Exploring the effect of changes in land use on soil quality on the eastern slope of the Cofre de Perote Volcano (Mexico)

Changes in land use on the eastern slope of the Cofre de Perote Volcano (Mexico) appear to have a negative effect on soil quality. In this study, we use a multivariate data set to research whether the change in land use has affected soil quality and to identify the indicators that best represent variability of the original data set. An elevation transect was identified as follows: upper segment (US), middle segment (MS) and lower segment (LS). The following nondisturbed areas and farm fields were sampled: US: pinus forest (PF), corn cropland (CP), and abandoned cropland (AC); MS: tropical cloud forest (TF), corn cropland (CC), and grassland (GL); LS: oak forest (OF) and sugarcane (SG). Sixteen soil chemical, physical, and biological attributes were measured on each site of interest. It was shown that the change in land use caused a reduction in organic material content, especially on MS and LS. The highest acidity was recorded in nondisturbed soils and abandoned cropland. Microbial biomass-C (C_m) and the microbial quotient (C_m/C) were altered the most on MS and LS. C_m and mineralized N (Nm) decreased from US to LS. Bulk density (BD) increased with the change in land use, especially on LS. Principal component analysis was used to analyze soil quality overall. The first principal component (PC1) explained 46% of the total variance of the data set, and seven soil attributes had significant loadings. C, N, and total porosity (TP) were negatively weighted and were contrasted with Mg, ECEC, BD, and C_m/C. The second principal component (PC2) explained 16% and had significant positive loadings on Ca, inorganic nitrogen (Ni), and C_m. LS soils had the highest PC1 scores and US soils the lowest. The positively high PC1 scores recorded for LS soils revealed a greater sensitivity to changes in land use. In US, there were no significant effects on PC1 caused by land use change, while in the MS, positively high PC1 scores obtained in the CC soil were related to greater microbial activity and a decrease in C and N. In LS, SG soil had significantly higher PC1 scores than OF soil, indicating an increase in microbial activity.