© 2001 Heron Publishing—Victoria, Canada
Internal remobilization of carbohydrates, lipids, nitrogen and phosphorus in the Mediterranean evergreen oak Quercus ilex
Bénédicte Cherbuy (1), Richard Joffre (1), Dominique Gillon (1) and Serge Rambal (1)
1. Centre d'Ecologie Fonctionnelle et Evolutive, C.N.R.S., Dream Unit, 1919 Route de Mende, 34293 Montpellier Cedex 01, France / Received April 14, 1999
Summary
Remobilization of internal resources is an important mechanism enabling plants to be partly independent of external nutrient
availability. We assessed resource remobilization during the growing period in woody and foliar tissues of leafy branches
of mature evergreen Mediterranean oak (Quercus ilex L.) at three field sites. We compared nonstructural carbohydrates, lipids, nitrogen and phosphorus pools in leaves and stems
before bud burst (March) and at the end of the growing period (July). We also experimentally defoliated leafy branches to
determine the storage function of old leaves. Changes in pools of carbon compounds in leaves and stems during spring and in
response to defoliation indicated that foliar and woody tissues could provide carbon to support shoot growth. Independently
of stem age, soluble sugar and lipid pools decreased significantly during spring. Changes in leaf pools between March and
July involved all compounds measured except starch and were accompanied by a 5%; decrease in mean leaf biomass. During the
same period, 15%; of the nitrogen and 25%; of the phosphorus were removed from leaves. In contrast, woody tissues did not
remobilize nitrogen or phosphorus. Our results support earlier hypotheses that leaves of evergreen species have a primary
role in resource remobilization.
Keywords:
defoliation, growth, nutrient storage, resource remobilization.
