SAMPLE PLOTS IN" SILVICULTURAL RESEARCH 23 



manent plot work it is necessary as a means of studying the develop- 

 ment of individual trees or classes of trees. 14 



If only a control of stand data, i.e., number of trees and basal 

 area, is desired, chalk marks, bark scratches, or light blazes made 

 on each live tree as it is measured will suffice. Powdered chalk and 

 carpenter's chalk are both much more satisfactory for use on rough- 

 barked trees than keel chalk or crayon. Light bark scratches and 

 blazes can be made quickly with any one of several types of bark 

 scratchers now on the market, such as that shown in plate 3. The 

 most satisfactory method of making individual trees permanently 

 identifiable is to give each an individual number. This is done 

 usually by attaching a numbered metal tag to the tree or by painting 

 a number on the bole. Several methods are shown in plate 5. 

 Each of these methods of identifying the tree has marked advantages 

 and disadvantages. In some cases local conditions make one method 

 decidedly superior to the other, in other cases the choice is entirely 

 arbitrary. 



Under some circumstances, such as in method-of -cutting studies, 

 the identification of a tree cannot be left wholly to stem markings of 

 any kind. Logging may so damage the markings on the trees that 

 they cannot be restored with certainty. On plots located in parks 

 and on other recreational areas, markings may be banned for 

 esthetic reasons. In some situations, markings on trees provoke 

 curiosity to such an extent that they are likely to be destroyed. In 

 such conditions the trees should be identified by means of a stem 

 map (p. 50), either with or without individual tree markings. 



In order that mortality may be correctly recorded, trees dead at 

 the time of plot establishment should be cut down or heavily blazed 

 so that at the next measurement there can be no doubt as to which 

 trees have died during the interval. 



TAGS VERSUS PAINTED NUMBERS 



Tags are easily and quickly applied; they can be used on rough 

 and on smooth-barked trees with equal facility, and ordinarily do 

 not need renewal during the life of the experiment. On the other 

 hand, nails driven into trees to hold tags may cause swellings that 

 make diameter measurements inaccurate, or may cause splits several 

 feet long. Tags can easily be removed by trespassers, and may be 

 knocked off by falling trees or branches ; they sometimes corrode so 

 that the numbers become illegible (62) ; and they may be grown over 

 by the trees and buried in the wood. On fire plots, tags are likely to 

 be unsatisfactory because of melting. Further, if a tagged tree is 

 eventually felled and sent to the mill, embedded nails may ruin the 

 saw. 



Painted numbers have the following advantages: They do not 

 injure the trees in any way and can be read quickly at a distance: 

 they cannot easily be removed or changed; no time is lost in pre- 

 paring them, as in punching out tags ; and their use permits numbering 

 the trees independently of any series of numbers on ready-stamped 



14 The discussion in this section relates primarily to trees in the 4-inch and larger 

 diameter classes, although in some studies trees even of the 1-inch diameter class may be 

 individually measured and recorded. Usually trees in the sapling stage or smaller are 

 classed as reproduction (p. 48). 



