27 



contents and value of the forest at different periods of its 

 growth. 



Unfortunately, there are not enough groves in Hawaii of the 

 necessary age to be used for the construction of yield tables, and 

 all that can be done at the present time is to indicate in a general 

 way the age at which the Eucalyptus plantation may be cut. 



It should be remembered that the first few years in the life 

 of a tree are spent in forming roots and crown, during which 

 time very little merchantable wood is grown. In the case of the 

 rapid-growing blue gum, this period covers at least five or six 

 years, and it is only at the end of that time that it begins to pro- 

 duce valuable wood. To cut the trees at that time is like draw- 

 ing out money deposited in a bank just before the interest on it 

 becomes due. Therefore, if it is at all possible to avoid it, no- 

 young trees should be cut. 



As a tree grows in age and size, the percentage of sapwood 

 decreases rapidly and the lumber becomes more valuable. Fur- 

 ther than as determined by this general principle, the age of the 

 trees to be cut must depend on the purpose for which the wood 

 is to be used. If fuel wood is the main crop, the trees may be 

 cut in rotations of eight or nine years, but it must be remember- 

 ed that sapwood makes poor fuel and that the young trees there- 

 fore make inferior firewood. 



If fence posts are desired, the plantation may be cut when the 

 majority of the trees are 10 to 13 inches in diameter or larger. 

 The stand at that time would be nine to twelve years of age. 



If railroad ties or telephone and telegraph poles are to be the 

 main consideration, the trees should be at least 15 or 16 inches 

 in diameter measured 4 l / 2 feet from the ground. The stand 

 would then be 12 to 20 years of age, according to the locality. 



If the forest is grown for the production of wharf piles, lum- 

 ber or large timbers, it is best to keep the trees for at least 25 

 or 30 years, at which time, if grown on favorable situations, the 

 trees may be more than 20 inches in diameter and 100 feet high. 



Methods. 



If a second crop is expected, it is necessary to take certain 

 precautions when cutting the first stand of trees. The ability 

 of the stumps to ratoon has already been discussed, and it was 

 mentioned that the time of the year when the trees are cut has 

 a decided influence on their sprouting capacity, the months from 

 November to March being the most favorable in this respect. 



