Cool temperatures, a short growing season, frequent forest fires, and thin, acidic soils covering permafrost are among the many challenges faced by plants in this ecozone. The open, stunted forests of the Taiga Shield are dominated by a few highly adaptable tree species such as Black Spruce and Jack Pine. These forests are mixed with innumerable bogs and other wetlands, scattered stands of Paper Birch and Trembling Aspen, and bare rock outcrops dominated by colourful lichens and ground-hugging shrubs.
Forest fires add to the distinctive mosaic of the Taiga Shield by creating a patchwork quilt of plant communities that vary widely in species composition and age. Although fire often destroys large areas of forest and occasionally threatens human activities or property, it also has a renewing effect on the landscape by triggering new growth, purging forests of insect pests and disease, and increasing the variety of habitats available to wildlife.
Permafrost is another major influence, especially in low areas where the soggy ground or active layer above the permafrost regularly freezes and thaws. As trees grow in these ever-shifting soils, they often tip in random directions, giving the impression of a "drunken forest."