The secret Sierra: the alpine world above the trees

What is like to live in a place of bare rock, vertical walls, and windswept ledges, where snow covers the ground for much of the year and temperature changes of thirty degrees or more is the daily norm? The Alpine Sierra Nevada, the rugged mountain world above treeline, presents this challenge to all living things venturing into its extreme environment. From the tiny meadow vole to the delicate alpine flower growing between slabs of broken rockfall, all that live within this diverse, thin-aired landscape have developed specialized adaptations just to survive.