What is the Tree Line?

Nothing gets me as excited as when I am walking with my owners in the Rocky Mountains and we reach a point high up in the mountains when we are above the trees!  I love when we climb up to that point that trees can no longer grow and the only thing growing are some hardy lichens and herbs.

dog fish 1I love it – the amazing views, the sharp light, the harsh sun on a sunny day, the boulder fields and scree slopes.

I don’t know what it is, but it seems like everything is extra special there.  It always seems so magical to be above the tree line.

I guess, it could have something to do with the fact that usually when I get above tree line it is after a long, long hike and I am exhausted.

But, why is there a tree line, and why is that tree line at different elevations in different areas?

There is a lot that comes into play, but basically at some point the climate (the weather in an area over the year) is just too harsh for trees to survive.  It is a combination of things including too cold, too short of a growing season, too much snow and ice, or too windy, but possibly the most important factor is just that it is too cold for trees to survive.

mount elbert.jpg

Mount Elbert in Colorado – notice the areas above tree line towards the top of the mountain.

Tree line is not however a straight line that runs around a mountain.  In other words, it is not an abrupt transition from trees to no trees.  Tree line is different at different areas around the mountain depending on the specific location.  For example, certain areas may be more sheltered from wind, which would allow trees to grow higher there.

Or tree line may be different for the different sides of the mountain – for example, the side of the mountain that faces south may have a higher tree line than the side that faces north because the south facing side receives more sunlight (in the Northern hemisphere including the Rocky Mountains).

Tree line is also different in different areas of the world.  In Mexico tree line is at roughly 13,00o feet, in the southern Rockies (around Grand Teton National Park) tree line is at 10,000 feet, and in Alaska tree line ranges from 0 feet (sea level) to 4,000 feet.

Tree line tends to be higher in areas that have a warmer climate.  The equator is warmer than the north pole, so in general those areas that are closer to the equator (Mexico) have tree line at higher elevations than those areas farther from it (such as Alaska).

Anyhow, wherever you happen to be, in the Rockies, Mexico, or Alaska, tree line and the area above it is a magical place.  I think partly what makes it so magical is the fact that the time to visit above tree line when it is snow free is short.  You know that you are getting a glimpse into this other worldly place during the summer.  Enjoy it.