SPECIFIC LEAF AREA OF PINUS RADIATA AS INFLUENCED BY STAND AGE, LEAF AGE, AND THINNING

Specific leaf area (SLA) was determined annually for three Pinus radiata D. Don stands at Puruki from ages 2 to 12 years old and undergoing periodic thinning .The canopy SLA averaged 160 cm 2 /g but decreased with stand age from 190 to 150cm 2 /g, while the SLA of individual leaf age-classes ranged between 100 and 220 cm 2 /g. The most important cause of variation in canopy SLA, based on a theoretical analysis, was fascicle density. Density increased from 0.25 to 0.34 g/cm 8 with stand age and by 7% as leaf age increased from 1 to 2 years old. Additional smaller sources of SLA variation were due to random fluctuations in fascicle average dimensions and a reduction in the number of needles per fascicle with increase in stand age. Most of the variation in canopy SLA was accounted for by stand age (74%) and leaf age (10%).