unit area reflects a change in leaf density, not nitrogen concentration. Applying the
Mooney-Gulmon model to such cases is inappropriate, insofar as the observed variation
in leaf nitrogen content per unit area involves no difference in the total nitrogen costs
associated with a given investment in leaf tissue. Analysis should instead focus on the
significance of packaging a given amount of leaf tissue in an extensive photosynthetic
surface of relatively thin leaves with a low mass /area ratio, or in a less extensive surface