Ecosystem services valuation of Ikogosi Warm Spring and Olumirin Waterfall forest: a comparative assessment

A major problem in environmental resource management is assigning a value to natural resources so that they can compete favorably with other types of resources, especially mineral resources, in terms of their contributions to a nation's domestic product (GDP). This study profiled for the first time the ecosystem services offered by Ikogosi Warm Spring and Olumirin Waterfall forest, valued their ecosystem services, and compared them. The study employed the Millennium Ecosystem Assessment Framework to estimate the ecosystem services in the study areas. The study was conducted in two phases: field survey and laboratory investigation. The study identified four ecosystem services in the study areas. The total economic valuation estimated in 2022 was US$132.19 million. Ikogosi Warm Spring contributed US$78.37 million, while Olumirin Waterfall contributed US$53.82 million. The contributions of individual ecosystem services at Ikogosi Warm Spring were carbon sequestration (43.8%) > water regulation (29.93%) > water purification (15.96%) > oxygen potential (6.93%), > nutrient recycling (3.23%) > erosion prevention (0.09%). For Olumirin waterfall, the level of contributions of individual ecosystem services was carbon sequestration (39.94%) > water regulation (39.01%) > oxygen potential (13.98%) > water purification (2.75%) > erosion prevention (0.11%). This study has provided a database of the economic value of ecosystem services and benefits offered by Ikogosi Warm Spring and Olumirin Waterfall, and given information on the drivers of ecosystem degradation eroding these values. The study also provided a suitable framework to address the management of these resources.