Complex sentence: The bark of the lodgepole pine is fairly thin, minimizing the tree's defense to fire; however, the heat of these closed-cone pine forest rejuvenating fires open the cones to release the seeds.
Split into simpler sentences: The bark of the lodgepole pine is fairly thin, minimizing the defense the tree has to fire. The heat of these closed-cone pine forest rejuvenating fires open the cones to releasing the seeds.