pinus albicaulis

Why does this subalpine fir have no branches on one side?

Why does this subalpine fir have no branches on one side? Is it because of rockslides and avalanches? Or wind? Or plant hormones? It appears to me that biologists have not yet come up with a conclusive answer.

Subalpine larch: the "coolest" tree in the Pacific NW

What is a tree that lives only in the coldest and harshest ecosystems at timberline in the northern Cascades?