YIELD TABLES FOR EVEN-AGED STANDS 81 



of the time element we measure a large number of sample plots in 

 even-aged stands from youth to maturity, in different site qualities, 

 and as fully stocked as possible. Use data collected (or used) in 

 Problem 35. 



B. Method of Procedure. 



1. Group the plots into 3 site qualities. 

 Method I.— Bauer's Method of Bands. 



(a) Plot the volumes (cubic feet) in acre terms on age. In each case 

 be sure to place the number of the plot with the plotted points. 

 (The data of Series IV are arranged according to site quahties.) 



(6) Enclose the plotted points between 2 regular curved lines. 

 Divide the space between them into 3 equal bands by first 

 indicating the proportional distances on the vertical lines 

 from the abscissa axis at each 10- or 20-year point and then 

 join the indicating marks by regular curves. 



(c) Include all plots in the highest band in Site Quality I, those 

 in the middle in Site Quality II, and those in the lowest in 

 Site Quality III. 



Method II.— The Site Factor Method. 



(a) Determine the site factor for each plot by means of the following 

 formula : 



a 



in which F = the site factor; 



/i = the height of the average tree, which is to be 

 determined from a height-diameter curve. The 

 height of the average tree is to be taken as the 

 height shown for the tree of average diameter; 

 B = basal area in square feet per acre; 

 a=the average age of the stand. 

 (6) Divide all the site factors into 3 groups of equal numerical 

 range in volume. All plots whose site factor falls within the 

 range of the highest group ^nW belong to Site Quality I, 

 those of the middle group into Quality II, and those of the 

 lowest into Quality III. 

 (c) Determine the basal areas and plot. 



id) Arrange the results obtained by the two methods in a compara- 

 tive table. 



2. Determine the normality of stocking by Bauer's Method as follows: 

 (a) Draw an average curve and exclude from the investigation all 



I)lots whose volumes vary by more than 7.5 per cent from the 

 average. These are either abnormally stocked or understocked. 



