 |
| Titel |
Photosynthetic responses to altitude: an explanation based on optimality principles |
| VerfasserIn |
Han Wang, Iain Colin Prenticce, Tyler Davis, Trevor Keenan, Ian Wright, Changhui Peng |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250139088
|
| Publikation (Nr.) |
 EGU/EGU2017-2263.pdf |
|
|
|
|
|
| Zusammenfassung |
| Increasing altitude is commonly accompanied by a declining ratio of leaf-internal to ambient CO2 partial pressures (ci:ca; hereafter, χ) and an increase in carboxylation capacity (Vcmax), while carbon assimilation (A) shows little to no change. Here we provide a consistent, quantitative explanation for these responses based on the ‘least-cost hypothesis’ for the regulation of χ and the ‘co-ordination hypothesis’ for the regulation of Vcmax. With leaf temperature held constant, our analysis predicts that the cost of maintaining water transport capacity increases with altitude (due to declining atmospheric pressure and increasing vapour pressure deficit, VPD) while the cost of maintaining carboxylation capacity decreases (due to the enhanced affinity of Rubisco for CO2 at low O2 partial pressures). Both effects favour investment in carboxylation capacity rather than water transport capacity. The response of A then reflects the competing effects of stronger CO2 limitation at low ci versus increased radiation penetration through a thinner atmosphere. These effects of atmospheric pressure are expected to be most strongly expressed in herbaceous plants that can maintain leaf temperatures in a narrow range. In leaves closely coupled to the atmosphere additional effects of declining temperature on photosynthesis are expected to modify but not obliterate those of pressure. |
|
|
|
|
|
|