Stand density, on the contrary, appeared to affect severity of spiral grain (table 7). Of 

 the 10 trees having a spiral grain ratio of 1:10 or more severe, 9 occurred in open -grown 

 stands. Trees having a spiral grain ratio of 1:11 to 1:20 were also more numerous in open- 

 grown stands. 



Table 7. - -Relation of direction and severity of spiral grain to stand density 



Stand 



density 



Grain slope direction 



Left \ Right \ Straight 



Grain slope ratio 



1:10 or 



more severe 



1:11 to 

 1:20 



1:21 or 

 less severe 



Number of trees 



Open 

 Dense 



52 

 47 



91 

 86 



7 

 17 



42 

 26 



99 

 123 



Total 



99 



177 



24 



10 



68 



222 



Although table 7 does not show any apparent effect of stand density on direction of spiral 

 grain, a more detailed analysis of the data showed that stand density had a very marked effect. 

 Western larch is a very intolerant species; as a result, stand density strongly affects both 

 diameter growth rate and length of live crown. Although diameter growth rate was not meas- 

 ured, live crown length in percent of total tree height was recorded for each tree. All trees 

 having a spiral grain ratio of 1:50 or more severe were sorted out and examined more criti- 

 cally. When the ratio of number of trees having left-hand spiral grain to the number of trees 

 having right-hand spiral in each crown-length class was plotted over crown length, figure 1 

 resulted. This shows a very striking relation between crown length and direction of spiral 

 grain. By inference, this figure suggests a definite relation between stand density- -and hence 

 diameter growth rate--and direction of spiral grain. Trees in open stands, i.e., trees with 

 long crowns and rapid growth rate, tend to have grain that spirals to the left. Trees in very 

 dense stands, i.e., trees with short crowns and slow diameter growth, tend to have grain that 

 spirals to the right. 



Experimental Pole Farm at Newport, Washington 



A study designed to establish the correlation between spiral grain and the twisting of poles 

 was installed at Newport, Washington, during August 1952. This consisted of 40 poles --2 rep- 

 lications in each of 20 categories. The selected poles represented four degrees of seasoning 

 (green and air seasoned 1, 2, or 3 years) and five classes of spiral grain (straight, left severe, 

 left moderate, right severe, and right moderate). The poles classified as "straight grain" had 

 a slope of grain of 1:201+; moderate spiral had a slope of grain between 1:35 and 1:65; and 

 severe spiral grain had a slope of grain less than 1:15. Distribution of the sample poles is 

 shown in table 8 . 



The selected poles were either 40 or 45 feet in length and of pole class 3, 4, or 5. All 

 poles were butt treated and set in the ground approximately 6^ feet. The poles were positioned 

 in two rows, extending east and west, on either side of a railroad rail, and approximately 6 

 feet from the rail. A pipe was attached at the crossarm position of each pole with the pipe end 

 directly above the rail. A line and plumb bob was attached to each pipe end, and the iron rail 

 was marked to show an original point for each pipe . Subsequent measurements were based on 

 the departure from this reference mark (16). 



8 



