Methodological approach of a spatial distribution pattern of epiphytic algae on Apium nodiflorum leaves (L.) Lag. (Apiaceae)

A microhabitat scale study of spatial epiphytic distribution of a common Ap iaceae of karstic mediterranean springs has been carried out, on the leaf s ystem of Apium nodiflorum. Longitudinal and transverse zones along the leaf have been determined and separatetly analysed. In spite of a physiologic variability inherent in each sample, initial resu lts, based on a 48 leaflets sample, for each stage, reveal a non-random dis tribution of epiphytes on different architectural elements of the host-plan t. A homogeneity of algal communities is noted on the whole plant height fr om surface to base. The several scales necessary for this methodological st udy clearly show existence of microzones which are quantitatively and quali tatively representative for the whole epiphytic populations. These results, followed by later investigations on different plants must be useful as a technical approach for scientists and for water administrators in the river monitoring.