PAST INVENTORY DESIGN 



The precursor of this design was a two-stage approach very similar to that 

 described in "Developing the data framework for effective timber management" (USDA 

 Forest Serv. 1962). The first stage of the former inventory consisted of an extensive 

 sample of about 200 ground- examined locations. At each ground location, a cluster of 

 10 sampling points was established to select trees for measurement. The ground samples 

 were stratified by estimates of volume per acre as interpreted on aerial photos at a 

 scale of 1:15,840. Stratum weights were estimated by photo interpretation of several 

 thousand points systematically located on the aerial photos. 



The second stage of the data framework consisted of examination of selected stands 

 that had been defined on the aerial photos by discontinuities in texture (reflecting 

 stocking and crown-size differences) or apparent tree height. The selection process at 

 this stage was highly subjective because the purpose of the examination was to locate 

 stands that would be likely candidates for particular programs--thinning , cleaning, 

 overwood removal, etc. Ground examination of the stands selected used a series of 

 sampling points along a transect within the stand. 



In past practice, the timber management plan has been based entirely on the first 

 stage inventory. Volumes of timber to be harvested and acreages of stands to be 

 assigned various silvicultural treatments were estimated from the first stage sample. 

 The second stage of stand examination became a procedure for verifying on the ground 

 whether a particular treatment was indeed needed, and for presenting the manager with 

 a limited number of alternative areas on which to assign priorities for a particular 

 programed action based on expected costs and benefits. 



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