Soil erosion and hydrological response to land abandonment in a central inland area of Portugal

Abstract

This paper analyses the effects of land abandonment on runoff and sediment yield in a central inland area of Portugal. Rainfall simulation experiments were performed in areas of traditional land use (land cultivated with cereals) with various types of soil plant cover associated with the period of abandonment (4-5 years, 15-20 years and 30-40 years) in two different seasons, namely under very dry conditions and after a long wet period.Statistical analysis showed a notable difference between the cultivated soils and those abandoned for a long period of time, which included appreciable vegetation recovery, higher organic matter content and negligible overland flow and soil loss. Cereal cultivation, in particular ploughing, is a very negative land management practice, due to the high runoff and soil loss. Within 4-5 years a crust develops over abandoned soils with sparse herbaceous plant cover, particularly after a dry season, which enhances runoff and sediment yield. In scrubland and oak plots, although marked water repellency was registered at the end of a dry, warm season, its influence seems to be irrelevant in terms of overland flow and erosion yield. The major factor in controlling overland flow and reducing soil erosion rates appears to be the role played by vegetation in protecting the soil surface and supplying organic carbon to the top layer.

The effects of farmland abandonment and plant succession on soil properties and erosion processes: a study case in centre of Portugal

“…The results obtained concur with those of other studies in showing the importance of vegetation, and especially the litter cover, in improving certain physical and chemical components of the soil and reducing soil erosion (Trimble 1990;Kosmas et al 2000;Fu et al, 2004;Nunes et al, 2010Nunes et al, , 2011Durán-Zuazo et al, 2012). …”

Historical aspects of soil erosion in the Mejerda catchment, Tunisia

“…In fact, water erosion processes result in decrease in crop yields, loss in water potential, and are a cause of recurrent natural catastrophes (e.g. Nunes et al 2010, Sullivan, 2011.…”

Soil Erosion Under Different Land Use and Cover Types in a Marginal Area of Portugal

“…This hydrological and erosional behaviour, together with the soil properties, is closely interrelated and well understood in terms of the dynamics of plant and litter cycling. Vegetation and litter reduces direct raindrop impact on the soil, prevents the formation of mechanical crusts, enhances infiltration capacity and reduces soil erodibility (Nunes et al, 2010). In these soils, long-term spatially structured vegetation patterns play an important role in addition to cover, by increasing the stability and resilience of the system (Boer & Puigdefabregas, 2005;Cammeraat & Imeson, 1999).…”

“…This hydrological response is also affected by the lack of macroporosities, meaning that only a little water infiltrates into the soil matrix. The soils also offered weak resistance to penetration (Nunes et al, 2010). The growth of cereals results in increased soil cover, which explains the higher runoff time and lower overland flow and sediment yields.…”