Mineral contents of chalk grasslands in relation with sheep grazing involved in conservation management systems

In order to assess the relations between mineral contents of chalk grasslands and their conservation management, the dominant plant species in two plots (ungrazed and grazed) were sampled monthly for mineral analysis. Mineral data were also collected for a mean sample of the phytocenosis and the leaves and barks of scrubs occurring in the ungrazed plot. The main results are: a deficiency in copper from the phytocenosis of the two plots; a higher content in phosphorous for the grazed plot from species present in the two plots (Achillea millefolium, Brachypodium pinnatum, Origanum vulgare); a mineral reservation in trace elements (Cu, Zn, Fe, Mn) from three herbaceous species of the grazed plot (Ranunculus bulbosus, Thymus praecox, Veronica teucrium). Mineral contents of barks from scrub species are classically lower than herbaceous species. However, some leaves (Fraxinus excelsior, Cornus sanguinea, Crataegus monogyna) are as rich in calcium as herbaceous species. Therefore, few differences exist between mineral contents of the two phytocenosis. Nevertheless, conservation management systems with sheep grazing have to pay a special attention to the mineral resources of chalk grasslands for the realisation of grazing systems in agreement with the objectives of biological conservation.