Litter decomposition processes are poorly studied in the savannahs. Leaf litter decomposition of the twenty-four contrasting plant species including trees, shrubs and grass species, was studied in the sudano-guinea savannahs of Ngaoundere, Cameroon. The litterbag technique was used to assess litter mass loss and single exponential model was adopted to estimate decay rate constants. Initial litter thickness varied from 0.02 to 1.11 mm, area from 4.27 to 245.89 mm2, sclerophyllous index from 0.01 to 1.75 mg.mm-2, density from 0.21 to 87.50 mg.mm-3, and specific mass area from 0.57 to 185.46 mm2.mg-1. Litter cellulose content varied from 3.79 to 11.84%; lignin from 2.84 to 8.12%, NDF from 21.35 to 80.41%, and total phenolic compounds from 0.47 to 17.76%. During the 52 weeks of the field experiment, mean dry mass remaining of litter samples was significantly between 8.05 and 75.22% of initial litter dry mass for C. papaya and C. regidus respectively. Litter decomposition rate constant (k) significantly ranged from 0.003 (C. regidus) to 0.121 %.week-1 (C. papaya). Litter mass remaining (LMR) was positively related to thickness (R2 = 0.605, P<0.01), Sclerophyllous index (R2 = 0.446, P<0.05), Specific mass area (R2 = 0.569, P<0.001), lignin (R2 = 0.631, P<0.01) and phenolic compounds (R2 = 0.618, P<0.001). The litter decomposition rate constant (k) was negatively related to thickness (R2 = 0.602, P<0.01, n=12), Sclerophyllous index (0.542; P<0.05), Specific mass area (0.419; P<0.05) and phenolic compounds (0.530; P<0.01). It can be concluded that litter decomposition is affected by plant species diversity, plant groups and physico-chemical traits of litters in the sudano-guinea savannahs of Ngaoundere, Cameroun. These preliminary results would contribute to understanding the mechanism of litter decomposition in general and in these savannahs in particular.

Litter production which is important for understanding nutrient cycling and assessing productivity in forest ecosystems is poorly studied in the African savannahs, particularly in the savannahs of Cameroon. Thus, litter production and organic compounds of the thirty-six (36) contrasting plant species were studied in the Sudano-guinea savannahs of Ngaoundere, Cameroon. Litter collected in framework of 50 cm x 50 cm under the three tree of each plant species in three sites of the savannahs of Ngaoundere during the period of their maximum fall that from November and January. After two years of collection, mean annual litter production varied from 0.36 in S. longipedunculata to 10.06 t.ha-1.year-1 in F. polita at Dang, from 0.14 in G. aqualla to 9.39 t.ha-1.year-1 in V. paradoxa at Biskewal, and from 0.35 in G. aqualla to 3.64 t.ha-1.year-1 in S. guineense var. macrocarpum at Wakwa. Contribution of leaf litter, fruits and wood were respectively more than 50%, 1.40% and 32% to the total litter. Litter production varied from 2.35 t.ha-1.year-1 at Wakwa to 2.91 t.ha-1.year-1 at Dang, but the sites did not differ significantly among them. Litter cellulose content varied from 4.11 in P. hookeri to 11.84% in V. doniana, that of lignin from 2.28 in V. paradoxa to 8.12% in V. doniana, that of NDF from 21.35 in S. guineense var. guineense to 75.73% in S. guineense var. macrocarpum, and that of phenolic compounds from 0.47 in V. doniana to 16.11% in C. molle. Litter production and organic compounds content were affected by plant diversity, but not by sites in the Sudano-guinea savannahs of Ngaoundere, Cameroon. These results would contribute to well select plant species for their domestication and to management of Adamawa savannahs of Cameroon.

Few studies on effects of termites on litter decomposition have been done in African savannahs, particularly in the Adamawa savannahs of Cameroon. In the framework of management of resource quality to restore or improve soil fertility of farming systems of Sudano-guinea savannahs of Ngaoundere, Cameroon, study on termites’ control of leaf litter decomposition of eight plant species was conducted on the field. The selected plant species are Bixa orellana, Erythrina sigmoïdea, Ficus polita, Maytenus senegalensis, Mucuna stans, Piliostigma thonningii, Vitex madiensis and Vitellaria paradoxa. Leaf litter samples were incubated in situ using litterbags of 2 mm mesh during 24 weeks in two plots out of canopy, corresponding to two treatments, with and without termites. Experimental design was split-plot with three replications. Collected data was carried out on litter dry mass remaining (LMR). Results showed total mass loss at the end of incubation time (24 weeks) and decomposition rate constants (k) differed significantly among plant species for the two treatments. The values ranged respectively from 23.05% and 0.012 week-1 in V. madiensis to 61.93% of initial dry mass and 0.046 week-1 in P. thonningii for treatment without termites and from 43.88% and 0.022 week-1 in B. orellana to 91.51% and 0.095 week-1 in P. thonningii for treatment with termites. These macro organisms fasted litter decomposition in all plant species, with intensity variation according to species. Litter mass loss and decomposition rate constant (k) correlated with litter thickness, density, area and specific area mass, and these relationships were influenced by the presence of termites. Globally litter decomposition was influenced by termite activities and resource quality. These results contributed to understand litter decomposition process in the sudano-guinea savannahs of Ngaoundere in order improve soil fertility, nutrient cycling and some plant species domestication.