Methodologies for soil erosion and land degradation assessment in mediterranean‐type ecosystems

Abstract

The detection of spatial distribution and temporal development of soil erosion processes and forms on abandoned land still represents a great scientific challenge. Abandoned fields as a result of land use changes during the past century can frequently be found in the Mediterranean. The former fields are generally used for grazing and therefore are highly complex concerning the variability of soil erosion processes.A three-step research method is used for assessment and evaluation of soil erosion processes. By means of rainfall simulations, test plot monitoring and large-scale aerial photography, erosion processes are quantified and scenarios are presented for three test sites in northeast Spain.With a large-scale test plot monitoring the development of soil erosion processes can be evaluated. Areas with predominantly increasing soil erosion activity are classified as unstable, whereas areas with unchanged or decreasing soil erosion activity are classified as vulnerable or stable. Forty to 70 years after abandonment and change to grazing all observed test areas show a progressive degradation. The proportion of unstable areas reaches around 50 per cent. The extension of unstable areas, characterised by a combination of increasing erosion activity and decreasing vegetation cover, is highest within the semi-arid Ebro Basin reaching 29 per cent of the whole area. Dense vegetation cover does not always correlate with stability in erosion and increase in cover does not generally lead to a stabilisation of erosion processes. Even under increasing vegetation cover of more than 60 per cent high erosion and runoff rates are possible particularly in connected rills and on sheep trails. Therefore, grazing on abandoned fields is the critical factor leading to further degradation.

Contrasted Impact of Land Abandonment on Soil Erosion in Mediterranean Agriculture Fields

“…The process of abandonment can be considered as a world-wide change associated to a progressive abandonment of traditional agricultural practices, which is enhancing land degradation processes by increasing sediment and water yield (García-Ruiz and Lana-Renault, 2011;Ruiz-Sinoga and Martinez-Murillo, 2009;Ries 2010). However, we found that not always the abandonment results in higher soil erosion rates.…”

“…The non-planned abandonment of the agriculture land took place in developed regions due to the intensification and mechanisation of the agriculture after social and economic changes along the 20 th century. It is widely accepted that land abandonment results in a shift into the system behaviour that can enhance land degradation processes by increasing soil erosion by water Ries et al, 2010), biodiversity reduction (Cammeraat et al, 2005), changes in river discharges (Plieninger et al, 2014) and soil quality (van Hall et al, 2017). The abandonment of the agriculture land is part of the dynamic change in the land uses in developed countries, and the Iberian Peninsula is a good laboratory to research the impact on the ecosystems (García-Ruiz et al, 2010).…”

“…Herbs and shrub recover fast (<5 years) after the abandonment . However, vegetation recovery is by far slower in semi-arid areas as well as Mediterranean territories, where water is the key resource for plant recovery (Cammeraat et al, 2010;Ries, 2010;Ruiz-Sinoga and Martinez-Murillo, 2009). In cultivated fields, the removal of the weeds by tillage or herbicides results in extremely high erosion rates Prosdocimi et al, 2016a).…”

10 Years After: the Impact of EU Accession on the Slovenian-Austrian Cross-Border Area in Pomurje Region

“…The need for applying the sustainability into the new investments can be illustrated by the fact of year 2005 expenditure for the environment by which the Pomurje region was first among Slovenian region, financing the basic utilities, such as water and waste disposal (Vintar Mally et al, 2009). By inspecting the factors inducing change two-side relationship has been identified: on one side, the policy as for example the EU Common Agricultural Policy has induced the landscape change (Rodewald, 2004;Ries, 2010;Martinez-Casasnovas et al 2010), and on the other, the improved quality of life because of the beautified landscape has indirectly shaped minds, ideas, emotions and identities to introduce continuous projects which aim at creating the unified cross-border landscape like in the towns Gornja Radgona and Cankova (Moore, Whelan, 2007). These findings are also in line with the evaluation of the 2000-2006 programme which showed that CBC is especially beneficial for medium-or small size local communities in which physical investments are important drivers for generating territorial development impact, so is the newly established "soft co-operation", e.g.…”

Soil Erosion on Abandoned Land in Andalusia: A Comparison of Interrill- and Rill Erosion Rates

“…These values describe the hazard class of the tested plot against the called parameters. The class limits for runoff coefficient and sediment quantity were defined on the basis of the experience from about 400 rainfall simulations of the working group in semi-arid landscapes in North Africa and Spain during the past 16 years (e.g., [23,27,34]). For the definition of the sediment concentration class limits, we did not divide the sediment quantity and the runoff quantity, we defined other limits.…”