Allometric Equations for the Biomass Prediction in Azadirachta indica Plantations in Sub-Saharan Africa: A Case Study from Cameroon

This study took place in the Far North region of Cameroon. It aimed at developing and standardizing a specific allometric equation to neem Agroforets in Sub-Saharan Africa. A sample of twenty (20) individuals of Azadirachta indica was cut over all the diameter classes, located between 5 and 105 cm. The dbh and height were measured. Biomass of the compartments of leaves, branches and trunks were determined after drying and weighing. Different allometric equations between biomass and two tree parameters (diameter and height) were tested. The adjusted coefficients of determination (R2aj), the residual standard error (RSE) and the Akaike information criterion (AIC) were used to choose the best models. The main results show that there is a positive and significant relationship between the height of trees and diameter (R2 = 0.98; n = 20 and p ? 0.05). The best model for the prediction of the total Above Ground Biomass (AGB) in Azadirachta indica plantations is AGB = e(- 0.456 + 1.673 x ln (DBH)) with a coefficient of determination adjusted at 0.72

Expériences sylvicoles au Cameroun : Croissance, mortalité et adaptabilité des espèces de bois d’oeuvre dans la station forestière de Mangombé (1964 - 2010)

Au Cameroun, l’exploitation du bois a entraîné la réduction du couvert forestier et son appauvrissement en espèces de bois d’oeuvre. Pour remédier à cette situation, de nombreuses plantations forestières ont été crées, puis abandonnées quelques décennies plus tard pour des raisons diverses, ce qui n’a pas permis de capitaliser l’ensemble des connaissances sylvicoles escomptées qui devaient permettre de réhabiliter les forêts et limiter les risques d’épuisement des stocks d’essences commerciales. Le dispositif sylvicole de Mangombé fait partie de ces initiatives, il ne compte plus que 27 parcelles d’arbres constituées de 15 espèces sur une quarantaine plantées. Ce travail, présente l’état de cette station forestière à travers l’étude de la croissance, de la mortalité des arbres et de l’adaptabilité des espèces. Dans chaque parcelle, toutes les tiges ont été inventoriées et leur diamètre à 1,30 m mesurés. Ce paramètre a permis d’établir la structure de population et d’apprécier la possible rentabilité économique des espèces. Les meilleures performances de croissance des arbres sont obtenues chez Gmelina arborea Roxb. (Gme-1 : 56 m²/ha) ; Araucaria cunninghamii Aiton ex D. Don (Ara-1 : 63 m²/ha) et Aucoumea klaineana Pierre (Auc-3 : 80 m²/ha). Les valeurs élevées des écarts types indiquent une croissance disproportionnée des individus à l’intérieur des parcelles. Les espèces présentant une faible mortalité et une proportion importante de tiges exploitées ainsi que de bonnes caractéristiques de croissance comme G. arborea, Dipterocarpus alatus Roxb. ex G. Don. (51 m²/ha) et A. klaineana se sont mieux adaptées au site de plantation et peuvent être recommandées pour les initiatives de reboisement dans la zone. La faible production observée chez un nombre élevé d’espèces est économiquement non rentable au regard des investissements onéreux consentis à la mise en place de la plantation.© 2015 International Formulae Group. All rights reserved.Mots clés: Mangombé, Cameroun, plantation forestière, sylviculture, croissance des arbres, mortalité, adaptabilitéEnglish Title: Sylvicultural experience in Cameroon: Growth, mortality and adaptability of wood species in Mangombe forest plantation (1964 - 2010)English AbstractIn Cameroon, logging has led to a reduction in forest cover and an impoverishment of several wood species. To solve this problem, many forest plantations had been created, then abandoned a few decades later for various reasons. This did not make it possible for foresters and policy makers to acquire expected knowledge from these experiences, which would have led to forest rehabilitation and reduced the risk of commercial wood extinction. Mangombe tree plantation is part of these experiences, which is a remnant of 15 out of 40 originally planted tree species distributed in 27 plots. This work presents the state of Mangombe forest plantation through the study of the growth, mortality of the trees and adaptability of species. All the trees were censored and their diameters measured in each plot. These measurements facilitate the establishment of the population structure and appreciate the economic profitability of the species. The best growth performances of trees were obtained with Gmelina arborea Roxb. (Gme-1 : 56 m²/ha) ; Araucaria cunninghamii Aiton ex D. Don (Ara-1 : 63 m²/ha) and Aucoumea klaineana Pierre (Auc-3 : 80 m²/ha). High values of standard deviations indicate a disproportionate growth of the individuals inside the plot. Species presenting a low mortality and a significant proportion of exploited stems as well as good growth characteristics such as G. arborea, Dipterocarpus alatus Roxb. ex G. Gift. (51 m²/ha) and A. klaineana were better adapted to the site and can be recommended for future initiatives of afforestation in the zone. The low production of certain species is economically non profitable considering the high investment during the establishment of the plantation.© 2015 International Formulae Group. All rights reserved.Keywords: Mangombé, Cameroon, forest plantation, sylviculture, trees growth, mortality, adaptabilit

