Longevity and duration of radial growth in Douglas-fir branches

Duration of branch radial growth and longevity were summarized for 2153 branches immediately below the current live crown of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees in southwestern Oregon. Branch longevity averaged 24 years with a range of 4 to 72 years. The number of years without perceptible (13 × hand lens) annual branch radial growth averaged 8 years with a range of 0 to 49 years. Expressed as a percentage of branch longevity, the period lacking perceptible radial growth ranged from 0 to 93% with an average of 34%. As would be expected, greater longevity implied survival deeper into the crown; average percentage of longevity without radial growth also decreased with increasing depth into crown. The implications of branch growth patterns to stem growth and wood quality are discussed.