Effects of land terracing on soil properties in the Priorat region in Northeastern Spain: A multivariate analysis

The Priorat region, a traditional area for wine production in the Mediterranean mountain environment of NE Spain, has been undergoing drastic changes since the 1990s, with the conversion of abandoned and natural vegetation areas into new terraced vineyard plantations. In most cases, these land cover changes involve land terracing, with risers more than 2 m high and benches with the soil surface structure completely altered. The objective of this work is to analyse the impacts of these land transformations on soil physical properties such as texture, water retention and infiltration capacity in a sample area of the region. Soils are classified as Lithic Xerorthents and are locally called “llicorell”. For this study two different situations on a 100-m-long hillslope were studied: one in an undisturbed position, with natural vegetation and one in a disturbed two-year-old terraced vineyard. Samples of the soil surface from 0 to 20 cm were collected at several points along the slope for analysis of texture, organic matter and aggregate stability. At these locations, saturated hydraulic conductivity was measured using a disc permeameter. The results show that in these soils with a high percentage of coarse elements (> 60%), work carried out during land transformation produced changes in the particle size distribution of the fine fraction. In addition, levelling reduced the organic matter content of the cultivated soils. These changes affected hydraulic conductivity, water retention capacity (which decreased by 45%) and aggregate stability, as well as the relationships between all these variables.