Vegetation Characteristics and Deforestation at Two Mangrove Ecosystems Subjected to Varying Anthropogenic Influences: Case of Mtoni and Dege, Dar es Salaam, Tanzania

Abstract

Mangrove ecosystems are subject to over-exploitation, pollution, and conversion to other land uses from anthropogenic pressures. To understand the way different mangrove species, respond to the anthropogenic impacts, Mtoni and Dege mangrove ecosystems, with varying degradation levels were compared on vegetation characteristics, deforestation, and abiotic variables. The study adopted the line transect permanent plots method. In each sampling plot, mangrove vegetation characteristics and selected abiotic variables were assessed. Mangrove vegetation characteristics were tested using an independent t-test and a special t-test. Mangrove species diversity was calculated using Shannon-Wiener Index. Relationships of variables were tested using Spearman’s rank correlation coefficients. Findings showed that Mtoni had higher mangrove species diversity, richness, and evenness than Dege. Dege showed significantly higher mangrove density, basal area, and regeneration than Mtoni. Stump density was significantly higher at Mtoni than at Dege. In Mtoni, the basal area was significantly negative correlated with both salinity and organic matter. In Dege, basal area and salinity were significantly positive correlated. There was high mangrove degradation at Mtoni compared to Dege. It is recommended that participatory conservation and management interventions be undertaken. Mere protection from further exploitation is sufficient for Dege, while active restoration is recommended for Mtoni.