Resumo

MUJICA, C.R.; MILIONE, G.M.; BEA, S.A.  e  GYENGE, J.E.. Impacto en los flujos hídricos por la presencia de horizontes petrocálcicos en parcelas forestadas en ambientes de llanura. RIA. Rev. investig. agropecu. [online]. 2019, vol.45, n.3, pp.426-436. ISSN 1669-2314.

Around the world there are a lot of landscapes with presence of petrocalcic horizon, as well as in Pampas in South America. Ussualy these horizons constitute a barrier to the water flows, and even a reservoir of water for plant consumption. It is one of the most economically productive landscapes and, as in other regions that were naturally covered with pastures, these have been replaced by other usses. In many cases, these changes in land use have modified the water and solute flows and the most drastic example is afforestation due to its high water consumption and the selective untake of solutes. However, the effect of this practice on soils with the presence of a petrocalcic horizon has not been sufficiently studied. Within this region, hydrological variables of a paired grassland and afforestation plot with levels of petrocalcic horizons have been monitored, and a numerical model based on physical/biological processes and atmospheric contour conditions was developed, with the objective of quantifying water flows and the water available for the consumption of afforestation. The results of the model suggest hydraulic disconnection between afforestation and the water table due to the presence of the petrocalcic horizon, with only ~ 13% of total groundwater usage. Long periods of water stress are predicted during times of high atmospheric demand, and forest water consumption is restricted to that soil portions above the petrocalcic horizon. Transpiratory rates were similar (~ 700-723 mm year-1), or even higher than reported in the area. The petrocalcic horizon retains water and reduces deep drainage.

Palavras-chave : changes in land use; ecohydrology; petrocalcic horizon.