FOREST PROTECTION. 



143 



open and growing over may continue for many years , 

 until very conspicuous and peculiar wounds are formed. 

 In such cracks, insects and rot-producing fungi find favor- 

 able lodging-places, and as a result trees are seriously 

 injured, and are liable to decay in the trunk. There are 

 no practical remedies for such injuries. 



Wind. Injuries from wind are common where thin- 

 ning is done to a great extent at one time about shallow- 

 rooted trees, such as Spruce growing on moist soil. These 

 injuries can be avoided only by 

 thinning gradually. In many 

 such cases, on timber lands, grad- 

 ual thinning is impracticable, 

 and it is then best to cut all the 

 merchantable timber, for if left, 

 it is sure to be blown down. 



On our prairies, where the 

 soil is light and easily moved by 

 the wind, it is not uncommon to 

 have young seedling trees seri- 

 ously injured by the blowing 

 away of the soil around the 

 roots, which often leaves them 

 uncovered for three or more 

 inches. This injury usually takes 

 place in the spring, and may 

 be almost entirely prevented by 

 seeding the land to oats about 

 the middle of July, at the time 

 of the last cultivation. Sown 



at this season the oats form a 



, FIG. 51. Old frost- cracks 



good sod that serves to hold in Sugar Maple. 



the soil in place until spring, 



when it is easily broken up by cultivation, but even 



then the roots prevent the blowing away of the soil, 



