Changes with leaf age in stomatal function and water status of several tropical tree species.
Reich P. B., Borchert R.
Author Affiliation: Dep. For., Univ. Wisconsin, Madison, WI 53711, USA.
Biotropica 20 : 60-69
Abstract : Changes in diffusive resistance (r) and xylem pressure potential (P) were monitored in expanding, young, middle-aged and old (nonsenescent) leaves of deciduous Tabebuia rosea and Cordia glabra and evergreen Licania arborea, Anacardium excelsium and Mangifera indica at 2 sites in Costa Rica. In all species, expanding leaves had high r and P in situ and wilted soon after being exised. In fully expanded leaves, stomatal control decreased with increasing age, especially in the deciduous species. The observed differences in water relations between species were related to their ecological characteristics. M. indica and L. arborea, which continue to grow during seasonal drought, had leaves with the most sensitive stomatal response and the best control of water loss. Stomatal control of water loss was poorest in T. rosea, which is leafless for 4-6 months each year. Considering the generally long life-span of tropical tree foliage, age-related changes in stomatal behaviour and differences between species could have important ecological implications.