Browsing by Subject "Plant ecology"

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    Light microsite requirements of seedlings of some Afromontane forest tree species: the role of canopy gaps promoting regeneration
    (1989) Van Coller, Alan; Cowling, Richard M
    Predictions of microsite requirements for seven common Afromontane forest tree species were made by testing above ground relative growth rate (RGR) and photosynthetic response of seedlings of the respective species under different light intensities. Virgilia oroboides and Halleria lucida, with either a very high photosynthetic rate or RGR, were regarded to be pioneer species. Podocarpus latifolius was regarded to be a deep shaded species due to its low photosynthetic and RGR's. Rapanea melanophloeos, Ilex mitis, Olea capensis sub Ssp. macrocarpa and Kiggelaria africana either had moderately high RGR or photosynthetic rate and were regarded to be light shaded species. Predictions were tested in Grootvadersbosch (34ᵒ05's,20ᵒ50'E) forest, where frequency of seedlings beneath the canopy and under a canopy gap were recorded and tested using a x²-goodness of fit test, against the null hypothesis that there are equal frequencies of seedlings beneath the canopy and canopy gaps. Results confirmed predictions made for latifolius, O. capensis sub sp. macrocarpa, and R. melanophloeos. Low seedling frequencies for the other species, either due to a restricted distribution of adult trees (e.g. V. oroboides) or high levels of herbivore attack, made it difficult to test predictions. Significantly higher frequencies of seedlings of P. latifolius and O. capensis sub sp. macrocarpa beneath the canopy than in the gap of dry forest suggest that gaps in drier forests are stressful sites for regeneration. This led to the hypothesis of expecting a greater dominance of shade tolerant species in the canopy of dry forests than in moist forests. McKenzie's (1978) findings support this hypothesis. It was concluded that Afromontane forests are largely made up of deep or light shaded tree species, with pioneer species confined to forest margins. The role of canopy gaps can be seen to play a minor role promoting regeneration.
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    Open Access
    Prevalence and risk factors of overweight and obesity among children aged 6–59 months in Cameroon: a multistage, stratified cluster sampling nationwide survey
    (Public Library of Science, 2015) Tchoubi, Sébastien; Sobngwi-Tambekou, Joëlle; Noubiap, Jean Jacques N; Asangbeh, Serra Lem; Nkoum, Benjamin Alexandre; Sobngwi, Eugene
    BACKGROUND: Childhood obesity is one of the most serious public health challenges of the 21st century. The prevalence of overweight and obesity among children (<5 years) in Cameroon, based on weight-for-height index, has doubled between 1991 and 2006. This study aimed to determine the prevalence and risk factors of overweight and obesity among children aged 6 months to 5 years in Cameroon in 2011. METHODS: Four thousand five hundred and eighteen children (2205 boys and 2313 girls) aged between 6 to 59 months were sampled in the 2011 Demographic Health Survey (DHS) database. Body Mass Index (BMI) z-scores based on WHO 2006 reference population was chosen to estimate overweight (BMI z-score > 2) and obesity (BMI for age > 3). Regression analyses were performed to investigate risk factors of overweight/obesity. RESULTS: The prevalence of overweight and obesity was 8% (1.7% for obesity alone). Boys were more affected by overweight than girls with a prevalence of 9.7% and 6.4% respectively. The highest prevalence of overweight was observed in the Grassfield area (including people living in West and North-West regions) (15.3%). Factors that were independently associated with overweight and obesity included: having overweight mother (adjusted odds ratio (aOR) = 1.51; 95% CI 1.15 to 1.97) and obese mother (aOR = 2.19; 95% CI = 155 to 3.07), compared to having normal weight mother; high birth weight (aOR = 1.69; 95% CI 1.24 to 2.28) compared to normal birth weight; male gender (aOR = 1.56; 95% CI 1.24 to 1.95); low birth rank (aOR = 1.35; 95% CI 1.06 to 1.72); being aged between 13-24 months (aOR = 1.81; 95% CI = 1.21 to 2.66) and 25-36 months (aOR = 2.79; 95% CI 1.93 to 4.13) compared to being aged 45 to 49 months; living in the grassfield area (aOR = 2.65; 95% CI = 1.87 to 3.79) compared to living in Forest area. Muslim appeared as a protective factor (aOR = 0.67; 95% CI 0.46 to 0.95).compared to Christian religion. CONCLUSION: This study underlines a high prevalence of early childhood overweight with significant disparities between ecological areas of Cameroon. Risk factors of overweight included high maternal BMI, high birth weight, male gender, low birth rank, aged between 13-36 months, and living in the Grassfield area while being Muslim appeared as a protective factor. Preventive strategies should be strengthened especially in Grassfield areas and should focus on sensitization campaigns to reduce overweight and obesity in mothers and on reinforcement of measures such as surveillance of weight gain during antenatal consultation and clinical follow-up of children with high birth weight. Meanwhile, further studies including nutritional characteristics are of great interest to understand the association with religion, child age and ecological area in this age group, and will help in refining preventive strategies against childhood overweight and obesity in Cameroon.