Occurrence and intensity of wild boar disturbances, effects on the physical and chemical soil properties of alpine grasslands

BACKGROUND AND AIMS: Physical and chemical soil properties determine local plant conditions and resources, affecting plants’ ability to respond to disturbances. In alpine grasslands, wild boar disturbances occur at different intensities, what may affect differently their soil properties. Alpine soils from five contrasted plant communities were explored within and outside disturbances, accounting for an overall and community scale effect. Additionally, we analysed the effect of disturbance intensity on soil NO₃ ⁻-N and NH₄ ⁺-N. METHODS: Soils were analyzed for physical (bulk density, moisture content and electrical conductivity), and chemical properties (pH, total N and C, oxidizable C, C:N ratio, available K, P, Ca²⁺, Na⁺ and Mg²⁺). Resin bags were used to compare the effect of the disturbance occurrence and intensity on soil NO₃ ⁻-N and NH₄ ⁺-N. RESULTS: Bulk density, total N and NO₃ ⁻-N concentration were significantly higher in disturbed areas, while soil moisture, C:N, NH₄ ⁺-N, Na⁺, Mg²⁺ and Ca²⁺ concentrations were significantly lower. However, low disturbance intensity reduced NO₃ ⁻-N and increased NH₄ ⁺-N concentrations. CONCLUSIONS: Wild boar occurrence and intensity strongly alter physical and chemical conditions of alpine soils, increasing soil compaction, and altering the availability of N forms. These changes may affect most plant species, thus affecting the structure and dynamics of alpine plant communities.