CONCLUSIONS 



Logging damage to understory stands of seedlings, saplings, and poles was not 

 significantly different for two reproduction methods or for two initial volume classes 

 tested on the experimental area. Damage caused by D-8 tractors was the same as that 

 caused by D-4 tractors. Logging damage varied significantly only with level of reserve 

 volume. Damage was low for all methods of logging and management compared. 



The difference between levels of reserve volume could be expected. That is, cut- 

 ting more timber volume requires more trips by the logging tractors. The extra trips 

 might logically be expected to destroy more of the understory stands. The careful 

 planning and laying out of skid-trails plus the cooperation of fallers and skidders on 

 this sale probably held the damage to a reasonable amount. FaLlers were instructed to 

 fall trees uphill or downhill. Cat "skinners" were requested to use the same trail for 

 repeated trips whenever possible. At any rate, it was gratifying to find that heavier 

 cutting need not cause excessive increased damage to advance reproduction. 



Table 2. -- Effects of tractor sizes, reproduction methods, reserve volumes . 

 and initial volumes on logging damage to poles 



Average number of poles per acre 



Treatments 



Before 

 logging 



After 

 logging 



Destroyed b)- 

 logging 



Tractor size 

 D-4 

 P-8 



Re-0roductlon method 

 Stem selection 

 Group selection 



Level of reserve 

 Low 

 High 



Initial volume class 

 II 

 III 



196 

 160 



186 

 170 



166 

 190 



227 

 128 



Number 



172 

 141 



163 

 150 



143 

 170 



199 

 113 



Percent 



12 

 12 



12 

 12 



14 

 10 



12 

 12 



All treatments 



178 



157 



12 



Little difference in damage was caused by skidding with different sized tractors 

 even though many logs were too large for economical operation of the small tractor.— ^ 

 Also, the total damage was nearly the same in stands marked by stem selection and group 

 selection. With stem selection marking, the damage was lighter but covered more area; 

 whereas, with group selection marking, the damage was heavier on clearcut groups but 

 covered less total area. 



The careful planning, training, and supervision of the cutting may be largely 

 responsible for the negligible differences between all the treatments. In fact, the 

 most important conclusion from this study could be that if a logging iob is thoroughly 

 planned and closely supervised, none of the logging and management methods tested here 

 need result in excessive damage to advance reproduction in typical ponderosa pine 

 stands in central Idaho. 



Ij Wilson, Alvin K. , and Gordon H. Greenway. Costs of logging virgin ponderosa 

 pine in central Idaho. U.S. Forest Serv. Intermountain Forest and Range Expt. Sta. 

 Res. Paper 51, 15 pp., illus. 1957. 



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