74 SAMPLE PLOl^ STUDIES 



PROBLEM 35. (Field and OHicc.) Tmo J^ETioiiiMiNyVTioN of (Iuowth in 

 Even-aged Stands by the Measurement ok Standing 'J' ires. 

 Explanation. — In the method of the last problem (No. 33) it will be remem- 

 bered that good results can be obtained only when worked up in mature 

 stands, and that the results will then show the rate of growth of only those 

 trees which reach maturity. The method of this exercise will show the 

 average rate of growth of all trees throughout the life of the stand. As it is 

 only a comparatively small step from this exercise to the fundamental prob- 

 lems involved in the construction of yield tables showing the average total 

 stand per acre at any period in the life of the stand, the exercise is here out- 

 lined so as to cover the necessary work for these, namely to select the plots 

 located in different site qualities and to calculate values in terms per acre. 



This problem requires second growth even-aged stands of diiferent ages. 

 In order that a sufficient number of plots may ])e measured to insure CTiough 

 to illustrate the exercise the instructor should at the outset arrange the work 

 of each party in such manner that as large a range of ages will be olitained as 

 the conditions of the locality and the sis^e of the class will warrant. The 

 students should now be able to carry out this work without much super- 

 vision by the instructor, and the different parties can be scattered over a 

 wide territory. 

 Directions: 



Part I.— l^ield Work 



A. Parties. — 3 men in each. 



B. Equipment. — Determine what instruments and other equipment are 



necessary for each party, and have the instructor check your list before 

 starting for the field. The chief of party will be held responsible. 



C. Method of Procedure. 



1. Carefully lay off sample plots of re"? a-cre in stands of different ages. 



If good average conditions cannot be found in ^-acre plots, larger 

 plots should be used. In order that these same data may be used 

 in connection with the work in yield tables, some effort should be 

 made to secure them from different site qualities. 



2. Measure all trees at D.B.H. and record as in cruising. 



3. Number and describe the locality of each plot on the tally sheet. 



Use U. S. land subdivisions where possible. 



4. Determine the following information in the field with reference to 



each plot, using the Mean Sample Tree Method for determining any 



points requiring felled sample trees, 

 (a) The number of trees per acre. 

 {h) The diameter of the average tree, 

 (c) The volume of the average tree. 

 {d) The average height. (Measure 6 to 10 representative trees of 



the average diameter with the hypsometer and average.) 

 ie) The average age. 



