22 FORESTS OF THE HAWAIIAN ISLANDS. 



purpose, and it has been noticed that with the clearing of the lower 

 slopes these small streams have been perceptibly diminished/' 



The other and far more dangerous result to be feared in cutting 

 away the forest is the modification of climatic conditions so that there 

 will not be enough rainfall to insure the growth of sugar cane. 

 Kohala and Hamakua have barely enough rainfall to produce good 

 crops during the best seasons. Dr}^ seasons cut down the crop till 

 there is often no profit in it. In 1901 these districts produced 52,025 

 tons of sugar, worth 11,080,505 — 15 per cent of the entire crop of the 

 islands. In 1902 they produced onl}- 17,079 tons, in consequence of a 

 severe drought which affected the crop greatl}^ The crop of 1902 is 

 said to have been produced at a loss to the planters. Frequent 

 droughts such as that would soon put an end to the entire sugar indus- 

 try in these districts, for there is no possible supph^ of water except 

 rainfall. 



Throughout the Hawaiian Islands, but especialh^ in these two dis- 

 tricts, the influence of the forest upon both the amount and distribu- 

 tion of rainfall is a matter of common observation and experience. 

 Back of the sugar plantations in Kohala and most of Hamakua the 

 land does not rise above an elevation of 3,000 feet, and therefore lacks 

 the heavy rainfall which results from higher elevations. As the for- 

 ests have occupied the land above the plantations they to a certain 

 extent have answered the purpose of the mountains in cooling the 

 atmosphere and causing the saturated trade winds to relinquish their 

 moisture over the plantations. The evidence of this influence is con- 

 vincing, and seems capable of demonstration to some extent by meas- 

 urement. On the plains of Hamakua and the lower northeast slope of 

 Mauna Kea, where heav}^ fogs blow over from the ocean and mists are 

 of almost daily occurrence, the top of a single tree condenses enough 

 moisture to make the ground beneath it mudd}^ or even to cause water 

 to stand, while beyond the influence of the tree top the surface of the 

 ground may be entirely dry. At Punohu, where the Parker ranch 

 maintains a dairy, there is a short row of vigorous eucalypts about 

 100 feet high. These trees condense so much water that the ground 

 beneath them is always muddy. The ranch has taken advantage of 

 this unusual circumstance by placing beneath the tree tops a roof of 

 sheet iron which collects the water and runs it into a gutter, which 

 leads it into a tank. The water thus collected is sufficient for a large 

 number of stock. 



Since the reduction of the forest area has perceptibly diminished 



«The porosity of ^the soil in this district is remarkable. Between Waipio and 

 Laupahoehoe there is scarcely a single stream affording enongh water to flume cane, 

 and even in portions of Puna, where the rainfall is from 150 to 200 inches per year, 

 there are no streams whatever. The water which falls all sinks directly down and 

 appears in the form of springs only at the edge of the ocean. 



