FAUNA AND FLORA OF MANGROVE SWAMPS
237
canopy and to provide seedlings for regeneration. But the older trees
left in this way are very vulnerable to wind, and the occasional storms
may cause much and expensive damage. I n practice, nowadays, it is
more expedient to clear-fell an area. This area must be quite narrow to
allow easy and complete regeneration ; if wide, planting must follow.
Slash is a nuisance, it takes about three years to decay sufficiently to
collapse on to the surface of the soil. During this time seedlings may
not be able to reach the soil surface and so be hindered from growing.
At the game time also a good growth of ferns, either or both of the
species of Acrostichum, or of beach thistles Acanthus, may have grown
up through the slash and also prevent regeneration. Disposal of slash
is, then, an essential of good forest management.
Silvicultural practice also tends t o demand the removal of species
for which there is little or no demand. For example trees of Bruguiera
gymnorhiza, B. sexangula, B. parvijlora and Xylocarpus granatum are
all eliminated. X . granatztm finds a use only as fuel for convertirlg the
rhizophoras to charcoal.
Occasionally the mischievousness of monkeys and the nibbling of
crabs of the genus Sesarma will damage seedlings sufficiently to give a
poor regeneration.
2 . Other uses
At various times attempts have been made to utilize commercially
the tannins extracted from the bark of the rhizophoras. It seems unable
to compete with that from acacias. It would seem also that bark
obtained from African trees has a higher concentration of tannins than
samples from South East Asia. Is this a result of the drier climate of
the African mangal region?
Investigations into the possible use of mangroves for pulping have
been carried out by Australian workers in New Guinea (Rep. C.S.I. R.O.,
1953164, 1955/56). It would seem that woods of Excoecaria agallocha
and Camptostemon spp. are useful but the rhizophoras less so. Japanesc
interests have recently shown the possibility of using pulp from various
rhizophoraceous mangroves as sources of cellulose for rayon manufacture. This may utilize the large amounts of Bruguiera parviflora which
so often tend to replace a rhizophora forest after this has bccn cut
out.
The nypa palm is one of the most useful plants of the mangal. Its
leaves are cut and plaited into " atap " the principal thatching material
throughout South East Asia. I n poorer areas it is used to build the
houses as well. The inflorescences are tapped for sugar and for alcohol
production. The nibong palm is also a useful tree. Its " cabbage " is
237
canopy and to provide seedlings for regeneration. But the older trees
left in this way are very vulnerable to wind, and the occasional storms
may cause much and expensive damage. I n practice, nowadays, it is
more expedient to clear-fell an area. This area must be quite narrow to
allow easy and complete regeneration ; if wide, planting must follow.
Slash is a nuisance, it takes about three years to decay sufficiently to
collapse on to the surface of the soil. During this time seedlings may
not be able to reach the soil surface and so be hindered from growing.
At the game time also a good growth of ferns, either or both of the
species of Acrostichum, or of beach thistles Acanthus, may have grown
up through the slash and also prevent regeneration. Disposal of slash
is, then, an essential of good forest management.
Silvicultural practice also tends t o demand the removal of species
for which there is little or no demand. For example trees of Bruguiera
gymnorhiza, B. sexangula, B. parvijlora and Xylocarpus granatum are
all eliminated. X . granatztm finds a use only as fuel for convertirlg the
rhizophoras to charcoal.
Occasionally the mischievousness of monkeys and the nibbling of
crabs of the genus Sesarma will damage seedlings sufficiently to give a
poor regeneration.
2 . Other uses
At various times attempts have been made to utilize commercially
the tannins extracted from the bark of the rhizophoras. It seems unable
to compete with that from acacias. It would seem also that bark
obtained from African trees has a higher concentration of tannins than
samples from South East Asia. Is this a result of the drier climate of
the African mangal region?
Investigations into the possible use of mangroves for pulping have
been carried out by Australian workers in New Guinea (Rep. C.S.I. R.O.,
1953164, 1955/56). It would seem that woods of Excoecaria agallocha
and Camptostemon spp. are useful but the rhizophoras less so. Japanesc
interests have recently shown the possibility of using pulp from various
rhizophoraceous mangroves as sources of cellulose for rayon manufacture. This may utilize the large amounts of Bruguiera parviflora which
so often tend to replace a rhizophora forest after this has bccn cut
out.
The nypa palm is one of the most useful plants of the mangal. Its
leaves are cut and plaited into " atap " the principal thatching material
throughout South East Asia. I n poorer areas it is used to build the
houses as well. The inflorescences are tapped for sugar and for alcohol
production. The nibong palm is also a useful tree. Its " cabbage " is