<p align="justify"> <span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span>Soil organic carbon (SOC) mineralization was carried ...<p align="justify"> <span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span>Soil organic carbon (SOC) mineralization was carried out on soil samples collected from two depths: 0 - 20 cm and 20 - 40 cm for all land use (LU) types (grasslands, croplands, natural forest/fallow lands, cocoa/palm plantations, and settlement/agro-forests). Microbiological analyses were carried out by measuring microbial activity in 40 g of dried soil samples wetted to 60% water holding capacity and incubated at 27 °C. Carbon dioxide (CO<sub>2</sub>) emission was measured for 10 weeks using a CO<sub>2</sub> trap. Descriptive and graphical analyses of CO<sub>2</sub> respiration were done using CO<sub>2 </sub>emission data. Models were developed to describe CO<sub>2</sub> respiration and the first order kinetic model provided best fit to C-mineralization. Potentially mineralizable carbon (C<sub>o</sub>) and C-mineralization rate were higher in grasslands than other LU types, indicating a higher rate of microbial activity and carbon cycling. Metabolic quotient was higher in forest/fallow lands and reflects greater stress of the microbial community and a high requirement of maintenance energy. Grasslands enhanced more SOC accumulation and decomposition, suggesting a better carbon sink than other land use and management systems (LUMS). Microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) varied across LU patterns with maximum values in grasslands and minimum values in natural forest/fallow lands insinuating better soil quality for grasslands. MBC and SOC positively correlated with C<sub>o</sub> and C-mineralization, which intimates that C-mineralization is influenced by availability of MBC and SOC. Metabolic quotient (qCO<sub>2</sub>) negatively correlated with microbial quotient (MBC:SOC), depicting that higher values of qCO<sub>2</sub> signify difficulties in using organic substrates during microbial activity as a result of low MBC:SOC. Changes in LUMS affected the mineralization kinetics of SOC in the study area. </p>展开更多
This work assessed the impact of land use and land cover (LULC) change on the socio-economic conditions of the inhabitants in the Mount Bambouto Caldera from 1980-2016. To achieve this, three time series satellite ima...This work assessed the impact of land use and land cover (LULC) change on the socio-economic conditions of the inhabitants in the Mount Bambouto Caldera from 1980-2016. To achieve this, three time series satellite images;Landsat Thematic Mapper (TM) (1980), Landsat Enhanced Thematic Mapper (ETM) (2001), and Landsat 8 Operational Land Imager (OLI) (2016) scenes were employed to investigate the changes in LULC. The use of satellite images was supplemented with individual interviews, discussions with focus groups and key informants, and direct field observations. Five categories of LULC classes were identified namely: thick woody vegetation (natural forest and oil palms), light vegetation (croplands), savannah (grasslands), buildings (settlements), and bare grounds. The results showed that between 1980 and 2016, croplands, buildings and bare lands increased by 4%, 0.43% and 5.7% respectively while savannah/grassland and natural forest decreased by 4.4% and 5.8% respectively. Household survey revealed soil fertility decline and lack of credit schemes to be major constraints to crop production. Many religious holidays contribute to seasonal food shortages and the community faces a host of socio-economic and institutional challenges. Consequently, majority of house-holds are destitute, live in abject poverty;which is an indication of the need for interventions by government and other development stakeholders to tackle the problems of soil fertility, land use change and food insecurity.展开更多
Wild vegetables contribute immensely to the culinary basket and livelihoods of rural communities in sub-Saharan Africa, especially among the people of Lebialem highlands of south western Cameroon where at least 26 suc...Wild vegetables contribute immensely to the culinary basket and livelihoods of rural communities in sub-Saharan Africa, especially among the people of Lebialem highlands of south western Cameroon where at least 26 such species are consumed as vegetables. To promote the consumption of these vegetables, the nutritional quality of five preferred species in this area, Amaranthus dubius Mart. Ex Thell., Gnetum africanum Welw., Lomariopsis guineensis (Unerw.) Alston, Pennisetum purpureum Schumach and Vernonia amygdalina Del., was assessed using standard methods. L. guineensis had the highest carbohydrate, protein, calorific value and ash content, and the lowest fat content of 4.05%, very rich in K, Ca and Mg and the amino acids leucine, arginine, lysine, phenylalanine and histidine. The amino acid content was generally higher than 25 mg/100g. Steroids, flavanoids and tannins occurred in moderate to high levels in all five species. Alkaloids and saponins occurred at very low levels, while triterpenes only occurred at very low levels in P. purpureum. The quality of Lomariopsis guineensis, a fern recently reported for the first time as edible is very promising. Pennisetum purpureum, popular as a forage plant, has now been shown to be valuable in the human diet. The study has established the safe and rich nutritional value of these vegetables and that their consumption could combat malnutrition and prevent some of the common nutritionally-related ailments.展开更多
