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The leeward
slopes of all the Hawaiian Islands are much drier than the windward
slopes, and originally supported a variety of native dry forests
and shrublands. The dry leeward zone typically receives less
than 50 inches of rainfall annually, and the lower elevations
of the zone sometimes receive less than 10 inches per year. All
or most of the islands of Ni`ihau, Kaho`olawe, and Lana`i fall
into the dry leeward zone. |
 Dry
forests are usually open with a less layered structure than rain
forests. In the lowland areas, the dominant trees are wiliwili and
lama. Wiliwili are one of only two native trees that are deciduous.
This means they drop their leaves and remain bare for part of the
year. It is thought that the wiliwili trees do this because the
lack of water forces them to conserve energy that would normally
go into production of leaves. The soft, light wood was (and still
is) used for the outriggers of traditional Hawaiian canoes. The
bright red seeds were used in lei making, though many of the wiliwili
leis commonly seen today are from the non-native species |
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 Lama, also known as Hawaiian ebony because
of its black bark, is a member of the persimmon family. Lama wood
was used in medicine and placed in hula altars because the translation
of the name (torch, light, lamp) suggests enlightenment.
In contrast
to the rainforests, which have a very dense understory of ferns,
vines, and mosses, the open dryforest lands are dominated by
shrubs and grasses. `A`ali`i is a dominant shrub found in many
dry areas. The fruits look like papery capsules, and are used
in lei making. The wood from `a`ali`i was used by the ancient
Hawaiians for tools, spears, and weapons because of its extreme
hardness. Pili is an indigenous grass found in dry areas, that
was used for thatching on Hawaiians houses. |
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 Hawai`i has
only two native mammals, the monk seal, and the bat. `Ope`ape`a,
or Hawaiian hoary bat, was once common in the lowland forests,
but as its habitat was destroyed, the size of the bat population
also declined. It is now an endangered species. Hawaiian bats
depend on native trees for roosting. If the native forests can
be protected, then the bats will have a better chance for survival.
Of all
the zones, dry leeward vegetation has perhaps been the most seriously
impacted. In the upper regions, fire, feral goats, cattle grazing,
and the invasion of non-native grasses have caused the most damage.
Few examples of dry forest remain relatively intact. Almost none
of the lowland dry forest remains undisturbed today. Much was
burned and cleared by Hawaiians in the pre-contact period for
agricultural uses, and non-native trees and grasses replaced
the native vegetation. In historic times, many of these areas
were used for sugar and pineapple agriculture. There is currently
a team of scientists from different government agencies and private
organizations, that is working on a plan for the protection and
restoration of native dryland forests. |
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