Impactos de las plantaciones de pino y pastoreo sobre las propiedades hidrofísicas y SOM de los suelos alto andinos del sur del Ecuador

Abstract

In South America, high Andean ecosystems such as high montane forests and the páramos provide important ecosystem services; they are associated with high water regulation capacity and water retention properties of the soils. However, these soils have been altered by the establishment of pine plantations and grazing. The objective of this study is to evaluate the impacts of pine plantations and grazing on the hydro-physical properties and on the soils’ organic matter content (SOM) in southern Ecuador (2640 to 3758 m a.s.l.). In order to achieve this, seven study sites were selected and each one was parceled up into natural undisturbed plots, pine plantations, and grazing. All characteristics were considered at two different depths (0 - 10 cm, and 10 - 25 cm) in each plot. The results showed that the pine plantations and grazing sites in high Andean ecosystems produce changes (increments or reductions) mainly on the saturated hydraulic conductivity (Ksat), on the water retention capacity at pF 0 to 2.52, and on the SOM content; however, their impacts could not be generalized. The impacts of pine plantations were dependent on sampling depth, ecosystem type, plantation characteristics, and previous soil use. While the impacts of grazing are dependent on sampling depth, and soil management (grazing intensity and tilling activities). These relationships imply difficulties when evaluating impacts, and therefore, it is necessary to avoid generalizing the impacts on high Andean ecosystems at the regional scale.