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Closed-cone pines are a special type of pine adapted to coexist with fire. These pines have extremely hard, serotinous (pitch-covered) cones. These cones remain on the tree for long periods of time, sometimes so long that the tree trunk may begin to grow around them.

There are only two ways these cones may be opened: in the powerful jaws of a squirrel, or in a fire. When squirrels gnaw open these cones, they usually eat all of the seeds. Seeds released in this way are not a major part of the tree's life cycle, although some may germinate and keep the species alive in times of few fires. However, in a fire, millions of seed are released. Closed-cone pines are extremely flammable, and fires in these forests tend to be crown fires - huge fires which engulf and kill entire trees. These intense crown fires melt the thick layer of pitch surrounding the cones and cause them to slowly open. About the time that the fire has died down, the cones release all of their seeds. The seeds fall to the ashy ground, into an environment with abundant nutrients, few competitors, and ample light. The parent generation may all be dead, but in their fiery death they insure that their offspring will grow unhampered by any competitors.

Since closed-cone pine forests are propagated in single, distinct occurences, one will often find large stands of single-age trees. Since these forests obviously need fire to survive, they will be found in areas which are fairly dry and are prone to occasional lightning strikes, but contain enough moisture to keep pine trees alive. Probably the most suitable habitat for these trees is the coastal mountains of California. Here many closed-cone pines are found, including Knobcone Pine, Bishop Pine, Monterey Pine, and Bolander Pine. There are even two species of cypress which also exhibit the closed-cone phenomenom.

Closed-cone forests are threatened by, among other things, fire suppression. When fires are supressed, these forests grow old and decadent, and when a fire finally occurs, it is disasterous, and may kill the cones. However, changing attitudes towards fire management offer hope for these fascinating trees in the future.