158 CONSTRUCTION OF STANDARD VOLUME TABLES 



Dominant. Trees with crowns extending above the general level of the forest 

 canopy and receiving full light from above and partly from the side; larger than 

 the average trees in the stand, and with crowns well developed but possibly some- 

 what crowded on the sides. 



Co-dominant. Trees with crowns forming the general level of the forest canopy 

 and receiving full light from above but comparatively little from the sides; usually 

 with medium-sized crowns more or less crowded on the sides. 



Intermediate. Trees with crowns below, but still extending into the general 

 level of the forest canopy, receiving a little direct light from above, but 

 none from the sides; usually with small crowns considerably crowded on the 

 sides. 



Overtopped. Trees with crowns entirely below the general forest canopy and 

 receiving no direct light either from above or from the sides. These may be 

 further divided into oppressed, usually with small, poorly developed crowns, still 

 alive, and possibly able to recover; and suppressed or dying and dead. 



As currently used, overtopped trees are now classed as suppressed; and an 

 additional class, open-grown, is added, consisting of trees standing alone with 

 crown free on all sides. 



The bole is not described unless there is some marked peculiarity 

 which may explain an abnormal shape or volume and enable the investi- 

 gator later to decide whether to use or reject it in his tables. Such 

 peculiarities include forks, dead tops, abnormal or swollen butts, especi- 

 ally if the D.B.H. is affected, or other deformities in shape. The pres- 

 ence of rot, shake, or other internal defects may be noted, but does 

 not influence the subsequent measurements (§ 156) or volume of the 

 tree, unless its form is affected abnormally, as sometimes happens 

 when rot at the butt causes abnormal butt swelling extending beyond 

 D.B.H. 



135. Measurements Required to Obtain the Volume of the Tree. 

 Systems Used. While the object of measurements of the stem is to 

 obtain its volume, these also serve to record the form of the bole. The 

 diameter is taken (§ 29) at definite points, dividing the bole into lengths 

 which are recorded consecutively. The cubic volume of round logs 

 of any length is easily computed from the end diameters (Smalian 

 formula) if the proper precautions are taken to guard against the influ- 

 ence .of butt swelling (§29). But if the recorded diameters or form 

 of the trees are to be used to get average form or taper (§166) as well 

 as merely for volume, these measurements should be taken at the same 

 heights or intervals on all trees. 



For cubic volume, the log lengths into which the bole is cut by the 

 loggers may be disregarded. This factor would exert no appreciable 

 influence on the tree contents when the full volume of each log is accu- 

 rately obtained. 



There are three systems of taking these upper diameter or taper 

 measurements, as follows (Fig. 30, § 155) : 



