SAMPLE PLOTS IN" SILVICULTURAL RESEARCH 79 



Examples of the use of the symbols given are illustrated in figure 5, as follows : 



1. A dominant tree normal as to crown and bole, 

 la. A dominant tree with one-sided crown. 



lb. A fast-grown tree with large limbs, a better wolf tree, in the dominant 

 class. 



lc. A decidedly crooked or limby tree of poor quality in the dominant class. 



2. A codominant tree with normal crown and bole. 



2d. A codominant tree with crown suppressed or damaged owing to influence 

 of adjacent trees. 



3d. A suppressed tree with damaged crown. 



4d. An understory tree with crown damaged through influence of adjacent 

 tree. 



4f. A dead tree in the understory. 



METHODS OF PREPARING VOLUME AND YIELD TABLES 



VOLUME TABLES 

 (Report of a committee on standardization of volume and yield tables) 



The Forest Service has had in mind for several years a series of manuals 

 covering methods used in silvical forest research. At a meeting of forest ex- 

 periment station men held at the Forest Products Laboratory, Madison, Wis., 

 in March 1924, the need of such a series was clearly shown, and it was proposed 

 to establish certain definite standards for silvicultural and mensurational re- 

 search. Because of the growing demand for growth and yield studies, and 

 because no uniform methods were being followed, it was felt that these should 

 receive precedence. To insure that the field would be adequately covered and 

 the forestry profession fully represented, a committee of 9 was formed. 

 Three members were appointed from the Forest Service, 3 from the Society 

 of American Foresters, and 3 from the Association of State Foresters. The 

 committee immediately began studying different methods in use and pro- 

 posed, and decided to present those measures which it felt would result in 

 accurate and consistent volume and yield tables. It was not the pur- 

 pose of the committee so to standardize the preparation of these tables that 

 further research in mensurational fields would be precluded, but to present the 

 best practice now in fairly common use so that any agency preparing volume 

 and yield tables could proceed in confidence that its work would measure up 

 to a high standard of accuracy and completeness. In following these methods, 

 that agency would also have the benefit of previous mistakes and avoid many 

 of the pitfalls that beset the unwary. It is hoped that the committee's labors 

 will result in improved volume and yield tables, and that the outline here 

 presented will be followed by all forest agencies undertaking their preparation. 



The members of the committee have devoted considerable time to this task 

 and have cooperated heartily in a work which has developed numerous dis- 

 cussions. In addition to the suggestions offered by the committee members, 

 advice and comment were obtained from the various forest experiment stations, 

 several of which now have growth studies under way, and from foresters not 

 formally represented on the committee. Much of the burden of preparing this 

 material has been carried by Donald Bruce rather than by the chairman. 



COMMITTEE MEMBERS 



Forest Service Society of American Association of State 



Foresters Foresters 



Edward C. Behre H. H. Chapman J. S. Illick 



Donald Bruce T. S. Hansen M. B. Pratt * 



E. N. Munns, clwirman D. T. Mason E. O. Siecke 



FIELD MEASUREMENTS 



1. Diameter breast high should be measured 4% feet above average ground 

 level. 



2. The measurements should be taken with calipers, when possible, two 

 diameters at right angles being averaged. 



3. The diameter should be measured to the nearest one-tenth inch. 



4. Bark thickness should be recorded at b.h. 



