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The Mediterranean mountainous landscapes have undergone large-scale exploitation for millennia. In the Central Pyrenees, land abandonment has occurred since the 1950s, leading to a process of woody encroachment. The main objective of this paper is to shed light on the effects of different land use and land covers (LULCs) on soil organic carbon (SOC) and nitrogen (N) stocks, and on the composition of soil organic matter (SOM) after land abandonment in the Central Pyrenees. Five LULCs (8 specific sites) were selected through detailed land use change mapping. Soil and litter samples (n = 160) were collected and analyzed, including Tetramethylammonium hydroxide pyrolysis–gas chromatography. Organic carbon (Corg)/N ratios, Carbon Preference Index and Average Chain Length indices were calculated based on the distribution of fatty acids in order to determine the molecular composition and degradation of SOM. The results showed: (i) an increase in the dominance index and forest cover, at the expense of shrublands and agricultural fields, and a decrease in Shannon’s Diversity and Evenness indexes; (ii) LULC and depth had significant effects on SOC and N contents and stocks; (iii) SOC and N contents and stocks were higher in the meadows and young forests; (iv) significant differences were observed between meadows and young forests and the first stages of land abandonment considering the soil profile; (v) total decomposition of lignins and an omnipresence of unsaturated and saturated straight-chain fatty acids; and (vi) Corg/N values indicate that the origin of SOM is microbial. This study confirms that SOC accumulation after abandonment is a slow process, and the first stages of the woody encroachment decrease SOC stocks. Woody encroachment should be managed with measures based on scientific knowledge, but also considering the historic adaptation of agro-pastoral activities to the environment to ensure the proper functioning of ecosystem services and promote SOC storage in Mediterranean mountain soils.

This paper discusses the suitability of hand-held XRF analysis to extract palaeo-geochemical information from lacquer-peel soil sections that have been taken to document pedological information at geological and archaeological sites. This not only allows the study of sections from archaeological and geological sites that have since disappeared, but can also answer new archaeological questions on the nature of activities undertaken at such sites. Seven lacquer-peels, from different time-periods and different geogenetic backdrops, have been studied with hand-held XRF (Niton XL3t, GOLDD detector). Five of these lacquer-peels were studied to assess possible interference from mounting materials (glues, textiles and framing boards) used. Four of these lacquer-peels were studied for their palaeo-geochemical information. These lacquer-peels were taken from prehistoric agricultural plots and settlement sites, ranging in age from the Neolithic to the Iron Age. Values for Si, K, Al, Fe, Ti, Sr, Zr and Rb reflect lithogenetic and pedological processes. The contents of S, Ca and P were used as a proxy for anthropogenic influence. The lacquer-peels provided consistent and reliable geochemical readings with the hand-held XRF. Observed correspondence between pedological predictions, archaeological hypotheses and the measured results testifies to the suitability of hand-held XRF for palaeo-geochemical characterization. Interference from the primarily organic fixing- and mounting-agents used was absent. Consequently, hand-held XRF analysis allows extraction of palaeo-geochemical information from lacquer-peel soil sections, which opens-up a new potential data-set for reconstructing past pollution and to geochemically re-assess geological and archaeological sites from existent lacquer peels — adding a geochemical dimension to lacquer-peels of pedological, archaeological and geological sites.

Over the past years the Caesium-137 (137Cs) technique has been successfully applied in numerous environments all over the world. This technique is using the worldwide distribution of the anthropogenic 137Cs radionuclide and its redistribution associated with soil particles as an effective estimation of net soil-loss rates. In contrast to numerous studies on deep, often cultivated, clay soils with gentle to intermediate slopes, typical Mediterranean shallow stony soils on steep slopes have received less attention. In this paper, the landscape evolution over the past 37 years has been evaluated using the 137Cs technique for two lithological different areas under contrasting land use in the Álora case study area (Málaga, Spain). In soils on gneiss and serpentinite bedrock several transects have been selected on steep slopes up to 35° with mean soil depths from 37 cm for gneiss to 24 cm for serpentinite. Estimating net soil redistribution rates from radionuclide distributions depends on the calculation of the local area reference inventory and the used calibration technique. Several methods have been tested and final results were found to differ considerably. After careful parameter selection, the resulting net soil redistribution estimates for the different transects have been compared with simulations of a simple landscape evolution model, resulting in different possible scenarios of erosional response. Total net soil-loss for the study area range from 2.3±0.25 to 69.1±7.8 t ha−1 year−1 for serpentinite and gneiss slopes, respectively. Differences in total slope sediment budgets as well as differences along the transects reveal influences of landscape representation and land use. In this case the impact of soil translocation by tillage and resulting erosion rates are far more important than possible parent material induced differences. However, comparing the two sampled areas not only net rates but spatial patterns as well reveal important differences in distribution over the landscape of net erosion and net sedimentation zones., This research is supported by the Laboratory of Soil Science and Geology under the project “Multi-scale Landscape Process Modelling” at Wageningen University. The second author acknowledges the financial support through a post-doctoral fellowship of the Fundación Alfonso Martín Escudero (Madrid, Spain).

