Mangrove plantation experiments for controlling coastal erosion at Gazi Bay

Abstract

Horizontal distribution of mangrove species is a common phenomenon in mangrove ecosystems. In Kenya, where 9 species of mangroves occur, the seaward zone is normally occupied by Sonneratia alba and occasionally by Rhizophora mucronata. The present study was conducted in a low lying site previously dominated by S. alba. Our study aimed at testing the suitability of replanting R. mucronata propagules in low elevation site to control soil erosion and stabilize sediments. The experiment was set up in March 2005 with three treatments and a control group. R. mucronata propagules were planted directly into the sediment or inside bamboo encasements of various diameters. Field measurements included percentage mortality, shoot height increment (cm), diameter at second internode (mm), and leaf number. The results showed that the directly planted saplings had a significantly high % survival (p=0.01) as well as better growth performance (p<0.01) than the encased saplings. There was no significant difference between the bamboo treatments in both survival and growth performance.