34 



COLLECTION OF PLOT DATA 



FIELD NOTES AND FORMS 



Field notes demand special care. Measurements should be re- 

 corded in an orderly way, on forms devised specially for the study 

 or on forms in general use for similar work. All data required by 

 the project should be recorded at the time the work is done. If 

 columns are used for data of a character different from that indi- 

 cated by the form headings, or if data are entered in columns that 

 in the printed forms were left without headings, the changes and 

 insertions should be carefully made in the field. A standard set of 

 abbreviations of species names should be used in every study. Tech- 

 nical and common names of trees as given in the Check List (71) 

 and of other plants as given in Standardized Plant Names (2) 

 should invariably be followed. 



All notes should be completed in the field, and before the plot 

 is left the notes should be checked for completeness. All notes, 

 forms, and maps should be initialed and dated. Nothing should be 

 left to memory. 



All records must be legible and permanent. Printing is usually 

 more legible than script. Special care should be taken to make all 

 figures so distinct that they cannot be misread. Good-quality paper 

 should be used, and permanent ink or a pencil soft enough to make 

 reading easy but not so soft as to smear. Carbon duplicates of field 

 notes may sometimes be needed for field-station files, and serve as an 

 insurance against loss of valuable data. Each sheet or form for field 

 notes should bear a serial number. All forms should be made up on 

 sheets of uniform sizes, i.e., single sheets should be of such size that 

 they can readily be filed without folding or rolling, and can be bound 

 in standard covers. Use of miscellaneous odd-sized forms or, par- 

 ticularly, of small-sized forms should be discouraged. 16 



Some typical forms, used by the Forest Service, for the collection 

 of data from sample plots, and abbreviations and a numerical code 

 for use in recording such data, are given in the appendix (pp. 66 

 and 73). 



TREE MEASUREMENTS" 

 BREAST-HEIGHT DIAMETER 18 



The standard point for measuring breast-height diameter (d.b.h.) 

 is 4!/2 feet above the average ground level. This point should be 

 determined exactly for each tree with a measuring stick and should 

 be permanently marked on trees that are to be measured repeatedly. 

 On slopes the average ground level is a point vertically half-way be- 

 tween the ground levels immediately above and below the tree. Con- 



16 Standardization of the sizes of all forms used in forest research has much to com- 

 mend it. It facilitates filing and binding, makes for uniformity in the records, and tends 

 to reduce the number of forms needed. The standard unit should be ordinary letter 

 size (8 by 10% inches). Smaller or larger forms should be of some standard fraction 

 or even multiple of this size. 



17 The appendix contains a list of the instruments, tools, etc., needed in measuring trees 

 (p. 72) and a discussion of methods of preparing volume and yield tables (p. 79). 



18 The basal area of forest trees is more significant than their diameter, and could 

 as easily be measured directly if the proper graduations were put on tapes and calipers. 

 At present the fact that basal area is not readily measured or calculated, and that 

 " square feet per acre " is an unfamiliar conception, prevents its general adoption. Its 

 use should, however, be encouraged in every way. 



