Trees in the subalpine must find ways to survive and grow with long periods of deep snow. One way to manage this is by growing in clusters. The original trees in each group become established in longer periods of warm growing seasons and provide shelter and warmth required for the survival of nearby seedlings. Extreme winters limit the growth potential of trees when they stand individually, which is why the biggest trees at this elevation are those growing in clusters. As you continue uphill on the switchback, you'll be surrounded by many trees with crooked trunks. Both the mountain hemlock and subalpine fir are quite flexible. Under heavy snow loads, small trees may bend to the ground. If a tree is held in this position for a long time, the trunk adjusts to the strain and becomes permanently bent.