Leaf primary production in Posidonia oceanica: two reconstructive aging techniques give similar results

Leaf formation rate (number of leaves per shoot per year) and leaf primary production (g DW per shoot per year) of Posidonia oceanica were estimated i n three sites in the north-western Mediterranean using two aging techniques , namely lepidochronology and the internodal length. The techniques are bas ed on the seasonal variation of the sheath thickness and length of internod es, respectively, and permit the study of leaf dynamic features of P. ocean ica not only for the period under investigation, but also for a number of p receding years. The internodal length method permitted the reconstruction o f leaf dynamics for a higher number of past years. Lepidochronology provide d more accurate estimates, but displayed some technical constraints when ol d sheaths undergo decay. By comparing leaf formation rate and primary produ ction estimates, however, no significant differences between methods were d etected. On the basis of these results, the use of both aging methods is re commended as complementary procedures in studies focused on II oceanica dyn amics in order to optimise both the amount and accuracy of the data collect ed. (C) 2000 Elsevier Science B.V. All rights reserved.