Soil degradation and desertification induced by vegetation removal in a semiarid environment (original) (raw)
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Land use and soil-vegetation relationships in a Mediterranean ecosystem: El Ardal, Murcia, Spain
CATENA, 1995
Several pedological (water retention capacity, hydraulic conductivity, distribution and stability of aggregates, organic matter content, texture) and vegetal charateristics (litter production and litter decomposition, below ground biomass), have been studied in a transect of the Experimental Field of E1 Ardal (SE, Spain). This transect reflects several typical land use types of a Mediterranean semi-arid environment. The main objective of this paper is to study soil-vegetation and land-use relationships and to analyze de dynamics of field abandonment. The results show a close relationship between soil development and vegetation characteristics, a notable difference between soils from cultivated plots and those in a semi-natural state, and an appreciable recovery of the soil characteristics of plots where cultivation has been abandoned. 0341-8162/95/$09.50
The Science of the Total Environment, 2003
We investigated the influence of agricultural management and various plant covers related to the period of abandonment on soil properties, erosion and nutrient depletion in a typical Mediterranean area with sandy loam shallow soils. Cultivated soils (CS) with insufficient management, 5 year abandoned soils covered with meadow (A5), 25 year abandoned soils covered with dense scrubs (A25), 50 year abandoned soils covered with cork trees (A50) and soils in a 50 year pine reforested area (P50) were studied over a period of 6 months (May-October 1999). The soils were classified as Lithic Xerorthents. Both the differences in soil properties and response to rainfall events were mainly attributed to the different vegetation types and stages in land management. Principal components analysis (PCA) was performed on the results, by running the overall data determined after five rainfall events. The factors extracted by PCA of the samples by variables matrix represented the response of the environments to different rainfall intensities as a function of management or natural evolution after abandonment. CS environments showed the highest runoff and sediment yield as well as the highest amount of dissolved organic carbon (DOC) and nitrogen in runoff water. The sequence of abandonment (A5, A25 and A50) showed approximately the same runoff production, whereas eroded sediments (ES) and DOC were inversely correlated. Organic carbon in the ES and DOC in runoff water always increased with the period of abandonment, which accounted for consistent nutrient depletion. Nevertheless, the A50 environment (dominated by Quercus suber) showed the best soil properties, whilst the A25 environment with dense cover of Cistus monspeliensis and Calicotome espinosa seemed to cause a worsening effect on the soil's physical and chemical properties. This is probably because these environments are more severely damaged by wild fire occurrence. In terms of sediment yield, the P50 environment followed CS environment, indicating that reforestation followed by insufficient forest management may negatively affect both soil properties and response to the erosive action of rainfall.
Land use change effects on abandoned terraced soils in a Mediterranean catchment, NE Spain
CATENA, 2003
The Serra de Rodes catchment (NE Spain), enclosed in the Natural Park of Cap de Creus, represents a typical Mediterranean ecosystem. This semiarid environment, with hot summers and mild winters, has been progressively abandoned by farmers during the last century. Nowadays, most of hillside soils are abandoned and only small patches of vineyards and olive trees are cultivated with very low management and incomes. In this study, we have assessed the effects of land use and land use change on the main soil quality parameters. Along two altitudinal gradients, we selected 11 random environments representative of the current land uses, in sequence from cultivated to early abandonment. The different vegetation stages were grouped in four main land use types according to the age of abandonment: cultivated fields (vineyard and olive trees, 0 years), recent abandonment (dense and cleared shrubs, 5 years), mid-abandonment (cleared cork trees and dense olive trees, 25 years) and early abandonment (dense cork trees and pine trees reforestation, 50 years). Erosion plots were installed in the previously selected environments for soil physicochemical characterisation, throughout 1-year observation, monitoring nutrient losses, runoff volume and sediment yield data. Analysis of variance (ANOVA) indicates significant differences in the main soil quality parameters such as soil organic matter (SOM), total nitrogen (N), water holding capacity (WHC) and pH, among the selected environments under different land use conditions. Factor analysis of the principal components (PCA) enabled the identification of three soil quality indices: index of soil erosion and nutrient losses (SENL), index of soil quality and fertility (SQF) and index of vegetation cover and soil protection (VCP). Soil organic matter, nutrient supply, soil vegetation cover and soil compaction are critical for soil degradation in these environments and they must be managed appropriately in order to ensure continuous soil rehabilitation. Furthermore, the main conclusion
Area, 41(2): 129–138, 2009
Authors: Jordi Nadal, Albert Pèlachs, David Molina, Joan Manuel Soriano The cartography of land covers was used to study fertility and soil evolution in a mountainous Mediterranean area during the anthropocene period (Crutzen P J 2002 Geology of mankind Nature 415 23). The aim was to determine changes in fertility as agricultural lands were abandoned in the 14 000 hectare area that constitutes Sant Llorenç del Munt Natural Park in a pre-coastal Catalan mountain range (north-eastern Iberian Peninsula). The analysis of land covers using vegetation maps, orthorectified images and aerial photography has allowed us to differentiate six vegetation groups: holm-oak wood, pine grove, oak wood, scrub, active agricultural fields and abandoned agricultural fields. The anthropic covers over the past 100 years were subdivided into five categories: active fields and those abandoned over four time periods. Study variables include field shape (concave, convex, flat), orientation (north, south) and slope (ranging from 12º to 24º). The parameters used for the physical-chemical soil analysis included organic material, phosphorous and potassium; fertility was classified based on groups, types and classes. The results indicate that even when the visual appearance of certain landscapes is similar, the edaphic characteristics may be very different. Changes induced by human disturbance share this phenomenon. Therefore, land management should be considered globally, taking into account vegetation, soils and water as interdependent factors, since it is their interaction that produces landscape and most affects its evolution over time. Keywords: landscape dynamic, human disturbance, abandoned and active agricultural, fields, soil alterations, Mediterranean areas, last century scale processes
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Afforestation can improve hydrological processes, such as infiltration, in basins and, therefore, reduce the impact on human populations of floods, soil erosion, landslides, droughts, and climate variation. The aim of this work was to analyze how afforestation and other changes in land use influence infiltrability and the evolution of soils. Infiltration rates, soil water repellency, and physical and chemical properties of sandy loam soils were measured in four types of land: native holm oak forest, afforested 20-year-old pine forest, shrubs, and grasslands. Non-forest covers are the result of the degradation of native oak forests for centuries, while the pine afforestation in this study took place on a perennial wet mountain pasture (cervunalito). Our results show that soil infiltration rates are much higher in pine afforestation areas (857.67 mm·h−1) than in holm oak forest (660.67 mm·h−1), grasslands (280.00 mm·h−1), or shrubs (271.67 mm·h−1). No statistically significant differe...
Solid Earth, 2015
Land degradation resulting from improper land use and management is a major cause of declined productivity in the arid environment. The objectives of this study were to examine the effects of a sequence of land use changes, soil conservation measures, and the time since their implementation on the degradation of selected soil properties. The climate for the selected 105 km<sup>2</sup> watershed varies from semi-arid sub-tropical to Mediterranean sub-humid. Land use changes were detected using aerial photographs acquired in 1953, 1978, and 2008. A total of 218 samples were collected from 40 sites in three different rainfall zones to represent different land use changes and variable lengths of time since the construction of stone walls. Analyses of variance were used to test the differences between the sequences of land use changes (interchangeable sequences of forest, orchards, field crops, and range), the time since the implementation of soil conservation measures, rainf...
Journal of Arid Environments, 2010
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