Nutrition cycles in sessile oak (Quercus petraea Liebl.), Norway spruce (Picea abies L.Karst) and European beech (Fagus sylvatica L.) stands from Central Romania

In Romania, the sessile oak is widest spread species of all native species, forming a lower story vegetation. The European beech and Norway spruce cover 50% Romanian forest area. purpose this study was to analyze variability leaf nutrients, as well soil for oak, stands situated under different site conditions. studied sites are located in southern part Carpathian Mountains at altitudes varying from 600 m 1300 m. Leaves samples were collected twenty trees, three moments during growing season. same eight elements total form determined leave too: N, P, K, Ca, Mg, Fe, Cu Zn. II Level Intensive Monitoring Grid ICP Forests Programme. paper focuses on seasonal concentration variation macro leaves correlations between litter. addition, highlighted degree influence exerted by some properties foliar nutrients (through multiple regressions). obtained results show mobility greater noticed case certain elements. nitrogen concentration.