Etude expérimentale d'un écosystème sableux

Abstract

A multispecific closed-circuit sand ecosystem was fuelled by regular addition of soluble amino acids during 28 months (205 g C m⁻² year⁻¹). Bacteria and nematode densities undergo a similar evolution, divided into three main periods: the first 6 to 7 months (numerical decrease), from 6 to 7 to 20 months (numerical stability), after 20 months (numberical increase). Copepod densities are stable during the first seven months, then they exhibit an exponential increase until 14 to 15 month and, thereafler, a decrease. The inter-specific changes were followed for copepods and nematodes. One copepod species progressively overwhelms the fifteen others recorded. During 15 months, the nematodes specific diversity remains important. Although the number of rare species decrease progressively, the relative abundancy of the dominant species remains stable. After 15 month, the population changes according to a pattern of species succession.