LAUSR

Understanding soil responses to plant colonization is important for managing abandoned lands. We investigated the influence of species colonizing abandoned fields on soil components and properties related to C cycle and limiting nutrients (N, P) over time. A chronosequence was built of vineyards that had been abandoned over the past 50 years. Sixty-nine plots were chosen with different abandonment ages, and the soils in each plot were sampled under the influence of the dominant species in the area present in each one, obtaining a total of 132 samples. Total C and N content and available P content were determined in all these soils. Organic matter was fractionated by acid hydrolysis and three different fractions were differentiated into labile pool I and II and recalcitrant fraction. The soil properties and components with the greatest effect on the stabilization of organic matter were quantified, and the geomorphological factors that may influence these cycles were determined. The abandoned soils accumulated a large amount of C during the secondary post-abandonment succession. The various colonizing species showed differences in the accumulation of C and nutrients in the soils under their influence. Retama sphaerocarpa and Agrostis castellana accumulated more C and N than the rest of the species throughout the chronosequence. Despite the low content of inorganic colloids (clay and free Fe and Mn oxides) in the study soils, minor variations in these contents played a decisive role in stabilizing the organic matter.