文摘<p align="justify"> <span style="font-family:Verdana;"></span><span style="font-family:Verdana;"></span>Soil organic carbon (SOC) mineralization was carried out on soil samples collected from two depths: 0 - 20 cm and 20 - 40 cm for all land use (LU) types (grasslands, croplands, natural forest/fallow lands, cocoa/palm plantations, and settlement/agro-forests). Microbiological analyses were carried out by measuring microbial activity in 40 g of dried soil samples wetted to 60% water holding capacity and incubated at 27 °C. Carbon dioxide (CO<sub>2</sub>) emission was measured for 10 weeks using a CO<sub>2</sub> trap. Descriptive and graphical analyses of CO<sub>2</sub> respiration were done using CO<sub>2 </sub>emission data. Models were developed to describe CO<sub>2</sub> respiration and the first order kinetic model provided best fit to C-mineralization. Potentially mineralizable carbon (C<sub>o</sub>) and C-mineralization rate were higher in grasslands than other LU types, indicating a higher rate of microbial activity and carbon cycling. Metabolic quotient was higher in forest/fallow lands and reflects greater stress of the microbial community and a high requirement of maintenance energy. Grasslands enhanced more SOC accumulation and decomposition, suggesting a better carbon sink than other land use and management systems (LUMS). Microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) varied across LU patterns with maximum values in grasslands and minimum values in natural forest/fallow lands insinuating better soil quality for grasslands. MBC and SOC positively correlated with C<sub>o</sub> and C-mineralization, which intimates that C-mineralization is influenced by availability of MBC and SOC. Metabolic quotient (qCO<sub>2</sub>) negatively correlated with microbial quotient (MBC:SOC), depicting that higher values of qCO<sub>2</sub> signify difficulties in using organic substrates during microbial activity as a result of low MBC:SOC. Changes in LUMS affected the mineralization kinetics of SOC in the study area. </p>
文摘This work assessed the impact of land use and land cover (LULC) change on the socio-economic conditions of the inhabitants in the Mount Bambouto Caldera from 1980-2016. To achieve this, three time series satellite images;Landsat Thematic Mapper (TM) (1980), Landsat Enhanced Thematic Mapper (ETM) (2001), and Landsat 8 Operational Land Imager (OLI) (2016) scenes were employed to investigate the changes in LULC. The use of satellite images was supplemented with individual interviews, discussions with focus groups and key informants, and direct field observations. Five categories of LULC classes were identified namely: thick woody vegetation (natural forest and oil palms), light vegetation (croplands), savannah (grasslands), buildings (settlements), and bare grounds. The results showed that between 1980 and 2016, croplands, buildings and bare lands increased by 4%, 0.43% and 5.7% respectively while savannah/grassland and natural forest decreased by 4.4% and 5.8% respectively. Household survey revealed soil fertility decline and lack of credit schemes to be major constraints to crop production. Many religious holidays contribute to seasonal food shortages and the community faces a host of socio-economic and institutional challenges. Consequently, majority of house-holds are destitute, live in abject poverty;which is an indication of the need for interventions by government and other development stakeholders to tackle the problems of soil fertility, land use change and food insecurity.
文摘Wild vegetables contribute immensely to the culinary basket and livelihoods of rural communities in sub-Saharan Africa, especially among the people of Lebialem highlands of south western Cameroon where at least 26 such species are consumed as vegetables. To promote the consumption of these vegetables, the nutritional quality of five preferred species in this area, Amaranthus dubius Mart. Ex Thell., Gnetum africanum Welw., Lomariopsis guineensis (Unerw.) Alston, Pennisetum purpureum Schumach and Vernonia amygdalina Del., was assessed using standard methods. L. guineensis had the highest carbohydrate, protein, calorific value and ash content, and the lowest fat content of 4.05%, very rich in K, Ca and Mg and the amino acids leucine, arginine, lysine, phenylalanine and histidine. The amino acid content was generally higher than 25 mg/100g. Steroids, flavanoids and tannins occurred in moderate to high levels in all five species. Alkaloids and saponins occurred at very low levels, while triterpenes only occurred at very low levels in P. purpureum. The quality of Lomariopsis guineensis, a fern recently reported for the first time as edible is very promising. Pennisetum purpureum, popular as a forage plant, has now been shown to be valuable in the human diet. The study has established the safe and rich nutritional value of these vegetables and that their consumption could combat malnutrition and prevent some of the common nutritionally-related ailments.
