JOMAL OF ACMCCLTCRAL RESEARCH 
Yol. XXYIII Washington, D. C., May 31, 1924 No. 9 
DENSITY OF CELL SAP IN RELATION TO ENVIRON¬ 
MENTAL CONDITIONS IN THE WASATCH MOUNTAINS 
OF UTAH 1 
By C. F. KORSTIAN 
Associate Silviculturist , Appalachian Forest Experiment Station, Forest Service, 
United States Department of Agriculture 
INTRODUCTION 
Observers of plant life in the mountainous regions of the West are familiar with 
the striking zonation of the vegetation in series of altitudinal belts of distinctive 
composition. These range from sagebrush deserts or grasslands at the base of 
the mountains through successive altitudinal forms representing such diverse 
vegetative aspects as pinon-juniper woodlands, pine forests, aspen stands, 
Douglas fir, and, on the summits, subalpine spruce-fir forests. Except for the 
sagebrush and greasewood-shadscale associations, each zone is practically co¬ 
extensive with a forest type. 2 
The phenomenon of altitudinal zonation is of particular significance to the 
silviculturist and the range management specialist because of the fact that many 
of the problems of the growth and regeneration of forests and the development of 
the range can best be solved through a determination of the soil and climatic 
requirements of the different species of each zone. The relation of environ¬ 
mental conditions to the development of forest vegetation is thus of profound 
importance. For example, in designating the kinds and amounts of timber 
which can be cut from an area without prejudicing the future composition or 
rendering the forest liable to windthrow, the alert forester is continually making 
use of his fund of knowledge of the physiological activities and requirements of 
the various species in his region. In reforestation activities, success depends 
upon knowing the cause of successful growth and establishment or of partial 
success or failure of different species in various forest types under varied envi¬ 
ronmental conditions. Once the problems of growth and regeneration of forests 
have been solved, the forester should be able to determine readily what species 
1 Received for publication Feb. 28,1924—issued Nov., 1924. In the following pages authors are cited for 
the most important and the more recent researches. References are not given for material which is re¬ 
garded as a matter of common knowledge among scientists. To those who wish more complete citations 
for the period up to the time of their publication: Ewart’s excellent translation of Pfeffer's “Physiology 
of Plants” ( 102 ), Livingston’s “Role of Diffusion and Osmotic Pressure in Plants” (83), and Dixon’s 
“ Transpiration and the Ascent of Sap in Plants” (38) will be found of great service. In order to give the 
background for the work and to correlate the present work with that of previous workers in the subject, 
references to the more important literature are given in connection with the topical discussions. 
2 “Forest type” may be defined as a forest of essentially uniform character as regards composition and 
development due to given physical and biological factors by which it may be differentiated from other 
forests of unlike composition. It is evident, therefore, that the environmental conditions responsible 
for a given forest type must have been practically the same throughout the type at the time the forest was 
started and during its development. A forest type is usually designated by the name of the dominant 
tree species which determine the leading characteristics of the type. 
Journal of Agricultural Research, Vol. XXVIII, No. 9 
Washington, D. C. May 31, 1924' 
Key No. F-ll 
96039—24f-1 
(845) 
