WINDBREAKS. 49 
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 dis- 
tances. Professor Budd says that in parts of the great conti- 
nental plain of Russia, 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 pur- 
pose than high ones in protecting fields. Exactly what is meant 
by a low windbreak may be an open question, but for the pur- 
poses of this discussion a low windbreak may be considered 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 pro- 
tection 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 Cot- 
tonwood and Lombardy Poplar are generally short-lived trees 
when planted in this section, but when planted in locations 
where their roots reach the permanent water level their period 
of life may be considerably lengthened, and they may then even 
be regarded as long-lived trees. 
In starting a grove or windbreak on the prairie in this sec- 
tion, there is probably no better tree to begin with than the 
4 
