Nitrogen dynamics in Posidonia oceanica cuttings: implications for transplantation experiments

A N-15 tracer study was performed during an experimental transplantation trial of natural Posidonia oceanica cuttings. The experiment was done in situ at 17 m depth in the Revellata Bay (Calvi, NW Corsica, France). Despite high survival rates of transplants (>90%) after one year, the weight and the N content of transplants are significantly lower than those of reference plants. In absence of roots, the transplants are not able to meet their N requirement because, leaf uptake is insufficient to replenish the N lost during the natural leaf decay. This could constitute a major cause of long-term failure for transplantation experiments or natural recolonisation processes. The increase of the N-15 content in the roots shows that the plant re-allocates the nitrogen of one organ (i.e. leaves, rhizomes) to ensure the growth of another (i.e. roots). (C) 2003 Elsevier Ltd. All rights reserved.