FOREST PROTECTION 95 



form a very resistant barrier to wind, having long adapted 

 themselves to their environment by the formation of powerful 

 root-fastenings. A very important measure, and one con- 

 stantly employed in systematic woodland management, is to 

 arrange the fellings into a series whereby clearings always 

 proceed from the east or north-east to the west or south- 

 west. A forest block thus treated is composed of graded 

 steps the woods of different ages ; in it the oldest are found 

 on the east side, and the youngest on the west (see Fig. 30, 

 p. 138). 



A shelter-belt may be produced and maintained along ex- 

 posed borders of woods by thinning, from youth onwards, 

 the fringe of say thirty to forty feet of the plantation, so that 

 stout, thickly branched, storm-resistant trees result. Instead 

 of laying bare a young wood by felling part of the forest 

 close beside it, from which in the past it has received pro- 

 tection, a severance-cutting is sometimes made. A strip of 

 twenty to forty yards broad is cleared from the portion that 

 is shortly to be utilised, in order to encourage the margin 

 trees of the younger wood to develop stronger root and 

 branch systems. When possible, severance-cuttings should be 

 made at right angles to the direction of the prevailing wind, 

 and when the woods are in the pole-forest stage of growth. 



Felling operations in large even-aged forests are greatly 

 facilitated by these severance-cuttings. 



Snow. Damp snow falling in large flakes clings to trees, 

 and in the case of Pine and Spruce it is apt to form one 

 continuous cover or layer upon the crowns of a close forest. 

 This, owing to its great weight, bends and breaks the trees, 

 the danger being increased if frost follows the snowstorm and 

 prolongs the period that the trees have to sustain the burden. 



Evergreen conifers from twenty to sixty years old are 

 those which suffer most. In Germany it is found that forests 

 growing between 1,200 and 2,200 feet altitude are more 

 subject to injury than those at either greater or less elevations. 



Broad-leaved forest trees are able to resist damage from 

 snow through being without foliage in winter ; with them 



