Abstract:In order to reduce the increase of fuel prices, and improve the living conditions of the population, a study was carried out by Convention No. 1/IRAD/PCS ESA2-SDCC in the region of Garoua in Cameroon. The study aimed to characterize the behaviour of J. curcas associated with V. unguiculata in marginal soils in the Sahel region in order to improve the livelihoods of the farmers and promote its domestication in rural areas. It also aimed at pointing out the influence of two implantation techniques of J. curcas on the germination, the different quantities of NPK and cow dung, planting techniques and association with V. unguiculata var. lori on growth parameters of development and yield of J. curcas on the degraded marginal soils in the region. The experimental design was a completely randomized block with five levels of fertilization (F0: control; F1: 50 g; F2: 100 g of NPK 15-20-15; F3: 1 kg and 2 kg of cow dung) per plant. Two types of establishment propagator (Ge) and direct seedling (Se) with three replications were used. Data were analysed by Stratigraphic + and XLSTAT. Results showed that the propagator germination was higher than the direct seeding, 95% and 40% respectively. The Principal Component Analysis (PCA) of the parameters of growths and yield of J. curcas showed high correlation between the production of the leaves and the length of the leaves (R = 0.861; P ≤ 0.001). These parameters were correlated with the Biplot (F1 and F2) to 53.24%. It was opposed to the positives and imperfect correlation between the height and the recover parameters (R = 0.486; P ≤ 0.05). The treatments 100 g of NPK per plant and 2 kg of cow dung per plant induced strongly the development and yield of J. curcas and V. unguiculata adapted to marginal soils.

A study was carried out in the Mount Mandara area to assess the populations and renewal status of Parkia biglobosa, a multipurpose species. The study was aimed at contributing to the sustainable management of this resource. Transect methods were used to count individuals of P. biglobosa in fields. Results showed that the density of P. biglobosa was 7 individuals ha-1. The basal area of P. biglobosa individuals varied as follows: Mokolo area (21.41 m 2 ha-1) and Roua-plateaux Zoulgo (20.06 m 2 ha-1). In these zones, big trees of P. biglobosa with large diameters were quite numerous. The average diameters were 79.14 ± 5.04 cm, and the average height was 13.60 ± 0.96 m. The structure of the distribution among the diameters generally was bell shaped, but the distributions varied in each zone. The greatest number of individuals was observed in the [50-70 cm] and [70-90 cm] diameter classes, with a remarkable increased presence of individuals in class [130-150 cm]. The scarcity of the individuals in the diameter range of 10 to 30 cm was noted in the various zones, with their entire absence in the Roua-Plateaux Zoulgo and Méri zones. The rate of regeneration of P. biglobosa was 13 %. This rate was very weak compared to the socioeconomic importance of this species. This regeneration rate will not ensure continued population strength of this multipurpose species. This species is proven of importance, but its capacity of regeneration was too low to ensure its sustainability. It becomes imperative to develop effective strategies for its regeneration and conservation.

Published online at www.m.elewa.org on 31 st October 2018 https://dx.doi.org/10.4314/jab.v130i1.10 RESUME Objectif : évaluer la structure écologique et la production de fruits de Haematostaphis barteri pour fournir les informations nécessaires à une meilleure gestion et conservation de l'espèce au Cameroun. Méthodologie et Résultats : Dans quatre sites, 48 parcelles d'un hectare ont servi pour des inventaires forestiers de Haematostaphis barteri et 120 arbres l'ont été pour quantifier la production. La distribution de diamètre montre une courbe en J renversé, caractéristique des populations jeunes. La densité varie de 13 à 17 individus/ha. La surface terrière varie de 0,28 à 0,49 m²/ha, le diamètre varie de 17,31 à 20,57 cm. Le nombre de fruits par panicule et par arbre varie de 15 à 28 et de 2346 à 7877 respectivement. L'analyse des paramètres dendrométriques et de production montre une différence significative (P < 0,001) entre populations. Conclusion et Application des résultats : L'environnement est le facteur qui distingue le mieux les différentes populations et explique mieux les variations observées entre elles en ce qui concerne leurs caractéristiques structurelles et de production. Cependant il serait nécessaire de ressortir l'impact de la surexploitation sur la distribution et la production dans les différents sites.

A study was carried out in the Mounts Mandara to assess the diversity of edible plant species, to identify the use of the edible products, and to determine their socioeconomic value. Interviews of a sampling population were conducted randomly in 5 zones with 5 villages each and in rural and urban markets; a sample of 1020 persons was interviewed to evaluate and quantify the various products and determine their flows. The results showed that the edible plant products used in the area were: fruits, leaves, flowers, seeds, tubers, roots, barks and stems. These products were harvested from 61 plant species belonging to 29 families in which 54 species were fruit trees, 11 species produced leaves and / or flowers, 4 species produced seeds. The total annual quantity of products harvested was 1080.9 t in which: fruit (725.62 t); leaves (97.5 t), flowers (1.96 t), and seeds (255.82 t). The seeds of Parkia biglobosa were the most useful part by the populations of Mounts Mandara making "dawa-dawa" some traditional aromatic for a sauce. Exploited products were an important source of food and income for the people. Annually, exploited products generated at whole of 60 783 975 F CFA. The fruits were sold for 17 542 375 F CFA, the seeds yielded 36 676 900 F CFA, the contribution of the leaves was 5 452 820 F CFA and that of the flowers was 724880 F CFA, "dawa-dawa" brought, very popular, bring in a modest sum of 787 000 F CFA. Local people were developing interest in exploiting different bush products. The exploitation activities of the various products were intensifying; the requested species must be domestication to ensure the sustainable management.

Non-timber forest products (NTFPs) strongly contribute to livelihood security of forest-adjacent communities. This study examined the impacts of their harvesting on tree species diversity at the periphery of Mbam and Djerem National Park (Cameroon). Tree species diversity, with diameter at breast height (dbh) ≥ 10 cm, was analyzed in small plots (10 × 100 m) along seven 1-ha transects. Species diversity and floristic composition of undisturbed and disturbed sites were compared in order to obtain an indication of the impact of harvesting NTFPs. A total of 1294 stems was recorded, representing 99 species, 96 genera and 36 families. Shannon diversity index values were highest in undisturbed sites (H' > 3.5 bits), and lower in disturbed sites (H' < 3.5 bits). Analysis of variance showed significant differences in mean diversity measures between the two sites (p = 0.047). Mean number of stems cut within the disturbed sites was 15.5 ± 5.5 stems ha-1. The park's region was found to be rich in Euphorbiaceae, Caesalpiniaceae and Annonaceae. The survey highlighted the effectiveness of harvesting NTFPs in the region and its impacts on tree species diversity. Efforts should be made more in order to improve the protection of the park, and the development of a suitable regional conservation of biodiversity.