The implications of harvesting on the population s

Authors: A Rajkaran J B Adams

Publish Date: 2009/06/18

Volume: 18, Issue: 1, Pages: 79-89

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Abstract

The Mngazana Estuary has the third largest area of mangroves in South Africa 118 ha and one of the main environmental threats is the cumulative effects of long term small scale harvesting from local communities This study investigated the change in aerial cover of the mangrove forest over time and assessed the effect of harvesting on the microenvironment and the population structure of Rhizophora mucronata preferred harvested species in both harvested and nonharvested sites In 1982 there were 150 ha of mangroves of all species and since then 32 ha 21 of the forest area has been lost Areas of the estuary where mangroves have been completely removed showed significant differences in sediment characteristics Changes in population size ratios of adult trees to juveniles harvested sites—155 nonharvested sites 134 and significant differences in height structure are some of the indications that harvesting is affecting the mangrove populations Results show that while it is necessary to suggest proposals aimed at the sustainable use of the Mngazana mangroves it is equally important in the shortterm to make available alternative sources of materials to replace mangrove poles for building The formation of the Mngazana Mangrove Management Forum provides an ideal opportunity to drive Participatory Forest Management PFM but this would require scientific and management support The data shown here will provide ecological information required for PFMThe National Research Foundation The Cape Tercentenary Foundation and the University of Port Elizabeth are thanked for funding this research Department of Environmental Affairs and Tourism and Rob Wooding and Associates are thanked for the use of the 2002 aerial photograph of Mngazana Estuary The following people assisted in the field Vuyani Dayimani Nuette Gordon Phumelele Gama Gavin Snow Kithi Ngesi and Mike Brassil Dr Derek du Preez is thanked for his help with the GIS mapping Prof G Bate is thanked for his input on the paper The comments provided by the anonymous reviewers were much appreciated

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