2D) MANGROVE SWAMPS 
The main tree species in a virgin swamp are few in number, 
and the principal ones are of the botanical family Rhizopho- 
raceae. In this family there are found: Rhizophora candelaria 
and R. mucronata; Ceriops tagal and C. roxburghiana; and 
Bruguiera conjugata, B. parviflora, B. cylindrica, and B. sexan- 
gula. While these eight species are the ones most numerous 
in nearly all virgin swamps, scattered trees of pagatpat (Son- 
neratia caseolaris) often occur mixed with them or growing 
along exposed coral beaches. Api-api (Avicennia spp.) is some- 
times found scattered in the more open places. Occasionally, 
this last-mentioned tree grows in pure stands along the inland 
edge of a mangrove swamp. Trees of the genus Rhizophora 
are frequently the first to seed upon and occupy the newly 
formed mud flats (Plate I). They are prop-rooted species, and 
normally grow on those portions of the swamp most deeply 
flooded by the tides. Such places are usually confined to the 
area along or close to water channels, although on low swamps 
Rhizophora forest extends farther inland. Rhizophora mucro- 
nata predominates in the fringe of trees bordering on water- 
ways, while Rhizophora candelaria is by far commoner in the 
main forest within this outer fringe. 
Trees of the genus Bruguiera occupy the portion of the swamp 
in which the ground is barely, if at all, flooded at high tide. 
Such places are usually toward the inland portions of the 
swamp and often, probably in the majority of cases, comprise 
a large percentage of its total area. As the ground level is 
raised by the natural filling in of the delta, it often happens 
that areas occupied by these Bruguiera forests become so high 
that they are seldom, if ever, flooded. 
In open bays where the soil is mixed with considerable sand 
or coral limestone, there is a distinct frontal zone of Sonneratia 
caseolaris (Plate XVI), with some Avicennia officinalis. Wave- 
cut coral terraces often contain nearly pure stands of Sonneratia 
caseolaris. 
Several other trees occur in these salt swamps, usually along 
their inner edges or in places where the stands are light. These 
include Xylocarpus moluccensis, X. granatum, Lumnitzera lit- 
torea, and Aegiceras corniculatum. Heritiera littoralis (dungon- 
late) is common on the higher ground which is still within 
the zone affected by salt water. 
In swamp areas in which cutting has long been carried on 
the original and more valuable species are often largely replaced 
by Avicennia spp. (api-api). These species were considered to 
be of little value until the present fuel shortage. 
