THE FORESTS OF THE HAWAIIAN ISLANDS 



VAUGHAN MacCAUGHEY 



College of Hawaii, Honolulu, Hawaii 



The Hawaiian Archipelago, formerly known as the Sandwich 

 Islands, remote and isolated in the vast stretches of the North 

 Pacific, has long enjoyed botanical fame for the endemic charac- 

 ter of its flora. Its arborescent lobelias, violets, and composites 

 are widely known among phytogeographers. There is no other 

 region of equal area in the world that possesses so large a pro- 

 portion of peculiar and endemic plant species. Inasmuch as the 

 native vegetation is in the main perennial, woody, and arbores- 

 cent, this endemic quality is particularly noticeable in the 

 Hawaiian forests. A lumberman from Georgia, from Michigan, 

 or from Oregon, would find in Hawaiian woodlands not a single 

 familiar tree, not a single conifer, and but few species that even 

 faintly resemble those of continental forests. 



In any discussion of the Hawaiian forests it is necessary to 

 recognize the various types or classes of forest. These are de- 

 pendent upon two fundamental factors that profoundly affect 

 the geographic distribution of all the insular plant and animal 

 life. The first factor is topographic — elevation — and is due to 

 the mountainous character of the islands. The islands them- 

 selves are but the summits of a titanic submerged volcanic 

 mountain chain. Their peaks rise above the sea from 3000 to 

 14,000 feet. The second factor is meteorologic — the trade winds, 

 which blow from the northeast practically continuously through- 

 out the year. These winds give each of the islands distinctive 

 windward and leeward climates. The trade winds are heavily 

 water-charged and upon coming into contact with the upper 

 mountain slopes excessive precipitation results, in some places 

 amounting to 400 or 500 inches per annum. The leeward regions, 

 shut off by the mountains from these rain-bearing winds, are 

 arid, in some places having the aspect of veritable deserts. 



162 



