© 2007 Heron Publishing—Victoria, Canada
Dry-season leaf flushing of Enterolobium cyclocarpum (ear-pod tree): above- and belowground phenology and water relations
Keilor Rojas-Jiménez (1, 2), Noel M. Holbrook (3) and Marco V. Gutiérrez-Soto (1, 4)
1. Programa de Ecofisiología de Plantas Tropicales, Estación Experimental Fabio Baudrit, Universidad de Costa Rica, Apartado
183-4050 Alajuela, Costa Rica / 2. Present address: Instituto Nacional de Biodiversidad, Apartado 22-3100, Santo Domingo de Heredia, Costa Rica / 3. Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA / 4. Corresponding author (surdo26@racsa.co.cr) / Received October 8, 2006; accepted January 15, 2007; published online August 1, 2007
Summary
Above- and belowground phenology and water relations of Enterolobium cyclocarpum Jacq. trees in the dry forest of Santa Rosa National Park, Costa Rica were studied during two consecutive phenological cycles,
from November 1998 to June 2000. Aboveground phenological activity, including leaf shedding, growth and maturation of dormant
fruits, new leaf flushing and flowering, occurred during the dry season. Measurements of leaf water potential, stomatal conductance
and sap flow indicated that stomata of newly flushed leaves remained essentially closed until the onset of the first rains,
suggesting that the main factor accounting for the favorable water balance of dry-season flushed leaves was their capacity
to restrict water loss. Evidence of a contribution from stem and root water stores to shoot expansion was mixed because only
the first dry-season flushing episode monitored was accompanied by a marked decrease in stem and root water potentials. Fine
root production did not precede leaf flushing, occurred only after the onset of the rainy season and stopped under drought
conditions, suggesting that soil water content was the most important variable controlling fine root dynamics in this species.
Keywords:
fine roots, hydraulic architecture, leaf expansion, sap flow, stomatal conductance, tropical dry forest.
