Plant leaves were oven dried at 80 C to determine the C leaf
content and N leaf content using a CHN elemental analyzer (Perkin
Elmer 2400 series II CHNS/O elemental analyzer) and P, Mg, K
contents, using an ICP optical spectrometer (Varian Inc., Vista
MPX). For elemental analysis scandium was used as internal
standard after the leaf mineralization step.