Northern Arizona forests are being reshaped as part of a complex wildfire-prevention effort.

Some areas are being thinned mechanically while others are blackened intentionally by fire as part of the 2.4 million-acre Four Forest Restoration Initiative. The project made a major leap forward recently when nearly 600,000 acres were cleared for restoration.

The project is the largest of its kind within the U.S. Forest Service. It aims not only to lessen the chance of catastrophic wildfires but return the forest to conditions ideal for wildlife, streams and cultural resources.

The Forest Service has about two dozen similar efforts nationwide, mostly in in the western U.S., that reflect a focus on speeding up the pace and scale of forest-restoration work.

The first priorities often are in watersheds and the urban interface.