 |
| Titel |
Amazon tree stems respiration: Is the O2 influx a better measure? |
| VerfasserIn |
A. Angert, J. Muhr, R. Negrón Juárez, W. Alegria Muñoz, J. Q. Chambers, S. E. Trumbore |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058439
|
|
|
|
|
|
| Zusammenfassung |
| Respiration in tree stems strongly controls the tree carbon use efficiency. The rate of CO2 efflux from the stem has often been assumed to be a measure of stem respiration. However, recent work has demonstrated that stem CO2 efflux can either overestimate or underestimate respiration rate, because of emission or removal of CO2 by transport in xylem water. Here, we have used high precision measurements of O2 to estimate the ratio between local stem respiration and local CO2 efflux, in tropical forest trees. This approach is based on the much lower solubility of O2 in water relatively to CO2. The measured ratios between the stems CO2 efflux and O2 influx indicated that a large portion of the respired CO2 (~35% on average) is not emitted locally, and is probably transported upward in the stem. Our results indicate the existence of a considerable internal flux of CO2 in the stem. If the transported CO2 is used in the canopy as a substrate for photosynthesis, it could account for several percent of the carbon fixed by the tree, and perhaps serve as a mechanism that buffers the response of the tree to changing CO2 levels or to drought stress. We have also demonstrated that measurements of O2 uptake, while are more difficult to make, can be a more appropriate method to estimate stem respiration rates. |
|
|
|
|
|
|