GROWTH ON CUT-OVER AND VIRGIN WESTERN YELLOW 
PINE LANDS IN CENTRAL IDAHO 1 
By C. F. Korstian, Associate Silviculturist , Appalachian Forest Experiment 
Station, Forest Service 
PURPOSE OF STUDY 
The western yellow pine ( Pinus ponderosa) , because of the superiority of its 
lumber, its abundance, and its accessibility, is the most important commercial 
timber tree in the Boise, Payette, Weiser, Idaho, and Salmon National Forests 
in central Idaho. It is of the utmost importance, therefore, that the stands of 
this species be so managed as to insure an adequate stand of reproduction on 
cut-over lands and to maintain at its maximum the potential productivity of 
the type. In order to secure reliable information upon the establishment of a 
new forest, its growth and development, and to determine the basic principles 
governing silvicultural practice in this type, the Forest Service established a 
series of 16 permanent sample plots on the Payette National Forest in central 
Idaho in 1913 and 1914. The results obtained through the remeasurement of 
these plots in 1918 and 1919 brought out many points of interest concerning the 
management of western yellow pine stands in this region which are well worth 
attention. 
GENERAL CONDITIONS ON THE PLOTS 
Although these plots were established primarily to secure data on the growth 
of the reserved trees and natural reproduction in cut-over stands, unfortunately 
only three of them, plots Nos. 1-3, Table I, had been cut over when the logging 
operation was suspended in 1914. Nevertheless, they now afford a good com¬ 
parison between the increment in cut-over and in virgin stands, showing behavior 
of advance reproduction in the latter. The cutting on these plots approached the 
method of clear cutting with scattered seed trees, although plot No. 1 had quite a 
number of trees left because they were too young. The uncut plots Nos. 4 to 16 
give a good indication of the increment and mortality which may be expected in 
virgin stands. Furthermore, they afford interesting comparisons among three 
important sites common to the Intermountain region. 
The sample plots were laid out in representative virgin stands under a variety 
of topographic and soil conditions. 
The soil is a sandy to gravelly loam of granitic origin and is open, porous, and 
very gravelly on the south aspect. In the basins and on the north aspect the 
soil is less gravelly and more loamy because of a greater admixture of organic 
matter. 
i Received for publication Apr. 29, 1924—issued November, 1924. • 
Journal of Agricultural Research, 
Washington, D. C. 
(1139) 
Vol. XXVIII, No. 11 
June 14,1924 
Key No. F-15 
