An integrated evaluation of mangrove health and ecosystem value to local inhabitants: a blended ecological and sociological approach

Abstract

In Fiji, as in other Pacific Islands, mangroves provide substantial resources to local indigenous peoples. These resources include fuelwood, timber, food, and natural medicines. Despite this, Fijian mangroves are still lost or degraded by tropical cyclones, rising tides, tourism development, agriculture, and major construction. To gauge the future health of Fijian mangroves, and their value to local populations, it will be necessary to perform both ecological and sociological surveys to initiate long term monitoring programs. This study comprised detailed botanical and soil analyses of the Nasilai River mangrove forests in the Rewa region of Viti Levu, the largest Fijian island. As part of this study we interviewed local villagers to obtain information about their use of mangroves, their knowledge of sustainable management, and the risks related to climate change. In terms of flora, 28 species of trees and ferns were recorded, with Rhizophora and Bruguiera gymnorhiza dominating, which is typical for mangroves in this area. Similarly, soil physico-chemical properties, such as salinity, pH, nitrogen, and phosphorous were all within expected ranges. Local villagers obtained multiple benefits from the mangroves, such as timber, firewood, medicines, dyes, fruits, and marine shellfish. It appeared that mangrove degradation near to the villages was primarily due to human activities such as over-harvesting, bark removal, and dumping of domestic waste, rather than from climate change effects. Additionally, tree species such as lemons, guava, and papaya, proliferated in sites near human habitation, thus reducing mangrove floral integrity of these areas. Most villagers were aware of sustainable practices relating to mangrove harvesting, and of threats due to climate change. However, only one of two villages surveyed had experienced formal training in climate change awareness. This study provides essential baseline ethnobiological data for comparison with future studies that will enable any changes in flora, soil