568 
VAUGHAN MACCAUGHEY 
Although somewhat sheltered from the direct mechanical effects 
of the trades, Manoa and the other leeward valleys of its class are 
exposed to the periodical kona or southerly storms, which usually 
occur during the late winter and early spring (January to April). 
The kona storms are often characterized by heavy winds and excessive 
rainfall. 
The southwesterly exposure of Manoa shuts off its head from a 
considerable portion of the morning sunlight, and gives prominence 
to the afternoon heat and light. Manoa is much sunnier and warmer 
than are the narrow, windy, northerly facing valleys of the windward 
Koolau slopes. This climatic difference is sufficiently great to be 
reflected in the respective floras of these two types of valleys. 
I. THE REPRESENTATION IN MANOA OF THE HAWAIIAN ECOLOGIC 
ZONES 
In the Hawaiian Archipelago there are numerous well-defined 
ecologic zones. The representation of these life-strata in the Manoa 
region may be indicated as follows: 
1. Littoral, a. Humid littoral; windward. 
b. Arid or semi-arid littoral; leeward. The littoral of that 
portion of the coastal plain which lies to the seaward of Manoa 
Valley is of this type. 
2. Lowlands. Up to 1,000-1,500 feet; with humid and arid sections, 
depending upon relation of topography to trade winds, and 
distance from interior mountains. In Manoa Valley the low- 
land proper (valley floor) lies well below the 500-foot contour; 
in early times the lower forest zone came down to this level. 
3. The Forest Zone. a. The Lower Forest; 1,000-2,000 feet; with 
humid and arid sections. In Manoa this zone lies between 500 
and 1,200 feet, and is almost wholly of hygrophytic or semi- 
hygrophytic character, although some xerophytic forms do occur. 
h. The Middle Forest; 1,800-5,000 feet; variable with humid 
and arid sections on the various islands. In Manoa this zone 
is typical Oahuan rain-forest; highly hygrophytic, and very 
rich in endemic forms. Owing to the low elevation of the Oahu 
mountains, this is the highest zone, and 
c. The Upper Forest; 5,000-9,000 feet, is restricted to the 
high mountains of Maui and Hawaii. 
