SAMPLE PLOTS IN" SILVICULTURAL RESEARCH 49 



merely the aggregate number of trees in height classes, such as the 

 6-inch, 12-inch, or 24-inch height groups. Height may be determined 

 within 6 inches by placing a graduated stick against the tree. Data 

 based on exact measurement of individual trees are much more 

 valuable, however. 



When individual stems are tagged, actual heights are recorded. 

 Measurements should be taken from the ground line, with the excep- 

 tion that the heights of stump sprouts should usually be taken from 

 the point of sprouting. Each sprout should be considered as an indi- 

 vidual, unless the sprout clump is considered as a unit. Even then 

 it is often desirable to record the number and development of 

 individual sprouts, by clumps. 



In very small growth, when the effects of individual growth 

 factors are under observation actual height measurement should 

 be taken along the stem. Obviously, very careful measurements are 

 not necessary in the case of rapidly growing species or sprouts, and 

 in many cases will not be required after the tree has reached small- 

 sapling size. Where confusion is likely to occur otherwise, field data 

 should show how the measurements were taken. 



If the smaller trees on a treated plot are individually tagged, 

 measured, and recorded, this does not make it necessary that the 

 trees on the control plot be treated in the same manner. For the 

 control plot, data need be taken only on a certain number of trees 

 representative of the various height classes present. The purpose 

 of the study, the species, and the method of treatment will usually 

 determine which trees and how many shall be taken. 



Diameter measurements on very young stands are usually value- 

 less ; until the tree ha,s reached at least the 2-inch class an expression 

 of volume growth has little meaning. In some instances, however, 

 it may be desirable to take these measurements in order to extend the 

 diameter-height curves to their origin. When a diameter record for 

 very small trees is necessary the measurement should be made at a 

 point about 6 to 8 inches from the base to avoid root swell, which is 

 sometimes pronounced, particularly in coppice growth. Calipers 

 can be used. It is rarely necessary to mark the point at which the 

 measurements are taken. 



To determine the age of a young stand, some of the stems should 

 be cross-sectioned at the ground line. This method will probably be 

 adequate for every species except longleaf pine. The age recorded 

 for planted stands is the number of years (growing seasons) since 

 planting. (Records for such stands should show, however, how old 

 the trees were when planted.) 



A crown classification is usually meaningless as applied to repro- 

 duction. In describing reproduction it may be highly important, 

 however, to indicate the relative thriftiness or vigor of the seedling, 

 sprout, or sprout clump. No valid classification of thrift or vigor 

 has yet been advanced. Among those suggested are relative vigor 

 in the stand, as indicated by quantity of foliage (as related to age 

 or size of plant) and freedom from suppressive shade or other com- 

 petition (as indicated by fullness of crown) ; character of foliage, in- 

 cluding density, general appearance, and color, and perhaps dry 

 weight of representative leaves; comparative height growth: and 

 thrift as judged on the standard of the average thrift of a plant of 



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