Litter decomposition and nutrient dynamics of ten selected tree species in tropical rainforest of Ebom, southwest Cameroon

Litter decomposition processes in tropical rainforests are still poorly understood. Leaf litter decomposition and nutrient dynamics of ten contrasting tree species, Entandraphragma utile, Guibourtia tessmannii, Klainedoxa gabonensis, Musanga cecropioides, Panda oleosa, Plagiostyles africana, Pterocarpus soyauxii, Strombosia scheffleri, Vitex grandifolia and Xylopia aethiopica were studied in the tropical rainforest of Ebom, Southwest Cameroon. After 23 weeks of field incubation in litterbags, mass loss of litter samples varied from 24.08% in E. utile to 92.35% in V. grandifolia. Decomposition rate constants (k) ranged from 0.014 in M. cecropioides to 0.165 week-1 in V. grandifolia. The nutrient content in original litter samples also varied widely among species and showed low levels of Na, P and Mg, and high levels of N, Ca and K. Averagenutrient releases was 89.04%, 60.80%, 46.19%, 40.99% and 24.17% of mean initial content for K, Ca, Mg, N and P, respectively. For nutrient-related litter chemistry, correlations with the mass losses at the end of litter incubation were significant (

Contribution of some water bodies and the role of soils in the physicochemical enrichment of the Douala-Edea mangrove ecosystem

The effect of enrichment of water bodies could be of serious crises to the mangrove ecosystem. Changes in physicochemical properties of some water bodies in the Douala-Edea mangrove ecosystem was investigated alongside the potential role of soils in controlling these parameters. Water and soil samples within the Douala industrial zones were collected in February 2010 and analysed using standard methods. The concentrations of cations and chlorides (Cl-) in the rivers increased from upstream to downstream and with depth. These parameters were not distinct with other anions which showed higher fluctuations around confluences. Many anomalies were obtained in streams and wells at vicinity of the industries. Mean Cl- concentrations in streams and wells around River Wouri (135.1 and 57.9 mg/l, respectively) were higher than those around River Dibamba (59.3 and 38,2 mg/l, respectively). A low retention capacity of the soils was observed by the non significant (P > 0.05) relationship between the clay fraction and cation exchange capacity (CEC). This makes the mangrove  ecosystem vulnerable to the increase nutrient from anthropogenic activities as indicated by the occurrence of Nypa Palms (Nypa fructicans) and Water Hyacinths (Echhornia cassipes). It is therefore imminent that the Douala-Edea Mangrove Ecosystem is being degraded.Key words: Soils, water, physicochemical properties, mangrove ecosystem