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- Title
Temporal variability in<sup>13</sup>C of respired CO<sub>2</sub> in a pine and a hardwood forest subject to similar climatic conditions.
- Authors
Mortazavi, Behzad; Chanton, Jeffrey P.; Prater, James L.; Oishi, A. Christopher; Oren, Ram; Katul, Gabriel
- Abstract
Temporal variability in the13C of foliage (d13CF), soil (d13CS) and ecosystem (d13CR) respired CO2 was contrasted between a 17.2-m tall evenly aged loblolly pine forest and a 35-m tall unevenly aged mature second growth mixed broadleaf deciduous forest in North Carolina, USA, over a 2-year period. The two forests are located at the Duke Forest within a kilometer of each other and are subject to identical climate and have similar soil types. The d13CF, collected just prior to dawn, was primarily controlled by the time-lagged vapor pressure deficit (VPD) in both stands; it was used for calculating the ratio of intercellular to ambient CO2 (Ci/Ca). A remarkable similarity was observed in the relationship betweenCi/Ca and time-lagged VPD in these two forests despite large differences in hydraulic characteristics. This similarity emerged as a result of physiological adjustments that compensated for differences in plant hydraulic characteristics, as predicted by a recently proposed equilibrium hypothesis, and has implications to ecophysiological models. We found that in the broadleaf forest, the d13C of forest floor CO2 efflux dominated the d13CR, while in the younger pine forest, the d13C of foliage respired CO2 dominated d13CR. This dependence resulted in a more variable d13CR in the pine forest when compared to the broadleaf forest due to the larger photosynthetic contribution. Given the sensitivity of the atmospheric inversion models to d13CR, the results demonstrate that these models could be improved by accounting for stand characteristics, in addition to previously recognized effects of moisture availability, when estimating d13CR.
- Publication
Oecologia, 2005, Vol 142, Issue 1, p57
- ISSN
0029-8549
- Publication type
Academic Journal
- DOI
10.1007/s00442-004-1692-2