Assessment of Asymmetric Mangrove Restoration Trials in Ogoniland, Niger Delta, Nigeria: Lessons for Future Intervention

Abstract

Mangrove restoration has been undertaken with varying degrees of success in many tropical and subtropical marine shorelines around the globe. However, mangrove reforestation in the Niger Delta, Africa’s largest delta and mangrove belt is, at best, rudimentary. Here, we present floristic results on two opportunistic artificial mangrove regeneration case studies aimed at restoring mangrove swamps damaged by oil pollution (Bodo Creek) and colonized by invasive Nypa fruticans (nypa palm) (Kono Creek) in Ogoniland, eastern Niger Delta, Nigeria. Nursery raised seedlings of the delta’s dominant Rhizophora racemosa were planted 1 m apart in zigzag fashion at both locations. Planting at the oil-polluted site was preceded by soil quality investigation and bio-stimulation with fertilizer, whereas at Kono Creek, there was no addition of fertilizer before and after planting. A 3-year post planting evaluation of survival rate, growth, and girth parameters showed better performance of mangroves at the Bodo Creek restoration than at the Kono Creek restoration, with survival rates of 72% and 12%, respectively. In sharp contrast to the Bodo Creek restoration, few stands of the planted mangroves at the Kono Creek restoration had started producing propagules. Investigations of soil quality, and where necessary, followed by remedial treatment, particularly augmenting key nutrients, are critical precursors of successful artificial mangrove regeneration.