908 
Journal of Agricultural Research voi. xxvii, no. m 
greasewood-shadscale association 
This association, in which the two dominant species are the grease- 
wood, Sarcobatus vermiculatus , and the shadscale, Atriplex confertifolia, 
occupy ridges which diversify the broad mud flats or salt flats which 
skirt the southern shore of the Great Salt Lake. 
According to the observations of Kearney, Briggs, Shantz, McLane, 
and Peimeisel ( 24 ), it occupies all areas where the water table is 
sufficiently high to make moist soil accessible to the deep-rooting grease- 
wood and where at the same time the upper foot or two are sufficiently 
dry to permit the growth of the shadscale. Where the water table is 
too low, as on the higher outwash slopes, this' association gives way to 
the shadscale association. Where the water table approaches the 
surface, the greasewood is associated with Allenrolfea instead of with 
shadscale, or else the greasewood is replaced by the more salt-tolerant 
Allenrolfea and Salicomia. 
In typical areas the two dominant species intermingle in approxi¬ 
mately equal numbers, but on the higher slopes shadscale is the more 
abundant while on the lower fringes of the association the greasewood 
is more abundant. In the lowest zone both the greasewood and the 
shadscale are apt to be dwarfed. 
In classifying our determinations it has been difficult to decide in a 
few instances whether individual collections should be referred to this 
association or to the salt flat communities. 
Table IX .—Physicochemical constants for species of the greasewood-shadscale association 
Growth form and species. 
Date. 
Freezing 
point 
depres¬ 
sion, 
A. 
Atmos¬ 
pheres 
osmotic 
concen¬ 
tration, 
P. 
Specific 
electrical 
conduc¬ 
tivity, 
K. 
Ratio, 
conduc¬ 
tivity to 
depres¬ 
sion, 
K/A. 
Chlo- 
rids 
per 
liter, 
Cl. 
SHRUBS AND HA W SHRUBS 
Sarcobatus vermiculatus (Hook.) 
Torr. 
1920. 
May 29 
...do. 
2.30 
1.89 
27.6 
22.7 
0.0589 
.0421 
O.0256 
.0222 
June 8 
2.12 
25-5 
.0482 
.0227 
6.0 
June 12 
2.21 
26.5 
.0508 
.0230 
7-5 
...do. 
2.94 
35-3 
.0648 
.0220 
14.3 
June 18 
2.34 
28.1 
.0507 
.0216 
7.0 
...do. 
2.50 
29.9 
.0518 
.0208 
8.8 
July 11 
3 - 3 2 
39-8 
.0626 
.Ol 88 
12.3 
July 16 
2.32 
27.9 
.0502 
.0216 
4.8 
Average. 
2.44 
29-3 
•0533 
.0220 
8.7 
Atriplex confertifolia (Torr.) S. 
Wats. 
May 29 
June 12 
2.60 
31-2 
38.6 
.0589 
.0711 
.0228 
3.22 
.0220 
30.2 
June 18 
3-29 
38.0 
.0636 
.OI93 
I 9 ‘S 
...do. 
3.21 
38.5 
.0672 
.0209 
21.2 
July 16 
6.22 
74.2 
.0970 
.OI56 
39*5 
July 18 
10.00 
118.5 
•1235 
.0123 
64.0 
July 27 
12.99 
153 -1 
. 1292 
.OO99 
64.4 
Average. 
5-93 1 
70-3 
.0872 
•0175 
39-8 
