EFFECT OF PROTECTION ON THE NUTRIENT CONCENTRATION AND UPTAKE OF SOME MEDITERRANEAN DESERT ANNUALS

The present study includes an evaluation of the effect of protection of a grazing ecosystem on the nutrient concentration and uptake in the organs of four annual species of non-saline depressions in the western Mediterranean region of Egypt. The concentration of macro- and micronutrients in different organs became lower due to the increase in biomass of individuals with protection. The maximum uptake of nutrients occurred during the early vegetative stage, except for a few cases in which the uptake in some species reached two peaks, one in the early vegetative stage and the other in the reproductive stage. The efficiency of the selected annual species in uptaking and accumulating nutrients was compared with rates of uptake of nutrients and amounts of nutrients accumulated in tissues of two species representing other life forms. The annuals and perennial herbs (ephemeroids) are in general more efficient in uptaking and accumulating nutrients in their tissues than perennial shrubs.