TIMBER ESTIMATING IN THE SOUTHERN APPALACHIANS 315 



result appreciably, since the average for cove or cove and lower slope 

 type is determined by the tally made by the special cove crews which 

 in turn governs the map and acreage of the type ; and the strip acreage 

 on the inferior type is too large to be affected by errors of a few trees 

 more or less at cove crossings, even if these did not compensate. 



PER CENT OF AREA TALLIED 



It is necessary to consider not only the location of the strips, but 

 also the per cent of the total area to be included in them. The size of 

 the units for which separate estimates are required, and the uniformity 

 of the timber within the types or stand classes recognized, are factors, 

 the effect of which upon the per cent of estimate necessary for a given 

 degree of acuracy, is well understood. The smaller the estimate unit 

 and the less uniform the stand of timber, the greater is the per cent of 

 area which must be covered by the strips. For the valuation of tracts 

 as a whole, this per cent varies inversely with the size of the tract, other 

 conditions being similar. This is apparent when one considers, for ex- 

 ample, that a five per cent estimate of a 200-acre tract means a tally of 

 only ten acres of timber, which is of little value in determining the aver- 

 age of an irregular stand, while the same per cent of a 5,000-acre tract 

 gives a tally of 250 acres, which is sure to be representative if the 

 strips are well located. 



When valuation is the sole purpose, it is not necessary to have as 

 accurate an estimate of inaccessible tracts with low stumpage values 

 as of relatively accessible bodies of timber with high stumpage 

 values. Under such circumstances, accessibility increases the per cent 

 of estimate necessary for a given degree of accuracy in valuation. 



The following range of per cents, except in exceptional cases, will 

 meet the conditions of the southern Appalachians, provided an esti- 

 mate is required which will be within ten to fifteen per cent of the actual 

 stand on the unit. A higher standard than this cannot be obtained 

 under average conditions without prohibitive expense. 



