Résumé
Specific leaf area (
SLA; m
2
leaf
kg
−1
leaf) is a key ecophysiological parameter influencing leaf physiology, photosynthesis, and whole plant carbon gain. Both individual tree-based models and other forest process-based models are generally highly sensitive to this parameter, but information on its temporal or within-stand variability is still scarce. In a 2–4-year-old
Eucalyptus plantation in Congo, prone to seasonal drought, the within-stand and seasonal variability in
SLA were investigated by means of destructive sampling carried out at 2-month intervals, over a 2-year period. Within-crown vertical gradients of
SLA were small. Highly significant relationships were found between tree-average
SLA (
SLA
t) and tree size (tree height,
H
t, or diameter at breast height,
DBH):
SLA
t ranged from about 9
m
2
kg
−1 for dominant trees to about 14–15
m
2
kg
−1 for the smallest trees. The decrease in
SLA
t with increasing tree size was accurately predicted from
DBH using power functions. Stand-average
SLA varied by about 20% during the year, with lowest values at the end of the 5-month dry season, and highest values about 2–3 months after the onset of the wet season. Variability in leaf water status according to tree size and season is discussed as a possible determinant of both the within-stand and seasonal variations in
SLA.