CLIMATE AND TREE GROWTH 113 



of 50 feet or so, up to 1500 feet, but, on the other hand, 

 thin soils and exposed aspects cease to produce timber at 

 700 or 800 feet, and the nearer the western coast-line is 

 approached the more this statement holds good. On 

 average soil it may be said, in a general way, that the 

 production of commercial timber of such trees as larch, 

 spruce, and Scots pine ceases on western aspects at eleva- 

 tions of 300 feet within twenty miles of the west coast- 

 line of Ireland and Scotland. Silver fir, Corsican pine, 

 etc., may succeed somewhat higher, but neither of these 

 species is much afTected by wind. Farther east, and on 

 sheltered aspects, these elevations may be increased by 

 200 or 300 feet in each case, and possibly more when 

 larch and spruce are alone considered, as these species 

 usually fail at high elevations in Britain more on account 

 of wind than lack of warmth during the growing season. 

 Fifty miles from the western coast-line a further increase 

 in elevation may be accompanied by fairly good timber 

 production, until, as already stated, it ceases at about 800 

 feet on exposed, and 1200 feet on sheltered aspects. 



In the Harz Mountains, lying within the same degrees 

 of latitude as Wiltshire and Dorsetshire, spruce produces 

 crops of timber at 2000 feet, containing 8000 to 10,000 

 feet per acre, and reaching a height of 95 to 100 feet. 

 In the Thuringerwald, in slightly lower latitudes, similar 

 crops are obtained. In the Belgian Ardennes second-class 

 localities for spruce, silver fir, etc., are found at 2000 

 feet. In the Black Forest, Bavarian Alps, Bomherwald, 

 etc., useful timber can be grown at 3000 to 4000 feet, 

 elevations which, of course, do not occur in Great Britain 

 to any extent. Going farther north the mountains of 

 Norway produce timber, of Scots pine and spruce, up to 

 1500 or 2000 feet, owing to the hotter summers and 

 greater length of the days during the months of June 

 and July. The absolute limits of tree growth in the Harz 



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