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Leaf and canopy responses to elevated CO{sub 2} in a pine plantation under free-air CO{sub 2} enrichment (FACE)

Journal Article · · Bulletin of the Ecological Society of America
OSTI ID:107094
; ;  [1]
  1. Brookhaven National Laboratory, Upton, NY (United States)
Free-air CO{sub 2} enrichment (FACE) was used to expose an intact lobolly pine forest ecosystem to elevated CO{sub 2}. Leaf conductance and canopy water flux measurements along with A{sub net}-C{sub i} curves were used to evaluate physiological responses of the dominant trees to elevated CO{sub 2}. CO{sub 2}-exposed trees showed minor (<7%) but significant reductions in sap flux density compared to trees under ambient CO{sub 2} conditions, but only when air saturation vapor pressure deficit (VPD) was low. Short-term (minutes) direct stomatal responses to elevated CO{sub 2} were also relatively weak. We observed no evidence of adjustments in stomatal conductance in current-year foliage grown under elevated CO{sub 2} for 80 days compared to foliage grown under ambient CO{sub 2}. Leaf net photosynthetic rate at 550 {mu}mol mol{sup {minus}1} CO{sub 2} was enhanced by more than 50% compared to the rate at ambient CO{sub 2}(350 {mu}mol mol{sup {minus}1}). Thus, leaf water-use-efficiency of loblolly pine at elevated CO{sub 2} was enhanced primarily by direct responses of photosynthesis to CO{sub 2} and was not mediated by stomata.
OSTI ID:
107094
Report Number(s):
CONF-9507129--
Journal Information:
Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 3 Vol. 76; ISSN BECLAG; ISSN 0012-9623
Country of Publication:
United States
Language:
English