Reflexions sur la theorie des ecosystemes: nouvelles vues pour une meilleure comprehension de la distribution de matiere et d'energie au sein d'un systeme viable

ABSTRACT

Seasonal periodicity of phytoplankton was studied in a eutrophic lake [Lake Aydat, Massif Central, France], from March to November 1985. Weekly samples were taken from both the euphotic and dysphotic zones [245 samples]. An attempt is made to check the general concepts of the theory of ecological succession using the H-diversity index of SHANNON and WEAVER. The population community of Lake Aydat appears to be constantly juvenile and permanently immature confirming the bias introduced by calculation of H, whose values are strongly influenced by the number of species present. In evaluating correlations between specific diversity [H] and several biotic parameters, some of our results approach the theoretic statements of FRONTIER. However some results contradict the ecological succession theory when specific biomasses H-based were considered. These findings imply that this concept should he further [rethought]