Rocketing numbers of pine beetles have decimated areas of forest from British Columbia to Colorado so large they can be detected by satellites, authorities say.

NASA says scientists use Landsat satellite imagery to map these pine beetle outbreaks and determine what impact the beetle damage might have on forest fires.

University of Wisconsin forest ecologists compared maps of areas hardest-hit by the beetles with maps of recent fires. Their preliminary analysis indicates large fires do not appear to occur more often or with greater severity in forest tracts with beetle damage. In fact, some beetle-killed forest swaths may actually be less likely to burn.

The results appear counter-intuitive, researchers say, but make sense when considered more carefully.

Green pine green needles appear to be more lush and harder to burn, but they contain high levels very flammable volatile oils. When the needles die, those oils begin to break down. As a result, depending on weather conditions, dead needles may not be more likely to catch and sustain a fire than live needles.

Both the beetles and fires hold the potential to significantly change Rocky mountain forests, Wisconsin forest Phil Townsend says, but both are also key to forest health.

"Both fire and beetle damage are natural parts of system and have been since forests developed," Townsend said. "What we have right now is a widespread attack that we haven't seen before, but it is a natural part of the system."