EXPERIMENT STATION BULLETINS. 



477 



White pine wimlbreali at East Lansing, 22 years old. There are two rows of trees, the 

 average height of which is 29 feet. 



WrNDBflEJiBAICS 



Windbreaks or shelter belts are useful in diminishing evaporation 

 from soil and plants. The influence of a Avindbreak is proportional to its 

 height and density. The shade cast by the trees has, however, a dam- 

 aging efl'ect on crops and the roots of the trees, if far reaching, may sap 

 the soil moisture for some distance on either side. Species should, 

 therefore, be used which have compact or deep reaching root systems. A 

 windbreak can be used for the production of fence posts or poles. From 

 the white pine windbreak at the College the seed is collected each seed 

 year, in 1918 one hundred pounds of seed being obtained, worth at that 

 time |2 a pound. 



For windbreaks a tree that retains its lower branches and which 

 makes a dense screen is desirable. It is also usually desired to use an 

 evergreen which retains its foliage all winter and to use a tree that 

 grows rapidly and which will give quick results. Of such trees the 

 Norway spruce, Scotch pine, Austrian pine and, where there are no 

 currant or gooseberry bushes in the neighborhood, white pine are the 

 best. For windbreaks it is best to plant a double row of trees, alter- 

 nating the trees in the rows and spacing them about 10 feet apart in 

 the row with about 8 feet between the two rows. If a single row of trees 

 is used a closer spacing is necessary so that the branches will interlace 

 and make a dense screen. 



If it is desired to produce fence posts, osage orange may be used. They 

 can be cut back every few years and will sprout from the stumps. Silver 

 maple and box elder are fast growing trees which are sometimes used 

 but the roots are far reaching and the branches are often broken by 

 heavy winds. 



