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Human‐induced afforestation has been one of the main policies for environmental management of farmland abandonment in Mediterranean areas. Over the last decades, several studies have reviewed the impact of afforestation activities on geomorphological and hydrological responses and soil properties, although few studies have evaluated the effects on water table dynamics. In parallel to human‐induced afforestation activities, natural revegetation occurred in abandoned fields and in fields where the intensity of human activity declined, driving the expansion of shrubs. This research addresses the spatial and temporal variability of water table dynamics in a small afforested sub‐catchment located in the Central Spanish Pyrenees. Differences between afforestation (Pinus nigra and Pinus sylvestris) and natural plant colonization (shrubs, mainly Genista scorpius, Buxus sempervirens, and Juniperus communis) and early abandoned meadows (G. scorpius), are analysed in terms of runoff generation and seasonal water table depth dynamics. Precipitation, runoff and water table datasets recorded for the 2014–2019 period are used. Results show a high temporal and spatial variability with large fluctuations in discharge and water table. Groundwater dynamics varied markedly over the year, identifying a wet and dry period with different responses suggesting different runoff generation processes (Hortonian flow during dry and wet periods, and saturation excess runoff during wet conditions). Furthermore, important differences are noted among the various land cover types: (i) in the natural revegetation area (shrubland and meadows) a marked seasonal cycle was observed with short saturation periods during winter and spring; and (ii) in the afforestation areas, the water table dynamics showed a seasonal cycle with a high variability, with fast responses and rapid oscillations. Likewise, the relationship between the depth of water table and hydrological variables was not straightforward, suggesting complex hydrological behaviour. [ABSTRACT FROM AUTHOR]

Water resources availability is one of the main concerns for policy makers around the world in present and future management plans. In the Mediterranean basin, this concern is increased given the extreme variability in climate and the intrinsic aridity conditions. Water resources in the Mediterranean region depend mainly on surface and subsurface supply from mountain areas. Because evapotranspiration comprises a substantial portion of the water budget, recent land cover changes due to cropland abandonment may change transpiration (TRANS) and water supply. Therefore, land management plans must account for these potential hydrologic changes to guarantee water availability in the upcoming decades. Short‐term changes to water yield have been shown to follow afforestation or natural revegetation, the main management strategies in abandoned cropland areas. Studies comparing long‐term trends of these management practices, however, are scarce due to the lack of long‐term hydrological data. In this study, we use the regional hydro‐ecological simulation system (RHESSys), to analyse long‐term changes and annual and seasonal trends in streamflow (STR) and transpiration following management of abandoned cropland areas. Annual mean values show significant differences between the three management scenarios for both streamflow and transpiration, while differences between climate scenarios are not significant. The Mann Kendall trend analysis shows significant changes to water yield compared to the situation before management. Depending on the total afforested area, afforestation could significantly decrease annual streamflow between 2.3%·decade−1 and 5.9%·decade−1 and increase annual transpiration between 1.1%·decade−1 and 3.5%·decade−1. These trends are attributed to changes during the first 30 years after management, while during the fourth and fifth decade, changes to water yield tend to stabilize or decrease. These results are substantial to optimize land management plans, ensuring sustainable hydrological and ecological ecosystem services. [ABSTRACT FROM AUTHOR]

Land abandonment followed by natural revegetation constitutes the main land‐use change in the Mediterranean mountains, affecting soil quality and soil organic carbon (SOC) stocks; however, there are few studies analysing the effects of cropland abandonment on soils in mid‐mountains. In the Leza Valley (Spain), 43.2% of the area was cultivated but abandoned during the 20th‐century. Natural revegetation gave rise to five land uses (LULCs): pastures (5 years), shrubs (Cistus laurifolius, 20–35 years), bushes (Juniperus communis, 35–50 years), young forests (Quercus pyrenaica) and old forests (>70 years). The aim of this research was to study the effects of natural revegetation of abandoned fields on physico‐chemical soil quality and SOC in various LULCs. In each of the LULCs, soil samples were collected every 10 cm, down to 40 cm depth, at three points, with a total of 60 samples being analysed (12 per LULC). In addition, plant species inventories were carried out. The results indicated (a) significant differences in physico‐chemical soil quality between the first years of abandonment and forests; (b) the SOC content increased with revegetation duration and decreased with increase in soil depth; (c) the highest SOC and TN stocks were found in the first 10 cm; (d) the results of the principal component analysis with all the data differentiate forests from shrubs and pastures. This study confirms the need to be aware of the effects of land abandonment and natural revegetation processes on the soil, in order to promote management strategies to preserve ecosystem services that agricultural marginal lands can provide. [ABSTRACT FROM AUTHOR]

