Vegetation of Southeast Asia Studies of Forest Types 1963-1965

while those of Sonneratia, Avicennia and Xylocarpus send up asparaguslike,
pointed pneumatophores. Some dominant species are also characterized
by a tendency toward vivipary, in which case their seeds
germinate before falling. >
Another outstanding feature of Mangrove forest is the zonation
of the different tree species, with definite delineation of the dominants
in strips or narrow belts, more or less parallel to the shore
line. This zonation is especially observable from the air. In
Southeast Asia, for example, Sonneratia alba, is the pioneer tree in
the Mangrove forest. Later, it becomes mixed with Avicennia along
the seaward margin. Hhizophora trees are on somewhat higher ground,
while species of Bru.niiera aevelop on the landward margin, often
extending to the extreme tidal limit of the swamps,
Rc-nge; The coastline of Thailand measures more than 1,250 miles
(2,000 km.) in length. A great part of this is flanked by stands of
Mangrove of variable extent. The total area of this swamp forest is
estimated at 725 square miles (1,620 sq. kms.). Of these, 286 square
miles are located along the southeast coast, as far as the Cambodian
border, and especially in the region of Khlung and Trat; and 1*39
square miles along the east and west coasts of the Peninsula, with
the greatest concentration in the Kra Isthmus, and extending for
about -500 miles from Ranong in the southwest to Krabi, including
the several islands in the Phuket bay, to the Malaysian border.
Appreciable stands of Mangrove, composed of tall trees, grow
along the coast of Canbodia. In South Vietnam extensive stands,
covering about 1,600 square miles, are found along the south coast
fiom Pointe de Canau to Cap Saint Jacques (Fig. 11). In North Vietnam
the Mangrove forest covers a much smaller nrea, of about 360 square
miles, confined to the coastal area northeast and southwest of
Haiphong.
Economic Importance: Because of the series of products obtained
from the Mangrove forest, it is of considerable importance in the
local economy of Southeast Asia, as In other tropical countries, In
Thailand, it ranks next to Teak in importance. Several tree species
are important sources of firewood. The one long in demand for charcoal,
furnishing the best quality, is Rhizophora conjugata. In
Vietnam, owing to long and extensive exploitation, this tree is now
becoming scarce, ar.d io being replaced by Bruc;uiera parviflora.
Timbers useful for rafters and general house construction are
furnished by: Rhjlzophora conjugata, Lumnitzera coccinea, Bruguiera
gyranorrhiza.and Carapa pbovata. Bruguiera parviflora and Avicennia
marina furnish poles for fish traps. Lumber, of small dimension, is
cut from Avicennia marina and Lumnitzera coccinea. Timbers furnished
by Bruguiera gysmorhiza, Excoecaria agal.l.ocha and Lumnitzera conjugata
are used for piling in heavy construction.
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