Nitrogen distribution in yound Norway spruce (Picea abies) trees as affected by pedospheric nitrogen supply

abonos nitrogenados arginina arginine azote contenido de materia seca cycle de l'azote dry matter content exsudat exudados exudates feuille floema glutamina glutamine hojas leaves nitrogen nitrogen content nitrogen cycle nitrogen fertilizers phloem picea abies sap savia teneur en azote xilema xylem