Present address: Department of Ecology and Evolutionary Biology, University of Kansas, Room 8020 Haworth Hall, 1200 Sunnyside Avenue, Lawrence, KS 66045-7534, USA.
Temporal scaling of physiological responses from gas exchange to tree rings: a gender-specific study of Acer negundo (Boxelder) growing under different conditions
Article first published online: 2 APR 2004
Volume 18, Issue 2, pages 212–222, April 2004
How to Cite
Dawson, T. E., Ward, J. K. and Ehleringer, J. R. (2004), Temporal scaling of physiological responses from gas exchange to tree rings: a gender-specific study of Acer negundo (Boxelder) growing under different conditions. Functional Ecology, 18: 212–222. doi: 10.1111/j.0269-8463.2004.00838.x
- Issue published online: 2 APR 2004
- Article first published online: 2 APR 2004
- Received 4 August 2002; accepted 22 August 2003
- age effects;
- carbon isotope ratio;
- cultural conditions;
- dioecious tree;
- temporal scaling;
- water stress
- 1Plant responses to water availability may change over time due to seasonality, interannual variation and developmental changes. Our past investigations demonstrated that male and female Boxelder (Acer negundo) exhibit differences in their responses to water availability. Here we use the genders as a model system to: (1) examine if cultural conditions have an effect on instantaneous gas exchange and time-integrated carbon isotope discrimination (Δ); (2) compare these physiological responses across a range of temporal scales (seasonal, annual, interannual); and (3) describe the responses of the genders at different ages to water availability.
- 2Under well watered conditions, differences in instantaneous leaf gas exchange and Δ were observed between the genders at all developmental stages. Within a gender, Δ was similar throughout the growing season and between years, indicating a conserved physiological set-point despite changing growth conditions. When water stress was imposed, females exhibited greater reductions in photosynthetic rate and higher stomatal limitations to photosynthesis than males.
- 3For well watered plants, a strong correlation existed between time-integrated intercellular leaf [CO2] calculated from Δ(c̄i) and ci obtained from instantaneous gas exchange. However, when drought was imposed this correlation weakened in males and was non-existent in females.
- 4This study indicates that instantaneous gas exchange and integrated Δ values can be used to characterize leaf-level responses to water availability when growth conditions are relatively constant. However, when water availability fluctuates, care must be taken in equating these measurements because changing conditions may decouple responses integrating different time-scales, and the degree of this decoupling may vary even at the subspecies (gender) level.