PHILIPPINE MANGROVE SWAMPS 
By WILLIAM H. BROWN AND ARTHUR F.. FISCHER 
INTRODUCTION 
The mangrove swamps of the Philippine Islands apparently 
occupy between 400,000 and 500,000 hectares. No accurate 
survey of them has been made and the estimate of the area is 
based on reports from forest officers, Coast and Geodetic Survey 
maps, and forest maps. The area may exceed what is here 
given, but it is believed that it will not be less. The figure 
given includes also most of the areas of nipa swamps, as the 
classification has not, in most cases, been exact enough to show, 
in detail, how much of the swamp was in mangrove and how 
much in nipa. 
The term mangrove swamp is applied to the type of forest 
occurring on tidal flats along sea coasts. They are found fring- 
ing the shores of the islands of the Philippine Archipelago 
and extending inland along the streams where the water is 
brackish (Plate II). The conditions most favorable for their 
development are found in quiet bays into which flow large rivers 
whose lower reaches have little fall. 
The descending waters of the river are checked when they 
meet tidewater and deposit their sediment in the form of broad 
mud flats or deltas near the mouths of the rivers. 
These flats are usually cut by a network of channels through 
which the advancing and receding waters of the sea move. At 
extreme low tide the flats are exposed and often even the larger 
channels are dry. 
On these mud flats the trees and other plants which form the 
mangrove and nipa-swamp vegetation find conditions favorable 
to their development and, as the seeds of these species are 
distributed by water and can be transported for long distances 
without injury, the formation of flats and their seeding are 
practically simultaneous. The growth of all species is very 
rapid and the flats soon become dense forest, and remain so 
as long as the conditions which produced them are not disturbed 
(Plates III, IV). When the shore formation is favorable, new 
flats are formed beyond the old and the forest advances year 
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