RESULTS OF CUTTING IN THE SIERKA FORESTS. 
15 
Trees with large, well-formed crowns and dense foliage respond 
more promptly (usually during the first season after cutting) and 
attain a higher rate under the stimulus than trees with small, poorly 
formed crowns in which response is usually delayed from one to 
three years. Response is greater and more prompt on good than 
on poor sites. The maximum rate is attained in 7 to 10 years 
after cutting, but the stimulation is discernible for many years, de- 
pending on the rate of closing of the crown canopy, invasion of 
brush, etc. A heavy cutting, good distribution, and careful selection 
of remaining trees are necessary to secure the greatest response. 
NET GROWTH. 
Statements in the preceding discussion have been largely in terms 
of potential rather than net growth rates, in order to demonstrate 
more clearly the effects on growth of the factors mentioned. It 
may be of interest to consider what the actual net returns have been 
from the areas under consideration. This may be seen from Table 
12. The Feather River, Sequoia-4, and Tahoe plots represent ex- 
amples of the reduction of net increment by- the loss of a few large 
trees. On the better sites net growth has been excellent, amounting 
in some cases to over 400 board feet per acre annually, or more than 
3 per cent. 
Table 12. — Stand, losses, and net increment per acre, 1911 to 1921. 
Plot. 
Type. 
Stand. 
Annual loss. 
Net annual in- 
crement. 
Site. 
Trees, 4 
inches 
up. 
Volume, 
board 
feet. 
Trees. 
Volume. 
Board 
feet. 
Per cent. 
Ill 
Shasta-11 
Mixed... 
...do 
JP-WFi 
Mixed... 
...do 
SP-YP i 
...do 
83.9 
54.4 
23.1 
51.5 
73.5 
38.4 
37.7 
53.3 
34.5 
51.8 
45.5 
32.7 
62.2 
6.500 
9,880 
15, 520 
10,065 
20,000 
18,570 
24,100 
10,870 
11,350 
12,930 
21,710 
12,700 
20,780 
Per cent. 
0.33 
.53 
.80 
.28 
.83 
.46 
.87 
.83 
.10 
.81 
.57 
.03 
1.46 
Per cent. 
0.06 
.36 
.68 
.31 
.55 
.11 
.26 
.85 
.22 
.63 
.60 
60 
53 
53 
130 
76 ± 
265 ± 
225 
200 
294 
325 
80 
440 
470 
0.92 
III— 
III 
Shasta-6 
Tahoe 
.54 
.34 
II- 
1.29 
II 
11+ 
Feather River, 1-8 
.38 
1.43 
11+ 
.93 
II 
Sequoia-3 
YP 
...do 
1.84 
I 
Sierra 
2.59 
I 
Sequoia-1 
SP-WF. 
SP-YP . 
YP 
SP-WF. 
2.51 
I 
Sequoia-4 
.37 
I 
Sequoia-6 
3.46 
Stanislaus- 1 
.12 
2.26 
Average 
49.4 
14,998 
.61 
.39 
205 
1.37 
» JP= Jeffrey pine; WF= white fir; SP= sugar pine; YP= yellow pine. 
INJURIOUS AGENCIES. 
Loss in number of trees, averaging 0.61 per cent annually since 
cutting, seems rather high, but it is due to the fact that most of the 
trees were small, occasioning but slight volume loss, and died during 
the first few years after cutting from injuries received during brush 
burning and logging. Other causes of loss, principally among small 
trees, were snow, suppression, and, in white fir, engraver beetles 
(O ecoptog aster) . The greatest volume losses were due to wind and 
bark beetles {Dendroctonus) in yellow pine, and to mistletoe in 
Douglas fir on the Shasta plots, the latter being the only case of seri- 
