110 



ELEMENTARY FORESTRY. 



only to burst open again the next winter. This alternate burst- 

 ing 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 favorable 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 thinning 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, thinning is im- 

 practicable, 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 seed- 

 ling trees seriously injured by the blow- 

 ing away 4 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 mid- 

 dle of July, at the time of the last 

 cultivation. Sown at this season the 

 oats form a good sod that serves to 

 hold the soil in place until spring, 

 when it is easily broken up by cultiva- 

 tion, but even then the roots prevent 

 the blowing away of the soil. Occa- 

 sional strips of grass are also a pre- 

 ventive of this injury, or mulching may 

 be resorted to. 



Snow Crust. The settling of a 

 snow crust that has formed on the top 

 of deep snow drifts may cause injury to 

 young trees by stripping off their 

 branches and breaking the stems. It 



