Growth and Development of Rhizophora spp. Seedlings on Different Substrates and Insertion Level in the Wouri Estuary Mangrove (Douala, Cameroon)

Abstract

Mangroves are threatened with extinction worldwide. Many mangrove reforestation projects have been developed, but very few have achieved their restoration objectives. With the ambitions to contribute for rehabilitation of mangrove ecosystems, the aim of this study was to assess the effects of substrate composition and level of insertion on the growth and development of Rhizophora seedlings in nurseries. The experiment was conducted in a semi-lighted nursery set up in situ. Rhizophora propagules were reared on three types of mangrove substrates (type 1: 75% of mud and 25% of sand; type 2: 50% of mud and 50% of sand, and type 3: 25% of mud and 75% of sand) with different levels of insertion (at ¼; ½ and ¾). Seedling heights and diameters were recorded, as well as the time of appearance of the first leaves and the variation of number of leaves. The greatest average height (40.2 ± 7.48 cm) and the highest mean diameter (1.2 ± 0.01 cm) were obtained for the substrate composed of 75% mud and 25% sand. The best growth and development of seedlings were recorded on the substrate type 1 with an insertion at ¼. Seedling production at ¼ insertion of substrate type 1 appeared the most effective combination. The production of Rhizophora seedlings on the substrate combining 25% Sand and 75% Mud with an insertion level at 1/4 seems to be the best method for the complete restoration and rehabilitation of the mangrove ecosystem of the Wouri estuary.