Effect of vegetation degradation on the soil quality of green spaces in a tropical megacity (Lubumbashi, DR Congo): potential implications for ecosystem services

Abstract

Urban soils are degraded by a range of human pressures, including vegetation degradation, leading to modifications of physical and chemical characteristics, and affecting important ecosystem services. We assessed the impact of vegetation degradation in six urban green spaces (bare soils versus vegetated soils) on the physical (texture, soil bulk density and structure) and chemical (pH, CEC, OC, N, P, K, Cu and Mn) qualities of soils in a tropical megacity (Lubumbashi, DR Congo). Vegetated soils presented better physical and chemical qualities than bare soils. Vegetated soils were characterized by a high clay and silt content and a good consistency (structure), while bare soils were characterized by a high sand content and high bulk density. Vegetated soils were characterized by higher pH, OC, N, C/N, OM, CEC, P, and K. There was no significant difference in Mn or Cu between bare and vegetated soils. Cu was highly variable between sites (from 99±61 mg.kg-1 in VS-CHL to 8559±151 mg.kg-1 in BS-ZOO). Our results demonstrate that the destruction of vegetation, leading to bare soil, negatively affects soil properties and may interfere with ecosystem services provided by urban soils in tropical climates.