaining greater C gain under elevated CO₂ as a result of increases in canopy N content and higher photosynthetic N-use efficiency. The ecosystem-level consequence of the enhanced requirement for N and the exchange of plant C for N belowground is the dominance of C storage in tree biomass but the preclusion of a large C sink in the soil.
authors.affiliation: Program of Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Drake
authors.forename: Anne
authors.initials: A
authors.lastname: Gallet-Budynek
authors.forename: Kirsten S
authors.initials: KS
authors.lastname: Hofmockel
authors.forename: Emily S
authors.initials: ES
authors.lastname: Bernhardt
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Billings
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jackson
authors.forename: Kurt S
authors.initials: KS
authors.lastname: Johnsen
authors.forename: John
authors.initials: J
authors.lastname: Lichter
authors.forename: Heather R
authors.initials: HR
authors.lastname: McCarthy
authors.forename: M Luke
authors.initials: ML
authors.lastname: McCormack
authors.forename: David J P
authors.initials: DJ
authors.lastname: Moore
authors.forename: Ram
authors.initials: R
authors.lastname: Oren
authors.forename: Sari
authors.initials: S
authors.lastname: Palmroth
authors.forename: Richard P
authors.initials: RP
authors.lastname: Phillips
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Pippen
authors.forename: Seth G
authors.initials: SG
authors.lastname: Pritchard
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Treseder
authors.forename: William H
authors.initials: WH
authors.lastname: Schlesinger
authors.forename: Evan H
authors.initials: EH
authors.lastname: Delucia
authors.forename: Adrien C
authors.initials: AC
authors.lastname: Finzi
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000378:metabolism*; D002980:Climate; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism*; D058458:Nitrogen Cycle; D009657:North Carolina; D018517:Plant Roots; D012988:Soil Microbiology; D014197:Trees / Q000254:growth & development*
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen