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Aim/Objectives: In order to assess the fallow contribution on the carbon cycle and soil organic matter restoration, a study of the carbon dynamics was undertaken in fallow systems of 1, 2, 5 and 20 years old in the Ngaoundere savannahs of Cameroon.
Methodology: Carbon stock was estimated in 100 m2 plot for shrubs, in 1 m2 plot for understorey, litter and earthworm casts, and 0.0625m2 plot for fine roots and soil. The experimental design was randomised complete block with three replicates. The age of fallows was the mean treatment whereas the plots were the replicates.
Results: The results showed that the phytomass increased with fallow age, except that of shrubs. Soils and earthworm casts were the mean carbon sinks in the four fallows, with more than 55.61% and 26.24% of the total carbon stock respectively in the soil and earthworm casts. The total carbon stock increased with fallow age, from 34.54 in the young fallows to 154.52 tC.ha-1 in the old fallows. In the same way, vegetation and soil carbon increased with fallow age except that of shrub. The results showed that the carbon stock was influenced by floristic composition and spatial distribution of the vegetation, which related to fallow age.
Conclusion: These preliminary results will contribute to the understanding of the impact of fallow age on the global carbon cycle and awareness in the conservation of fallows for the environment protection.