6 CIRCULAR 3 3 3, U.S. DEPARTMENT OF AGRICULTURE 



Decisions should be made as far in advance of field work as is 

 possible regarding the number, size, shape, and distribution and 

 grouping of plots and subplots, width of isolation strips, and size 

 of area outside the plot that is to be treated or retained for further 

 work. Advance decision is necessary also as to the kind and num- 

 ber of measurements and other data to be taken, how these are to 

 be taken and recorded, and what instruments are to be used. 



The methods to be used in compiling the data should always be 

 considered before the system of recording them is decided upon. 

 Thus, if some device such as & punch-card tabulating machine can 

 be used, provision for its use should be made in coding and record- 

 ing the data in the field. (See appendix, p. 73, for numerical code 

 applicable to sample-plot work.) 



Establishment of the plots is only the beginning of the job; the 

 necessity of periodic remeasurements constitutes a mortgage upon 

 the future. The establishment of a series of permanent plots during 

 the slack time of one season may easily result in a burdensome 

 schedule of work during a subsequent season when demands on 

 time are greater. Whenever possible, a study involving a series of 

 plots should be so planned that remeasurements are staggered over 

 the years and thus no one season's work is made much heavier than 

 another's. 



The plan cannot be hard and fast ; field and other conditions will 

 inevitably necessitate changes in it from time to time. The investi- 

 gator should be constantly on the alert for new ideas and extra data 

 that will aid in the solution of silvicultural problems. An active 

 mind should supplement every working plan, no matter how com- 

 plete (6). 



A detailed plan of work for the study should be written before 

 the field work of plot establishment is begun. This should begin 

 with a clear-cut statement of the purpose of the study and of each 

 plot. Next a set of definitions to be used throughout the study 

 should be prepared. These should be so complete and unequivocal 

 that, if necessary, a second worker wholly unfamiliar with the pre- 

 vious work can take up the study at any point and carry it on to its 

 conclusion. 



The written plan should describe the conditions to be met in the 

 experiment, such as the site, age, density, and normality of the stand. 

 Any factors, such as soil conditions, topography, drainage, slope, or 

 exposure, that are to be considered in the study, should be outlined, 

 doubtful points cleared up, and alternative proposals as to future 

 procedure described. 



The plan should record specifically the number, size, shape, and 

 distribution of plots and subplots, the width of isolation strips, the 

 kind and number of measurements to be taken, the methods of 

 measurement, the instruments to be used, and related matters. The 

 progressive steps in plot establishment should be described in full. 

 If the plots are to be given some form of treatment, the plan should 

 outline the methods to be followed. Trees to be cut or trees to be 

 left should be described, method of logging or otherwise removing 

 products outlined, and the question of slash disposal settled. Be- 

 yond this, there should be an indication of the time or season when 

 the treatment should be carried out. 



