american samoa - University of Hawaii at Manoa

example on Tutuila is the climbing reed-like
Flagellaria gigantea (lafo). Some other vines
appear to be independent of the ground and grow as
epiphytes.
The other major lifeform in the forest is that of
epiphytes. An epiphyte is a plant that grows on trees,
using them as a place to grow while deriving no
nutrition from them (as a parasite would). The most
common epiphytes in the rainforests of Tutuila are
ferns and orchids. Most of the 49 orchids of Samoa
fit into this category, particularly members of the
genus Dendrobium and Bulbophyllum. Epiphytes
are light-loving species that cannot survive in the
shady conditions on the forest floor, and
consequently live perched upon the branches and
upper trunks of the trees where the light conditions
are better. They have to have some form of
attachment to the tree, and they must be somewhat
xerophytic to survive away from the moisture-laden
soil. The two rainforest communities, lowland
forest and montane forest, are discussed below.
5. Lowland Forest
This is the high tropical rain forest that covered
most of the area of the park prior to the arrival of the
first Polynesian settlers in Samoa. It currently
covers the ridges and valleys on the north coast up
nearly to the highest elevations where it is replaced
by montane forest. Some of these ridges,
particularly the upper portions between Fagasa and
the TV transmitter, have recently been disturbed by
taro plantations, and much of the same area was
extensively damaged by the recent hurricanes.
However, most of the lowland areas east of Toa
Ridge (just to the east of the TV transmitter) and
west of Afono are covered with native lowland
forest that is relatively undamaged by the recent
spate of hurricanes. Three types of lowland forest
are distinguished below: valley lowland forest,
coastal lowland forest, and ridge lowland forest.
a. Valley Lowland Forest - This is the forest that
covers alluvial valleys near the coast. It is the same
as the Dysoxylum lowland forest on coral rubble
described on Ta'u (Whistler 1992b). The alluvium
is deposited by streams, and the larger and broader
the valley, the greater the area of this forest. The
species that dominate here are probably adapted to
moist loose soil conditions, and are generally absent
or insignificant on the ridges, which presumably
have drier, denser soil. This is one of the habitats
most suitable for villages, and it is likely that
Fagasa, Vatia, and Afono were covered with this
type of lowland forest prior to settlement. The only
area of this now within the park is at Amalau, but it
is disturbed.
A plot in valley lowland forest was sampled on
the west side of the stream in Amalau Valley inland
from the road (see Appendix B: plot 10). This area
is dominated by Dysoxylum maota (maota), which
had an estimated relative dominance of 46%. The
tree species second in dominance is Planchonella
samoensis (mamalava). Also common are
Inocarpus fagifer (Tahitian chestnut, ifi) and
Myristica fatua (Samoan nutmeg, 'atone). Other
significant trees present are Canarium vitiense
(ma'ali), Kleinhovia hospita (fu'afu'a), Bischofia
javanica ('o'a), Cananga odorata (ilangilang,
moso'oi), Elaeocarpus ulianus, Macaranga
st@ulosa (lau fatu), and Ficus scabra (mati).
This vegetation is very similar to one sampled in
a similar bay called Aiga, just to the west of A'asu
on the northwest coast of the island (Whistler 1980).
In that plot Dysoxylum spp. (listed mostly as D.
samoense, perhaps incorrectly) had a relative
dominance of 74%. The most numerous trees there
were Myristica fatua and Barringtonia samoensis
(falaga). The latter species, which is related to the
littoral Barringtonia asiatica, is typical along
streams. It was also common at Amalau outside of
the plot area along the stream. While there is no
distinct riparian forest in Samoa, two
species-Barringonia samoensis and Inocarpus
fagifer are typical along streams (Fig. 18).
There is another area of this type of forest below
the road in Amalau Valley. It is somewhat
disturbed, but is also dominated by Dysoxylum
maota, with a subcanopy primarily dominated by
Myristica fatua. Another similar forest was
described in the Ta'u report, based on a sample made
there in 1976 (Whistler 1980). In that sample, the
dominant tree was determined to be Dysoxylum
samoense with a relative dominance of 86% (D.
maota is not found on the island), an unusually high
degree of monodominance for lowland forest.