Soil water regime of grassland communities along subtle topographic gradient in the Flooding Pampa (Argentina)

DI BELLA CE; COSENTINO DJ; LORETI J; STRIKER GG; GRIMOLDI AA

Soil and Water Research

Czech Academy of Agricultural Sciences

Lugar: Praga; Año: 2016 vol. 11 p. 90 - 96

1801-5395

Three plant communities positioned along a subtle topographic gradient, referred to as upland, intermediate and lowland positions, characterize the landscape of the Flooding Pampa Grasslands of Argentina. Although it is believed that the structure and functioning of plant communities at each position are in close relationship with their hydric regime, this has never been quantified. More than 800 measurements of soil water content during four years, along with soil water retention curves, and physical and chemical parameters of soils were assessed at each position. Results showed that water availability along the year varied among positions in accordance to differences in hydrological balance and soil water retention capacity of each of them. Water retention increased in relation to clay and organic matter content from the upland to the lowland position. The upland position, with more soil sand content, registered severe drought events during late spring and summer, without flooding periods in any season. The intermediate and lowland positions, with more soil clay content, remained flooded for several weeks during winter and spring, and they manifested less severe summer droughts than upland position. Moreover, the lowland position resulted more hydromorphic than the intermediate one. These spatial and temporal variations of water regime and soil parameters characterizing the upland, intermediate and lowland positions concur with different plant communities associated to each of them.