Biogeohydrodynamic in the Forested Humid Tropical Environment
Séance spécialisée Bull. Soc. géol. France, 2002, t. 173, no 4, pp. 347-357 Sol, altération, érosion Toulouse, 30-31 mai 2000 Biogeohydrodynamic in the forested humid tropical environment : the case study of the Nsimi small experimental watershed (south Cameroon) JEAN-JACQUES BRAUN1,2,BERNARD DUPRÉ2,JÉRÔME VIERS2,JULES RÉMY NDAM NGOUPAYOU3, JEAN-PIERRE BEDIMO BEDIMO4,LUC SIGHA-NKAMDJOU4,RÉMI FREYDIER2,HENRI ROBAIN1,5, BRUNOT NYECK3,JACQUES BODIN1,PRISCIA OLIVA2,JEAN-LOUP BOEGLIN1, SÉBASTIEN STEMMLER6 and JACQUES BERTHELIN6 Key words. – Lowland humid tropics, Small experimental watershed (SEW), Mass balance, Biogeochemistry, Hydrological func- tioning, Chemical and physical weathering, Laterite Abstract. – This paper summarizes a six-year study of the Nsimi Small Experimental Watershed (SEW), considered as a model for the South Cameroon humid tropical ecosystem. When this small watershed was set up, no similar survey of input/output hydrobiogeochemical fluxes in granitoid rocks in stable cratonic environment was available, to our knowledge, on any site close to the Equator. Moreover, this is the first attempt, world-wide, to combine different ap- proaches in hydrology, (bio)geochemistry, mineralogy, crystallography, microbiology, geophysics and pedology. Re- search is based on (1) regular hydrobiogeochemical surveys in various water reservoirs of the SEW ecosystem (atmospheric deposits, groundwater and stream), (2) surveys related either to the organisation and composition of dif- ferent reservoirs in the superficial layers (basement rocks,
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