Effect of greenspaces on soil hydrology within urban ecosystems.

Abstract

Urban greenspaces provide a regulatory ecosystem service for some of the hydrological processes within urban ecosystems. However, soil hydrological properties can vary with variations in urban vegetation type having an impact on the hydrological balance. This study was carried out to determine the effect of urban vegetation type, species and its management within urban ecosystems to deliver a water regulatory service (with soil moisture content, water infiltration rate, hydraulic conductivity as indicators). The research combines data from field and plot measurement. At the field scale, 78 fragments located in Bedford, Luton and Milton Keynes, UK, over a range of soil textures (clay, clay loam, sandy loam and silty clay loam) were investigated. The vegetation types were categorised as managed grass, managed herbaceous, shrubs, trees over managed grass, trees over unmanaged herbaceous, unmanaged herbaceous and woodland/trees. Infiltration rate was not different for the different vegetation types while unsaturated hydraulic conductivity was greater for the managed grass 308 ± 223 mm d⁻¹ than the unmanaged herbaceous 88 ± 51 mm d⁻¹on sandy loam soil. Experimental treatments at plot scale were investigated. A combination of floristic (3 levels: “no”, “some”, “many”) and structural (3 levels: “short”, “medium”, “tall”) manipulation on each plot and 1 non-manipulated plot, located in Cranfield, UK, on a clay soil. There was no difference in infiltration rate, hydraulic conductivity and soil moisture content related to species richness or plant height. The results of the study show that urban vegetation type, increased species richness, and plant height do not negatively impact infiltration rate, and soil moisture content, while hydraulic conductivity is increased using the managed grass on a sandy loam soil. Therefore, the planting of mixed and species rich and different urban vegetation type is encouraged for its other values in the society.