Influence of urban land use types on ecosystem services in two rapidly urbanizing cities of southwestern Nigeria.

Abstract

Many ecological functions in cities are based on urban soils. In order to meet the needs of the expanding human population and the ensuing strain on natural resources, it is essential for soil-based ecosystems to function. Approximately 80% of the total urban land use in Akure and Okitipupa, Nigeria, are used for commercial, residential, and agricultural purposes. Thus, we investigated the potential of these three urban land use types (ULUTs) to offer a variety of ecosystem services in the two different cities. Soil properties that serve as proxy indicators for four ecosystem services were measured in the ULUTs: hydraulic conductivity (Kunsat) and available soil water for rainwater retention; soil organic carbon (SOC) stock for carbon storage; soil microbial respiration (SMR) for the capacity to support biological activity; and soil compaction (PR) and total nitrogen (TN) for promoting plant growth. The location and ULUT resulted in distinct ecosystem service provisioning. In comparison to Akure, Okitipupa soils had lower PR (1.0 vs 1.1MPa) but higher Kunsat (36.9 vs 10.3cmh-1), SOC stock (6.9 vs 5.7Mg C ha-1), and SMR levels (35.2 vs 23.6mg CO2-C g-1 soil). Commercial soils exhibited more compaction than residential and agricultural soils but less SOC stock and Kunsat, and TN in both locations. The properties of the urban soils showed that the soils could support a variety of ecosystem services. Different soil properties at the city level led to variations in the potential for ecosystem services in various locations, and these variations were observable in commercial, residential, and agricultural soils. Understanding urban soils would thus necessitate both cross-city comparative studies as well as within-city examinations of the potential for ecosystem services for various urban land use types.