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Growth and maintenance respiration in stems of Quercus alba after four years of CO 2 enrichment
Author(s) -
Wullschleger Stan D.,
Norby Richard J.,
Hanson Paul J.
Publication year - 1995
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1995.930108.x
Subject(s) - respiration , respiration rate , growing season , biology , horticulture , botany , cuvette , woody plant , zoology , physics , quantum mechanics
Atmospheric CO 2 enrichment is increasingly being reported to inhibit leaf and whole‐plant respiration. It is not known, however, whether this response is unique to foliage or whether woody‐tissue respiration might be affected as well. This was examined for mid‐canopy stem segments of white oak ( Quercus alba L.) trees that had been grown in open‐top field chambers and exposed to either ambient or ambient + 300 µmol mol −1 CO 2 over a 4‐year period. Stem respiration measurements were made throughout 1992 by using an infrared gas analyzer and a specially designed in situ cuvette. Rates of woody‐tissue respiration were similar between CO 2 treatments prior to leaf initiation and after leaf senescence, but were several fold greater for saplings grown at elevated concentrations of CO 2 during much of the growing season. These effects were most evident on 7 July when stem respiration rates for trees exposed to elevated CO 2 concentrations were 7.25 compared to 3.44 µmol CO 2 m −2 s −1 for ambient‐grown saplings. While other explanations must be explored, greater rates of stem respiration for saplings grown at elevated CO 2 concentrations were consistent with greater rates of stem growth and more stem‐wood volume present at the time of measurement. When rates of stem growth were at their maximum (7 July to 3 August), growth respiration accounted for about 80 to 85% of the total respiratory costs of stems at both CO 2 treatments, while 15 to 20% supported the costs of stem‐wood maintenance. Integrating growth and maintenance respiration throughout the season, taking into account treatment differences in stem growth and volume, indicated that there were no significant effects of elevated CO 2 concentration on either respiratory process. Quantitative estimates that could be used in modeling the costs of woody‐tissue growth and maintenance respiration are provided.