Iron sesquioxides in temperate-humid forests of the state of Hidalgo, Mexico.

To t a l i r o n d i s s o l v e d a n d i r o n nforms extracted with acid ammoniumoxalate, sodium pyrophosphate anddithionate- citrate- bicarbonate were studied inAlisol soils in the municipality of Acaxochitlán,State of Hidalgo, México. The studied soilspresent different kind of forests: Pinus patulaschlecht and Cham (Pp), Pinus teocote, (Pt) and Quercus spp, (Q). The objective of this research is to determine if the vegetation modifies the different fraction of iron (Fe) in the soil. The highest total iron content (14.5% of Fe2O3) was observed in the soils with Pp vegetation, the highest percent of ferrihydrite (38.0% of total Fe present in the soil) and ofiron-organic matter complex and amorphousiron oxides (20.9% and 16.3% respectively oftotal Fe in the soil) were found in the Pt forest.Free iron forms (56.7% of total Fe in the soil)and crystalline iron forms (goethite/ hematite)were predominant in the soils with Pp forest.The most weathered soil was the one withQ vegetation, a higher evolution in the processof iron oxi-hydroxides structural organizationwas found in the soils with Pt and Pp. The type of forest vegetation influences the degreeof soil evolution, and distribution, contentand forms of Fe oxides in order of highestto lowest total Fe content in the soil wasPinus patula > Quercus spp > Pinus teocote.