Vegetative cover varies widely; alpine environments contain various herbs, lichen and shrubs, whereas the subalpine regions are dominated by tree species such as Alpine Fir and Englemann Spruce. The natural grasslands in this ecozone have not fared well. Most existing prior to European settlement have vanished, thanks to fire suppression, introduced species, and cattle grazing. Extensive wetlands are infrequent in the mountainous portions of this ecozone. On slopes, wetlands are generally restricted to small transitional and non-forested bogs, marshes and skunk cabbage swamps. Much of the valley wetlands have been destroyed by urbanization and agriculture.