RừNG NGậP MặN Độ TUổI NHỏ CUNG CấP LƯợNG LớN VậT RụNG GIàU DƯỡNG CHấT CHO THủY VựC

Abstract

Mangrove swamps are key ecosystems along theVietnamcoast. Although mangrove litter is thought to represent an important input of organic matter and nutrients to the coastal aquatic systems, the factors determining the quality and size of this litter flux have not been studied so far. We monitored leaf, stipule, twig, and reproductive litter monthly in monocultures of Rhizophora apiculata mangrove forests of 7, 11, 17 and 24 years old in the Camau province, Mekong Delta, Vietnam. Litter traps were used to measure litter fall production from June 2001 till May 2002. Total litter fall was in the range of 8.86?14.16 tDW.ha-1.yr-1. Leaves were the main component, and represented 70% of litter fall production in all stands. Total litter fall was lower in the older stands but reproductive litter was higher in these stands (17 and 24 years). Biomass of leaf litter was highest between the end of the wet season and the beginning of the dry season. Phosphorus and nitrogen levels were higher in younger than in older stands. Overall, our study indicates that young stands produce the highest input of litter, nitrogen and phosphorus to the surrounding aquatic system. Consequently, these stands may give the largest boost to fisheries.

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