144 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



20. Branch-growth of Douglas Fir. 



By M. L. Anderson. 



Examination of a number of Douglas fir plantations will at 

 once bring out the fact that the growth and size of the branches 

 varies considerably in different localities. There seem to be 

 very few actual data available which would help one to a 

 knowledge of the reasons for this variation. We hear it said 

 that the branch-growth depends upon the planting distance or 

 that it is dependent upon the locality factors, but the collection 

 of figures which would help to solve this problem to some extent 

 ought not to be a difficult matter. It is undoubtedly a point 

 of great interest because of its bearing upon timber quality, 

 thinnings and planting distances. The result of a few measure- 

 ments made recently in two Douglas fir woods on Novar Estate, 

 Ross-shire, may prove interesting. 



The first wood, A, on the right bank of the River Glass, one 

 mile west of Evanton Bridge, stands at an altitude of about 

 250 feet. The slope is fairly steep and the aspect is north or 

 north-west. Where the measurements were made the wood is 

 well sheltered. The soil is a deep, friable reddish sandy-loam 

 over Old Red Sandstone conglomerate, and is apparently formed 

 from a sandy glacial deposit. It is free from gravel and boulders, 

 at least in the upper 12 inches. The drainage is, by nature, 

 excellent. 



The second wood, B, lies in the Novar experimental area, 

 about one mile north-west of Evanton Bridge over the Glass 

 and one mile north-east of Wood A. The altitude is about 

 250 feet, the slope negligible and the aspect, if anything, south- 

 east. The part of the wood in which measurements were 

 made is also well sheltered. The soil is a reddish loam about 

 I to 2 feet deep over a layer of white sand of varying depth, 

 over boulder clay from an Old Red Sandstone formation. It is 

 a heavier and probably more fertile soil, but less porous than 

 in Wood A. Rounded stones and small boulders occur. The 

 subsoil is essentially different in nature to that of the first wood 

 and is more retentive of moisture. 



As far as can be seen, the two woods, growing one mile 



