Salt leaching leads to drier soils in disturbed semiarid woodlands of central Argentina

• Published in: Oecologia 2013-04, Vol.171 (4), p.1003-1012
• Main Authors: Marchesini, Victoria A., Fernández, R. J., Jobbágy, E. G.
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animal and plant ecology; Animal, plant and microbial ecology; Argentina; Biological and medical sciences; Biomedical and Life Sciences; Biota; Chlorides; Chlorides - analysis; Deforestation; Ecology; Ecosystem; ECOSYSTEM ECOLOGY; Ecosystem ecology - Original research; Electric Conductivity; Electric properties; Electrical conductivity; Environmental changes; Environmental degradation; Forest soils; Fundamental and applied biological sciences. Psychology; General aspects; Groundwater; Growing season; Humidity; Hydrology/Water Resources; Leaching; Life Sciences; Models, Biological; Moisture content; Plant Sciences; Plants; Salinity; Salts; Semiarid environments; Semiarid lands; Shrubs; Soil - analysis; Soil moisture; Soil salts; Soil water; Soil water content; Soils; Vegetation; Vegetation dynamics; Water - analysis; Water content; Water Movements; Water potential; Water storage; Woodlands
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-012-2457-y

Disturbances in semiarid environments have revealed a strong connection between water, salt and vegetation dynamics highlighting how the alteration of water fluxes can drive salt redistribution process and long-term environmental degradation. Here, we explore to what extent the reciprocal effect, that of salt redistribution on water fluxes, may play a role in dictating environmental changes following disturbance in dry woodlands. We assessed salt and water dynamics comparing soil-solution electrical conductivity, chloride concentration, soil water content (SWC) and soil matric and osmotic water potential (Ψ m , Ψ os ) between disturbed and undisturbed areas. A large pool of salts and chlorides present in undisturbed areas was absent in disturbed plots, suggesting deep leaching. Unexpectedly, this was associated with slight but consistently lower SWC in disturbed versus undisturbed situations during two growing seasons. The apparent paradox of increased leaching but diminishing SWC after disturbance can be explained by the effect of native salt lowering Ψ os enough to prevent full soil drying. Under disturbed conditions, the onset of deep drainage and salt leaching would raise Ψ os allowing a decline of Ψ m and SWC. Soil water storage seems to be modulated by the presence (under natural conditions) and partial leaching (following selective shrub disturbance) of large salt pools. This counterintuitive effect of disturbances may be important in semiarid regions where deep soil salt accumulation is a common feature. Our results highlight the importance of water—salt—vegetation coupling for the understanding and management of these systems.