16 BULLETIN 1294, U. S. DEPARTMENT OF AGRICULTURE 
mixed stand of western yellow pine, sugar pine, and Douglas fir, 
partially killing the crowns of nearly all trees but failing to kill any 
tree outright. In the fall of 1915, when the rate of growth for the 
previous decade was determined by measuring the annual rings, the 
stand failed to show noticeable external damage from fire. Many 
trees which had badly scorched crowns in 1910 had recovered, and 
only one tree had succumbed to fire injuries during the five years. 
The growth at breastheight was measured separately for the five- 
year periods before and after the fire. It was found that 16 per cent 
of all the trees measured grew at the same rate for both periods, 
while 68 per cent grew more slowly and 16 per cent grew more rap- 
idly after the fire. The growth of one tree fell off 69 per cent, while 
none of those increasing made a greater gain than 14 per cent. 
Averaging all trees, the growth in basal area after the fire was only 
83.6 per cent of the growth before the fire, while the volume growth 
was correspondingly reduced by about 25 per cent. The stand on 
this particular plot was 43,230 board feet to the acre, and the vol- 
ume growth for the five-year period before the fire was 1,945 board 
feet to the acre, or 390 board feet each year. The reduction of 25 
per cent means a loss of nearly 500 board feet per acre for the five- 
year period. Checks on adjoining unburned areas showed no change 
in rate for the two half decades. 
In 1919 a similar study was made on the Shasta National Forest 
of an area burned in 1914. Growth figures were obtained by taking 
increment borings on a number of trees of different species, selecting 
only those individuals whose growth had not been affected by the 
death of near-by trees. For each tree were recorded the species, 
diameter, total height, percentage of crown killed by fire, growth for 
five years before the fire, and growth for five years after the fire. 
Table 5 shows that a reduction of growth of 30.8 per cent occurred 
on the trees studied, which on the poor site represented amounted to 
50 board feet to the acre each year. 
TABLE 5.—EHffect of crown injury on current rate of growth * 
Reduc- Basis 
Amount} tion of 
of crown | diameter 
killed growth | Number} Average 
of trees height 
Per cent | Per cent Feet 
17 11.0 9 68 
25 28.5 12 71 
33 32. 0 19 68 
50 39. 0 10 58 
67 56. 5 4 57 
230.8 
1 Data obtained 5 years after burn, for all species; Shasta National Forest. 
2 Average (weighted). 
The table further brings out clearly that the degree of reduction 
of diameter growth varies directly with the percentage of the crown 
killed by the fire. With only 54 trees as a basis, perhaps it can not 
be stated without qualification that this relation generally exists; 
but such a relation agrees with what is known of the function of the 
crown in the growth of the tree, 
