Hawaiian Montane Bogs

The montane bogs of this zone occur largely in clusters on the high plateaus, such as Alaka’I Swamp on Kaua’i or on flat-topped ridges as on the summit areas of Maui. Many occur on impervious ground but in the extreme high rainfall areas such as on the summit area of Mt Wai’ale’ale where rainfall exceeds 12 m per year this is not necessary. The vegetation is mostly composed of a hummocky matrix of sedges, mostly Rhynchospora lavarum and the endemic Oreobolus furcatus (Cyperaceae), and Sphagnum moss, but may include other endemic sedges such as Carex montis-eeka (Cyperaceae) and various grasses. Many of these bogs are important for local endemics. For example, the Silversward Bog of Mauna Loa includes the endemic silversward Argyroxiphium kauense (Asteraceae), while bogs on Maui include the closely related endemic ‘greensward’ Argyroxiphium grayanum. These are absent from the bogs on Kaua’I but here can be found the candelabra-like endemic Lobelia kauensis (Campanulaceae), while the endemic Lobelia grayana grows on the margins of certain Haleakala bogs. Other bog-based endemics include the peculiar Plantago krajinai (Plantaginaceae) with its large, white, wooly, deeply veined leaves.

Hawaiian Styphelia Heath Scrub

Above the Metrosideros tree line at about 2200 m the conditions become dryer due to the fact that the wet trade winds fail to rise over the mountains but deflected around the sides. The forests on Hawai’i and Maui therefore give way to savanna or parklands and pastures but above or intermingled with these are heathland scrub dominated by microphyllous or sclerophyllous species. The main shrub is Styphelia tameiameiae, but depending on location this may be accommpanied by various endemic species such as Coprosma montana (Rubiaceae), Dubautia ciliolata (Asteraceae), Geranium cuneatum (Geraniaceae) or Vaccinium reticulatum (Ericaceae).  Between the scrubs the bracken Pteridium aqulinium var. decompositum can be common, together with several endemic grasses including Deschampsia nubigena, Panicum tenuifolium and Trisetum glomeratum (Poaceae).

References

Campbell, D. H. 1933. The flora of the Hawaiian Islands. Quarterly Review of Biology, 8: 164-184.

Carlquist, S. 1970. Hawaii A Natural History. The American Museum of Natural History.

Kitayama, K. & Mueller-Dombois. 1992. Vegetation of the wet windward slopes of Haleakala, Maui, Hawaii. Pacific Science, 46: 197-220.

Mueller-Dombois, D. 2000. Succession and zonation of the vegetation in the volcanic mountains of the Hawaiian Islands. Acta Phytogeographica Suecica, 85: 31-40.

Mueller-Dombois, D. & Fosberg, F. R. 1998. Vegetation of the Tropical Pacific Islands. Springer.

Stone, B. C. 1967. A review of the endemic genera of Hawaiian plants. Botanical Review, 33: 219-259.

Wagner, W. L., Herbst, D. R. & Sohmer, S. H. 1999. Manual of the Flowering Plants of Hawai’i. Volumes 1 & 2. Bishop Museum Special Publication 97. Bishop Museum Press.