UMR INAPG/INRA/ENGREF 518, 16, rue C, Bernard, 75231 Paris, France. aubert@inapg.fr|UMR INAPG/INRA/ENGREF 518, 16, rue C, Bernard, 75231 Paris, France. aubert@inapg.fr|UMR INAPG/INRA/ENGREF 518, 16, rue C, Bernard, 75231 Paris, France. aubert@inapg.fr|UMR INAPG/INRA/ENGREF 518, 16, rue C, Bernard, 75231 Paris, France. aubert@inapg.fr