The seed that started this tree landed in a really fortunate place.  The tree is growing much lower in elevation than should be possible.  At 6,300 feet in central New Mexico it is much to dry for Ponderosa pine.  At this level it should be Pinon and Juniper.

How did this happen?  The tree is growing in a drainage.  While it was young there must not have been any years with rainfall heavy enough to roll rocks and gravel down the streambed.  There must have been enough rain in those years for the roots to become well established.  

Now that it is mature only age, disease or man may be a problem.  

This is a closeup of the bark of the tree shown above.  Ponderosa Pine is a fire adapted species and this thick fire resistant bark protects the tree from the heat of quick burning ground fires.  IN fact, the tree "encourages" fire because the needles it drops are very flammable.  The needles don't pack down and dry quickly in the desert air.  

Unfortunately, years of fire prevention have left many Ponderosa Pine forests with such heavy material on the ground ready to burn the resulting fire will be to hot.  The tree can only resist so much heat for so long before it is killed.  

It makes a difficult situation for forest management.