EFFECTS OF NUTRIENT AVAILABILITY AND NEIGHBORS ON SHOOT GROWTH, RESPROUTING AND FLOWERING OF ERICA-MULTIFLORA

To test if low soil fertility and competition limit the performance of Mediterranean shrubs, and if the effects of competition on plant perf ormance were modified by soil fertility, we subjected shrubs of Erica multiflora to a factorial field experiment of fertilization and remova l of neighbours around target plants. After 18 months of treatment, fe rtilization had stimulated the growth of pre-existent sprouts and biom ass allocation into stems to new sprouts, but decreased the frequency of sprout flowering. Removal of neighbours increased the number and bi omass of new sprouts, the probability of sprout flowering and the biom ass of flowers. Fertilization slightly enhanced sprout recruitment and the probability of sprout flowering when neighbours were removed, but did not modify the other parameters of plant performance. According t o our results, both low soil fertility and competition limited plant p erformance. Competition was slightly more intense in fertilized plants , but only in determining sprout and flowering bud stimulation.