The wetlands of Belize are a complex mosaic of mangrove, hummock and littoral forest, saltmarsh, and mangrove scrub, interspersed by shallow lagoons and channels. The gross differences in vegetation zoning between each transect were found to result from the variations in the combined topographic, hydrological and palæoenvironmental conditions. In general, pH levels for all transects were high, and did not vary from north to south as may have been anticipated from the effects of Belize's precipitation gradient or from the difference in substrate geology.
In the simplest sequence, the predominantly mangrove sections are succeeded inland by patches of wet grassland and palmetto scrub and occasionally, on higher well drained land, by "broken ridge" - a form of pine and scrub savanna. The tallest and densest mangroves are found in the south around Temash River. The sediment properties, in a similar sequence from the coast, show a decrease in the percentage loss on ignition, total exchangeable bases and several of the exchangeable cations, predictably Na but also Mg and Ca. The detailed relationship between the vegetation zones and the sediment-soil properties is the subject of forthcoming publications.
The results of detailed transect surveys and ground checking permitted the production of a second edition of the National Mangrove Map. The four sheets covering the country offer considerably improved accuracy in the delimitation of mangrove distribution. The impact study reveals the very heavy loss of mangrove in the Belize City area, with significant but lesser disturbances around Dangriga, at the mouth of the Stann Creek Valley and near small coastal towns. The annual rate of mangrove destruction close to Belize City has risen from 0.3% in 1961 to 3.6% in 1991 and is accelerating. Clearance for new housing projects accounts for most of the loss, with tourism, transport and industrial developments accounting for the additional disturbance. Although clearance has so far been highly localised, virtually no care has been taken to minimise environmental impact and the effects of pollution, erosion and sedimentation and the loss of nursery sites is still unknown. Guidelines for the conservation and alternative management strategies for the Ministry of Natural Resources have been produced.
|This picture shows an extract of the National Mangrove Map (Second Edition).
It shows the area around Belize City, similar in extent to the earlier Landsat TM image
It has been classified to show only the mangrove cover.
Mangroves are classified on this map according to their height and density. Tall dense mangroves are shown in black; Medium dense mangroves are shown in red; Dwarf mangroves (dense to open cover) are shown in blue; Areas of mangrove savanna (not included in this extract) would be shown by oblique parallel blue stripes.
The survey has proved timely for both predictable as well as unforseen reasons.
It is well known that mangrove destruction and disturbance has been increasing along the length of the Yucatàn Peninsula's coastline. This is particularly evident around coastal towns such as Belize City and Dangriga in Belize or resorts such as Cancún in Mexico. This is the result of natural population growth, urban expansion and an increase in tourism. This work examines the main sites of vegetation clearance in Belize.
The unforseen element is the discovery of numerous small mangrove communities in scattered wetlands well inland from the coast; in one instance (Booth's River) they were found over 50 miles from the sea with no present day or recent marine connection. A number of these rare communities are at present protected, since they lie on lands owned by the conservation organisation Programme for Belize
Two reports were produced during the project:
Mangrove distribution, vulnerability and management in Central America
ODA-OFI Forestry Research Programme, Contract No. R4736.
P.A. Furley & J.A. Ratter (editors)
The wetlands of Belize: ecology, environment and utilisation
Occasional publication, Department of Geography, The University of Edinburgh
ISBN 0 900475 22 6
P.A. Furley & D.M. Munro (editors)
Further publications (articles in refereed journals) are currently in preparation.