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A survey was conducted between October 2010 and June 2011 to determine the diversity, distribution, and abundance of plants in 4 sites of the Lebialem highlands and to relate species diversity and abundance to altitude and soil types. Twelve (12) plots, each of 1 ha (250 × 40 m), were surveyed at the submontane and montane altitudes of the sites. One hundred (100) species belonging to 82 genera were identified with the genera Cola and Psychotria being the most represented. Vulnerable species included Guarea thompsonii, Schefflera hierniana, Allanblackia gabonensis, Cyclomorpha solmsii, Vepris trifoliolata, and Xylopia africana. Species such as Xymalos monospora, Tricalysia atherura, and Piptostigma oyemense present in the study area were endemic to Cameroon. Diversity and distribution of plants were affected by parameters such as the altitude and the soil type. Soil analysis revealed that diversity in the study area was affected by the organic carbon, nitrogen, calcium, and the cation exchange capacity of the soil.

Municipal solid waste generated in our cities, with an unprecedented population growth, has resulted in degrading environmental quality, thus a major problem for policy makers. The extent of Pb, Cu, Zn, Cd, Hg and Zn contamination in soils of the studied area, where vegetables were grown, using metal contamination factor (CF) and pollution load index were assessed. The concentrations of heavy metals studied were in the order Cu > Zn > Cd > Hg > Pb > Ni, with the highest value (in mg/kg) for Zn (14.15±0.73), Cu (14.15±1.59), Cd (6.57±1.71) and Hg (6.29±0.97) recorded in site SS1. The geoaccumulation index (Igeo) indicated that sites SS3, SS4 and SS5 were uncontaminated, moderately contaminated (1< Igeo<3) for Zn, landfill was moderately to heavily contaminated (1< Igeo<3) for Cu, Cd and for swamp only Hg. Contamination factor (CF) for soils indicated that site SS1 had a very high degree of contamination (CF > 6) for Cu and Cd while the swamp, old dumpsite and downstream had a low contamination (CF<1). The landfill area is moderately contaminated and considering the age and other anthropogenic factors, this environment may become highly polluted in future. This present work could serve as a landmark for contemporary research in ecotoxicology .

Background The Orchidaceae are noted for their floral diversity. In the Mount Cameroon Region (MCR), the genus Bulbophyllum is the most represented genus of the entire flora of this region. Despite the large number of different species in Orchidaceae, very little is known and documented about the orchids in Cameroon at large, in the MCR in particular. Orchids are widely used in flower gardens and trade. The aim of this study was to assess the floristic value of the orchids compared with those of other parts of the world and equally assess species which are used in herbal medicines. Methods This research was carried out in the MCR and the main flower market in Cameroon. Semi-structured questionnaires were administered to vendors, buyers, and cultivators at a ratio of 1:1:1, as well as to herbalists and cultural use indices computed. A total of 107 flower gardens in all gardening localities (07) of the region were sampled. Results A total of 66 out of 107 gardens had at least one orchid species. Five orchids which are hybrids cultivated by vegetative propagation are traded as ornamental plants in the MCR. A total of 23 species were used for herbal treatment of certain ailments. The ethnobotanical richness of orchids was scored at 6.86. Ansellia africana had the highest cultural importance index (CI), relative importance index (RI), and the relative use index (RNU) while tradactyle tridactylites had the lowest. It was also found that most orchids were used for clairvoyance that is highly associated with myths or folklore and also for external application. Conclusion The level of awareness on uses of orchids in the MCR is low. Many people consume orchids mixed with different species of plants for herbal treatment. Orchid trade is used as a part of subsistence by orchid cultivators and vendors.

This study was carried out in the Mount Cameroon region to evaluate the effects of green manure and fertilizer on the growth and yield of maize. There were eight treatments: Calliandra prunings, Calliandra prunings + fertilizer (60kg/ha NPK), Gliricidia prunings, Gliricidia prunings + fertilizer, Senna prunings, Senna prunings + fertilizer, fertilizer only (120 kg/ha NPK) and control. Results showed that biomass of prunings in the first pruning was highest in Calliandra (5314kg/ha) and this was significantly different from those of Senna (2909kg/ha) and Gliricidia (2112kg/ha). Nitrogen input from the prunings was highly significant (P<0.05) in Calliandra prunings (217 kgN/ha) and least in Gliricidia species (69.0kgN/ha). Maize grain yield in the different treatments was not significantly different in the first and second planting seasons. The highest grain yield during the third cropping season was observed in Calliandra + fertilizer (4696kg/ha) and least in control (3332kg/ha). It was also noted that nitrogen uptake was highest in plots supplied with fertilizer only and lowest in control. Weed biomass was highest in control and in plots supplied with fertilizer only. Soil chemical changes after three cropping periods showed variable changes in treatments. There was decrease in bulk density in plots supplied with Calliandra prunings.

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Creation of protected areas is a cornerstone of nature conservation. However, with increasing population, the pressure on land for agriculture increases, especially in peri-urban areas. We investigated land-use changes in a peri-urban forest reserve subject to anthropogenic influence and assessed the extant plant community structure through various indices. The results show that there is active forest conversion into farmland, and this conversion affects surrounding waterbodies as well. A new guild of species dominates under anthropogenic activity and comprises cocoa farms and mosaic forest. Cocoa Farms were more diverse (H = 3.08) than Dense Forest (H = 2.75) yet both were strikingly dissimilar with high carbon stocks in Cocoa Farm (128 Mg/Ha) compared to Dense Forest (51.6 Mg/ha) indicating that the forest is highly degraded. Land cover change predictions indicate further increase in forest conversion to farmland and accommodation. Our results show that legislating protected areas needs to be accompanied by consistent monitoring, and poverty alleviation alternatives that relieve pressure from forests, if conservation is to be successful. ARTICLE HISTORY

Indiscriminate use of fertilizers by vegetable growers and poor water quality of irrigational water characterize vegetable production in most parts of Cameroon. The concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the soil, cabbage and carrot cultivated in Santa, North West Region, Cameroon were assessed to determine potential ecological and human health risk associated with the consumption of these two vegetables. Heavy metal concentrations were determined using a ContrAA 300 Atomic Absorption Spectrophotometer after microwave digestion. The concentrations of As (0.51 mg/kg and 0.38 mg/kg), Co (1.41 mg/kg and 1.39 mg/kg) and Pb (1.36 mg/kg and 1.31 mg/ kg) in the cabbage and carrot, respectively, were above the WHO/FAO, permissible limits for human consumption. Health risk index values for Co in cabbage (2.31 mg/kg) and carrot (2.26 mg/kg) indicated significant risks from Co exposure. Geo-accumulation Index indicated that soils from most sites were contaminated. The populations consuming these vegetables are at risk of As, Co and Pb toxicity. Monitoring and sensitization of farmers on the effects of indiscriminate use of agrochemicals is very necessary to protect the health of consumers and preserve the soil quality.