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 gra sslands and their conservation management, the dominant plant species in two plots (ungrazed and grazed) were sampled monthly for mineral an alysis. Mineral data were also collected for a mean sample of the phyt ocenosis and the leaves and barks of scrubs occurring in the ungrazed plot. The main results are: a deficiency in copper from the phytocenos is of the two plots; a higher content in phosphorous for the grazed pl ot from species present in the two plots (Achillea millefolium, Brachy podium pinnatum, Origanum vulgare); a mineral reservation in trace ele ments (Cu, Zn, Fe, Mn) from three herbaceous species of the grazed plo t (Ranunculus bulbosus, Thymus praecox, Veronica teucrium). Mineral co ntents of barks from scrub species are classically lower than herbaceo us species. However, some leaves (Fraxinus excelsior, Cornus sanguinea , Crataegus monogyna) are as rich in calcium as herbaceous species. Th erefore, few differences exist between mineral contents of the two phy tocenosis. Nevertheless, conservation management systems with sheep gr azing have to pay a special attention to the mineral resources of chal k grasslands for the realisation of grazing systems in agreement with the objectives of biological conservation.