PRACTICE OF TIMBER ESTIMATING 187 



1. TYPE AND PLOT SYSTEM 



According to this method the land to be passed on is 

 divided up into types of known area and approximately 

 like stand, without, however, necessarily leaving marks on 

 the ground. Through these subdivisions of his area the 

 cruiser travels, studying the size, height, density, and con- 

 dition of his timber, and forming as he goes an estimation 

 of the average stand. This estimate he checks by a number 

 of sample plots, run out with the tape, and examined with 

 care. The plots are usually laid out either in square 

 or circular form, though the strip system is perfectly 

 applicable. 



Very satisfactory results have been arrived at by this 

 method where a considerable area in sample plots has 

 been surveyed or where the estimator is a man of judg- 

 ment and experience. But choosing a few sample plots to 

 represent a tract is recognized as a very delicate matter. 

 Beginners generally select too good a piece, and the man 

 who is really competent to do it can usually make a close 

 guess at the whole thing. As with all other methods of 

 estimating, area should be known from surveys, and. that 

 in not too large units. 



A good example of the application of this 

 system comes from a national forest super- 

 visor who had to estimate for a timber sale 

 a tract of some 1200 acres. It lay in the 

 form shown, with a ridge running down 

 the middle of it, which naturally formed 

 the first line of subdivision. The tract was 

 therefore surveyed with compass and chain and a dividing 

 line run along the ridge top. 



Then on each side of the ridge three distinct types of 

 timber stand were recognized. The heaviest timber, red 

 fir of good size, was in the middle; the north end was 

 lighter, with a mixture of lodgepole pine; the south end 

 had been damaged and rendered very thin by fire. These 

 blocks were therefore blazed out and roughly surveyed? 

 Thus the land was divided into six compartments of ap- 

 proximately even stand and of known area. 



