Cronosecuencia de un suelo y su clasificacion en un area originalmente ocupada por bosque mesofilo de montana | Soil chronosequence and its classification in an area originally occupied by mountain cloud forest
2005
Bautista-Cruz, A. | Gutierrez-Castorena, M. del C. | Castillo-Sanchez, R.F del | Etchevers-Barra, J.D.
Tropical mountain cloud forests (TMCF) are common in mountainous humid subtropical areas. These ecosystems are among the most endangered, as they are commonly cleared for cropping. After fertility decreases, the plots are abandoned and secondary forests invade the area. The role of such changes in soil taxonomy is unknown. Therefore, we studied a chronosequence originally occupied by a TMCF with five stages: corn field, and forests of ca. 15, 45, 75, and > 100 years after abandonment, at El Rincon, State of Oaxaca, Mexico. At each stage, we described a soil profile and conducted physical, chemical, mineralogical, and micro-morphological analyses of the horizons for soil classification. We detected umbric and cambic horizons, at early stages of succession, and folistic and sombric horizons, at mature stages. As the age of the forest increased, acidity and the soil organic layer, with its three degrees of decomposition (sapric, hemic, and fibric), increased, fungi dominated, and primary minerals, such as chlorite and muscovite, were altered. Finally, the build up of gibbsite was inhibited, apparently by the high content of soil organic matter. All the forest soils were in the order Inceptisols. However, soils from young forests (ca. 15 and 45 years after abandonment) were classified as Humic Dystrudepts. By contrast, soils of latter stages (> 75 years) were Typic Dystrudepts. The crop soil belongs to the order Entisols and the suborder Typic Udhorthents. We found two diagnostic horizons not previously considered in the Inceptisols: a sombric horizon and a folistic horizon in the soil of > 100-year-old forest. We propose the subgroup Sombric to be included in Inceptisols with a sombric horizon.
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