26 BULLETIN 316, U. S. DEPARTMENT OF AGRICULTURE. 
with sediment, or cut away by the river, is too valuable agriculturally 
to be used for forest plantations. This leaves only overflow lands 
for forest- purposes, and the condition of these is so unstable as to 
make the artificial establishment of plantations too precarious an 
investment to attract capital. The inferior timber on the ground 
and the natural reproduction will therefore continue to be utilized 
instead of better species being planted. Under these conditions the 
probability of success in forest management is greater with willow 
than with cottonwood. 
The main problem in the management of bottom lands is how to 
encourage the best species. In this discussion the lands considered 
are those lying below the 35-foot stage of the river. Above this 
mark the willows are usually replaced by better species. The lower 
areas are covered by a mixture of black willow, cottonwood, and 
sandbar willow, the last being both the most prolific and the least 
desirable. In the management of such areas the only way at present 
of encouraging the best species is to cut intelligently the material 
used in revetment work. By hmiting the cuttings to stands of 
sandbar willow and leaving the cottonwood and black willow, the 
prevalence of the sandbar willow can be much reduced. In mixed 
stands, 7 to 12 years old, where all three species occur, all the cot- 
tonwood and enough of the black willow to stock the ground com- 
pletely should be left. If from 200 to 300 trees of cottonwood or 
black willow be left to the acre, the first crop of willows for revetment 
will suffer but a slight reduction and the second crop of sprout growth 
will receive but little shading from the trees left. The third crop of 
revetment willows will necessarily be smaller, but such a thinning 
can easily be made profitable; then after the period of these two 
crops, ranging from 10 to 15 years, the original trees left will soon 
make a complete canopy. By this method, at practically no ex- 
pense more than directing the cutting of the brush, a worthless 
area covered with mixed growth may be converted into timberland 
of considerable value. In further thinnings the cottonwood, if 
present, should be favored except on land that is receiving large 
accretions. On such land the black willow generally survives the 
cottonwood. 
CHARACTERISTICS OF WILLOW WOOD. 
Willow is characteristically a light wood. It varies considerably 
in weight in different species and under different growing conditions. 
The wood of the slow-growing species and shrubby forms is usually 
heavier than that of the larger and more rapid-growing species. 
The diamond willow is heavier and harder than the other native 
willows of economic importance. There is little difference in the 
weight of the wood of black, white, and crack willows, the specific 
gravity ranging from 0.4 to 0.45. 
