Impacto de la cobertura vegetal y las actividades antrópicas sobre la formación del suelo en una microcuenca de páramo en la cuenca del Río Yanuncay-Quebrada Cuevas

Abstract

This thesis aims to study the effect of vegetation cover and anthropogenic activities on soil formation in a páramo micro-catchment in the upper part of the Yanuncay basin (Cuevas stream). Non-allophonic Andosols are the main soils in the study area where the overgrazing and burnings are the common agricultural practices. Three types of vegetation were identified, grass páramo (Pj), cushion páramo (PHA), and Polylepis (BP) forest. 6 soil catenas were made and 18 soil profiles were studied for the distinct types of vegetation. Results of the statistical analyses show that the availability of cations and Si is low, whereas the availability of Al and Fe is high and these elements are strongly correlated to organic carbon. The upper horizons present values of pH lower to 5, bulk density is lower to 0.9gr/cm³, and the values of the ratio of Alp/Alo are between 0.5 and 1. These findings indicate that the páramo soils of the southern Ecuador are non-allophonic Andosols and the alumínic-organic complexes prevail, while the formation of allophones is limited, therefore these soils are well developed. Our analysis show that there are two patterns between vegetation groups, apparently the grass páramo and Polylepis forest have the same behavior, as they do not show significative differences. On the other hand, the results for the cushion páramo show a distinct behavior in comparison to the other two groups. Land use plays an indirect role but important in soil development, particularly the Pj and Pha are subjected to overgrazing of animals and burnings, these agricultural practices contribute further to disturb the biogeochemical cycle of páramo ecosystems