Population dynamics of Garcinia lucida (Clusiaceae) in Cameroonian Atlantic forests.

Garcinia lucida Vesque (Clusiaceae) is a highly valued non-timber forest tree. The bark and the seeds are exploited and commercialised for medicinal purposes and palm wine processing in Cameroon, Gabon and Equatorial Guinea. The bark is often removed over almost the entire circumference of the stem, leading to high mortality. To identify the processes or the life stages that influence the population dynamics and to forecast the potential effects of harvesting, a demography study was carried and a matrix model was constructed to characterise the population dynamics of G. lucida in the South Cameroonian Atlantic humid forests. The study revealed that height and diameter growth values were very low and may constitute biological disadvantages for the dynamics of the species. The flowering and fruiting model, the absence of seed dormancy, and the high germination and seedling survival rates constituted advantages for the population dynamics, which is characterised by effective regeneration strategies. Rates of growth, survival and fecundity allowed calculations of transition probabilities of the matrix model. The value of the dominant eigenvalue (lambda) was 1.063, slightly higher than the value expected for stable populations. The sensitivities of lambda to changes showed that the population growth was most sensitive to changes in tree growth, particularly in the seedling stage. Elasticity analysis showed that growth and fecundity elements had much lower contributions to lambda, indicating that the harvesting of seeds may have a low impact on population growth. However, the population growth was highly sensitive to changes in survival probability, particularly among trees of 5-10 cm, diameter at breast height (dbh). The last stages, containing the large reproductive individuals over 10 cm dhb, which are interesting for the bark extraction, accounted for lowest elasticity, indicating that the extraction of bark may have at least a low impact on population growth. Thus, there maybe a good scope for sustainable extraction of G. lucida bark in these stages. The size-class 5-10 cm dbh proved by loop analysis to be the most important reproductive stage for population maintenance. However, individuals in this size-class are also exploited by forest gatherers, and increased exploitation pressure on trees in this size-class is likely to have a considerable impact on the population growth and to compromise the scope for sustainable exploitation of this resource. (C) 2002 Elsevier Science B.V All rights reserved

Ecological research in the perspective of using forest in adaptation to climate change in Cameroon (Central Africa)

Understanding the vulnerability of forest and forest related sectors to climate change, mainstreaming the use of forest into adaptation strategies are some of the challenges faced by forestry research, developers and stakeholders. Despite the multiple efforts to mitigate climate change, it is well established that climate change will occurred and will increase the vulnerability of developing countries, particularly the poorest population. This group of population is well reprented in developing countries and depends mainly on rain related activities for their basic subsistence. As they rely on forest resources for their subsistence, looking in these natural resources ways to help them cope with these changes is the challenge of the forest and climate change managers. For the research communities of the developing countries, it not always evident on how to shift from the existing ecological research framework to the new one in which they assess vulnerability of forest but also their use in the adaptation to climate change. The current presentation in the context of Cameroon highlighted (1) the impact of climate change in forestry related sectors, (2) The current ecological research infrastructure, (3) what is needed to properly integrate forest resources uses in adaptation plan and thus enable the proper use of forest resources to adapt to climate change

Structure of cocoa agroforest of Southern Cameroon

This study determined the structure of cocoa plantations along a continuous gradient of market access, population density and resource use intensity in the humid forest zone of southern Cameroon. The study area comprises the sub-regions of Yaoundé, Mbalmayo, and Ebolowa. Market access, population density and resource use intensity all decreased from the first to the third sub-region. For cocoa and associated plants, we determined (i) the density; (ii) the basal area across strata; (iii) the total structure of associated plants; and (iv) the typology of agroforest based on cocoa and other trees (including Musa species and oil palms). Cocoa agroforests of southern Cameroon present a variation of structures that offer several management options for biodiversity conservation and fulfilment of other socio-economic and ecological services

Structure and composition of cocoa agroforests in the humid forest zone of Southern Cameroon

Published online: 23 April, 2016The distribution and composition of the tree component inside cocoa agroforests plays an important role in the economic and ecological services offered by these plantations. The presence of these plant components appears to be influenced by several factors controlling the introduction and management of associated plants inside cocoa agroforests. To date, few studies have tried to evaluate the horizontal and vertical distribution of plants inside cocoa plantations in Cameroon. This study determines the structure of cocoa plantations in Southern Cameroon. Field data were collected in 60 cocoa plantations belonging to 12 villages located along a contiguous gradient of market access, population density and resource use intensity in the humid forest zone of southern Cameroon. This study area comprises (i) the sub-region of Yaoundé, (ii) the sub-region of Mbalmayo, and (iii) the sub-region of Ebolowa. Market access, population density and resource use intensity all decreased from the first to the third sub-region. For cocoa and associated plants, we quantified (1) the density (2) the individual number, the species composition and the group uses of plants (edible, timber, medicinal, etc…) distribution across strata, and (3) the basal area in the 60 cocoa plantations located in the three main sub-regions. Results are presented for each sub-region and the whole study area. The paper develops cocoa agroforest typologies and discusses possible implications of cocoa agroforest structure diversity in the achievement of economic and ecological services