Variation in specific needle area of old-growth Douglas-fir in relation to needle age, within-crown position and epicormic shoot production.

Variation in specific needle area (SNA; cm2 projected fresh needle area g-1 oven-dried needle weight) was investigated in relation to needle age, within-crown position and epicormic shoot production in 450-year-old Douglas-fir (Pseudotsuga menziesii Mirb. (Franco) var. menziesii) trees.