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• Cropland abandonment significantly affects soil physico-chemical properties. • Differences between revegetated practices after farmland abandonment occurred. • Afforestation triggered higher soil organic carbon than natural revegetation. • Grassland sites enhance the accumulation of soil organic carbon. • Labile fractions are higher in both vegetated sites than in grasslands. Mediterranean mountains are sensitive agroecosystems that have suffered intense land use and land cover changes (LULCC) during the last century. From the middle of the twentieth century, most of the cultivated lands in Mediterranean mountains were abandoned, allowing the recovery of vegetation (through natural revegetation and afforestation programmes). To examine the effects of farmland abandonment, secondary succession (natural revegetation) and afforestation, an intensive soil sampling was carried out in the Araguás catchment (Central Spanish Pyrenees) including sparsely vegetated areas (badlands), grasslands, shrublands and afforested sites. LULCC were mapped, and soil physico-chemical properties were analysed in reference sites (unaltered areas during the last centuries) and in the different land uses. Likewise, the soil organic carbon (SOC) content in the bulk soils and in the fractions separated by density fractionation have been studied. This study evidenced that farmland abandonment led to a mosaic landscape with different land use and land covers. Results show that LULCC significantly affect soil physico-chemical properties (soil texture, stoniness, pH, SOC, total carbon, CorgN ratio, bulk density and field capacity). Significant differences were observed between secondary and afforested sites following farmland abandonment. Afforestation triggered higher SOC than shrubland sites (natural revegetation) (1.4 and 1.1% respectively), suggesting a slower process of organic matter accumulation after farmland abandonment in the natural revegetation compared to afforestation. The significant role of grassland sites for enhancing the accumulation of SOC has been also confirmed. The results showed also significant differences in the relative contribution of each organic fraction to the bulk SOC: the amount of labile fraction (free and occluded labile fractions) is significantly higher in afforested and shrubland sites (58.1 and 51.2% respectively) than in grassland sites (36.8%). Understanding the effects of LULCC on soil properties and SOC dynamics is essential when planning post-land management practices after farmland abandonment. [ABSTRACT FROM AUTHOR]

The perception of the population linked to Cameros Viejo (Iberian System) about the revegetation process and its impacts on the natural environment is studied. We carried out 40 depth semi-structured interviews. The interviewee' answers are corroborated with the results of scientific works carried out in the study area and in other nearby areas of the Mediterranean mountains. Moreover, it is observed that the local population shows a more realistic perception than the foreign population about the changes in the natural environment. [ABSTRACT FROM AUTHOR]

Background and aims In the last decades, large areas undergo a revegetation process as a result of land abandonment, producing significant environmental and landscape impacts. In this paper, revegetation impacts are identified. We present the solutions proposed by scientists to control the negative impacts of revegetation, from a literature review from studies carried out in Europe. Results Some scientists suggest letting the revegetation process continued to contribute to the naturalisation of the landscape, reduce soil erosion, increase carbon sequestration and encourage recreational use of the territory. Other scientists, however, suggest the need to control the revegetation processes and retrieve abandoned land with productive purposes (extensive livestock and leisure), environmental objectives (reduction of fires and increasing biodiversity) and preserve cultural landscapes. Conclusion The scrubland clearing and extensive livestock is an appropriate strategy to manage abandoned lands, combining environmental, landscape and socio-economic benefits. [ABSTRACT FROM AUTHOR]

Large areas worldwide have been affected by farmland abandonment and subsequent plant colonization with significant environmental consequences. Although the process of farmland abandonment has slowed down, vegetation recovery in abandoned lands is far from complete. In addition, agricultural areas and pasture lands with low-intensity activities could be abandoned in the near future. In this foreword, we review current knowledge of the impacts of farmland abandonment on water resources and soil conservation, and we highlight the open questions that still persist, in particular regarding terraced landscapes, afforested areas, abandonment of woody crops, traditional irrigated fields, solute yields, long-term trends in the response of abandoned areas, and the management of abandoned farmland. This Special Issue includes seven contributions that illustrate recent research into the hydrological, geomorphological, and edaphological consequences of farmland abandonment. [ABSTRACT FROM AUTHOR]