Wildfires that kill all or most of the trees are stand replacement wildfires. When this event occurs at a large scale (especially in excess of 500 acres), it is an unnatural and damaging ecological event in Southwest ponderosa pine. It takes more than 50 years for most catastrophic fire sites to begin growing a forest again. It will take in excess of 250 years before any old growth returns.
Historically. wildfires were low intensity, and frequent, visiting the same acre generally every 4-6 years. Stand replacement wildfires were rare; the largest known fire on the Coconino Plateau was less than 500 acres. There are no known catastrophic wildfires in the ponderosa pine type of any consequential size on the Coconino National Forest until 1947.
Currently.wildfires are infrequent, but of very high intensity. On average, about 50% of a modern wildfire is a stand replacement event, and usually in very large patches from 100’s to 1000’s of acres in size. Annually on the Coconino Forest, an average 1,500 forested acres are catastrophically burned each year. Since 1947, about 40,000 acres have been lost to stand replacement wildfire, or about 5% of the Coconino National Forests ponderosa pine forest type. The rate of acres lost to catastrophic wildfire is increasing at a geometric rate.
How serious is this situation? Simply, we cannot sustain our pine forests with the current rate of stand replacement wildfire. If the current rate of stand replacement wildfire remains the same (indicators are that the rate is increasing!), then half of the pine forest of the Coconino National Forest will be reduced to grasslands by the time the Pumpkin and Pipe fires of 2000 will again support an old growth forest. The ecological loss is staggering: in the vicinity of Flagstaff, a half dozen each of Mexican spotted owl territories and northern goshawk territories were lost or badly damaged since 1994, all in seven short years.