Pedological diversity and the geoecological systems of Sierra de Guadalupe, central México

Abstract

The Sierra de Guadalupe, located north of Mexico City, is an important geoecological system of the dry Mexican basin. Its topographical features, lithological materials and soil characteristics infl uence its biodiversity and ecosystem processes; conversely, patterns of biodiversity affect the soil properties at different scales. Unfortunately, although widespread land disturbance, severe soil degradation, and slopes severely affected by slumps and landslides are present in this region, soil and landscape preservation strategies have received surprisingly little attention. This paper attempts to examine and defi ne the pedodiversity context that characterizes the geoecological system of the Sierra de Guadalupe. We consider that characterizing this system provides a unique and indispensable tool for evaluating the environmental risks of the geoecosystem as well as the interactions and interrelations in the environment. The goals of this paper center on the rationale to identify soil units, determine their spatial distribution, defi ne their variation in soil morphology and properties, and to classify them appropriately.

Our results revealed that the studied soils are derived from volcanogenic materials that are too young to be strongly weathered. Uncultivated and incipiently developed soils, polycyclic soils and buried soils were detected in the study area. Their soil characteristics and properties are ascribed mainly to successive processes of mass movement, erosion and redeposition (K cycles) as well as to their spatial arrangement on the slope profi le. Laboratory analyses showed that these soils are slightly acid and rich in organic matter. In addition, they have high cation exchange capacity saturated by Ca2+ and Mg2+. The clay fraction is composed of halloysite > kaolinite > smectite. The soils exhibit large quantities of SiO2, besides total oxides abundances in the order SiO2>Al2O3>Fe2O3, which indicates their incipient degree of weathering. We conclude that the characteristics of the Sierra de Guadalupe soils can be explained within the context of a slope model, with an erosional and depositional toposequence pattern, common in the dry lands of the Mexican basin.