Natural disturbances are fundamental to forest ecosystem dynamics and have been used for two decades to improve forest management, notably in the boreal forest. Initially based on fire regimes, there is now a need to extend the concept to include other types of disturbances as they can greatly contribute to forest dynamics in some regions of the boreal zone. Here we review the main descriptors—that is, the severity, specificity, spatial and temporal descriptors and legacies, of windthrow and spruce bud worm outbreak disturbance regimes in boreal forests—in order to facilitate incorporating them into a natural disturbance-based forest management framework. We also describe the biological legacies that are generated by these disturbances. Temporal and spatial descriptors characterising both disturbance types are generally variable in time and space. This makes them difficult to reproduce in an ecosystem management framework. However, severity and specificity descriptors may provide a template upon which policies for maintaining post harvesting and salvage logging biological legacies can be based. In a context in which management mainly targets mature and old-growth stages, integrating insect and wind disturbances in a management framework is an important goal, as these disturbances contribute to creating heterogeneity in mature and old-growth forest characteristics.

Standing deadwood is an important attribute of old-growth boreal forests and it provides essential microhabitats for deadwood-associated species. In managed boreal forests, short rotations tend to limit the amount and diversity of standing deadwood. This study evaluates if the anthropogenic supply of deadwood attributes through tree girdling or by providing nest boxes may favor deadwood-associated species. We studied the short-term response of saproxylic beetles, foraging woodpeckers, and secondary cavity users to snag and cavity supply in 50 to 70-year-old black spruce stands. In spring 2015, we girdled 8000 black spruce according to two spatial distributions (uniform and clustered), and we also installed 450 nest boxes of six different sizes at three distances from the forest edge. Using trunk window traps, we captured significantly more beetles in sites with girdled trees than in control sites in both 2015 and 2016. We also recorded a trend of a greater abundance of beetles in clusters of girdled trees than within uniformly distributed girdled trees. Trypodendron lineatum (Oliver) dominated beetle assemblages, representing 88.5% of all species in 2015 and 74.6% in 2016. The number of beetles captured was 7× higher in 2015 than in 2016. In contrast, we observed greater amounts of woodpecker foraging marks in fall 2016 than in either fall 2015 or spring 2016. Woodpeckers foraged significantly more in clusters of girdled trees than within uniformly distributed girdled trees. Woodpeckers’ foraging mark presence was positively associated with the proportion of recent cuts at 1 km around the study sites. Five Boreal Chickadee (Poecile hudsonicus Forster) pairs used nest boxes and occupied smaller box sizes that were located away from the forest edge. Our study showed that structural enrichment can be effective in rapidly attracting deadwood-associated species within managed forest stands.

Dead wood decomposition begins immediately after tree death and involves a large array of invertebrates. Ecological successions are still poorly known for saproxylic organisms, particularly in boreal forests. We investigated the use of dead wood as nesting sites for ants along a 60-yr postfire chronosequence in northeastern coniferous forests. We sampled a total of 1,625 pieces of dead wood, in which 263 ant nests were found. Overall, ant abundance increased during the first 30 yr after wildfire, and then declined. Leptothorax cf. canadensis Provancher, the most abundant species in our study, was absent during the first 2 yr postfire, but increased steadily until 30 yr after fire, whereas Myrmica alaskensis Wheeler, second in abundance, was found at all stages of succession in the chronosequence. Six other species were less frequently found, among which Camponotus herculeanus (Linne), Formica neorufibarbis Emery, and Formica aserva Forel were locally abundant, but more scarcely distributed. Dead wood lying on the ground and showing numerous woodborer holes had a higher probability of being colonized by ants. The C:N ratio was lower for dead wood colonized by ants than for noncolonized dead wood, showing that the continuous occupation of dead wood by ants influences the carbon and nitrogen dynamics of dead wood after wildfire in northern boreal forests.

Insects are the most diverse group of organisms on Earth with 952,794 described species (Roskov et al. in Species 2000 & ITIS catalogue of life, 2021). They account for 85% of arthropod species, 67% of animal species and 47% of all species currently known on the planet (Roskov et al. in Species 2000 & ITIS catalogue of life, 2021).

The whitespotted sawyer, Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae), is one of the most damaging wood-boring insects in rece