Back to Search
Start Over
Seasonal and diel variation in xylem CO2 concentration and sap pH in sub-Mediterranean oak stems.
- Source :
-
Journal of experimental botany [J Exp Bot] 2016 Apr; Vol. 67 (9), pp. 2817-27. Date of Electronic Publication: 2016 Mar 24. - Publication Year :
- 2016
-
Abstract
- Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*].<br /> (© The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)
- Subjects :
- Carbon Dioxide metabolism
Circadian Rhythm
Hydrogen-Ion Concentration
Plant Stems chemistry
Plant Stems metabolism
Plant Stems physiology
Quercus physiology
Seasons
Temperature
Trees metabolism
Trees physiology
Xylem metabolism
Xylem physiology
Carbon Dioxide analysis
Quercus metabolism
Xylem chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1460-2431
- Volume :
- 67
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Journal of experimental botany
- Publication Type :
- Academic Journal
- Accession number :
- 27012285
- Full Text :
- https://doi.org/10.1093/jxb/erw121