© 2001 Heron Publishing—Victoria, Canada
Seasonal and interannual variations in carbon isotope discrimination in a maritime pine (Pinus pinaster) stand assessed from the isotopic composition of cellulose in annual rings
Annabel Porté (1) and Denis Loustau (2)
1. INRA Unité de Recherches Forestières Méditerranéennes, Avenue A. Vivaldi, 84000 Avignon, France / 2. INRA Pierroton, Station de Recherches Forestières, Laboratoire d'Ecophysiologie et de Nutrition, BP45, 33611 Gazinet Cedex,
France / Received August 18, 2000
Summary
Stable carbon isotope composition (δ; ‰) was measured on cellulose extracted from maritime pine (Pinus pinaster Aït.) tree rings to investigate inter-tree and interannual variability (7 trees, 20 rings per tree, each ring divided into
early and late wood). A model of stand primary production coupled to water balance was used to calculate the stand annual
water-use efficiency (WUE).
Inter-tree variability in discrimination (maximum 2.88‰ in late wood in 1989, 2.69‰ in early wood in 1983) was as large as
interannual variation (maximum 2.72‰ in late wood, 2.05‰ in early wood). Tree size did not explain these differences. Relationships
were found between annual discrimination and climate variables such as annual rainfall, summer temperature and vapor pressure
deficit (VPD). Higher correlations were found with late wood discrimination. Early wood discrimination was shown to be related
to previous-year late wood discrimination. Late wood discrimination was also related to soil water availability. Stand annual
WUE was only weakly related to tree ring carbon discrimination.
Keywords:
inter-tree variability, soil water availability, vapor pressure deficit, water-use efficiency.
