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European abandoned lands have been increasing in recent decades, and this is occurring in a climate change scenario in which the consequences of their interactions are still little known. We tested the hypothesis that the functionality of abandoned lands responds differently to year‐to‐year climate variations depending on the time since the cessation of agricultural activity. We constructed a chronosequence in Mediterranean abandoned vineyards at six different years of abandonment in 2016 (1, 3, 7, 11, 25, 40), in a current vineyard and in land not dedicated to vineyards. Soil total organic carbon (TOC), total nitrogen (TN) and available nutrients, enzyme activities relating to the main macronutrient cycles and plant‐community attributes were studied at 24 sites over three consecutive years. A total of 144 samplings were performed. TOC, TN, most enzyme activities and plant species density increased throughout the chronosequence, although interannual climate variability also had a significant influence. The extreme drought event increased the activity of enzymes related to the carbon (C) and nitrogen (N) cycle, as well as the stock of TOC after a subsequent decrease in TOC when environmental conditions became favourable. In contrast, plant species density and the cover of certain plant functional traits such as mycorrhizal symbiotic plants (Cistaceae) and N‐fixers (Fabaceae) decreased significantly. Our results also demonstrated that extreme drought events had a higher negative impact on lands that had been abandoned for longer. We therefore conclude that extreme drought events damage the functionality of Mediterranean abandoned agrosystems, thus affecting all its compartments and jeopardising its functionality.

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Calcareous amendments are being used in Tuber melanosporum truffle plantations in attempts to eradicate Tuber brumale. However, there are no studies available which provide soil analysis and statistical data on this topic. We studied 77 soil samples to compare the values for carbonates, pH and total organic carbon in T. brumale truffières with the values for T. melanosporum truffières on contaminated farms and in natural areas. Statistical analyses indicate that the concentrations of active carbonate and total carbonate in the soil are significantly higher in T. brumale truffières than in T. melanosporum truffières, but that there are no significant differences in pH and total organic carbon. We conclude that liming would not suppress T. brumale ectomycorrhizas in contaminated T. melanosporum farms, and calcareous amendments do not therefore seem be a means of eradicating T. brumale in these farms.

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A set of periurban calcareous agricultural Mediterranean soils was spiked with a mixture of Cd, Cu, Pb and Zn at two levels within the limit values proposed by current European legislation, incubated for up to 12 months, and subjected to various one-step extraction procedures to estimate mobile (neutral salts) and potentially mobile metal fractions (complexing and acidic extraction methods). The results obtained were used to study metal extractability patterns according to the soil characteristics. The analytical data were coupled with mineralogical investigations and speciation modelling using the Visual Minteq model. The formation of soluble metal-complexes in the complexing extracts (predicted by the Visual Minteq calculations) led to the highest extraction efficiency with complexing extractants. Metal extractability patterns were related to both content and composition of carbonate, organic matter, Fe oxide and clay fractions. Potentially mobile metal fractions were mainly affected by the finest soil fractions (recalcitrant organic matter, active lime and clay minerals). In the case of Pb, scarce correlations between extractable Pb and soil constituents were obtained which was attributed to high Pb retention due to the formation of 4PbCO3·3PbO (corroborated by X-ray diffraction). In summary, the high metal proportion extracted with complexing agents highlighted the high but finite capacity to store potentially mobilizable metals and the possible vulnerability of these soils against environmental impact from metal accumulation.