Chapter 11 - Boreal forests

Abstract

Boreal forests are the northernmost forests on the planet, dominated by species of spruce, fir, larch, pine, birch, and aspen, with large tracts of intact primary forest, as well as industrial forests, frequently logged for timber and pulp for paper and packaging products. Natural disturbance regimes include large, high-severity crown fires resulting in even-aged mosaics of pine and birch-aspen forests, frequent surface fires with uneven-aged larch and pine forests, and infrequent fires, where gap dynamics caused by insects, windthrow, and disease create uneven-aged conifer forests. Boreal forests grow at high latitudes where large magnitudes of warming are expected. They are subject to multiple mechanisms of change in a warming climate, including the susceptibility of trees to drought and heat stress, increasing insect infestations, increasing frequencies of fires and compound wind and fire disturbances, and more infestations of invasive species. With a high-magnitude warming scenario, changes would include replacing the dominant conifer species with birch and aspen and replacing boreal forests along the southern margin of the biome with temperate forests or grasslands.