Incorporating Biodiversity into Sensitivity Maps of the Niger River Delta

ABSTRACT Using the basis that communities having high biodiversity are inherently more valuable as an ecological resource, the authors have derived a preliminary system of classifying the tropical environments of the oil-producing delta regions of Nigeria based on a number of field-collected parameters that measure the degree of biodiversity as well as potential spill persistence and difficulty of cleanup. Physical parameters to be measured include type of substrate, presence of near-surface groundwater and inhibiting layer, and extent of surface debris. Biological parameters include tree density (stocking), coverage by grasses and shrubs in the under-story, plant condition, species richness and diversity (mammals, reptiles, amphibians, birds), important medicinal or endangered species, and special or unique biological features. Each factor is given assigned weighting values based on over 20 years of oil spill experience. The weighting given to spill persistence factors is 25%, while 75% is given to biological parameters. The sum of species richness and diversity is one-third of the entire valuation. Once all parameters are measured and tallied, sensitivity classification will be divided into five to ten categories. Initial data collection was undertaken during 1999. Additional fieldwork to collect and test each factor is planned for the year 2000. Sensitivity maps, including the classification of both coastal and inland habitats, will then be prepared in a GIS (Geographic Information System) format.