42 ELEMENTARY FORESTRY. 



strip of land near it in permanent meadow or use it for a 

 rotation that does not take in crops that require very early 

 planting. But even with spring planted grains it is more than 

 probable that windbreaks properly planted are an advantage 

 when their benefits are considered for a series of years. It 

 ofttimes happens that low windbreaks are more beneficial 

 than high windbreaks in holding the snow on the land, for the 

 high windbreaks often form a great drift that may remain late 

 in the spring, while the low windbreak nowhere forms a large 

 drift, but spreads the snow for long distances. Professor 

 Budd says that in parts of the great continental plain of Rus- 

 sia, where the climatic changes are much the same as in this 

 section, the use of low windbreaks in wheat fields is very 

 common. 



Height of Windbreak. From the preceding paragraph it will 

 be seen that low windbreaks may often serve a better purpose 

 than high ones in protecting fields. Exactly what is meant 

 by a low windbreak may be an open question, but for the 

 purposes of this discussion a low windbreak may be consid- 

 ered one under twenty feet in height. In Russia and at the 

 experiment station at Indian Head, Manitoba, windbreaks of 

 Artemisia tobolksiana, which seldom grows more than eight 

 feet high, are often used. About farm buildings windbreaks 

 cannot be too high, and for this purpose the largest, longest 

 lived trees should be used. 



Kinds of Trees for a Windbreak. In too many instances too 

 many tree planters on the prairies have put out exclusively 

 quick-growing, short lived trees, such as the Cottonwood and 

 Lombardy Poplar and after fifteen or twenty years they have 

 found their trees dying and nothing coming on to take their 

 places. The quick growing kinds are very desirable as a 

 protection for the near future, but they are often short lived 

 and should never be planted alone. Among them should be 

 planted a sufficient number of long lived and perhaps slower 

 growing kinds to afford protection in later years when the 

 short lived kinds have died out. The soil and location have 

 much to do in determining the longevity of varieties; for 

 instance, the Cottonwood and Lombardy Poplar are generally 

 short lived trees when planted in this section, but when 



