The Author 



Michael G. Harrington received his B.S. degree in 

 forest science in 1970 and M.A. degree in fire ecology in 

 1977 from the University of Montana. He assisted in fire 

 effects research intermittently at the Northern Forest 

 Fire Laboratory from 1968 until 1977. In 1977, he be- 

 came a Research Forester with the fire effects project in 

 the Rocky Mountain Forest and Range Experiment Sta- 

 tion in Tempe and later in Flagstaff, AZ. While with Rocky 

 Mountain Station, he conducted prescribed fire applica- 

 tion and effects research in Arizona and Colorado pon- 

 derosa pine forests. He transferred to the Intermountain 

 Fire Sciences Laboratory, Intermountain Research Sta- 

 tion, Missoula, MT, in 1 987 where he currently is conduct- 

 ing research on the use of silviculture and fire in forest 

 health restoration. 



Research Summary 



Prescribed underburning was carried out in three sea- 

 sons in a second-growth ponderosa pine stand in south- 

 western Colorado. After burning, 526 trees with various 



levels of crown scorch were tagged and surveyed annu- 

 ally for 1 years to evaluate mortality and subsequent 

 tree fall. Of the 123 dead trees, 75 percent fell within 

 the study period. Even though a smaller percentage of 

 autumn-killed trees fell than spring- or summer-killed 

 trees (62 percent versus 78 percent), the difference was 

 not significant. Fall rate differences were not noted 

 among trees from 2 to 1 6 inches d.b.h. Two factors stood 

 out as significant in evaluating tree fall differences fol- 

 lowing fire mortality: percent crown scorch and length of 

 time between fire injury and death. Trees that died with 

 greater than 80 percent crown scorch had about an 80 

 percent probability of falling within the 1 years regard- 

 less of length of survival after injury. Trees that died from 

 less than 80 percent crown scorch and that died within 

 the first postburn year had a 75 percent probability of 

 falling. However, trees that died from less than 80 percent 

 crown scorch but that survived for 2 or 3 postfire years 

 had a 27 percent probability of falling. Even though this 

 study was relatively short, these findings have significance 

 for those concerned about the quality of standing dead 

 trees for wildlife habitat and about the rate of down, 

 woody fuel build-up after prescribed burning. 



Intermountain Research Station 

 324 25th Street 

 Ogden, UT 84401 



