Browsing by Subject "land use change"

Now showing 1 - 4 of 4
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    Erosión y desertificación.-Biophysical- and socioeconomic aspects of land degradation in the Guadalentin (SE-Spain): towards understanding and effective soil conservation
    de Vente, J.; Solé-Benet, A.; Boix-Fayos, C.; Nainggolan, D.; Romero-Díaz, A.; Universidad de Murcia
    ABSTRACT Desertification and land degradation have been widely studied in the Guadalentin basin (SE Spain) through various national and international research projects. Most important identified degradation types are due to soil erosion, soil surface crusting, aridity, soil organic matter decline and salinisation. On the one hand, political and socioeconomic drivers have caused important land use and management changes, which have formed an important driver for further land degradation. On the other hand, soil conservation practices were initiated by the government and by individual land users, although there is very limited knowledge on their effectiveness. The objective of this work is to provide an overview of previous studies that addressed land degradation in the Guadalentin and to present an integrated synthesis of the main biophysical- and socioeconomic factors identified in these studies as being responsible for land degradation, with a focus on feasible soil conservation strategies. In overall, there has been strong emphasis on the study of biophysical characteristics related to climate, vegetation, soil, flooding, hydrology, and partially on the socioeconomic and political drivers of land degradation. The latter especially focussed on the effects of agricultural subsidies on land use changes and land degradation. Most studies have concentrated on the headwaters of the Guadalentin and on areas with (semi-) natural vegetation. Important examples of issues that remain under-researched are: 1) costs of land degradation (on-site and off-site), 2) effects of different conservation strategies on the short- and long-term, on-site and off-site, 3) the effect of large-scale land conversion by land levelling and urban expansion, and 4) the future implications of land managers’ decisions on land degradation.
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    Erosión y desertificación.-Efectividad de los proyectos de restauración hidrológico forestal para el control de la erosión en cuencas mediterráneas
    Castillo, V. M.; Boix Fayos, C.; De Vente, J.; Martinez-Mena, M.; Barberá, G. G.; Universidad de Murcia
    RESUMEN Extensive land use changes have occurred in many Mediterranean catchments as a result of reforestation and the abandonment of agricultural activities. Besides this, the establishment of check-dams has been promoted to reduce soil erosion and sediment transport. In this study a combination of field work, mapping and modelling was used to test the influence of land use scenarios with and without sediment control structures on sediment yield at catchment scale. Model simulation shows that in a scenario without check-dams, the land used changes between 1956 and 1997 caused a progressive decrease in sediment yield of 54%. In a scenario without land use changes but with check-dams, about 77% of the sediment yield was retained behind the dams. Both land use changes and check-dams are effective measures decreasing sediment yield in catchment, however they act at very different temporal scales. Land use changes are long-term sustained sediment control measures compared with check-dams, which are short-term effective sediment control measures.
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    Erosión y desertificación.-Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment
    Boix-Fayos, Carolina; Martínez-Mena, Maria; de Vente, Joris; Albaladejo, Juan; Universidad de Murcia
    ABSTRACT The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositional wedges behind check-dams was estimated in a Mediterranean catchment in SE Spain. The 57 % decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m-2 yr-1. The mineralassociated organic carbon (MOC) represented the 70 % of the soil carbon pool, the particulate organic carbon (POC) represented a 30 % of the soil carbon pool. The average sediments/soil enrichment ratio at the subcatchment scale (8-125 ha) was 0.59 ±0.43 g kg-1. Eroded soil C accounted for between 2 % to 78 % of the soil C stock in the first 5 cm of the soil in the subcatchments. The C erosion rate varied between 0.008 and 0.2 t ha-1 yr-1. Observed changes in land use (decrease in agricultural areas) reduced soil C erosion, although sediments from non-agricultural sources are richer in organic C. At catchment scale from the 4 % of the soil C stock mobilized by water erosion, 77 % is buried in the sediment wedges behind check-dams. Soil C replacement due to increased vegetation cover between 1974 and 1997 represented a 36 % of the original soil organic C stock. All together represent an erosion-induced sink of soil organic C of 40 % compared to the original levels of 1974. We can conclude that the catchment is behaving as a soil C sink within the soil erosion subsystem as a consequence of the changes on the land use pattern that took place since the 1950’s. The meaning of this erosion-induced C sink in a wider C balance which takes into account soil respiration remains uncertain
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    Morfología Fluvial.-Carbon sequestration capacity in a semiarid ecosystem: A carbon balance approach
    Almagro, M.; López, J.; Boix-Fayos, C.; Albaladejo, J.; Martínez-Mena, M.; Universidad de Murcia
    ABSTRACT Here, we used two C balance approaches to estimate total belowground C allocation (TBCA) in three representative land uses in a Mediterranean ecosystem (late-successional forest, abandoned agricultural field, rainfed olive grove). Our objectives were: 1) to asses the response of TBCA and its components to changes in land use; 2) to evaluate how soil water erosion and changes in C stored in roots, soil and litter layer altered our estimates of TBCA; 3) to determine annual net ecosystem productivity, and examine C allocation patterns at each land use.