Diversité Floristique Et Structurale De Deux Forêts Communautaires Sous Exploitation Au Cameroun: Cas De Kompia Et Nkolenyeng

The attribution of community forests to local populations has emerged as a new participative management system of plant biodiversity in Cameroon. Further to the intensification of anthropogenic activities in these forests, the logging impact on this biodiversity remains poorly known. This study was conducted in two different community forests located in the Kompia and Nkolenyeng villages, respectively. It aims to provide information on the state of the flora and plant structure of the community forests subjected to logging activities. Floristic inventories were carried out in nine biotope types using the variable-area sampling method. A total of 2772 individuals with dbh ≥ 10 cm were recorded in the community forests. In the whole biotopes, the species richness ranges from 19 to 98 species, the Shannon diversity index from 3.63 to 5.99 and the Pielou evenness from 0.65 to 0.93. The density of trees ranges from 73 ± 27 to 661 ± 119 stems ha-1 , the basal area from 15.68 ± 13.14 to 70.05 ± 28.76 m² ha-1 , the mean diameter of 18.85 ± 4.80 to 57.39 ± 20.70 cm and the canopy height from 12.26 ± 1.22 to 25.18 ± 1.02 m, on the average between biotopes. The two community forests showed decrease in tree density, a proliferation of the pioneer species, increase of small-diameter light-demanding species, a scarcity of large-diameter trees, and lowering of canopy height. These changes could compromise the sustainable management of these forests and their ability to ensure long-term local development. The large number of useful species identified in the two community forests is a reason to reinforce the preservation and management measures of the plant biodiversity of these forest areas

Can the Mangombe forest plantation contribute to restore and conserve biodiversity?

This research, conducted in the tropical rainforest, is focused on restoration of tree diversity through natural regeneration mechanism in the 49 year-old Mangombe forest plantation. 12 plots were surveyed, 6 with large transects and the 6 others under regrowth. In each plot, two subplots with 400 m² each were demarcated for the inventory of all stems with diameter greater than 2.5 cm. A total of 2239 stems comprising 107 species distributed in 93 genera and 42 families were identified over 9600 m². There was a slight difference between species richness of plots with large transect (79 species, 72 genera and 35 families) and regrowth plots (85 species, 76 genera and 38 families) while the basal area in the plots with large transects (10.76 m²/ha) was significantly greater than that of regrowth (8.65 m²/ha). Species with high important value index have an affinity with forest undergrowth such as: Tabernaemontana pachysiphon, T. crassa, Mallotus oppositifolius and Heinsia crinita. The undergrowth is diversified with different life feature and a high number of small size trees indicating a vigorous regeneration. This can be favoured by: microclimate undergrowth, canopy gaps, abundance of litter fall that brings humus to the soil, type and age of plots, planted species and the complexity of spatial and vertical structure of the stand.© 2016 International Formulae Group. All rights reserved.Keywords: Mangombé – Cameroon, Natural regeneration, dense humid forest, tree plantation, biodiversit

Sequestered Standing Carbon Stock in Selective Exploited Timbers Grown in Tropical Forest: a Case Study from the National Park of Lobeke (Cameroon)

ABSTRACT The study was carried out in the National Park of Lobeke (Cameroon). It aimed to assess diversity and sequestration potential of some commercialized timbers under industrialisation pressure. We took place 37 transects of 5 ha each. All selected timbers of at least 5 cm of DBH were surveyed. 8, 619 individuals divided into 6 families, 6 genera and 9 species were recorded. Diospyros crassiflora (Ebene) was the most diversified species (ISH= 8.09); followed Terminalia superba (Frake; ISH= 2.08). Triplochyton scleroxylon (Ayous), Terminalia superba (Frake) and Entandrophragma cylindricum (Sapelli) were the biggest species of the flora with 549.01; 370.22 and 334.8 m² of basal area respectively. With a stock of carbon evaluated at 107.5 t C/ha, the ecological service from the selected species was estimated at 23,419,305 t of CO2 incorporated in their biomass as from now. In the context of REDD+, the conservation of forests are welcome in mitigating climate change for the humanity welfare

