The Role of Soils on the Hydrological Cycle of a Wetland Meadow (Vegas) in Southern Chilean Patagonia

Abstract

Wetlands occupy 4%–8% of the Earth's terrestrial surface and perform critical ecosystem functions, including water quality and quantity regulation, wildlife habitat provision and carbon storage. ‘Vegas’, wetlands in Chilean Patagonia, are unique ecosystems that play a vital role in water supply and forage productivity, which are essential for sheep farming, the region's main economic activity. This study aimed to analyse the spatial variability of soil functions, evaluate water dynamics and correlate hydrological behaviour with environmental characteristics in Patagonian Vega. Seven excavation sites were selected along a topographical transect, with soil samples collected at depths of 5, 30, and 80 cm. Sensors were installed to measure soil water content and matric potential. Analyses included WRC, Ka and Ks. Results showed hydric deficits for 84.3% of the evaluation period and a progressive decline in the water table. Air capacity and plant available water varied significantly across topographical positions and depths. Soils on summits and footslopes exhibited higher hydraulic conductivity but lower water retention compared to soils in the centre of the Vega, which remained saturated in deeper horizons. A strong correlation was observed between soil water content and evapotranspiration (ETo), whereas precipitation had minimal influence. Vegas acts as natural sponges, storing and releasing water according to seasonal demands. The central zone of the Vega plays a pivotal role in maintaining soil moisture and supporting forage productivity, while peripheral areas contribute to hydrological flows via surface and subsurface runoff. These results underscore the importance of treating Vegas as protected wetlands and adopting sustainable management strategies to conserve their ecosystem services in the face of climate change and increasing anthropogenic pressures. Patagonian Vegas exhibits significant spatial variability in soil functions, which are critical for water regulation and biodiversity support.