2.2. Seedling measurements
Total seedling height, basal stem diameter and annual height
increment were measured in mid-August after one and two
seasons of seedling growth using measuring tapes and digital
calipers. Visual indicators of seedling health, insect damage and
disease were documented annually. Ten undamaged leaves and
petioles were excised from the upper one-half of the canopy of 5–
10 randomly selected trees per planting block at the end of two
growing seasons. Excised leaves were flattened, transported to the
laboratory in coolers and the area of individual leaves was
measured within 24 h with a LICOR 3100 area meter (Lincoln, NE).
Leaf plane length was measured along the midrib and mass was
determined after drying samples at 60 8C for 48 h. Specific leaf area
was derived from projected leaf area per unit dry mass (Reich et al.,
1998). LeafNwas measured on dried, ground subsamples using dry
combustion (LECO 1000 CHN analyzer, LECO Corporation, St.
Joseph, MI) and used to report foliar N per unit leaf mass.