factors correlated with tree mortality were turpentine beetle attacks follow- 

 ing the fire and intensity of the fire itself as measured by surface conditions 

 around individual trees . 



Wiener's (6) extensive studies of mortality following fire in mature 

 ponderosa and Jeffrey pines showed several definite conclusions. He found 

 that trees were most vulnerable to fire injury during the active spring growth 

 period when terminal shoots and buds are tender. He determined that mortality 

 of ponderosa and Jeffrey pines is more closely correlated with bud kill than 

 with foliage kill. Fires that occur late in the season, after buds have formed 

 and hardened, often kill foliage but do not kill buds. If 50 percent of the 

 buds are uninjured, the tree is likely to survive. Wegener further concluded 

 that vigor of individual trees was an important factor in determining survival 

 following fire as well as determining disposition to insect attack. 



All the four studies cited above were made on large trees--principally 

 sawlog material--with the view of aiding in salvage cutting operations. The 

 same important questions apply to young stands. Just how much fire can a 

 young ponderosa pine tree withstand and still live? How much increment will 

 be lost from scorched trees? How soon will they recover? 



Answers to some of these questions were sought on an area on the Colville 

 Indian Reservation, Washington, that supported a 30- to 40-year-old stand of 

 ponderosa pine that was burned by a wildfire in July 1949. In September follow 

 ing the fire 200 trees were selected for observation and study; they ranged in 

 diameter from 2 to 12 inches (only a few of the trees were larger than 7 inches 

 d.b.h.); the variation in burning damage was from "little" to 100 percent crown 

 scorching. Diameter, heights, and crown classes were recorded, and the trees 

 were tagged. Injury was evaluated on the basis of the percentage of crown 

 killed, and the 200 trees were grouped into eight damage classes by percentages 

 as follows: 0-24, 25-49, 50-59, 60-69, 70-79, 80-89, 90-94, and 95-100. At the 

 time of the first observations the scorched needles, dried to a bright yellow 

 color, were still retained on the trees. The extent of crown injury was 

 readily apparent (fig. 1). 



Tree mortality was observed and recorded in the fall of 1950 and 1951, 

 1 and 2 years after the fire. In 1957, 8 years following the fire, a final 

 check was made on mortality, and diameters and heights were remeasured .— ^ 



3/ Raymond J. Boyd and Albert R. Stage, foresters, Intermountain Forest 

 and Range Experiment Station, Forest Service, U. S. Department of Agriculture, 

 Research Center, Spokane, Wash., made final measurements for this study. 



2 



