Agroforestry is a new practice of sustainable soil use in the mountainous Sierra Sur de Oaxaca area of Mexico. Coffee is also a common cash crop grown in the region. The objective of this study was to investigate the pedodiversity in the area. Soil development is very complex, and is influenced by slope parameters and parent materials. Several soil groups are found in the area investigated: Alisols, Umbrisols, and Cambisols. Morphology, chemical properties, and mineralogical composition of the clay fraction of these soils were studied. The soils vary in the extent of weathering, morphology, and chemical properties, which are important to farming in the area. Most of the soils have heterogeneous parent material. The distribution of major soil types of the area is related to mass movement along the slopes, both past and present. The studied soils represent a chronosequence from unleached and unweathered Cambisols to Alisols, characterized by strong clay illuviation and dominance of kaolinite and gibbsite in clay fraction. A mosaic of landslides and gullies of various ages, formed by catastrophic events such as earthquakes and hurricanes, form the pedodiversity of the area studied. Key words: Landslides, chronosequence, pedodiversity, Cambisols, Umbrisols, Alisols

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La degradación del suelo es una de las principales amenazas ambientales, ya que su deterioro y pérdida de calidad implica la reducción de su capacidad para prestar diferentes funciones y servicios ambientales; por ello, es necesario su diagnóstico y evaluación desde etapas tempranas a partir del estudio de sus propiedades físicas, químicas y biológicas, consideradas como indicadores de su calidad.El objetivo de esta investigación consistió en seleccionar un grupo mínimo de indicadores de calidad del suelo para la zona de estudio, ubicada en la región norte del Estado de México, mediante la aplicación de métodos estadísticos multivariados, para, posteriormente, determinar la sensibilidad de cada uno de estos indicadores sobre los diferentes usos de suelo. Se tomaron 25 muestras de suelo a 30 cm de profundidad para sitios representativos de cinco condiciones de uso, en las cuales se analizó un grupo de 17 propiedades físicas, químicas y biológicas.A través de pruebas de correlación lineal y de un análisis de componentes principales que explicó el 89% de la varianza total en el suelo se obtuvo un grupo mínimo de indicadores compuesto por el carbono orgánico del suelo, nitrógeno total, pH, densidad aparente, contenido de arcillas, fósforo y potasio. Los análisis de varianza y la prueba de Tukey (p< 0.05) determinaron diferencias significativas de estas variables para los usos de suelo, indicando que, en la medida en que se intensificó la alteración en los suelos, hubo una disminución hasta del 40% en el contenido de carbono orgánico, nitrógeno total y otros nutrimentos; por el contrario, se incrementó la densidad aparente y el contenido de arcillas. La aplicación del grupo mínimo de indicadores de calidad en el suelo obtenido para este estudio es una herramienta eficiente para diagnosticar su condición actual y contribuir en la toma de decisiones sobre su manejo y conservación.

Since soil CO₂ flux is a key component of ecosystem carbon balance, quantifying its contribution to the ecosystem carbon flux and understanding the factors that underlie its temporal variation is crucial for a better comprehension of ecosystem carbon dynamics under climate change and for optimal ecosystem use and management. Our objectives were to quantify the contributions of total soil CO₂ efflux (<em>F</em>_S) to ecosystem respiration (<em>R</em>_E) and heterotrophic soil CO₂ efflux (<em>F</em>_H) to <em>F</em>_S in two <em>chinampa</em> ecosystems with different natural grass covers. We also aimed to identify the main environmental drivers of seasonal variability of these contributions. The CO₂ fluxes were measured on each site about every 14 days from September 2008 to August 2009 in the Xochimilco Ecological Park in Mexico City using dark chamber techniques. For two studied sites, <em>R</em>_E,<em> F</em>_S and <em>F</em>_H were estimated on average as 94.1 ± 8.5, 34.7 ± 3.5 and 16.5 ± 1.7 (± S.E.) mg C-CO₂ m^-2 h^-1, respectively. &nbsp;On average over the study period and sites, the annual cumulative <em>R</em>_E, <em>F</em>_S and <em>F</em>_H fluxes were 824 ± 74, 304 ± 31 and 145 ± 15 g C m^-2 year, respectively. The <em>R</em>_E, <em>F</em>_S and <em>F</em>_H varied between the winter and summer seasons; this variation was explained mostly by seasonal variations of soil temperature, soil water content and shoot plant biomass. Temperature sensitivity of CO₂ fluxes depended on vegetation type and plant growth differences among the sites and decreased in the following order: <em>R</em>_E &gt; <em>R</em>_s &gt; <em>R</em>_H. The contribution of <em>F</em>_S to <em>R</em>_E and <em>F</em>_H to <em>F</em>_S for the two studied sites and period averaged about 38% and 50%, respectively regardless of the site vegetation type, but the degree of <em>F</em>_S/<em>R</em>_E and <em>F</em>_H/<em>F</em>_S variability depended on the differences in seasonal dynamics of plant cover. The contribution of <em>F</em>_Hto <em>F</em>_S varied from 37% in summer to 73% in winter at the site without a seasonal shift in dominant plant species, but <em>F</em>_H/<em>F</em>_S was close to constant during the year at the site with a seasonal change in dominant plant species. During the cold period, the contribution of <em>F</em>_Hto <em>F</em>_S increased following plant growth decrease. The linear regression analysis showed that plant biomass was the dominant factor controlling the seasonal variation of <em>F</em>_H/<em>F</em>_S ratios, whereas the plant biomass dynamic followed the dynamics of soil water content, water table depth, and soil temperature. Our results suggest that seasonal variation of soil contribution to total fluxes from the <em>chinampa</em> ecosystem is locally differentiated. These differences were related to differences in seasonal dynamics of cover productivity which has been associated with localization of soil water content. This finding has important implications for assessing the contribution of the chinampa ecosystem to the global carbon budget.