CORVALLIS, Ore. -- A new study of forest lands that burned in the 1990s in northern California and southwestern Oregon has concluded there is a "fair to excellent" chance that an adequate level of conifers will regenerate naturally, in sites that had no manual planting or other forest management.

The research, to be published Wednesday in the Journal of Forestry by scientists from Oregon State University, examined the recovery of conifers on 35 plots that had burned in wildfires from 9 to 19 years ago, and generally found a high level of naturally-regenerating tree seedlings.

Although the abundance of natural regeneration appeared to be variable and growth often slow, there was no evidence of recent conifer mortality or suppression leading to seedling death.

Total conifer density and the types of tree species varied quite a bit depending on elevation, but the density of surviving conifer seedlings was as much or more than typical densities in 60-100 year old stands in this region, which is about 100 to 1,000 trees per acre. Traditional old growth forests of this region, with trees 250 or more years old, often had as few as 20-40 large trees per acre.

About 10 percent of the plots studied already had larger trees that were considered "free to grow" by forestry standards. The scientists said the height of competing shrubs had "quite likely" slowed after one or two decades, and "we predict that conifer mortality will remain low and height growth will accelerate as individuals continue to emerge above the shrub layer." The study also showed that trees would regenerate at considerable distances from seed sources.

"The natural regeneration on many of these sites is actually much higher than needed to restore a forest," said Jeff Shatford, a senior faculty research assistant in the OSU Department of Forest Science. "We expect that the high density of young trees we observed will thin out naturally over time."