Table 4. -Summary of missing or seriously damaged leave trees by logging characteristics, 



shelterwood units 



Characteristic 



Block 1 1 



Block 21 



Blocks 1 1 and 21 





Acres 



Trees/acre 



/Acres 



Trees/acre 



Trees/acre 



Slope, percent 













0-25 



3.72 



23.9 



0.15 







23.0 



25-50 



20.65 



13.4 



5.26 



26.1 



16.0 



50-75 



9.79 



10.0 



15.00 



20.1 



16.1 



75-100 



0.95 



11.6 



1.19 



32.8 



23.4 



Cross slope angle, percent 













0-15 



15.81 



13.56 









0-15 



15.81 



1 1.0 



6.64 



19.4 



13.5 



15-30 



13.56 



13.9 



4.38 



21.0 



15.7 



30.45 



4.76 



17.9 



4.49 



2.7 



20.2 



45-60 



.39 



18.0 



5.96 



26.5 



26.0 



60-90 



.58 



15.9 



.39 



2.6 



10.4 



Load capacity, lb 













Over 10,000 



18.01 



16.3 



12.25 



22.2 



18.7 



5,000-10,000 



1 1.99 



10.0 



7.51 



22.2 



14.7 



2,500-5,000 



3.44 



7.6 



.50 



16.0 



8.16 



2,000-2,500 



1.50 



14.7 



.19 



21.1 



15.4 



< 1,000 



.16 



6.2 



1.15 



32.2 



29.0 



greater the clearance of the carriage above the 

 ground and, during lateral yarding, this should 

 mean greater control over the movement of the 

 logs. Moreover, during longitudinal yarding, the 

 angle between the logs and ground should be 

 greater— approaching full suspension— and this 

 should reduce the likelihood of damage adjacent 

 to the corridor. 



for the carriage to be relatively close to the 

 ground— at least during the lateral yarding 

 phase— simply because of the limited amount of 

 line for lateral extension in the systems used at 

 Coram. If this is true, then the onset of lateral 

 inhaul would result in pronounced lateral excur- 

 sion of the carriage and supporting cables, which 

 could damage trees adjoining the corridor. 



There is only weaksupport forthis hypothesis in 

 the data from block 21, and it is contradicted 

 somewhat by the data from block 1 1. Combining 

 the data from blocks 11 and 21 indicates that 

 damage is minimized at intermediate load capa- 

 bilities, and increases with both high and lower 

 load capabilities. One explanation may be that 

 above a certain load capability, the potential 

 advantages of large carriage clearance during 

 lateral yarding cannot be realized due to the 

 limited length of dropline. That is, it is necessary 



We also speculate that where load capability is 

 high the system tends to be loaded heavily and 

 operated at high speeds— thereby increasing 

 propensity for damage during both the lateral and 

 longitudinal yarding phases. In any event, we are 

 unable to draw any firm conclusions regarding the 

 influence of load capability on incidence of 

 damage. 



In summary, ourCoram datasupportthe hypoth- 

 esis that damage to residual trees in partial cuts, 



9 



