JAMES C. SPACE 



1 . 9622 

 I2R312 



UNITED STATES DEPARTMENT OF AGRICULTURE 

 FOREST SERVICE 



immmufi forest & raue EXPERmm snr/oiv 



OCDEN UTAH 



No. 66 May 1959 



EFFECTS OF A WILDFIEIE ON MORTALITY AND GROWTH OF YOUNG 



PONDEROSA PINE TREEsi ^ 



Donald W. Lynch^/ 

 Division of Forest Management Research 



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Despite the present significant accomplishments in fire prev^tionT V7ild- 

 fires do occasionally burn through valuable young stands of ponderosa {^ine 

 timber. Prescribed burning, too, is sometimes practiced in order '-rl) reduce 

 fire hazards, to eliminate logging slash, or to thin young stands .'^ Whether 

 the fire is accidental or planned, foresters should be able to appraise its 

 effects on future mortality and growth. Few fires, even those that burn out 

 of control, kill every tree in the stand. Damage ranges from a mild scorching 

 of the lower branches on some trees to a complete crown burning and severe bole 

 injury on others . 



Ponderosa pine usually is classed as a relatively fire-resistant species. 

 Flint (I) as early as 1925 evaluated fire resistance of northern Rocky Moun- 

 tain conifers on the basis of bark thickness, root habit, resin content of 

 bark, branching habit, stand habit, and relative inflammability of foliage. 

 He classed ponderosa pine second only to western larch in fire resistance on 

 the basis of all these characteristics. Starker (4) listed ponderosa pine 

 third on his list of fire-resistant trees of the Pacific Northwest; he ranked 

 western larch and Douglas-fir first and second, respectively. 



A study of fire damage in a ponderosa pine forest in Arizona (2) showed 

 close correlation between mortality and length of live crown destroyed in 

 poles and mature timber. No trees that had 50 percent or less of their crown 

 burned were dead 16 months after the fire. Where more than 60 percent of the 

 crown was killed, 64 percent of the trees were dead; and where 80 percent and 

 more of the crown was killed by the fire, 80 percent of the trees died. Other 



l_/ Grateful acknowledgment xs made to Henry Wershing, formerly Forest 

 Supervisor, Colville Indian Agency, for helping in the establishment, photo- 

 graphing, and subsequent observation of the study plot. 



2/ Forester, Intermountain Forest and Range Experiment Station, Forest 

 Service, U . S. Department of Agriculture, Research Center at Boise, Idaho. 



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