1006 
Journal of Agricultural Research 
Vol. XXX, No. 11 
species has been shown to establish 
itself even under full light if favorable 
conditions obtain. These conditions 
are sufficient moisture to sustain the 
seedling over the critical dry season, 
and a mineral soil or moisture-holding 
surface. 
If surface moisture is the deciding 
factor, the protection of the overstory 
serves only to prevent desiccation of 
the soil below the critical point. But 
vegetation, even under the canopy of 
a forest, may create unfavorable sur¬ 
face soil conditions, as was noted in the 
studies in green timber. 
Locally it is possible that the chemi¬ 
cal contents of the soil, for example 
acid conditions in poorly drained sites, 
may preclude the establishment of the 
spruce, but such areas comprise so 
small a percentage of the type that in 
specifying the guiding silvicultural rules 
this may be omitted from considera¬ 
tion. Such conditions call for detailed 
investigations of the factors of site con¬ 
trolling reproduction of the species. 
Shade may inhibit the restocking of 
spruce, but to do so it must be very 
dense, and only in rare instances will 
the lack of light preclude restocking. 
In cut-over areas this factor does not 
operate, and may be dismissed. 
The Xyack tracts therefore indicate 
that where the surface litter is deep 
and is not broken up in logging, Engel- 
mann spruce seedlings will not survive; 
nor will they come in in forest open¬ 
ings on flats or other dry sites. On 
moist mineral soil, however, and on 
burned-over ground spruce will estab¬ 
lish itself; also where forest litter is 
thin. Grass cover is a dangerous com¬ 
petitor for moisture, and is liable, if 
not certain, to eliminate Engelmann 
spruce reproduction. In general, the 
decisive factor appears to be surface 
soil moisture available to the seedling 
during critical periods of the dry 
season. 
THE RUBY CREEK AREA 
The Ruby Creek area was cut over 
in 1917 and 1918 by a varied series of 
methods, designed to bring out the 
most favorable form of management 
for spruce stands. The marking plan 
prepared by J. Kittredge, jr., in 1916, 
has been followed throughout with a 
few modifications. Marking was done 
to reserve single seed trees, seed trees 
in groups, in strips, and in blocks. 
The slash has been uniformly piled 
and burned, most of the burning being 
done in 1918. 
During the summer of 1921 a field 
examination was made of the area to 
ascertain the results of cutting. The 
method used in the field examination 
consisted of running strips 0.1 chain wide 
between groups for reproduction and 
soil surfaces, and chain-wide strips for 
standing trees and windfalls. Only on 
those portions of the tract where trees 
had been reserved singly and in groups 
had the logging and slash disposal 
proceeded sufficiently far to permit 
drawing anv conclusions (pi. 6, A and 
B). In all, 7 strips 5 to 15 chains in 
length were run. Of these, 4 strips 
were on areas where the slash was 
burned in 1920 and 1921 and so could 
not yield valid data for definite con¬ 
clusions, though they will furnish the 
basis for future comparisons. One 
strip was run 15 chains from a seed 
group roughly following the contour 
on a northwestern exposure with a 
20 per cent gradient. The survey of 
this strip is shown in Table VI. 
Table VI.— Reproduction of Engelmann spruce by seedlings and by milacres 
stocked; Ruby Creek area 
[Basis: Strip 15 chains long by 0.1 chain wide, 150 milacres] 
Engelmann spruce 
Other species 
Totals, 
Data obtained 
— - 
— 
all 
1 
Burned Mineral Cover 
Burned 
Mineral Cover 
surfaces 
Stocking by species and surfaces: 
Number of seedlings on strip _ 
8 
46 12 
7 
28 13 
114 
Number jjer acre of actual area _ 
53 
303 80 
47 
187 87 
757 
Number per acre of each kind of surface a . 
405 
2,300 109 
356 
1,405 118 
Milacres b stocked, by species and surfaces: 
Number of milacres on strip_ ... 
4 
19 10 
6 
25 10 
74 
Number per acre___ _ 
26 
127 67 
40 
166 67 
c 493 
« Burned surface, 13.2 per cent of actual area; unburned mineral surface, 13.3 per cent; slash and veg¬ 
etative cover, 73.5 per cent. 
b Milacre: A quadrat 6.6 feet by 6.6 feet or 0.001 acre. 
c The total number of milacres stocked with seedlings of each species is 493, but since more than one 
species may occur on the same milacre, a smaller number of milacres stocked to all species will result. 
That number is 413. 
