The Detwiler Fire exploded in size over the last few days, but this fire may behave differently because of what it is burning.

Let's go back to the beginning of the 2011 winter season to understand what is happening. Following the last big rain and snow season in 2010-11, the Sierra and California had all the water it needed, and life was good.

Beginning the following season, the pattern changed and we began a four year major drought. The Central and Southern Sierra was hit especially hard with very warm temps and dry conditions.

This was the bark beetle's opportunity to take off and it did. Various droughts and warm winters are allowing the bark beetle in the Sierra and Rockies a rare opportunity to grow it's population. Cold wet winters will cut the populations down, but we have seen the same thing all over the west. The bark beetles burrow into the trees and kill pines and other species. The result is a patchwork of healthy forests with millions of dead and dying trees intermixed, making the problem difficult to manage.

Dead trees in the path of growing fire

Some estimates claim the drought helped the bark beetle kill millions of trees in the Sierra and create a situation that forest managers have never seen before.

There are many programs to help promote tree removal by loggers and other groups, but it's not an easy problem to tackle. Trees are big and heavy and the equipment needs to match the problem. In many cases, it simply isn't realistic to remove the trees next to healthy trees in steep and rugged terrain or trees that are no threat to life or property.

They do remain a hazard, however, for fires and that's what makes the Detwiler Fire dangerous to forecast. A dead tree can be very explosive when it comes to fire growth because the wood can burn hotter with the lack of moisture in the bark and limbs.

I've been to Mariposa on the way to Yosemite and when you see it with your own eyes it is hard to put into words. The forests nearby have been devastated by the bark beetle and there are dead and drying trees everywhere. This is the exact terrain the fire is burning in now, and as it gets closer to Mariposa will only complicate the already difficult days ahead.

Rob Carlmark