The closely packed clumps of tall, spire-like trees you see across these meadows are sometimes called "tree islands." They start when a seedling, usually a subalpine fir, finds enough shelter near a rock or plant that it can become established. That seedling may then shelter other seedlings and a tree island starts to form. 

Tree islands moderate the climate for seedlings in many ways. In winter their flexible branches provide shelter from winds and cold nights. Less snow accumulates under tree islands than in open meadows. On sunny days the dark trees are heated by the sun, speeding the melting of snow beneath them in springtime. This results in a longer growing season for plants near tree islands, than for plants in open meadows.