Canadian Forestry Jourrial, January, 1920 



cases even less, will give a reasonably accuiale 

 basis for an estimate of the whole. On smaller 

 areas, or where the conditions which show much 

 variation, it is necessary to cruise at least ten 

 per cent of the area. 



THH FIRST STEP IN A SURVEY. 



In conducting a forest survey the hrst thine; 

 to do is to establish an accurately measured 

 base-line. If a convenient surveyed line does 

 not exist it is necessary to run one out, leaving 

 marks at every five or ten chains to which the 

 cruised strips can be tied. 



The survey should be laid out so ti.'at the 

 strips run at right angles to the ridges and 

 streams, otherwise misleading tallies, which do 

 not represent average conditions, will be se- 

 cured. The width of the strips will depend on 

 the nature of the forest. In open woods the 

 cruiser may be able to see for a chain on each 

 side of the line, but in dense spruce woods he 

 may be able to see only a rod on each side. 



The cruising party may consist of two to 

 four men. In large timber two men may suf- 

 fice, but in small, dense timber it is better to 

 have three or four. The party is guided by a 

 compass-man who, in addition to maintaining 

 the direction with a hand-compass, keeps track 

 of the distance travelled and usually takes notes 

 on the topographical features. The distance is 

 sometimes measured by pacing but usually by 

 means of a tape-chain attached to the compass- 

 man's belt, the end of each chain being marked 

 by a scratch on the ground, blaze or broken twig. 

 In two men parties the cruiser watches the rear 

 end of the chain and tallies the diameter at 

 breast-height and the height class of each tree 

 in the strip. The height class can be recorded 

 in different ways but it can, perhaps, be most 

 readily expressed by the number of logs of a 

 certain length that the tree will cut. When 

 more than two men are used, the additional 

 men call out the sizes of the trees within the 

 strip to the rear chain man who acts as tally- 

 man. The diameters, in some cases, are meas- 

 ured by calipers, but usually the cruiser's eye 

 soon gets trained to estimate the size with 

 sufficient accuracy. 



Tally sheets should be changed with each 

 change in the forest type so that when all the 

 cruising lines are completed the boundaries of 

 the various types such as heavy timber, light 



timber, muskegs, burns, etc., can be mapped 

 in and the areas of each determined. 



The total volume can be obtained with great- 

 er accuracy by working up the volume on each 

 type separately than by lumping all the samples 

 together and applying the average to the total 

 area. The greatest source of error in tim- 

 ber estimating has always been in the area to 

 which the detailed estimates are applied. Most 

 of the old "experienced" cruisers can tell with 

 remarkable accuracy the amount of timber 

 which can be cut on a given area, but the varia- 

 bility of the stand in almost every forest area 

 necessitates as much care in estimating the areas 

 of the various types as in estimating the amount 

 of timber on the areas cruised. 



TELLING A TREE's CONTENTS. 



Long experience in checking estimates by cut- 

 ting has enabled many cruisers to tell the con- 

 tents of a tree with great accuracy especially 

 in types with which they are familiar. Th 

 judgment of estimators is not always reliabl 

 and it has been found much safer to base the 

 estimates of the stand on actual tree tallies anc 

 volume tables which give the average contents 

 of trees of various diameters and heights. These 

 volume tables are based on the actual measure- 

 ments of a large number of trees. Unfortun- 

 ately, very little has yet been done officially 

 in Canada in preparing volume tables, but the 

 United States Forest Service has publishec 

 tables for the species of trees found here anc 

 with some adaptation to local conditions these 

 can be used in Canada. Most Canadian forest- 

 ers engaged in this kind of work have, however 

 developed volume tables of their own. 



The ordinary strip survey supplies data foi 

 a good working map and, if elevations are taken 

 frequently with an aneroid barometer and check 

 ed up faithfully with known elevations on the 

 base-line, a contour map can be made which 

 will be of great value in laying out logging 

 operations. 



It must be remembered that the accuracy oJ 

 the survey depends on the proportion of the 

 area actually cruised and, though a five per 

 cent cruise may give a reasonably accurate idea 

 of the total stand on a large area, it is almost 

 sure to be found deficient in detail when applied 

 to a small area as a basis of a small logging 

 operation. 



