TIMBER CRUISING 



1487 



cent of the tract. Where the spacing is 5 chains, 20 per normal trees are taUied as iiwasiirciiicnts. giving an ini- 

 cent of the tract is covered. For any bnt very small personal volume control of the sound timber. Allow- 

 areas, a 20 per cent cruise is sufficiently accurate even ances for abnormal form and visible defect are tallied 

 for high priced stumpage. by trees as opinions. Allowances for unseen defect, 

 The second brings in the use of "Volume Tables." A breakage in falling, and other shortages, are made by 

 volume table for any kind of timber, Douglas fir, for types, or other subdivisions, rather than by trees. 

 example, is a table that gives the average scale for The form in which the results of a cruise, or forest 

 Douglas fir trees according to diameter breast-high (/. e. survey are presented, is an iniixntant consideration. A 

 43^2 feet above ground) outside the bark, and merchant- topographic map, with contours, and timber types dis- 

 able length. Thus, from a volume table prepared by tinctly outlined is most essential. This furnishes a bird's- 

 the United States Forest Service, one can read that a eye-view of all conditions of interest to an owner, opera- 

 fir 36 inches in diameter, and having a log length of 170 tor or jirospective purchaser. The cruise figures may be 

 feet, contains on the average, 2,020 feet if scaled with the put directly on the map, or tabulated separately bv units 

 Scribner Rule. The volume table is made uj) from a of area. A separate cruise sheet or sheets furnish a corn- 

 large number of measurements of trees of all sizes, taking pact summary of kinds, quantities, and sizes of timber, 

 the diameter breast-high outside the bark (which can A written rejjort covers all points not graphically shown 



always be actually measur- 

 ed, and, therefore, does not 

 need to be estimated) and 

 the scale of the whole tree 

 by logs according to the log 

 ride. Of course, these meas- 

 urements are taken from 

 felled trees, and the scale 

 of the trees 36 inches in 

 diameter breast-high, for 

 instance, is averaged, so 

 that one volume figure is 

 obtained that will apply to 

 all trees of that species 36 

 inches in diameter and 

 within a certain range of 

 merchantable height. 



In using a volume table it 

 will be borne in mind that 

 its figures are average 

 figures, and that local 

 measurements must always 

 be taken on each tract so as 

 to determine whether the 

 timber on the i)articular 

 area cruised will scale bet- 

 ter or poorer than the aver- 

 age shown by the table, and how much better or 

 poorer. 



From 80 to 95 j)er cent of all sound trees of any species 

 within any type of stand fall within a normal range of 

 variation as to form of bole, and the relationship between 

 base diameter and average volume can readily be deter- 



40 Chains 



Cruise Line 



01 



I'LA.X SHOWING ARRANGEMENT OF CRUISE LINE.S ON QUARTER 

 SECTION (160 ACRES) 



The dash lilies represent the cruiser's line of travel. The light solid 

 lines on either side of the dash lines are boundaries of the strip within 

 which all trees are tallied. The topographic features between cruise 

 lines are mapped as far as can be seen on the line of travel, thus filling 

 in from line to line. 



on the maps and cruise 

 .sheets, including a discus- 

 sion of logging conditions, 

 markets, etc. The whole is 

 calculated to give the fol- 

 lowing results : 



1. A reliable basis for 

 valuation. 



2. A basis for an efifec- 

 tive plan of operation. 



3. The best possible 

 location of roads, camps 

 and other improvements. 



4. A reduction in loss 

 from windfalls and normal 

 decay. The felling areas 

 can be adjusted with refer- 

 ence to the need of prompt- 

 ly cutting damaged or over- 

 mature timber. 



5. The preservation of 

 knowledge relating to the 

 property. \\'ithout a sur- 

 vey system, much informa- 

 tion may depart with those 

 who hapj)en to possess it. 



6. Reduction in loss in- 

 cident to change of management in an operating 

 company. ,\n adequate forest survey provides a new 

 manager with a mass of essential knowledge ready for 

 his use. 



7. Efficiency of fire protection system. 



The cost is not the least important point in connection 



mined by taper measurements on a comparatively small with forest surveys and cruising, though it has been left 



number of trees within each type in conjunction with until the last. The charge for a complete showing as 



volume tables based on taper measurements of large outlined above, rarely exceeds two cents per thousand 



numbers of trees. The base diameters of these sound feet, and usually is nearer one cent. 



A. C1IUISTMA.S su(;gkstion 



Are you puzzled about the selection of Christmas gifts? 



Why not give a year's subscribing membership in the American Forestry Association as a gift. It will cost 

 you $3.00, and the member will receive American Forestry Magazine for a year. 

 This will be an ideal Christmas gift for a child or an adult. 

 Send the money to the Association and a Christmas Card will be sent you to present on Christmas Day. 



