AN ECONOMIC STUDY OF ACACIAS. 37 
need only to be watered every evening and to be thinned so that the 
plants will stand an inch or so apart. 
SPROUTING AND LAYERING. 
All the tanbark wattles sprout readily from the stump, and this 
method of crop reproduction is especially valuable when acacias are 
grown for firewood. The sand-reclaiming acacias will root even from 
the recumbent stems. This helps them to spread over the ground. 
This natural layermg process can be aided by slashing the lower 
branches, bending them down, and covering the gash with earth. 
A. saligna and A. longifolia thus treated spread almost as well as 
willows. 
GENERAL CONCLUSIONS. 
The most important fact derived from an economic study of 
acaclas In California 1s that after some fifty years many species of 
acacia have proven themselves to be entirely at home over large 
areas, and have in fact become naturalized. They are worth the 
careful investigation of tree planters and foresters, for they fill a 
place which is not occupied by any other group of exotic trees. 
Since many of them make only slight requirements on moisture and 
soil, their cultivation need not interfere with that of other exotic 
trees for special products, such as the Japanese chestnut, cork oak, 
camphor tree, date palm, eucalypts, algaroba or carob, and maritime 
pine. 
The unique field occupied by acacia tanbark and by some other 
products, especially the gums, and the usefulness of the best acacia 
“woods would seem to justify the general conclusion that plantations 
properly located and managed are as likely to prosper in America as 
in other countries. But before extensive commercial operations are 
decided upon there is need for more complete and painstaking work 
upon the acacias—their growth and their products—the study to 
be based upon American-grown trees. As yet the rates of growth’ 
and the yields of various species on different soils, especially under 
plantation conditions, are not definitely determined. Unless such 
preliminary scientific investigation is undertaken and its evidence 
accepted, it is likely that industries based upon acacias may be 
exploited too hastily, and, therefore, present failures will give set- 
backs such as have resulted where the culture of any particular tree 
has become a fad. These failures are likely to do much to deter 
properly qualified persons from entering upon an industry which 
should ultimately become established on solid foundations. 
So far, acacias have been planted in the United States simply as 
ornamentals, and the information secured from a study of these 
specimens has been chiefly cultural. They have proved that the 
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