Soil Organisms Effect on Leaf Litter Decomposition of Four Selected Plant Species in the Sudano-Guinea Savannahs of Ngaoundere, Cameroon

摘要

Few studies were carried out on the influence of soil organisms on the litter decomposition in savannahs of Adamawa, Cameroon. The goal of this study is to determine the total influence of the soil organisms on the litter decomposition of four important socio-economic species of sudano-guinea savannahs of Ngaoundere. These species are Terminalia glaucescens, Ficus sycomorus, Hymenocardia acida and Daniellia oliveri. The experimentation was carried out in situ using the litterbags method in two plots, treated and control with the insecticide naphthalene. 72 litterbags of 10 0,01g each one were incubated in each of the 2 plots during 24 weeks. A taking away of 3 samples of each species was carried out at 2, 4, 6, 10, 16 and 24 weeks. The soil organisms were also sampled at 12 and 24 weeks of incubation. At the end of the experiment, nine taxonomic groups were collected in the two plots during 12th and the 24th week of incubation. The control plot has a total taxonomic composition of fauna (9 groups) and an average of total density (426.25 ind./m~2) higher than that treated (8 groups and 362.50 ind./m~2). At the end of incubation, the total remaining dry mass is significantly lower in the control plot (9%) than in that treated (42%). By species, this remaining dry mass and the rate of litters decomposition differ significantly between the two plots for all the species, except for that of Terminalia glaucescens. The number and the density of the soil organisms obtained in control plot where higher than that obtained in treated plot. The soil organisms thus influence the litter decomposition in savannahs of Ngaoundere, but this influence is varying according to the species and the time of incubation. These results could contribute to the management of the fertility of the soil in savannahs in general and those of Ngaoundere in particular.