Due to its modest data demands and transparent model structure, the Universal Soil Loss Equation (USLE) remains the most popular tool for water erosion hazard assessment. However, the model has several shortcomings, two of which are likely to have prominent implications for the model results. First, the mathematical form of the USLE, the multiplication of six factors, easily leads to large errors whenever one of the input data is misspecified. Second, the USLE has a modest correlation between observed soil losses and model calculations, even with the same data that was used for its calibration. This raises questions about its mathematical model structure and the robustness of the assumed parameter values that are implicitly assigned to the model. This paper, therefore, analyzes if the USLE could benefit from mathematical model transformations that, on one hand, mitigate the impact of incorrect input factors and, on the other hand, result in a better fit between model results and observed soil losses. For the analysis, we revisit the original data set and consider the USLE factors as variables rather than their common interpretation as parameters. We first use both nonparametric and parametric techniques to test the robustness of the implicit parameter assignments in the USLE equation. Next, we postulate alternative mathematical forms and use parametric test statistics to evaluate parameter significance and model fit. A tenfold cross-validation of the model with the best fit tests the sensitivity of the parameters for inclusion or exclusion of the data. The results show that the USLE model is not very robust, however, only slight model improvements are obtained by drastic modifications of its functional form, thereby sacrificing the simple model structure that was intended by its designers. © 2002 Elsevier Science B.V. All rights reserved.

Tree growth and inclination on sloping land is affected by mass movement. Suitable analysis of tree growth and tree form can therefore provide considerable information on mass movement activity. This paper reports a new, automated method for studying the temporal and spatial aspects of mass movement activity. Ringwidth data from only a few cores per tree are required. The method uses filtering techniques and statistical time series analysis. Preliminary results for two landslides in the Barcelonnette area of the French Alps show a relative stability of movement activity over the last hundred years (no trend) and short periodicity (six to seven year periods) of mass movement activity. The advantages of the method (over other, mostly visual, methods) are its clearness, flexibility, repeatability and rapidity. However, further testing is needed to examine its reliability.

Rotational landslides (slumps) varying in size can develop at different slope angles in the same type of cohesive regolith material. Therefore it is possible to set up independent equilibrium equations for these rotational slides of different size. In this way, a good estimate of the mean strength parameters of a certain type of material can be obtained on the basis of a number of these independent equilibrium equations. This can be done by means of regression analyses and the correlation coefficients and variances give a good indication of the reliability of the estimate of the strength parameters. In this paper the strength parameters of two regolith materials on schist and claystone are determined in this way and compared with the strength parameters measured in the laboratory.

Mediterranean environments are especially susceptible to soil erosion and to inappropriate soil management, leading to accelerated soil loss. Sustainable Land Management (SLM) practices (such as reduced tillage, no-tillage, cover crops, etc.,) have the potential to reduce soil, organic carbon (OC), and nutrient losses by erosion. However, the effectivity of these practices is site-dependent and varies under different rainfall conditions. The objective of this paper was to evaluate the effects of SLM practices in two rainfed systems (a wheat field and an almond orchard) representative of a large area of the driest Mediterranean regions - on runoff, soil erosion, particle size distribution, and OC and nutrient (N and P) contents in sediments. The influence of the rainfall characteristics on the effectiveness of the SLM practices was also evaluated. The SLM implemented were: reduced tillage (RT) in the wheat field and almond orchard and reduced tillage combined with green manure (RTG) in the almond orchard; these were compared to conventional tillage, the usual practice in the area. Open erosion plots were set up to monitor the effects of SLM on soil carbon and nutrients and on soil erosion after each rainfall event over six years (2010 2016). The results show that the SLM practices evaluated resulted in increased organic carbon (OC) and nutrients (N and P) contents in the soil, and reduced runoff, erosion, and mobilization of organic carbon and nutrients in sediments. Reductions in runoff of 30% and 65% and decreases in erosion of 65 and 85% were found in the wheat field and almond orchards, respectively. In addition, the total OC, N, and P losses in the wheat field were reduced by 56%, 45%, and 64%, respectively, while in the almond field the OC, N, and P losses were reduced by 90% under RT and by 85% under RTG. The beneficial effect of the SLM practices on soil erosion was observed within 18 months of their implementation and continued throughout the six years of the study. Furthermore, the effectiveness of tillage reduction with respect to erosion control and carbon and nutrients mobilization was highest during the most intense rainfall events, which are responsible for the highest erosion rates in Mediterranean areas. Our results support the key role of SLM practices under semiarid conditions as useful tools for climate change mitigation and adaptation, given the expected increase in high-intensity rainfall events in semiarid areas. © 2019 The Authors This study site has been funded by several national (CYCIT AGL201125069//CICYT AGL2010-20941//CGL2013-42009-R//CGL2014-55-405-R), Regional (Séneca Foundation: 08757/PI/08//19350/PI/14), and European Commission H2020 (F6 DG RTD 037046 and Grant 728003, DIVERFARMING projects). Joris de Vente acknowledges support from a Ramón y Cajal research grant (RYC-2012-10375) and María Almagro was supported by the Juan de la Cierva Program (IJCI-2015-23500).