Existing comment:
The brown spots in the trees are caused by bark beetles. Adult beetles burrow into the bark and lay eggs. At the same time, they release pheromones that tell other beetles that this tree is a good target and that attracts other beetles to the same tree. The larva that hatch eat the area below the bark, disrupting the flow of water, sap and nutrients up and down the tree. By the time the pine needles change color to reddish brown, the beetles are gone. There's been a drought in the area which makes the trees less able to defend themselves against these beetles. A healthy tree will immediately release resin that kills off the eggs and hole but drought-weary trees can't do this.
These beetles and brown spots exist throughout this area of the country and they've made quite a few forests plaid. The park service policy on infestations is that they can't do much if the problem is natural. The beetles are native to the area and the drought isn't affected by human actions (although its made worst by the increasing human development of the area). |