104 THE DEVELOPMENT OF BRITISH FORESTRY 



above the ground, as compared with that at ground-level. 

 With good wind-resisting species, as ash, beech, Corsican 

 pine, silver fir, etc., the effect of wind is greatly counter- 

 acted by good soil, and timber of respectable size can be 

 grown up to 1000 or 1200 feet in inland counties, but at 

 these elevations good deep soil is, of course, exceptional. 



Much importance is also attached to the fact that trees 

 on the edge of a wood are most affected by wind, and it 

 is assumed that belts of suitable species can render the 

 plantation behind not only immune against wind damage, 

 but are also able to counteract the usual effects of wind 

 upon the growth and height of the trees. On flat land 

 this is, of course, to a great extent the case, and in a 

 plantation of any size the trees gradually increase in 

 height as they recede from the windward edge of the 

 wood. In exposed districts this gradual rise of the tree 

 crowns occurs at an angle of about 45° with most 

 species, trees such as silver fir and ash rising more 

 rapidly. But on slopes facing the wind the effect of a 

 shelter screen upon the ultimate height growth of the 

 trees is very slight. The influence of an older screen, 

 however, upon the young crop for the first few years can 

 scarcely be over-estimated, and success in many situations 

 depends almost entirely upon the provision and mainten- 

 ance of such trees at regular intervals. While, however, 

 much can be accomplished by judicious treatment in this 

 way, the fact still remains that wind is a powerful factor 

 in preventing tall, straight stems, and a prolonged height 

 growth is only possible below the 500 feet contour line, 

 or in situations sheltered by surrounding ground, as in 

 valleys on north-east slopes, and other sites possessing a 

 local climate of their own. 



Given similar soils and situations, and considering the 

 growth of the hardier trees alone, there is probably no 

 great difference between British and continental climates 



