Why can't trees grow in the tundra?

The Tundra biome can't support every tree but that doe'nt mean it has none. In this case the fewer trees that thrive well are usually the ones that have addapt real fast . The cold can reach up to -56 degrees which makes the precipitation fall in sheets of snow (this makes survival a struggle.) The short growing seasons don't help either.

The hard and compact ground can sometimes only support low growing trees for example moss.

Unlike a tropical rainforest, this biome has little nutrience that can help a tree grow.