Soil moisture changes after land abandonment in the Central Spanish Pyrenees

Abstract

The European mountainous areas, such as the Pyrenees, have suffered important land use changes since the beginning of the XX century. These changes affect the plant cover recovery process and then the runoff and sediment production. Soil moisture can be a key factor in the evolution of the abandoned land. It determines the vegetation recovery, runoff generation, sediment detachment and soil development through runoff and infiltration processes. This paper aims to study the influence of land-use and seasonality on soil moisture. Measurements were carried out weekly during 1997 and 1998 by means of the Time Domain Reflectrometry method. The selected land-uses were: Cereal (fertilised and with artica management), Fallow, Meadow, Abandoned (after fertilised cereal and artica management), Burnt (two plots under different post-fire recovery conditions), and the Control plot, which is a dense Scrubland. The results show that land-use is a key factor in the seasonal and spatial variability of soil moisture. The scrubland, meadow and fallow plots showed always a higher water content (> 30 % of soil moisture mean annual value), meanwhile the abandoned land stored less water (23 %). Burnt, artica and cereal plots had intermediate values. Seasonally, summer used to be the driest period as year 1998 confirmed. Nevertheless the year 1997 was extremely wet during summer due to the high rainfall values. Soil moisture was always higher than 10 %, even during the driest periods. Previous weekly rainfall and antecedent soil moisture explain 80 % of the variability. No relationship was found between the soil moisture changes and the variability amongst plots throughout the studied period.