134 FOKESTS, WOODS, AND TKEES 



slender. The Thuya also greatly improved the soil by its 

 thick layer of decaying leaves. Natural seedlings of both 

 species were very numerous and vigorous in open spaces. 

 Partly blown down and partly felled, the plantation 

 yielded, 36 years after planting, 7430 cubic feet (quarter- 

 girth measurement under bark), or an average annual 

 increment of over 200 cubic feet per acre. In wet climates, 

 as at Benmore, where the rainfall is over 100 inches, this 

 mixture of Douglas fir and Thuya yigantea may be tried 

 with success. 



Douglas fir has so far been fairly free from insect or 

 fungus attacks, but this immunity may not continue. As 

 a precaution, extensive continuous plantations of this tree 

 should be avoided ; these should be interspersed with belts 

 or clumps of beech. Douglas fir is of remarkable utility in 

 what may be called interplanting, that is, filling up gaps 

 in ordinary woods that happen to be thin and poorly 

 stocked. It is also invaluable for converting coppice or 

 coppice with standards into ordinary high forest, as it usually 

 thrives on soils which carry coppice and in a short time 

 suppresses by its vigorous growth the coppice shoots. 



Home-grown timber of Douglas fir ranks in quality 

 between Scots pine and larch ; but it surpasses both in 

 dimensions, and is more valuable than either when properly 

 grown in dense plantations. It is equally durable with 

 larch, the proportion of heartwood at 50 years old being 

 about 70 per cent. It converts well, keeping straight when 

 long sizes are sawn ; and if carefully stacked it dries 

 quickly and is not liable to warp. It is somewhat lighter 

 in weight than spruce. Home - grown timber has been 

 used on the Scone estate for gates, doors, and fencing ; and 

 was sold for railway sleepers and pit timber. Grown on a 

 long rotation, the timber will be found suitable for carpentry 

 and joinery. 



Common Spruce. — In addition to the common spruce, 

 Picea excelsa, which is a native of continental Europe, there 

 are two other species of the genus of value to foresters, 



