34 
BULLETIN 933, U. S. DEPARTMENT OF AGRICULTURE. 
factory development of plantations. It affects the crown density 
and directly limits the number of trees to the acre under which the 
proper growing conditions may be maintained and the best material 
produced. The number of trees to the acre required to maintain a 
continuous crown coyer is. of course, largest in the early history of 
a plantation and decreases with age, either naturally, through the 
crowding out of the less rapid growing individuals, or under manage- 
ment through their removal in thinnings. In the case of walnut 
close spacing (see " Spacing," p. 42) at the start is more practicable 
than with many other species, because of the relatively low cost of 
nuts and planting. This close spacing tends to reduce, although it 
can not always prevent, the profuse branching of the trees at a 
height of about 6 feet. When, however, the crowns commence to 
crowd each other badly, some beginning to take the lead and others 
to fall behind, it is poor economy to maintain such a density, and 
thinnings become imperative. Left to themselves, these even- aged 
plantations develoj) so uniformly that the dominant trees do not 
much exceed their lesser neighbors in height, the thrift of the whole 
stand is lowered by mutual suppression, and the stand is in a' condi- 
tion of stagnation. Ultimately, the crowns become very much re- 
duced and stag headed, and water sprouts come out profusely on the 
trunks. These water sprouts grow slowly until the tree dies or is 
released by the death of neighboring trees: whereupon the sprouts 
take a new lease of life, and the tree develops into a topless branchy 
stub of no use for any purpose. 
The combined effects of poorly chosen site and overcrowding are 
shown in a plantation in Jackson County. Mo. Although the plan- 
tation is 82 years old, few of the trees are merchantable. The stand 
is situated on a hilltop, which, in this western region, is too dry for 
walnut ; consequently, the trees of the outermost row, exposed to full 
light on one side, have poor development, branch low. and are prac- 
tically worthless. The effects of overcrowding upon the condition 
both of the trees inside the plantation and of those in the outer row 
may be summarized as in Table 14. 
Table 14. 
Average 
diameter 
breast 
high. 
Percentage of total number of 
trees. 
Healthy. 
Water 
spouted. 
Decayed. 
Outer row 
Inches. 
17.1 
12. 7 
65 
34 
IS 17 
63 a 
