Assessing changes in flora distribution of Akoka forest ecosystem, 52 years after urban encroachment using field surveys and integrated remote sensing data

The numerous benefits and the need to conserve urban forest is increasingly been acknowledged by scientists, land managers as well as decision makers. However, unlike the developed regions of the world, urban forest composition and structure in developing countries such as Nigeria remains the most threatened and least-studied. Using intensive field surveys and remote sensing data, this study investigated changes in species composition and structure of nine vegetation types in Akoka between 1962 and 2014. Field data on individual species was collected along a belt transect laid across the nine vegetation boundaries. Species composition, richness and diversity differed among the vegetation types as well as between 1962 and 2014. Species composition ranged from 3 to 19 across the vegetation types and was highest in fresh water swamp forest. While brackish marsh land had highest total number of individual, fresh water swamp forest located near the parks and garden had the least likely due to its nearness to ceaseless human disturbance. The species diversity was generally low across the vegetation types, and varied between 1.32 in brackish marsh land to 2.63 in mangrove swamp forest. The overall initial vegetation of Akoka had significantly fragmented and diminished between 1962 and 2014. Compared to 1962, the percentage vegetation cover by the major vegetation types had reduced, indicating that while anthropogenic disturbance persisted, little or no effort was put in place to improve their restoration. Overall, our findings pointed to the needs for sustainable management of urban forest with keen attention being paid to restoration.