Survey Method 



The initial survey in 1932-33 was made by the compilation method and 

 gave very detailed statistics on the forest resource at that time l/. A 

 type map was also prepared. Since the cost of repeating periodically 

 such a survey to obtain current statistics would be prohibitive a samp- 

 ling method was designed and followed on the resurvey in 1943-44. Brief- 

 ly, this consisted in taking data on about 4,000 l/20-acre plots five 

 chains apart along parallel cruise lines, spaced three miles apart and 

 disposed in a north-south direction. Because of the differences in 

 methodology the results of the two surveys are indicative of significant 

 trends rather than of actual interim changes. 



A check between the all-species volume as derived from the sampling 

 method and the 1933 estimates adjusted for interim growth and drain in- 

 dicated a very close correlation, 1,870 million and 1,827 million board 

 feet, respectively. However, there were marked differences in volumes 

 by species, as shown by the following comparisons: 



Species 



: 1944 

 : resurvey 

 rMillion board 



: 1933 survey 

 : adjusted 

 feet, Scribner 



:Correlation 

 : factor 



Western white pine 



143.1 



238.5 



0.6 



Ponderosa pine 



248.5 



277.7 



0.9 



Western larch 



394.5 



457.4 



0.9 



Douglas-fir 



537.6 



364.1 



1.5 



Grand fir 



2 79.7 



230.0 



1.2 



Western redcedar 



158.3 



147.2 



1.1 



Western hemlock 



50.2 



19.0 



2.6 



Engelmann spruce 



9.7 



25.1 



0.4 



Lodgepole pine 



42.0 



67.4 



0.6 



Hardwoods 



6.3 



0.1 



6.3 



Total 



1,869.9 



1,826.5 



1.0 



1/ The results of this survey are reported in Forest Survey Release No. 

 8, Forest Statistics Benewah County, Idaho, issued by the Northern 

 Rocky Mountain Forest and Range Experiment Station in September, 1937. 



2/ The 1944 resurvey volumes divided by the adjusted 1933 volumes. 



-6- 



