“…Determining the leaf nitrogen concentration that maximizes net carbon gain is of particular interest since a large proportion of leaf nitrogen is contained in photosynthetic enzymes (Kirk and TilneyBassett, 1978;Huffaker, 1982;Evans, 1983;Cowan, 1986;Field and Mooney, 1986;Evans and Terashima, 1987;Yamashita and Fujino, 1987). Consequently, leaf nitrogen correlates highly with photosynthetic capacity (Mooney, Ferrar and Slatyer, 1978;Gulmon and Chu, 1981;Evans, 1983;Field, Merino and Mooney, 1983;Field and Mooney, 1986).…”