SAMPLE PLOTS IN SILVICULTURAL RESEARCH 7 



A systematic scheme for recording the data should be included in 

 the written plan. The forms to be used should be prescribed, with 

 column headings specifically indicating what data are to be recorded. 

 Abbreviations and symbols to be used throughout the study should 

 be set down. (See appendix, pp. 73 and 76.) 



NEED OF CARE IN RECORDING PLOT ESTABLISHMENT 



Anyone who establishes a permanent sample plot should recognize 

 that he thereby assumes responsibility for furnishing future workers 

 with a complete picture of conditions on the plot at the time of its 

 establishment. Not only must each plot be properly marked and 

 all measurements be in perfect order, but all notes and records must 

 be full and complete. Otherwise, the plots may fail to yield the 

 desired results and those who in later years become responsible 

 for their care and for analysis of the data may be led into serious 

 mistakes. Many a silvicultural study has failed to give even par- 

 tial answers to the questions involved largely because the person 

 who established the plots failed to make some of the essential 

 measurements or failed to make a systematic record of his obser- 

 vations. 



The need of care in making plot records is intensified by the 

 improbability that the worker who establishes a given series of 

 plots will himself remeasure the plots over a long period. In very 

 few instances have plots been remeasured over a period of 20 

 years, or even 15 years, under the personal direction of the same 

 man by whom they were established. 



CREW ORGANIZATION 



Under most circumstances, the most efficient crew for sample-plot 

 work is one composed of three men. The leader of the party should 

 be a permanent member of the research organization responsible for 

 the work. Before going into the field he should become thoroughly 

 acquainted with the purpose and plan of the study, and with exist- 

 ing plot data. The two other members need not be permanent 

 members of the organization, but should be acquainted with forest 

 practices and with the instruments used in the work and should be 

 thoroughly reliable. If a 2-man crew is used, the helper should be 

 familiar with sample-plot procedure. Details of organization will 

 vary according to the character of the plots and other features of 

 the plan of work. The smoothness with which the work proceeds 

 will depend upon the experience of the crew members and, especially, 

 upon their energy and their interest in the work. 



NUMBER AND DISTRIBUTION OF PLOTS AND SUBPLOTS 



How many sample plots are needed to solve a given problem in- 

 volving treatment depends upon the conditions of the experiment and 

 the degree of accuracy demanded in the results. The general tend- 

 ency is to establish too few plots. Foresters have too frequently 

 failed to realize the complexity of a silvicultural problem or to ask 

 themselves how probable it is that the answer obtained from one pair 

 of contrasted plots would agree very closely with the answer from 



