american samoa - University of Hawaii at Manoa

APPENDIX D. THE OFU UNIT OF THE NATIONAL PARK OF
AMERICAN SAMOA
INTRODUCTION
Part of the island of Ofu in Manu'a is to be
included in the National Park of American Samoa,
principally because of the superb reefs located there.
A botanical survey was carried out on the island on
the 14th to the 16th of June 1992. The island, which
is about 7.5 km2 (3 mi2) in area, is located about 95
km (60 mi) east of the main island of Tutuila. It is
part of the caldera rim of an ancient volcano, and is
separated from the somewhat similar, adjacent
island of Olosega by a narrow strait now crossed by
a concrete bridge. The highest elevation of Ofu is
Mt. Tumu at nearly 500 m (1621 ft) elevation. A
single village is present on the west side of the
island, but several houses and a small terminal
building are located next to the airstrip, which lies in
an east-west direction at the south-central tip of the
island. Perhaps only two houses are found adjacent
to the park area itself.
The area under consideration is a narrow strip of
land along the southeast-facing coast, extending
from just east of the airport to Asaga Strait that
separates Ofu from Olosega. This includes the
pinnacle called Sunitao Peak that extends up to 230
m (750 ft) elevation. The road from O h Village to
Olosega represents the landward edge of the park
boundary. Although not in the original proposed
boundaries, the steep slopes leading to Mt. Tumu are
important to the integrity of the park, so they, along
with the summit of the island, were included in the
present study.
Ofu is a very small island, and it is not surprising
that it has a flora much smaller than that of Tutuila;
its flora is also much smaller than that of the nearby
Ta'u documented in the early study for the National
Park Service (Whistler 1992b). A checklist of the
island is found in the vegetation study of American
Samoa (Whistler 1980). Perhaps only three species
found on Ofu are not found on Tutuila; Psychotria
garberiana, which is endemic to Manu'a, Gyrocar-
pus americanus, which in American Samoa is repor-
ted only from Ofu (Nu'utele Islet), and Crateva
religiosa, which in American Samoa is reported
only from Ofu.
THE VEGETATION
The plant communities found on Ofu are the
same ones described from the park area on Tutuila.
Each of the natural communities present will be
briefly described. For more general remarks about
these communities and the disturbed communities
(managed land, secondary scrub, secondary forest),
see the comparable sections in the discussion of the
vegetation of Tutuila.
1. Herbaceous Strand
The herbaceous strand is found along the whole
length of the beach from the airstrip to the bridge
separating the two islands. It is very narrow in
extent, and is mostly not distinct from the littoral
forest, largely because of its extensively damaged
condition. The shore from the airport to Mt. Sunitao
is a sandy beach, but at Sunitao it becomes rocky
and almost vertical in places, before returning to
sand just before the bridge.
The dominant plants on the sandy beach is the
beach morning-glory vine Ipomoea pes-caprae
(beach morning-glory, fue moa) with lesser
amounts of the littoral grasses Lepturus repens,
Stenotaphrum micranthum, and Thuarea involuta.
Other species present include Vigna marina (beach
pea, fue sina), Triumfetta procumbens, Portulaca
samoensis, Digitaria setigera, Tacca leonto-
petaloides (Polynesian arrowroot, masoa), and
Chamaesyce atoto. All of these, except for
Chamaesyce and Triumfetta are found within the
Tutuila park. Several other species of weeds are
present, but they are secondary in importance to the
native species.
The dominant herbaceous plants on ~initao
Peak
are Phymatosorus scolopendria (lau magamaga) on
rocky places and Lepturus repens on the gravel of
talus slopes. Other native plants present include
Portulaca samoensis, Portulaca lutea, Hedyotis
foetida, and Mariscus javanicus. These plants are
mixed in with shrubs, which will be noted below
under littoral shrubland.