24 



7. During the first ten years of a plantation, lieight growth may 

 be measnred annually or biennially. 



8. From the tenth year, measurements of both height and diameter 

 may be taken at five 3^ear intervals, pieferably when the trees are 10, 

 15, 20, 25, and so on, years of age. 



9. Measuremejits should be made during the resting period of 

 growth. 



10. Diameter measurements sliould be made at the same height, 

 and at approximately the same temperature. ( Breast height is foui* 

 and one-half feet above ground. ) 



11. Height growth sliould be given in feet and teuths of feet; 

 diameter growth should be given in inches and tenths of inches; 

 volume growth should be given in cubic feet and to three decimals. 



12. ^laximum current height growth is the greatest growth in 

 height of any one tiee during the season of growth just passed. 



i;^. The average current height growth is determined by adding 

 the lengths of the i)ast year's shoots of all the trees in the plantation 

 and dividing the sum thus obtained by the number of trees. 



14. The mean annual height growth of a plantation is determined 

 by adding the total heights of all trees in the plantation and divid- 

 ing the sum by the number of trees to obtain the average height at 

 the time of measurement. This average must then be divided by the 

 number of years the trees are old. 



15. The mean annual diameter growth is determined by adding the 

 sectional areas of all trees in the plantations, as found from diameter 

 measurements, and dividing the sum b}^ the number of trees in the 

 plantation. The re^5ult will be the average sectional area at the time 

 of measurement. From this may be found the average diameter. 

 The average diameter is then divided by the number of years the 

 trees are old to obtain the mean annual diameter growth. 



1(). Having the average height and diameter of the trees in a 

 plantation at any time, the volume of such a tree is determined by 

 finding a tree of such size and making careful volume measurements 

 of it. The volume of such a tree, called the "mean sample tree," 

 multiplied by the number of trees in the plantation, will give the 

 volume of the whole plantation. (See Graves' Mensuration, pp. 228 

 and 229.) This volume divided by the number of years the trees 

 are old will give the mean annual volume growth. 



17. When material is removed, the date should be given. 



18. Explanation of Crown Classes: 



Predominant — When Ihe crown of the tree is ])artially or wholly 

 above the general level of the top of the canopy. 



Dominant — When the crown has light from above and very little 

 from the side, being one of those making up the more or less even 

 canopy height. 



Intermediate — AVhen the crown has no light from side and only 

 a small amount from the to]). 



Suppressed — When the crown receives no light from top or side 

 and the tree is in a weakened condition by reason of insufficient light. 