Carbon storage in cashew plantations in Central Africa: case of Cameroon

This study aimed to assess the carbon storage in cashew plantations in the Sudano-Sahelian zone of Cameroon. Quantification of stocks of biomass and carbon dioxide contained in agroforestry systems has become an international priority within the framework of the implementation of REDD + mechanism. Three cashew plantations were selected according to age classes (0–10 years; 10–20 years and over 20 years) in the four subdivisions (Bénoué, Faro, Mayo-Louti and Mayo-Rey). The experimental device installed is a complete random Fisher block with five repetitions. A 100 m × 20 m transect method was undertaken to assess the biomass. Allometric equations were used to assess carbon stock in biomass and laboratory analysis was used to assess soil carbon stock. Carbon stocks varied following the subdivisions and ranged from 69.29 to 96.67; 62.24 to 82.61; 59.00 to 90.64 and 66.14 to 84.03 tC/ha respectively in Bénoué, Faro, Mayo-Louti and Mayo-Rey. Soil carbon stock varied following the subdivisions and ranged from 22.03 to 30.33; 20.12 to 25.43; 19.21 to 25.73 and 21.06 to 24.51 tC/ha respectively in Bénoué, Faro, Mayo-Louti and Mayo-Rey. The highest total carbon stock was recorded in Bénoué subdivision (81.85 ± 13.55 t C/ha). The cashew plantation is actively sequestering carbon showing the potentiality to mitigate global climate change. Finally, these results are also an important economic, ecological and dynamic informative value to serve as a basis for guiding any program of action aimed at the conservation and sustainable management of this species

Vegetation structure, carbon sequestration potential and species conservation in four agroforestry systems in Cameroon (Tropical Africa)

ABSTRACT As the rate of forest degradation continues to rise, agroforestry may serve as a way of conserving species and carbon sinks. The aim of this study was to assess agrobiodiversity and carbon sequestration potential in agrosystems in Cameroon. Three age groups of agrosystems were studied. Data were collected in 100x50 m2 quadrates. Density ranged from 53.17±0.08 to 1463±50.11; basal area from 2.07±0.00 to 988.39±16.13 m2/ha; Shannon diversity from 3.3±0.71 to 3.68±0.72; Carbon storage from 12.1±0.27 to 54.65±1.38 t C/ha for 1-10-year-old agrosystems with lowest values in neem; 34.78±0.87 to 71.34±1.6 t C/ha for 10-20-year-old stands with lowest values in cashew; 28.24±0.04 to 108.51±2.46 t C/ha for +20-year-old stands with highest values in eucalyptus; Carbon sequestration potential from 296.7±1.98 to 859.33±10.01 t CO2eq/ha. The highest carbon stocks were found in eucalyptus stands (p<0.05). Several endogenous species, especially Afzelia bipindensis (EN), Leptoderris ledermannii (EN), Mansonia altissima (EN), Entandrophragma cylindricum (VU), Nesogordonia papaverifera (VU), Quassia sanguinea (VU), Vitellaria paradoxa (VU), Afzelia africana (VU), Erythrina senegalensis (LC), Detarium microcarpum (LC), senna spectabilis (LC), were assessed. Other overexploited species, especially Carissa edulis, Zanthoxylum zanthoxyloides, Adansonia digitata, Securidaca longepedonculata, were assessed as well. The studied systems are significant CO2eq sinks and refuge centre for agrobiodiversity

Diversity and structure of Prunus africana (Hook.f.) Kalkman stands in the Tchabal forest massif: A case study from Adamawa Cameroon: Phytodiversity of Prunus africana (Hook.f.) Kalkman in Cameroon

The aim of this work is to provide basic data for a better knowledge of Prunus africana (Hook.f.) Kalkman stands through a non-exhaustive floristic inventory in the Sudano-Guinean zone of Cameroon. Transects of 2,000 x 20 m² were installed in these stands in the Tchabal forest massif. The inventory concerned timbers with dbh ≥ 10 cm. Herbaceous were counted according to the "sigmatiste zuricho-montpelléraine” method. In total, 25 families distributed in 41 genera and 46 species and for herbaceous, 19 families distributed in 42 genera and 46 species were recorded in the stands. The stands of Bontadji and Horé-Déo are the richest. Euphorbiaceae, Fabaceae, Ficus thonningii Blume and Croton macrostachyus Hochst. ex Delile are the most abundant taxa in each site. The Fongoy I locality stands are the most diversified (ISH: 0.87 ± 0.07; H': 0.99 ± 0.01). There is a floristic similarity of about 30% between localities. The stands of Fongoy I are very dense and basal area (D=394 ± 0.31 individuals/ha and BA= 25.80 ± 8.05 m²/ha). Structural analysis shows an "L" shape attesting to the presence of future stems. This observation is supported by the vertical structure of the stands. This information constitutes an important argument for the protection of the environment