12 BULLETIN 153, U. S. DEPARTMENT OF AGRICULTURE. 
SPACING. 
The proper spacing for trees in a plantation depends largely on | 
the habit of the species and the character of the site. In general, | 
the more tolerant the trees and the more unfavorable the’site the - 
closer should be the spacing. White pine is so tolerant that it must — 
be planted as closely as 4 by 4 feet, in order to have the lower branches 
killed by shading at an early age. Close-spaced stands must be 
thinned sooner than open-spaced ones, and if the owner does not 
intend to make such a thinning when needed he should use a wider 
spacing. With practically all species close spacing requires a thin- 
ning before the stand is 20 years old, and in the case of some, especially 
intolerant or rapid-growing trees, such as cottonwood, by the time 
it is 10 years old. The trees removed in the early thinnings required 
by close spacing would usually be unmerchantable; hence, if the site 
is favorable, a wider spacing is usually best. Wide spacing, more- 
over, reduces initial cost and will give larger trees than can be grown 
in the same time in a closely spaced plantation in which early thin- 
nings are not made. 
Gn the less favorable sites, however, close spacing is best. The 
greater number of trees per acre offsets the higher mortality among 
the young plants on poor situations and also gives a thicker crown 
cover, and hence better protection of the soul. The relatively large 
amount of fs alling leaves and litter, moreover, mixes with the soil, thus 
actually improving it. 
Close spacing gives clearer but comparatively slender boled trees; 
wide spacing results in more or less branchy trees of compar atively. 
large diameter. This is well illustrated in the case of two plantations 
of white pine near Clermont, lowa, on very similar sites. In one 
of them the trees were originally spaced 1 by 64 feet and in the other 
16 by 16 feet. When 43 years old the trees planted 1 by 64 feet had 
reached an average diameter of 74 inches and an average height of 
53 feet; the lower branches were dead to a height of from 20 to 30 
feet and were falling off. At the same age the trees planted 16 by 
16 feet had reached an average diameter of 12.3 inches and an average 
height of 60 feet, and though the lower branches were dead to a 
height of from 20 to 30 feet they were still persisting. Of two plan- 
tations of European larch near Sac City, Iowa, on similar sites, one 
spaced 8 by 8 feet has, after 28 years, reached an average diameter 
of 7.6 inches and a height of 47 feet, with the lower branches dead 
o a height of from 20 to 30 feet. The other, spaced 10 by 12 feet, 
at the same age shows an average tree diameter of 9.2 inches and a 
height of 43 feet, the trees having been pruned artificially to a height 
of 20 feet. 
Old plantations have done much to indicate the relative spacings 
to which different species are adapted. These spacings are given 
under the discussions of the respective species. 
