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Abstract Detail


Environmental Physiology

Teskey, Robert [1], McGuire, Mary Anne [2].

Measurement of stem respiration of sycamore trees involves internal and external fluxes of CO2 and transport of CO2 from roots.

CO2 released by respiring cells in tree stems can either diffuse to the atmosphere or dissolve in xylem sap. In this study, the internal and external fluxes of CO2 released from respiring stems of five sycamore (Platanus occidentalis L.) trees were calculated. Mean rates of stem respiration were highest in mid afternoon and lowest at night, and were positively correlated with air temperature. Over a 24 hour period, on average 34% of the CO2 released by respiring cells in the measured stem segment remained within the tree. Of this amount, based on measurements using 13CO2 as a tracer, approximately one-third is refixed by cortical and leaf photosynthesis. CO2 efflux to the atmosphere consisted of similar proportions of CO2 derived from local respiring cells (55%) and CO2 that had been transported in the xylem (45%), indicating that CO2 efflux does not accurately estimate respiration. A portion of the efflux of transported CO2 appears to have originated in the root system. A modification of the method for calculating stem respiration based on internal and external fluxes of CO2 (McGuire & Teskey 2004) was developed to separate efflux due to local respiration from efflux of transported CO2.


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1 - University of Georgia, School of Forestry and Natural Resources, Athens, GA, 30602, USA
2 - Universty of Georgia, School of Forestry and Natural Resources

Keywords:
dark respiration
sap flux.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P01039
Abstract ID:1754


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