36 Forest Mensuration 



The following METHODS OF VALUATION SURVEYS might be 

 distinguished : 



I. Cutting sample trees. 



a. Sample trees selected for about five diameter classes, each 



class containing about one-fifth of the number of trees pres- 

 ent (Draudt-Urich method). 



b. Sample trees selected for about five diameter classes, each 



class containing about one-fifth of the sectional area of all 

 trees present (Robert Hartig method). 



c. Sample trees selected as average-diameter-trees of the entire 



forest (Old Bureau method). 



d. Sample trees selected at random e. g., from dead and down 



trees (C. A. S. method applied in the Balsams; Algon 

 Universal tables; Graphic method). 



e. Stem analysis, together with investigations as to thickness of 



bark. 



II. Without cutting sample trees. 



a. Measuring height and diameter and estimating form figure of 



sample trees. 



b. Measuring rectified heights and diameters. 



c. Measuring merely diameters and estimating form heights. 



d. Photographing sample trees, having a scale say a stick 6 feet 



long on the picture. 



III. With the help of volume tables. 

 IV. With the help of yield tables. 



PARAGRAPH LVIII. 



FACTORS INFLUENCING THE SELECTION OF SAMPLE PLOTS. 



If sample plots are taken, there must be determined: 



a. The number, situation and distribution of the sample plots. 



b. The absolute and relative size of the sample plots. The Bureau of 

 Forestry prescribes sample plots equalling from I to 4 l /2% of the forest. 

 The "Forest Reserve Manual" prescribes 5% or more. 



c. The form of the sample plots and the manner by which the size of 

 the sample plot is ascertained. 



In Europe an ordinary workman calipers, on an average, 5,000 trees 

 (in maximo 12,000 trees) per day. In Pisgah Forest 500 trees is a good 

 day's work for one estimator and one helper. 



