Impact of elevated CO2 and nitrogen fertilization on foliar elemental composition in a short rotation poplar plantation

The experiment was carried out on a short rotation coppice culture of poplars (POP-EUROFACE, Central Italy), growing in a free air carbon dioxide enriched atmosphere (FACE). The specific objective of this work was to study whether elevated CO2 and fertilization (two CO2 treatments, elevated CO2 and control, two N fertilization treatments, fertilized and unfertilized), as well as the interaction between treatments caused an unbalanced nutritional status of leaves in three poplar species (P. x euramericana, P. nigra and P. alba). Finally, we discuss the ecological implications of a possible change in foliar nutrients concentration. CO2 enrichment reduced foliar nitrogen and increased the concentration of magnesium; whereas nitrogen fertilization had opposite effects on leaf nitrogen and magnesium concentrations. Moreover, the interaction between elevated CO2 and N fertilization amplified some element unbalances such as the K/N-ratio.