La variabilidad de la salinidad y humedad en la génesis de suelos de un humedal

Abstract

Salts are an important factor in the formation and evolution of soils, and their classification. Saline wetlands are permanently or frequently flooded environments, which normally causes the development of halohydromorphic soils and halophytic vegetation. The aim of this work was to study the genesis of halohydromorphic soils in a saline wetland in San Luis (Argentina). The area studied was the depression called “Bajo Las Saladas”, located at 33º 37’ South latitude and 65º 25’ West longitude, with an area of 120.7 ha. The physiognomic types of vegetation in different sub-landscapes were delimited. Descriptions of the soils and depth to the water table were carried out in the monitoring plots located in each physiognomic type. The horizons were sampled, analyzed and the soils were classified. In the flat sector, soils of the halophilic bush were classified as typic Haplustolls. In the saline depression sublandscape, the physiognomic type Halophilic bush (dominated by Atriplex spp.) occupies the less saline soils, with higher pH and deeper water table, and the soils were typic Ustorthents or typic Epiaquents. In the more humid and saline areas there are patches of creeping halophilic bush (dominated by Sarcocornia neei), open meadows of Distichlis spicata, dense meadows of D. spicata and in the areas with greater flooding and anoxia, free of vegetation saline beaches. Those soils were classified as typic Epiaquents showing different distribution of horizons, some with glei horizons. Several factors intervene jointly in the genesis of these soils, such as water table depth, salinity, micro-relief, texture, and degree and duration of flooding.