Forest Mensuration 37 



PARAGRAPH LIX. 



SIR DIETRICH BRANDIS' METHOD. 



The Brandis method is indicated where the object at stake consists in 

 a rapid survey of the stumpage on large tracts, like the vast Teak and 

 Bamboo forests of upper Burmah. 



Traversing existing trails of known length on horseback, the estimator 

 records the diameter of each tree within a given distance (say 200 yards) 

 on either side of the trail. 



The widths of the strips traversed* multiplied by the length of the trail 

 yields the area of the sample plot. The number of the trees of the 

 various diameters found on the sample strip appears from the records. 



PARAGRAPH LX. 



PINCHOT-GRAVES METHOD ADOPTED ON DR. WEBB'S ESTATE. 



1. Sample acres, measuring 4 x 40 poles, are irregularly laid into 

 swamps, hardwood slopes and spruce slopes. The sum total of the sam- 

 ple acres is Z l / 2 % of the total acreage. 



2. The length of a sample acre is actually chained off, whilst the width 

 is ascertained (two poles to the left and two poles to the right of the 

 chain) by tape, by pacing and by estimating. 



3. The sites of the sample acres are not marked on maps. 



4. All trees on the sample acres are calipered; a number of heights 

 are taken on each sample acre; for each sample acre the average diam- 

 eter, the average height and the number of trees are ascertained. 



5. From these averages is deduced, for all sample acres, the average 

 diameter, the average height and the number of trees. All these data, 

 of course, must be given for the various species separately. 



6. From volume tables previously constructed the volume of the trees 

 having average height and average diameter is obtained and is multiplied 

 by the average number of trees. 



7. This multiplication yields the volume of the average sample acre. 

 Objections to this method of valuation survey are: 



a. The tree of average diameter has neither average volume nor 



average height. 



b. The average diameter should be obtained from the fraction "total 



sectional area over number of trees." It cannot be obtained 

 correctly from the fraction "sum total of diameters over num- 

 ber of trees." Similar objections hold good for average height. 



c. Guessing at the width of a strip, in dense growth, is rather risky. 



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