YIELD CAPACITIES OF THE PURE YELLOW PINE TYPE 
ON THE EAST SLOPE OF THE SIERRA NEVADA MOUN¬ 
TAINS IN CALIFORNIA 1 
By S. B. Show 
Silviculturist , Forest Service, United States Department of Agriculture 
INTRODUCTION 
East of the Sierra Nevada Mountains in California the predomi¬ 
nating and most important forest type is western yellow pine (Pinus 
f ionderosd ). This type is represented by pure stands extending over 
arge areas, in contrast with the characteristic mixed forest in which 
yellow pine is commonly found west of the Sierras and on the coast 
ranges. The lower precipitation on the east slope, the poorer soils, 
and shorter growing season, by creating conditions unsuitable for the 
more exacting sugar pine (.Pinus lambertiana) and the firs, account 
for these pure stands and also for a generally lower rate of growth 
than is found elsewhere in the pine region. These conditions prevail 
over a considerable strip of country, and the east-slope pine in Cali¬ 
fornia is a part of merchantable stands of pure or nearly pure yellow 
pine ranging from western Washington ana Oregon down to Arizona 
and New Mexico, all in many respects similar. 2 
Cutting in these western yellow pine forests is proceeding rapidly, 
both on national and private forest lands, and it is therefore impor¬ 
tant with regard to the possibility of obtaining new timber crops to 
study the productive capacity of the forest soils and to determine the 
amount of wood which can be produced with careful forest manage¬ 
ment. An immediate problem in practicing forestry on large areas 
of virgin forest is to develop a method for determining from the forest 
itself the productive capacity of a given area; for yellow pine stands 
vary tremendously in this region. 
Yellow pine stands have been so little investigated that the tech¬ 
nique of yield studies as applied to this species is itself a subject for 
investigation. The present study, which covered a large area in the 
eastern half of the Lassen National Forest, aimed not only to present 
preliminary information on yields of different qualities of forest land 
and on the probable rotations that will be used in growing the second 
crop of timber, but also to develop methods of procedure which 
might be applicable in similar investigations in other regions. 3 
FIELD METHODS 
It soon became apparent that the traditional field methods for 
studying forest yields would have to be modified in order to meet 
the rather unusual conditions which were encountered in these stands. 
1 Received for publication May 26, 1925; issued December, 1925. . . _ . 
2 The definition of a pure stand, which seems well established by usage, is one in which the dominant 
species forms 80 per cent or more of the total stand. This definition has been accepted and used m the 
present study. _ _ _ „ A _ _ r . , , 
3 Assistance in field work was given by Duncan Dunning, E. N. Munns, and A. E. Wieslander; m 
office work by Miss D. H. Vinther and Vance S. Brown. The project here reported was carried out m 
1919. 
Journal of Agricultural Research, 
Washington, D. C. 
( 1121 ) 
Vol. XXXI, No. 12 
Dec. 15, 1925 
Key No. F-32 
