56 

 KOA SUITABLE FOR ARTIFICIAL REFORESTATION. 



By C. S. JuDD, Superintendent of Forestry. 



That our native koa {Acacia koa) is very suitable for artifi- 

 cially reforesting our denuded slopes has been proved by the 

 planting operations of the Division of Forestry on the Honolulu 

 W^atershed forest reserve which were begun in November, 1913. 

 The accompanying illustration shows one of the koa trees which, 

 although slightly over two years old, is already fourteen feet 

 high and four inches in diameter at the base. Koa trees were 

 planted on the upper slopes of the Makiki valleys fifteen by 

 fifteen feet apart and already on Sugar Loaf the growth has 

 been so rapid that before very long a solid forest canopy will 

 be established. 



On the lower slopes and in the valleys kukui trees were planted 

 and these too are showing up very well. Before long, all of 

 this part of Honolulu's source of water supply will consequently 

 receive better protection by this reestablished forest. Both koa 

 and kukui are easy to raise from seed and easily handled in 

 planting operations. 



A SIDELIGHT ON THE MAUI FOREST TROUBLE. 



By C. S. JuDD, Superintendent of Forestry. 



The death of native trees in the Koolau forests on Maui, which 

 began in 1906, was ascribed by Mr. H. M. Curran primarily to 

 heavy winds, acting on the forest, the normal vigor of which had, 

 by adverse soil conditions, excessive moisture, and the opening 

 of the forest by grazing and ditch construction, been reduced to a 

 point where it was unable to withstand any further increase of 

 unfavorable conditions. 



The trouble was determined by Dr. H. L. Lyon to be due 

 directly to chemically active agents in the soil which killed the 

 roots which penetrated the soil to a depth of two inches or more. 

 The trees that were thus killed were located mostly on the flat 

 ridges where the drainage was poor and where there was an 

 abundance of standing water. Every variety of tree in the 

 afifected area succumbed to the attack. 



A sidelight on this trouble comes from the other side of the 

 globe and is described in the Indian Forester of October, 1915. 

 In Northern India there has been a widespread death of the 

 seedlings of sal, Shorea rohusta, the most extensively used timber 

 tree of that region. Studies made at Dehra Dun of the trouble, 

 which comes into operation in the rainy season, especially in the 

 months of July and August, have ascribed the cause to "an in- 

 jurious soil factor" produced by lack of sufficient oxygen for 

 root-respiration combined with the presence of toxic substances 

 in the soil which are directly poisonous to the roots. The cause 



