SAMPLE PLOTS IN SlLVlCULTTTRAIi RESEARCH 13 



In the absence of an available area definitely dedicated to re- 

 search, plots should be established on public rather than privately 

 owned forests. Public ownership provides stability of tenure and 

 of management policies, and a degree of protection usually greater 

 than that on private land. On privately owned lands economic in- 

 fluences operate to bring about rapid changes in ownership or poli- 

 cies, often in spite of the owner's wishes. Even the best of leases 

 expire, and cooperative agreements terminate, often at times when 

 the value of the plots is at its maximum. Corporations are more 

 likely to hold land under a continuing policy than individuals. 



Even on a public forest, before selecting a stand for plot estab- 

 lishment it is necessary to give careful consideration to present and 

 prospective modification or use of the area as in timber sales, recrea- 

 tion, or grazing, and to the possibility of the area's being removed 

 from research use as by reservation for municipal watershed pro- 

 tection. 



AGREEMENTS WITH FOREST MANAGERS AND OWNERS 



Before sample-plot work is begun on a publicly owned forest 

 other than an experimental forest, approval of any needed restric- 

 tions should be obtained from the supervisory officer in charge of 

 the area. As soon as field work on the plots is completed, both the 

 supervisory officer and the resident ranger, guard, or caretaker 

 should be supplied with maps and data showing exactly the area 

 to which restrictions apply. If possible, it should be arranged that 

 the local supervisory officer visit the plots in company with one of 

 the responsible research workers. 



TTlien plots must be located on private land, full cooperation of 

 the owner should be obtained in advance. The extent and location 

 of the area involved should be shown on a map, and the owner's 

 agreement to whatever restrictions must be placed on its use should 

 be obtained in writing. A specimen form of agreement for this 

 purpose is given in the appendix (p. 89). 



LOCATING PLOTS WITHIN THE STAND 



Plots should be located well within the selected stand, so that plot 

 conditions may be truly representative and free of the influence of 

 surroundings not typical of the stand. Particularly should they 

 be so located as to be free of " border " influences such as exist 

 along roads and at the edges of clearings, fields, or other openings 

 in the stand. Highways have an especially marked influence upon 

 soil drainage, upon crown development, upon the minor vegetation 

 near the break in the canopy, and upon air movement. (See dis- 

 cussion of isolation strips, p. 11.) 



Plot location should aim at uniformity as to geologic factors (rock 

 outcrops, soil depth, and soil character), physiographic factors 

 (slope, exposure, elevation, and drainage), history (as to fire, cut- 

 ting, grazing, insects, diseases, wind), and stand factors (crown 

 cover, density, stocking, age, species composition, and distribution 

 of tree sizes), unless differences due to variation in these factors 

 are to be studied; and in the latter case uniformity within the in- 

 dividual plots is desirable, in conjunction with divergence between 



