Influence of land use on hydro-physical soil properties of Andean páramos and its effect on streamflow buffering

Abstract

The páramos biome of the northern Andes is a collection of high-mountain tropical grassland wetland ecosystems that provides important ecosystem services including hydrological buffering and water supply. Human activities in these ecosystems transform vegetation cover and soil hydro-physical properties, affecting their hydrological performance and water quality and quantity. Here, we conducted a systematic review on the influence of land use (agriculture, livestock grazing, and afforestation) on the hydro-physical properties of páramo soils and analyzed its implications for streamflow buffering. Our review protocol identified 32 relevant papers, from which key hydro-physical properties linked to streamflow variability were available: soil organic matter (SOM), soil organic carbon (SOC), porosity, bulk density, saturated hydraulic conductivity, and water retention capacity (WRC). The analysis shows that soils with native cover are characterized by a porous structure that allows a high WRC and SOM content. Agriculture increases macroporosity but it leads to bare fallow plots that promote loss of nutrients and SOM. Burning generates hydrophobic aggregates that affect WRC. Livestock grazing produces soil compaction and increases bulk density, reducing infiltration and WRC. Lastly, afforestation with exotic species (e.g. pines, eucalyptus) decreases SOM and WRC by changing soil structure. In general, the analyzed land-use activities generate hydrophobic aggregates, increase bulk density, promote erosion and runoff, and impair hydrological buffering capacity. This integrated evidence from multiple empirical studies can be used to effectively communicate the effects of different land use practices on páramo soils, provide information for modelling in data-scarce situations, and contribute to decision making processes for land use planning and conservation.