or where there is plentiful supply of moisture below the surface. Its
fuel value is not high, though the quantity of its wood production
compensates for its poor quality, nor does it make good fence posts.
Where quick growth is the main consideration, however, it is a good
tree to plant. The varieties known as Norway and Carolina poplar
are the best.

Green ash and hackberry are also hardy against both cold and moisture,
but of slow growth. Their wood is durable in contact with the soil,
making them suitable for fence posts. Where it succeeds black locust
combines many of the desirable qualities to the highest degree. It
is a rapid grower, makes excellent fence posts and has high fuel
value. It is not as hardy against frost as cottonwood and ash,
and while it has been planted successfully in sheltered locations
on high plateaus, its success where frosts occur during the summer
months is problematical. A closely related species, honey locust,
is more frost-hardy but less desirable in other respects, though an
excellent tree nevertheless. Other fairly hardy and drought-resistant
trees are osage orange and Russian mulberry. Their value for fuel
and fence posts is high, but they will not succeed in the most
severe situations. Box elder is hardy and has been widely planted,
but it is of low fuel value and short lived.

In favorable localities at low altitudes, where moisture is abundant
either through natural precipitation or from irrigation, the number
of species which are adapted to woodlot planting is largely increased.
Black walnut, black cherry and hardy catalpa are probably the most
valuable of these. The latter, however, is sensitive to early and
late frosts.

WINDBREAKS

The planting of windbreaks and shelter belts around dwellings and
fields is of prime importance to the settler in an open country.
Nothing adds more to the comfort of the dweller than a belt of
timber about the home to protect it from the wind. Orchards need
windbreaks to save them from injury in a wind-swept country, and
gardens are more successful when surrounded by trees. One of the
most important functions of the windbreak, however, is the saving of
soil moisture within the protected area, for it is a well established
fact that evaporation takes place more rapidly when there is a
movement of the atmosphere than when it is calm. It is safe to
say that a windbreak is effective in preventing evaporation for
a distance equal to ten to fifteen