SAMPLE PLOTS IX SILYICULTUBAL BESEARCH 3 



under a high degree of control. Soils of uniform texture can be 

 used: temperatures can be controlled by growing the plants in a 

 greenhouse ; watering can be applied artificially ; length of day can 

 be artificially extended or reduced: and the pedigree of the plants 

 may be known. In dealing with annual field crops greater diffi- 

 culty is encountered: but with care some factors can be controlled 

 very closely, and if it is necessary to repeat the experiment no great 

 difficulty stands in the way. In forestry, such control and ready 

 repetition are practically out of the question. The forest is a long- 

 time crop, the individual specimens are large, the units of measure- 

 ment are not always exact, and volumes often cannot be measured 

 easily or with a high degree of accuracy. Furthermore, genetic 

 characteristics are not fixed, environmental factors cannot be so reli- 

 ably measured, and the previous history of the area, which is often 

 a major controlling factor, is seldom known. These difficulties 

 create an extreme need of care in planning and in conducting 

 silvicultural experiments. 



The great need of information on forestry measures has caused 

 many men to undertake research on their particular problems. Too 

 often, the desire to get something under way quickly or to take 

 advantage of transient favorable conditions has led an investigator 

 into tasks for which he was not adequately trained or for which he 

 had not made adequate preparations. In numerous instances, inex- 

 perienced and incompetent workers detailed to establish a series of 

 sample plots have failed to take into account some of the essential 

 particulars. As a result, much investigative effort has yielded con- 

 flicting or fragmentary answers, or no answers at all, to the questions 

 it was intended to solve. 



It is the purpose of this circular to present to foresters with 

 research responsibilities an outline of the technic of sample-plot 

 procedure, in order that the standards of such work may be 

 raised, that findings from studies of data obtained in one region may 

 be applicable in other regions, and that silvicultural research as a 

 whole may yield conclusive results in less time. The publication 

 deals with the requirements of good silvicultural research as these 

 are known in 1934. Since the wide range of forest conditions and 

 the large number of forest species in the United States make it im- 

 possible to present all the different refinements of technic that 

 apply locally, this discussion attempts only to outline the technic 

 that is generally applicable, leaving it to the individual worker to 

 exercise his own initiative, ability, and ingenuity in deciding which 

 methods apply best to conditions in a given locality. 



The publication is concerned primarily with field methods. In 

 most cases the purpose of the work will dictate the method of 

 compiling the data. It should be remembered the real value derived 

 from plots comes from the analysis of data, not from establishment. 



This presentation of research methods is not to be taken as an 

 effort to standardize research. Such an effort would be highly unde- 

 sirable. Research can progress only if research agencies are per- 

 mitted freedom of thought and action. So long as these agencies 

 maintain the high standards of accuracy and thoroughness and the 

 continuity required by silvicultural research, they are entitled to 

 considerable latitude as to the details of procedure. 



