TREES FOR WATER CATCHMENT AREAS 131 



climatic requirements. It has not proved very successful 

 as an isolated, ornamental tree in the milder parts of the 

 British Isles, being prone to Chermes attacks, and often 

 weakened by excessive production of cones. It is much 

 more at home in the colder parts of Scotland, where it 

 promises to be a valuable tree, as it is quite unhurt by the 

 severest frost and is never injured by the heaviest snowfall. 

 At Durris, Ardverikie, and Corrour, it is extremely hardy 

 (Fig. 28) and resists wind better than any other conifer. 

 Planted out on exposed sites, it has done well even on 

 peaty soil. At Ardverikie it is the most vigorous of all 

 the trees that have been planted there, enjoying immunity 

 from fungus and insect attacks and producing natural 

 seedlings in great abundance. Seedlings raised at Durris 

 and Ardverikie from home-grown seed are very vigorous. 

 It does not bear much shade, and fails where there is lime 

 in the soil. In its own home it produces the most 

 valuable timber of all the American silver firs, the wood 

 being heavy, hard, and firm, and working easily and well. 

 At Durris the wood is white and soft, but closer in the 

 grain than that of Abies grandis. 



This species should be planted pure in the protection 

 zone, when this is pushed high up in the heather moor. 

 In this way in the west of Scotland it may be planted up 

 to 1200 or 1300 feet, making a useful belt above the 

 limit of the main-crop trees. It seems to be the most 

 suitable species for use in an attempt to raise the timber- 

 line on exposed sites on peat in the Highlands of Scotland 

 and in the west of Ireland. Useful in this way at high 

 altitudes it should never be planted at low elevations. At 

 Craigo, near Montrose, not far from the coast at a low 

 elevation a plantation of six acres of this species, 40 years 

 old, shows only moderate growth, the trees being about 

 46 feet high by 4 feet in girth. 



Douglas Fir. — This is perhaps the most valuable tree 

 that has been introduced. It produces an enormous volume 

 of excellent timber, and comes to maturity in a short term 



