284 METHODS OF TIMBER ESTIMATING 



Forest types Accuracy of the better class of cruisers greatly 



increased by careful elimination of blank 

 areas and containing net area of timber to 

 which reduction factor from stand per acre 

 is applied for total 



Cull factor Usually neglected on account of deficiencies in 



Doyle scale 



Corrections from strip estimate for 



average stand This is based on general inspection and count- 

 ing since no systematic strips are run 



Many Southern cruisers have adopted more systematic methods of late. 



Yale Forest School Method in Southern Pine. 



Width of strip 10 rods — 2| chains 



Number of strips per forty 2 



Per cent of area estimated 25 



Measurement of distances By pacing 



Measurement of trees Count of the trees on the strip, tally of one- 

 third to one-fifth of the timber by mechan- 

 ical selection to avoid choice. 



Diameters Tallied by eye 



Merchantable height Tallied by eye in 16-foot logs and half-logs of 



all trees whose diameters are tallied 



Volume on strip From volume table for trees talhed multiplied 



by 3, 4 or 5, according to per cent talhed 



Forest types Areas not stocked with merchantable timber 



eliminated by mapping. Net area of timber 

 obtained. Types not usually separate 

 within a forty except on the map 



Cull factor By per cent of total estimate 



Correction from strip estimate for aver- 

 age stand Careful inspection at stated intervals of stand 



on remainder of forty. Comparison by 



weighted volumes with stand estimated. 



^^'cighted correction factor applied to area 



* estimated to obtain proper stand per 



forty 



Horseshoe Method. This is a modification of the strip method, by which two 

 strips are practically combined in one by running a horseshoe or angular course 

 through the forty as shown in Fig. 59. This results, first, in a saving of time, cut- 

 ting down a certain amount of travel from one strip to another; second, in a better 

 inspection of the timber and, it is thought, in a better average, since the strips run 

 in both cardinal directions. This method was employed extensively by a firm of 

 Southern timber cruisers, who used a 10-rod strip, thus running 25 per cent of the 



Pacific Coast Method. 



Width of strip 10 rods, or 2\ chains 



Number of strips per forty 4 



Per cent of area estimated 50 



Measurement of distances By pacing 



