PLANTATIONS IN CALIFORNIA. 7 



spacing is of especial importance. Wide spacing favors diameter 

 growth and wide branching, while close spacing stimulates height 

 growth and favors the development of clear straight trunks free from 

 branches. If trees are grown too far apart they receive too much 

 light, branch out, and tend to become scrubby and scraggy. On the 

 other hand, if planted too close together proper growth is interfered 

 with, and the trees tend to become tall and spindling. Between these 

 two extremes there is a spacing which will result in the most desirable 

 height and form of a tree, as well as in the best diameter growth. 

 This optimum spacing of eucalyptus varies with the species, the quality 

 of the soil, the amount of available moisture in the ground, and the 

 amount of precipitation. In general it may be stated that spacing on 

 poor soil should be closer than on good soil, since the rate of growth on 

 the former will be slower, and it is necessary to plant more trees to the 

 acre to form a close crown cover and establish forest conditions as 

 soon as possible. However, since there may be insufficient food and 

 moisture for the trees on the poor soil, thinnings should be made early, 

 so as to give the best trees a chance to develop. On the other hand 

 spacing on good soils need not be as close, and thinnings need not be 

 made as early. In the two groves giving the heaviest yield per acre 

 in California, the Newark grove and the Fruitvale grove, the spacing 

 is 6 by 6 feet. This is probably merely a coincidence, since the best 

 growth is usually found in the case of trees growing singly or in nar- 

 row belts of from two to ten rows of trees. Much more data will have 

 to be collected before a definite conclusion can be reached on the best 

 spacing of eucalyptus. 



Cultivation. There is no doubt that cultivation stimulates growth 

 in the first few years. In a case where the water table is fairly near 

 the surface and the atmosphere is very hot and dry, cultivation may 

 save a plantation by keeping it alive until the roots tap the water 

 table and the trees are able to take care of themselves. To this extent 

 cultivation will increase the growth, and therefore the yield, in the 

 early years of the plantation's life. It will probably affect the final 

 yield to a small extent. The chief advantage lies in the fact that 

 cultivation insures a more flourishing and more rapid growth for the 

 first few years when the trees need it most. 



Methods of management. The ultimate yield will no doubt be in- 

 fluenced by the number and severity of the thinnings which might 

 be made from time to time, but as there are practically no old groves 

 of eucalyptus in California which have been systematically thinned 

 no definite statements can be made. This is a matter which must be 

 worked out in practice, and any estimates at present would be mere 

 guesses. It is safe to say, however, that the ultimate yield will be 



