Can old-growth forests managed by irregular shelterwood treatments maintain habitats suitable for an indicator species of old boreal forests?

Irregular shelterwood treatment (IST) is a silvicultural method involving successive partial harvests to promote regeneration under forest canopy, particularly suited for maintaining irregular stand structures and, under certain conditions, conserving old-growth forest attributes. However, its effectiveness remains poorly documented. The Black-backed Woodpecker ( Picoides arcticus (Swainson)), a species associated with old-growth forests and early decay dead wood, was selected as a focal species to study old-growth boreal forest managed with IST. We assessed habitat selection at landscape and home range scales in managed and unmanaged forests. At the home range scale, we evaluated foraging and nest site selection. Selection was determined using Manly's selection ratios and generalized linear models with a logit link. At the landscape scale, the probability of establishing a home range increased with the proportion of IST, and individuals selected IST in proportion to its availability. At the home range scale, the probability of selecting a foraging site increased with snag diameter and woody debris volume, while only the diameter of snags predicted the probability of selecting a nest site. These attributes show no significant difference between IST and old-growth forest classes. Black-backed Woodpeckers use IST, transition, and true old-growth forests in proportion to their availability. Our findings suggest recent IST can provide suitable breeding habitat for Black-backed Woodpecker, particularly when large-diameter snags are retained.