DISCUSSION AND 

 CONCLUSIONS 



At Coram the terrain was fairly steep and not 

 entirely ideal for skyline yarding; also some de- 

 manding removal specifications were applied to 

 some units. Despite this, shelterwood trees came 

 through pretty much intact, and we feel that the 

 following factors will influence the amount of 

 damage incurred in similar situations: 



1. Damage to leave trees is related to stand 

 conditions. The fewer trees in the stand and the 

 fewer marked for leaving, the less the damage. 

 Curiously, though, the number of trees actually 

 killed was only weakly related to cut volume. 



2. Damage is related to the logging specifica- 

 tions. We expressed this as "expected damage," 

 which collectively included utilization specifica- 

 tions and understory protection requirements. 



3. Damage appears to be related to slope 

 steepness, cross-slope angle to the skyline, and 

 load capacity of the skyline setting. Data only 

 moderately supported this idea, but observations 

 tell us these three factors are important and could 

 be more precisely assessed with different ap- 

 proaches to study. 



4. On portions of cutting units where protection 

 of the understory was specified, two factors in- 

 fluenced damage. Fewer understory trees were 

 damaged in the shelterwood units than in group 

 selection orclearcut units(but data are too limited 

 for statistical validity). In all types of cutting units, 

 the larger the understory tree, the greater the 

 proportion sustaining serious or fatal damage. 

 This was true even though small (seedling) trees 

 were much more numerousthan poles. Apparently 

 larger trees are less resilient and thus more easily 

 damaged than small trees. 



As cautioned at the outset, these findings are 

 based on a "case study" approach, but should be 

 useful as a first estimate of likely damage under 

 similar conditions. We would suggest that to refine 

 these data, studies be specifically designed to 

 monitor logging damage and operations, for ex- 

 ample, to separate damage from falling, lateral 

 yarding, main line lifting and hauling, and so on. 



15 



■fc U. S. GOVERNMENT PRINTING OFFICE: 1981 -777-028/72 REGION NO 8 



