452 COORDINATION OF FOREST SURVEY 



is more certain, and the area so stocked with trees which will probably 

 survive can be better determined. 



For both these classes of timber, the best method of determining the 

 area, and consequent future growth, during the forest survey, is to record 

 on each strip the per cent of total area on the strip which is stocked 

 with young timber, on the basis of probable survival to maturity. 

 This per cent is then reduced to acres for the strip. The average size 

 and age can also be noted. Seedlings and saplings can be separately 

 noted, or thrown together, depending on the intensiveness of the work 

 and size of area. 



A second method of record on the basis of area, formerly used in the 

 Southwest, was to note the reproduction in general terms, based on 

 whether the stocking was sufficient to replace the present stand. If so 

 it was termed excellent. Different per cents less than this were termed 

 good, fair, poor, and none. This system does not distinguish between 

 the areas of mature and young timber or consider the relation which 

 one bears to the other. 



To supplement the per cent method of ocular guessing at areas 

 restocked, plots may be laid out at given intervals, on which the areas 

 stocked can be mapped, and computed in terms of acres. The per cent 

 of the plot thus shown as reproduced serves to correct the ocular work 

 and to check the results. 



Methods for Poles. With poles, the area method can still be applied 

 directly in even-aged stands, by mapping. In many-aged stands, a 

 choice of two methods is offered. Either the area per cent can be used 

 as for saplings, but separately, and the number of trees in this class 

 ignored as before, in which case merely the average size and age of the 

 poles on each strip is recorded with the per cent of area occupied, or 

 instead, the poles may be counted. 



The purpose of the count is to obtain a second basis of comparison 

 with the empirical yield table. The latter should show the number 

 of trees per acre required at different ages. The yield table data may 

 be made to include pole sizes, by including plots of this age in construct- 

 ing the normal tables of yield. In case this has been done, the area 

 occupied by poles can be very roughly determined by means of the 

 numerical comparison with the empirical table. For instance, if poles, 

 averaging sixty years old and 7 inches in diameter run 120 per acre 

 in the normal table, and the reduction per cent is 66f , the empirical 

 stocking is 80 poles per acre. A count of 8000 poles on the area indicates 

 an area of 100 acres stocked with pole sizes. 



A definite plan for the determination of the stocking with poles must 

 be made preliminary to undertaking the timber survey. Trees which 

 are part of an even-aged mature stand, but which are not yet merchant- 



