Influence of former cultivation on the unique Mediterranean steppe of France and consequences for conservation management

Abstract

In Europe, the actual landscape has been mainly influenced by human activities. Agricultural intensification led to a considerable habitat loss and fragmentation, especially for dry semi-natural grasslands.

This current study investigates the impact of former melon and cereal cultivation (cultivation period: 1950–1987) on the semi-natural vegetation of the Crau, representing the last xeric Mediterranean steppe in France.

Today, the ex-cultivated melon and cereal fields are characterised by different vegetation compositions, species richness and evenness compared to the undisturbed steppe community. Also the abiotic conditions (N, P, K, pH, soil granule fractions) have been changed by former cultivation practices. The rather transient seed bank of the steppe was depleted during the cultivation periods; ancient weed species and ruderals now determine the seed bank of the ex-cultivated fields.

It is concluded that the conservation of the last parts of undisturbed steppe must have absolute priority. A re-development of the original and unique steppe community on formerly cultivated fields may take decades or centuries, if at all.