May 3i, 1924 Cell Sap Density and Environmental Conditions 861 
a regularly graduated succession from the xerophytic sagebrush to the climax 
mesophytic spruce-fir type." These types were further divided into sites, 
differentiated chiefly on the basis of aspect and consequently varying as to 
moisture supply, rate of evaporation, temperature, and exposure to sunlight, 
e possible effect which altitude might have upon sap density was also taken 
into account in selecting some of the sites on which the various species were 
collected. 
In the Central Wasatch Mountains some 500 sap density determinations 
were made on representative trees, shrubs, and herbs of the above-mentioned 
types. The samples were collected in Big Cottonwood and Taylor Canyons 
lying near Salt Lake City and Ogden, Utah, respectively. In the Ephraim 
Canyon series of July, 1921, approximately 275 determinations were made of the 
sap densities of plants on the west slope of the Wasatch Plateau and on the 
desert in the adjacent San Pete Valley. 
Table VII.—Freezing point depressions and osmotic pressures of the sav of trees 
classified by species, locality, type, situation, altitude, and date of collection 
[Numbers in italics represent.averages of two or more determinations] 
Species and locality 
Juniperus utahensis 
(Engelm.) Lemm. 
Big Cottonwood Can¬ 
yon. 
Do.... 
Do__ 
Taylor Canyon*_ 
Do__ 
Do.. 
Type 
Situation 
Juniper. 
_do.. 
Southern aspect. 
Pinus ponderosa 
scopulorum Engelm. 
Big Cottonwood Can¬ 
yon. 
Do.. 
do__ 
Near Park City high¬ 
way. 
Beaver Creek_ 
Do_ 
Do...__ 
Big Cottonwood Can¬ 
yon. 
Do. 
Do.. 
..do. 
..do. 
.do. 
..do. 
.do_ 
-do___. 
.do_ 
.do.... 
.do_ 
_do... 
Isolated trees. 
Western yellow pine. Southern aspect. 
-do....do_ 
_do_ 
Eastern aspect.. 
Southern aspect. 
_do__.. 
_do_ 
Canyon bottom <■ 
Western yellow pine 
-do__.. 
_do__ 
Aspen-fir.. 
Do- 
Do. 
Do. 
Juniperus scopulorum 
Sarg. 
Big Cottonwood Can¬ 
yon. 
Do... 
Do...__ 
Do. 
Do__ 
Do.. 
Do... 
.do. 
.do. 
.do. 
.do. 
.do. 
Western yellow pine. 
Chaparral__ 
Western yellow pine.. 
Chaparral.... 
Western yellow pine" 
Chaparral_ 
_do_ 
Southern aspect, un¬ 
der light shade.o 
-do__.. 
Canyon bottom a_ 
Canyon bottom un¬ 
der snow. 
Southern aspect. 
.do. 
.do. 
.do. 
.do. 
.do. 
.do. 
a Planted, species exotic to this site. 
c Sample collected after a heavy rain. 
Alti¬ 
tude 
Date of 
collec¬ 
tion 
Depres 
sion of 
freezing 
point 
■ Os¬ 
motic 
; pres¬ 
sure 
Feet 
1920-1921 
Degrees 
C. 
Atmos¬ 
pheres 
5,000 
July 21 
2.19 
26.3 
5,000 
Sept. 17 
cl.82 
15.9 
5,000 
Dec. 10 
2.81 
27.8 
5,200 
Jan. 4 
2.12 
25.5 
5,200 
Feb. 28 
2.14 
25.7 
7,000 
-..do_ 
2.35 
28.2 
6,400 
July 21 
1.98 
28.2 
6,400 
Sept. 22 
1.44 
17.3 
6,400 
Dec. 10 
1.38 
16.6 
6,800 
Sept. 17 
1.47 
17.7 
7,000 
Sept. 16 
1.86 
22.4 
7,300 
...do_ 
1.82 
21.9 
7,600 
7,500 
...do_ 
1.77 
21.3 
July 7 
1. 57 
18.9 
7,500 
July 27 
1.85 
16.2 
7,500 
July 19 
1.86 
16.4 
7,500 
July 27 
1.85 
16.2 
7, 500 
Sept 20 
1.86 
I 6.4 
7,500 
Dec. 8 
1.17 
111 
6,400 
July 21 
2.41 
28.9 
7,600 
July 26 
1. 60 
19.2 
6,400 
Sept. 22 
0.99 
11.9 
7,600 
Sept. 7 
0.94 
11.3 
7,600 
Sept. 10 
0.9» 
11.1 
6,400 
Dec. 10 
2. 41 
28.9 
7,600 
Dec. 6 
2.17 
26.1 
ations of Clements ( 20 , 21). His 
to environmental:conditions “and=^^ 
a thi7;? a n n^ u ^i?rrv? r o a ren o t. resu,t ° r graduai changes io “ ssss^*5s«r?5^s 
