Study area
We conducted this study on federal forest lands in the eastern portion of the central Oregon Coast Range (44°30’0”N 123°30’0”W; Fig. 1). Vegetation consisted primarily of Douglas-fir (Psuedotsuga menziesii ) and western hemlock (Tsuga heterophylla ) forests typically growing on steep terrain with numerous and deeply incised drainages. The climate was cool and wet during winter (i.e., wet season; November 1 – March 31) with occasional sub-freezing temperatures and snow, and warm and dry in the summer (i.e., dry season; April 1 – October 31). Forest age was highly correlated with management history, fire, and land ownership. Old forests (>80 years old) were located primarily on federal lands in relatively small patches in a matrix of young forests (<80 years old) and non-forest (Kennedy & Spies, 2004; Linnell, Davis, Lesmeister, & Swingle, 2017; Wimberly & Ohmann, 2004). Young forests (22 – 44 years old) in this study were typical of the region and were established as plantations, which resulted in stands dominated by Douglas-fir trees with straight-boles, simple branches, few cavities, and highly interconnected live crowns.