1008 
Journal of Agricultural Research 
Voi. xxx, No. n 
On the basis of this detailed examina¬ 
tion of the sample strip, the surface of 
the whole area that was burned 
amounted to 13.2 per cent, the un¬ 
burned 86.8 per cent. Of the unburned 
soil surface, mineral soil represented 
13.3 per cent of the total area, slash 
cover 15.2 per cent, and vegetative 
cover 58.3 per cent. The vegetative 
cover was classified into three cate¬ 
gories according to height, and covered 
the area as follows: Under 5 inches, 
31.5 per cent; 5 to 18 inches, 25.4 per 
cent; over 18 inches, 1.4 per cent. 
The vegetative cover was analyzed 
in this manner to indicate the extent of 
the soil covering and the rankness of 
the vegetative growth. Very few spe¬ 
cies other than those found on the 
forest floor in the green timber were 
noted. Considerable stimulation in 
growth and increase in number of 
individuals took place following the 
cutting. Tiarella sp. appeared to be 
the most prolific and comprised the 
principal portion in the first group. 
The duff layer apparently is a very 
important factor in spruce reproduc¬ 
tion. On the area examined nearly 60 
per cent of the tract was covered with 
litter and duff, and measurements 
showed that this layer varied from 1 to 
3 inches in thickness. The duff is found 
to be most unfavorable to the estab¬ 
lishment of spruce seedlings on cut-over 
tracts. The spruce seed do not hold 
over or are not stored in the duff. This 
is contrary to the behavior of the repro¬ 
duction of western white pine ( Pinus 
monticola ) and Douglas fir. 
A careful analysis of Table VI will 
indicate the relative favorableness of 
the various surfaces to the establish¬ 
ment of the spruce. The burned sur¬ 
face yielded 761 seedlings to the acre, of 
which 405 were spruce; mineral soil 
bore 3,705 seedlings to the acre, of 
which 2,300 were spruce; vegetative 
and slash-covered surfaces yielded only 
227 seedlings per acre, 109 of them 
spruce. 
The burned spots were a disappoint¬ 
ment. More seedlings were expected to 
be found on them. This fact agrees, 
however, with general observations on 
spots where slash piles were burned. 3 
Apparently the soil is sterilized by the 
concentrated burn. The absence of 
weeds and grasses has been noticed, and 
likewise the absence of seedlings. Fur¬ 
ther study is needed to explain the 
consistent absence of seedlings on hard- 
burned spots for the first five years fol¬ 
lowing the burning. Yet the table indi¬ 
cates that burned surfaces are approxi¬ 
mately four times as favorable to seed¬ 
ling establishment as duff or litter. 
The mineral soil as represented by 
skidding trails and by the places where 
the duff layer is completely decomposed 
is shown by Table VI to be the most 
favorable surface for the establishment 
of spruce seedlings. It is nearly six 
times as favorable as the burned spots 
and over twenty times more so than the 
ground covered with litter and vege¬ 
tation. This is significant and requires 
recognition in the treatment of spruce 
stands. 
The important indication of Table 
VI is the unfavorableness of the 
litter soil cover to the establishment of 
spruce seedlings. This is corroborated 
by the results of a study of germina¬ 
tion of Engelmann spruce made in 1921 
by J. A. Larsen, shown in Table VII. 
Table VII.— Germination and survival of 
Engelmann spruce in different surfaces 
12,000 seed sowed in each surface, fall 19201 
Germination and survival, 
1921 
Ashes 
Bare 
soil 
Duff 
Germination: 
May 15. 
0 
0 
0 
May 23. 
429 
641 
274 
4 
40 
27 
June 20... 
10 
6 
*0 
July 15.| 
5 
15 
“0 
Total.- 
484 
689 
278 
Percentage of germination .. 
24 
34 
14 
Survival: 
Oct. 10_ 
400 
524 
2 
Percentage of survival..— 
S3 
76 
0.7 
• On the examination dates of June 20 and July IS, 
practically all the Engelmann spruce seedlings in 
the duff were dead. Larsen states that the duff 
layer was 2 inches deep and attributes the failure 
of the seedlings to inability of the roots to reach 
mineial soil before they were overtaken by dry 
conditions. 
Study of the Ruby Creek area indi¬ 
cates that reproduction of Engelmann 
spruce on cut-over areas is dependent 
on the seeding of the forest floor at the 
time of or following cutting. Mineral 
soil surfaces are found to favor the 
establishment of spruce seedlings by a 
ratio of more than 20 to 1 over that of 
duff surfaces. Reproduction on burned 
spots is not generally so prolific as that 
on mineral soil. 
i 45-acre sample plot, Whitman National Forest, Oregon; Seeley Lake sale area, Missoula National 
Forest, Montana; Beardmore sale area, Kaniksu National Forest, Idaho. 
