16 BULLETIN 153, U. S. DEPARTMENT OF AGRICULTURE. 
stands of slower growing species, such as ash, oak, or walnut. Intol- 
erant trees, such as cottonwood, European larch, black locust, or 
black walnut, require large openings in the crown cover. Cottonwood 
and European larch in particular die for no apparent cause except 
insufficient hght, even when apparently receiving an abundance. 
For white pme and Norway spruce the openings need not be large. 
There are no instances in this country where thinnings have been 
systematically carried on, and for this reason it is not possible to 
cite examples of their effect. The comparative size of trees grown 
in open-spaced and close-spaced stands, however, is something of an 
indication of the results to be expected from thinning, and a few exam- 
ples of this sort are given in Table 2. Comparisons should be made, 
of course, only between stands or rows of nearly the same age. 
TABLE 2.—Size of trees in open and close spaced stands. 
European larch. | White pine. Cottonwood. 
| | Aver: | | Aver- Aver- 
Nature of | Spac- | 28° C¥ || Nature of Spac- | 28¢ dk || Nature of Spac- | 28¢ ue 
: |Age.| “|, | ameter || : Age. P ameter. Age.| ~ ameter 
stand. | ing. breast || stand. | ing. Breast stand. ing. protest 
| high. | high. high. 
Yrs.| Feet. | Inches. || Yrs.| Feet. | Inches. Yrs.| Feet. | Inches. 
Grove..... 23| 8x8 7.6 || Grove 35 | 6x7 8.8 || Grove 12 | 54x 8 8.4 
Wos.-- | 28 | {10 x 12 9.2 ] Dot FY Gl ag Se St eve! By Done TBA aco} 3.9 
HOW «ck -- 28 (4) 1076)" 2 Doies 2: 39) | 4x4 8.1 Dose. - 35 | 84 x 84 13e5 
Grove...-.. 35| 8x8 105.02 )\, 2Do + sl) 435| 16x 16 A Zror |e ROWie eee 35 (3) 19.3 
Dons =: 35 | .74 x 73 POs eDOw 43 1x 64 7.5 || Grove 36 | &x 10 13.4 
Dosa - 37 | 8x8 10:0.) Rowse-.- 53 (2) 14.1 Dow 40 | 2x36 17.6 
Dione. : 35 | 3x7 7.4 || Grove 53 | 6x7 TANS Does 41] 6x6 12.3 
WOzss=: 39 | 33 x 33 7.0 || 
Darts 40| 4x4 8.3 | 
15 feet apart in row. 2 Trees 6 feet apart. 32 to 4 feet apart in row. 
PRUNING. 
Pruning is the removal of living or dead branches from a tree. 
The purpose is to improve the tree’s form; to increase growth in its 
leading shoot by eliminating some of the lateral shoots and to improve 
the quality of the lumber by getting rid of the source of knots. 
Most trees in forest plantations, especially those closely spaced at 
the start, will prune themselves; the additional value gained by 
pruning them by hand is usually not sufficient to pay for the opera- 
tion. The cost, therefore, would have to be reckoned as a fixed _ 
charge, to run at interest, against the final cost of the plantation. 
In small plantations, however, it may be possible for the owner him- 
self to do the pruning at odd times, and thus avoid an additional 
charge. Side branches can not well be pruned to a greater height 
than a man can reach from the ground with an axe, and this amount 
of pruning will scarcely have much effect in increasing the stumpage 
value of the timber. 
