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In this study, soils on 17 ski pistes in the Sierra Nevada, Spain, were investigated to identify changes induced by ski management practices and also to determine the effectiveness of grass seeding in restoring soil quality. When compared with unaffected reference soils, those of ski runs had substantial loss of organic carbon (−34%, −11.9 ± 3.6 t ha−1) and micropore volume and size (−33%, −0.07 ± 0.01 cm3 cm−3 and −48%, −1.62 ± 0.28 μm). Microstructure showed a dramatic reduction in organic cements and fungal hyphae. The organic content of soil seeded with grass significantly improved compared with soil not seeded or seeded unsuccessfully (P < 0.05), especially where the topsoil was reinstated. Organic C content, microporosity and soil respiration increased by 200% (+21 ± 5 t ha−1), 70% (+0.07 ± 0.03 cm3 cm−3) and 140% (+0.10 ± 0.04 mg CO2 g−1 day−1), respectively. Average micropore size in aggregates which in undisturbed soils was 3.40 ± 0.28 μm reverted to 3.52 ± 0.36 μm. However, the microstructure of the revegetated soils did not attain the levels of organic cements and fungal hyphae in the natural soils. Dolomite and salts were added to the soil to aid slope stabilization, fertility and de‐icing of access tracks. As a consequence, there were increases in pH, exchangeable sodium percentage (ESP), electrical conductivity, calcium carbonate equivalent and base saturation. The influence of management on soil properties was found to be greater than that of environmental factors.

A Quaternary fluvial chronosequence (Guadalquivir River, southern Spain), consisting of five soil profiles with estimated ages of 300 years (Haplic Fluvisol), 7000 years (Haplic Calcisol), 70 000 years (Cutanic Luvisol), 300 000 years (Lixic Calcisol) and 600 000 years (Cutanic Luvisol), was studied. Increasing soil age was associated with increases in: reddening, development of structure, clay content, dithionite-extractable iron (Fe d ) and aluminium (Al d ) and strengthening of X-ray diffraction (XRD) peaks for phyllosilicates and iron oxides; there were also decreases in pH and percentage of carbonates in the fine earth and lower XRD peaks for calcite and dolomite. These changes indicate that the principal pedogenic processes were weathering, clay illuviation, rubefaction and the weathering and leaching of carbonates. We have further characterized the pedogenetic chronosequence by quantification of ultramicrofabrics of ped interiors using image analysis (IA) techniques on images obtained with scanning electron microscopy (SEM). We have estimated morphometric ultramicrofabric parameters for particle clusters, skeleton grains and pore space. These are closely related to analytical, mineralogical and macromorphological properties. In the principal component analysis, the first two principal components of the combined morphological, analytical and mineralogical data accounted for 78% of the total variance. The first component (48%) is loaded by variables associated with clay illuviation, relative accumulation of iron and aluminium sesquioxides and the weathering and leaching of carbonates. The components are related to ultramicrofabric development trends. We tested several chronofunctions derived from analytical and morphometric attributes. The logarithmic model fitted best, and we interpret this as indicating pedogenetic processes that are converging towards a steady state.

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