Influence of vegetation cover and rainfall intensity on soil attributes in an area undergoing desertification in Brazil

Abstract

Desertification is a major environmental problem in arid, semiarid, and dry sub-humid regions throughout the world, which causes considerable reductions of ecosystem services, increased food insecurity, and poverty. The influence of vegetation cover and rainfall intensity on the dynamics of water infiltration, surface runoff, and soil loss was measured in situ in a desertification zone in the semi-arid region of Brazil. Twenty-four plots were evaluated in two areas, each with the same type of soil that is predominant in the region: 1) Luvisol with dense vegetation cover (LD) and 2) Luvisol with sparse vegetation cover (LS). A rainfall simulator was used to simulate either 60 or 100 mm h−1 of rainfall. Soil hydraulic conductivity, soil water retention curves, and soil carbon and nitrogen stocks were also determined. Water infiltration was greater in the LD (53 mm h−1) than in the LS (15 mm h−1), while the runoff rates were 27 mm h−1 for the LD and 61 mm h−1 for the LS. Rainfall intensity significantly influenced the time when runoff started and the runoff rate accelerated soil loss. Vegetation cover significantly influenced the total soil carbon and nitrogen stocks, as well as the saturated hydraulic conductivity of the soil. This is the first study in a semi-arid desertification zone of Brazil that used simulated rainfall to determine effects rain intensity on soil properties. The results of this study can be used as a reference for calibrating erosion models in areas undergoing a desertification process.