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WILLIAM MACNAE
further succession because the floating seedlings cannot reach the soil.
Much of the mangrove areas in Ceylon has been taken over by extensive
clumps of these beach thistles.
I n Malaya and western Indonesia several authors have described
R. stylosa as a pioneer on coral debris in the shelter of a reef (Ding
Hou, 1958). Its occurrence at Low Isles off the coast of north Queensland is compatible with this. R. nzucronata may occur in similar
situations off the eastern shores of Africa and off Madagascar.
R. apiculata has not been seen nor described from such localities.
According to Ding Hou (1958) it develops best in clay soils and under
conditions of reduced salinity. Nonetheless it is occasionally used by
man to encourage deposition of silt, and thereby t o act as a pioneer. I
suspect that this can only be done in areas of minimal tide. This use
of R. apiculata is common in Ceylon, as for example around Negambo
in areas which a previous generation of men may well have cleared of
mangroves. Seedlings of R. apiculata are collected and planted in a
row about 15 cm apart. This produces a dense hedge behind which
accretion can take place and in due course a new plot is added to the
garden of the “ owner ” (personal observation).
Aegialitis annulata was seen to act as a pioneer on coral debris a t
Low Isles but one doubts if it would form the beginning of a succession.
Species of Bruguiera and Xylocarpus and also Ceriops tagal all
develop under the shade of other trees or of themselves. Hence these
species are diagnostic of well-established mangroves and they themselves form an important stage in the development from mangrove to
freshwater-swamp forest or terrestrial forest.
IV. DISTRIBUTION OF TERRESTRIAL ANIMALS WITHIN THE MAN
“ Just the place for a snark! ” the Bellman cried,
Supporting each man on the top of the tide
As he landed his crew with care;
By a finger entwined in his hair.
Lewis Carroll: ‘‘ The Hunting of the Snark.”
When an animal ecologist regards critically the environment provided by the mangal he recognizes that several different kinds of unit
exist in this environment. I shall list five of these.
(1) The canopy of the trees, composed of the uppermost parts of the
trunks, the branches, twigs, leaves, flowers and fruits, is never reached
by sea water and only rarely by any spray: it constitutes an essentially terrestrial habitat and as such may be expected t o support an
essentially terrestrial fauna. I n general this is so, but few, if any,
detailed or even superficial studies of the environment or its fauna
have been made.
WILLIAM MACNAE
further succession because the floating seedlings cannot reach the soil.
Much of the mangrove areas in Ceylon has been taken over by extensive
clumps of these beach thistles.
I n Malaya and western Indonesia several authors have described
R. stylosa as a pioneer on coral debris in the shelter of a reef (Ding
Hou, 1958). Its occurrence at Low Isles off the coast of north Queensland is compatible with this. R. nzucronata may occur in similar
situations off the eastern shores of Africa and off Madagascar.
R. apiculata has not been seen nor described from such localities.
According to Ding Hou (1958) it develops best in clay soils and under
conditions of reduced salinity. Nonetheless it is occasionally used by
man to encourage deposition of silt, and thereby t o act as a pioneer. I
suspect that this can only be done in areas of minimal tide. This use
of R. apiculata is common in Ceylon, as for example around Negambo
in areas which a previous generation of men may well have cleared of
mangroves. Seedlings of R. apiculata are collected and planted in a
row about 15 cm apart. This produces a dense hedge behind which
accretion can take place and in due course a new plot is added to the
garden of the “ owner ” (personal observation).
Aegialitis annulata was seen to act as a pioneer on coral debris a t
Low Isles but one doubts if it would form the beginning of a succession.
Species of Bruguiera and Xylocarpus and also Ceriops tagal all
develop under the shade of other trees or of themselves. Hence these
species are diagnostic of well-established mangroves and they themselves form an important stage in the development from mangrove to
freshwater-swamp forest or terrestrial forest.
IV. DISTRIBUTION OF TERRESTRIAL ANIMALS WITHIN THE MAN
“ Just the place for a snark! ” the Bellman cried,
Supporting each man on the top of the tide
As he landed his crew with care;
By a finger entwined in his hair.
Lewis Carroll: ‘‘ The Hunting of the Snark.”
When an animal ecologist regards critically the environment provided by the mangal he recognizes that several different kinds of unit
exist in this environment. I shall list five of these.
(1) The canopy of the trees, composed of the uppermost parts of the
trunks, the branches, twigs, leaves, flowers and fruits, is never reached
by sea water and only rarely by any spray: it constitutes an essentially terrestrial habitat and as such may be expected t o support an
essentially terrestrial fauna. I n general this is so, but few, if any,
detailed or even superficial studies of the environment or its fauna
have been made.