Zach, A.; Horna, V. & Leuschner, C. (2010): <b>Diverging temperature response of tree stem CO2 release under dry and wet season conditions in a tropical montane moist forest </b>. <i>Trees - Structure and Function</i> <b>onlineFirs</b>, xx-xx.
Resource Description
Title:
Diverging temperature response of tree stem CO2 release under dry and wet season conditions in a tropical montane moist forest
FOR816dw ID:
712
Publication Date:
2010-01-01
License and Usage Rights:
Resource Owner(s):
Individual:
Alexandra Zach
Contact:
email:
alzac <at> gmx.de
37077 Göttingen
Germany
Individual:
Viviana Horna
Contact:
email:
vhorna <at> gwdg.de
Untere Karspüle 2
Albrecht-von-Haller Institute of Plant Sciences
Plant Ecology
Georg-August University Göttingen
37073 Göttingen
Germany
It is commonly presumed that plant respiratory CO2 release increases with increasing temperature. However, we report on very contrasting stem CO2 release (R S)?temperature relationships of trees in a species-rich tropical montane forest of southern Ecuador under dry and wet season conditions. Rates of R S were low and completely uncoupled from the dial temperature regime during the humid season. In contrast, during the dry season, R S was generally higher and temperature sensitivity of R S differed greatly in degree and even in the direction of response, indicating that temperature might not be the only determinant of R S. In order to explain the heterogeneity of R S, we related R S to vapour pressure deficit, wind speed and solar radiation as important abiotic drivers influencing transpiration and photosynthesis. Stepwise multiple regression analyses with these meteorological predictors either were biased by high collinearity of the independent variables or could not enhance the ability to explain the variability of R S. We assume maintenance respiration to dominate under humid conditions unfavourable for energy acquisition of the tree, thus explaining the pronounced uncoupling of R S from atmospheric parameters. In contrast, the drier and hotter climate of the dry season seems to favour R S via enhanced assimilatory substrate delivery and stem respiratory activity as well as elevated xylem sap CO2 imports with increased transpiration. In addition, tree individual differences in the temperature responses of R S may mirror diverging climatic adaptations of co-existing moist forest tree species which have their distribution centre either at higher or lower elevations.
Keywords:
| Ecuador | climatic adaptation | stem respiration | temperature sensitivity of respiration | tree species richness |
