Individual, though often stunted, trees may grow above tree line up to what is called the species line. These three zones usually occur within a hundred vertical feet of one another.

), Smith made this map, originally posted on Popville, of all 157,547 street trees. See the map. It’s pretty impressively detailed — zoom in on each colored dot to see what genus of tree it represents ...

First a word of explanation; the 'tree line' marks the beginning of the 'Alpine Zone', the area where the climate is too harsh to permit tree growth. It varies in Washington state, ranging between ...

Bristlecone pine and limber pine trees in the Great Basin region are like two very gnarled, old men in a slow-motion race up the mountaintop, and climate change is the starting gun, according to a ...