THE NATURAL ENVIRONMENT

Geography 101
     

 

ToC

LIFE

Animals

Biomes

Tropics

Temperate

Cold

Hawai'i

 

  

Hawaiian Vegetation

 
  1. What islands have alpine and subalpine ecosystems?
  2. Where were the wet forests located?
  3. What islands have only lowland dry ecosystems?
  4. Where are the largest remaining areas of native vegetation that have not been transformed by human activity?
  5. On O'ahu, Maui, Kaua'i, Lana'i, and Moloka'i what is the major native ecosystem that remains?
  6. Why does Hawai'i have a high extinction rate for native species?
 
BOX 1

A specialized area of biogeography deals with islands. Mountainous islands generally have a great range of climate conditions over small distances and, because of their isolation, also tend to have a very high percentage of endemic (found nowhere else) species.

Hawai'i exemplifies the compactness of biomes on tropical islands and also exemplifies how fragile and easily disrupted these plant and animal communities can be.

Before human settlement, the Hawaiian Islands housed a wide range of biomes, from lowland tropical forest, to desert, to high elevation alpine vegetation. The maps below show the original plant community distribution using a somewhat different classification than we used for the global biome maps.

hawaiian native ecosystems

Wet areas of the larger islands were covered with closed canopy forests of 'ohia, koa, olapa and other species, usually with a ground covering of ferns. These closed forests graded into more open woodland in drier coastal and leeward areas. (On the maps, mesic refers to areas with 125 to 250 cm (50 to 100 inches) of rainfall per year). The very driest leeward areas contained native grasses and dryland shrubs, most of which are gone today. In the high mountains of Maui and the Big Island, in the dry air above the trade wind inversion, scattered trees, such as mamane, grow on slopes between 1800 meters (6000 feet) and the tree line, at around 2700 meters (9000 feet). Above that level, only a few drought and cold tolerant alpine plants survive.

Today, most of the original vegetation has disappeared through clearing for agriculture and urban use, as shown in the map below. The extensive alteration of native ecosystems, along with the introduction of exotic (non-native) species, has greatly accelerated the rate of extinction of native plants and animals. Today, Hawai'i contains a full 30% of all federally listed endangered species in the United States.

hawaiian ecosystems today

(Source: Atlas of Hawaii, 3rd Edition, UH Press)
     
   

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