Infodoc : Sciences, Techniques et Culture

Tropical rainforest constitute one of the most complex ecosystems on the earth. The primary production and the carbon balance are mainly governed by the nutrient cycling, and the turn-over of organic matter is well known to play a major role in nutrient availibility for plants. So, the comprehension of this ecosystem functioning, particularly about nutrient cycling, is a real challenge in the current context of climate change. The litter decomposition is known as the continuum from litter fall to soil organic matter. Litter and organic molecules are gradually fragmented by temporal succession of various below-ground organisms, from macro-fauna to bacteria. However, the diversity of factors involved in this process makes its comprehension very difficult. Then, there is a lack of invest[...]

Tropical rainforest constitute one of the most complex ecosystems on the earth. The primary production and the carbon balance are mainly governed by the nutrient cycling, and the turn-over of organic matter is well known to play a major role in nutrient availibility for plants. So, the comprehension of this ecosystem functioning, particularly about nutrient cycling, is a real challenge in the current context of climate change. The litter decomposition is known as the continuum from litter fall to soil organic matter. Litter and organic molecules are gradually fragmented by temporal succession of various below-ground organisms, from macro-fauna to bacteria. However, the diversity of factors involved in this process makes its comprehension very difficult. Then, there is a lack of investigations about soil communities, considered as the "black box" of soil functioning. This lack of knowledge is induced by the complexity of soil as a biological system, as well as the problems in evaluating and manipulating the incredible diversity of soil organisms.
Recent studies suggest that the role of fungi is crucial for organic matter turn-over. Temperate mycotas are relatively better known than tropical ones, which diversity is throught to be greater. So, linking fungal diversity to resource availability anq quality remains now challenging, particularly in tropics. A shift in composition of microorganisms'communities in the course of decomposition would be due to progressive changes in resource quality and availability.
In this study, we tested this hypothesis with a microcosm experiment under controlled conditions using leaf litter from six tropical tree species of French Guiana. Fungal communities were analysed using a communities'genetic method : the Terminal - Restriction Fragment Length Polymorphism (T-RFLP)