Specific leaf area along a nitrogen fertilization gradient

Specific leaf area was measured for three dominant perennial grass species in a long term nitrogen fertilization experiment in an abandoned field in M innesota. The specific leaf area differed among the species and increased w ith increasing levels of nitrogen fertilization. This increase in specific leaf area was up to 82% for Agropyron repens and shows that the response of specific leaf area to nitrogen fertilization can be highly plastic. Increa sing specific leaf area within species, together with a species replacement , resulted in a 202% increase in leaf area index along the nitrogen gradien t, whereas the biomass increased by only 57%. One-third of this increase wa s attributed to species replacement and two-thirds to the change in specifi c leaf area within species. This plastic response of specific leaf area wit hin plant species substantially increases the aboveground competition for l ight along nitrogen gradients.