June 21,1924 
A Study of Douglas Fir Reproduction 
1237 
Table I .—Effect of slash disposal on seedlings of various ages and species under 
different cutting systems 
Number of seedlings remaining in 1923, by species and year of origin 
Slash disposal and cut¬ 
ting methods 
Douglas fir 
Engelmann spruce 
Limber pine 
1923 
1922 
1921 
Older 
1923 
1922 
1921 
Older 
1923 
1922 
1921 
Older 
Slash scattered: 
Shelterwood_ 
901 
267 
5,465 
5,009 
30 
20 
277 
525 
00 
40 
0 
30 
Selection.. 
1,277 
297 
2,455 
4,287 
50 
0 
89 
356 
20 
20 
0 
129 
Clear-cut.. 
59 
10 
178 
396 
0 
10 
59 
178 
20 
89 
30 
59 
Total_ 
2,237 
574 
8,098 
9,692 
80 
30 
425 
1,059 
40 
149 
30 
218 
Slash burned: 
Shelterwood .. 
505 
178 
4,900 
6,069 
59 
79 
624 
2,119 
20 
40 
69 
20 
Selection.. 
871 
346 
4,613 
3,594 
0 
0 
59 
822 
0 
10 
30 
69 
Clear-cut... 
109 
20 
446 
851 
0 
0 
30 
228 
10 
20 
40 
297 
Total... 
1,485 
544 
9,959 
10,514 
59 
79 
713 
3,169 
30 
70 
139 
386 
Table II .—Effect of slash disposal upon all seedlings , all methods of cutting com¬ 
bined, expressed in percentage of survival 
Method of slash disposal and year of count 
Percentage of survival of all 
seedlings by species 
Percentage of survival of es¬ 
tablished seedlings (3 years 
old and over) by species 
Douglas 
fir 
Engel¬ 
mann 
spruce 
Limber 
pine 
Douglas 
fir 
Engel¬ 
mann 
spruce 
Limber 
pine 
Slash scattered: 
1923 survival..... 
48 
28 
41 
48 
25 
36 
1922 survival.:... 
48 
28 
38 
48 
25 
33 
1919 survival.. 
51 
28 
35 
Slash piled and burned: 
1923 survival.... 
52 
72 
59 
52 
75 
64 
1922 survival... 
52 
72 
62 
52 
75 
67 
1919 survival.... 
49 
72 
65 
Since Douglas fir is the principal species and includes the bulk of the repro¬ 
duction it may be said that the method of slash disposal plays a minor part in 
germination and survival. The results for all the counts so studied are very 
consistent. The fir, if anything, shows a very slight preference for the areas 
from which the slash has been removed by fire. 
Engelmann spruce reveals a decided preference for slash-burnt areas, and a 
greater numerical survival there. This condition can be attributed largely to 
the fact that the cleared areas are more favorably located with reference to 
spruce seed sources. On a percentage basis this species survives somewhat 
better under slash, once it gets a start. The 1916 crop had 6.2 per cent surviv¬ 
ing in the open in 1919, and 15.4 per cent under slash. This ratio may not be 
strictly representative, for the majority of years, but is credible in view of the 
rather slow rooting of spruce, its tolerance to shade, and a sensitiveness to high 
temperatures, which equals though it does not exceed the sensitiveness of Doug¬ 
las fir. 
Limber pine exhibits a preference for the open both for germination and for 
survival, which is in keeping with the tree’s general demand for open conditions, 
and its habit of thriving in exposed locations. 
