Bois et forêts des tropiques

Abstracts & articles: n° 331
(1st quarter 2017)


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(In French, English and Spanish)

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Issue 331


 

HOW HAVE ENVIRONMENTAL CONCEPTS RESHAPED THE AGROFORESTRY CONCEPT?

M. Barisaux

Environmental sciences and concepts have evolved a great deal in the last three decades. This study aims to account for the way environmental concepts have changed and to describe the consequences for the concept of agroforestry. The study is based on a bibliometric analysis carried out on the Web of Science, and summarizes the literature collected on the subject. Examples are given to support the analysis: agroforestry-based coffee-growing in the Western Ghats in India, cocoa in Ivory Coast and jungle rubber in Indonesia. Agroforestry evolved considerably with the emergence of the biodiversity and ecosystem concepts, and conservation science now also covers ecosystems that have been modified by humans. The development of agroforestry can be compared with that of agroecology: a study on the Web of Science shows a similar pattern in the last two decades. Although the recognition of agroecology as a science has introduced new ways of managing agroforestry systems, the way agroforestry has developed and its broad scope of application may have disconnected it somewhat from reality on the ground and from the farmers who actually practice it. Precautions are therefore needed in designing and managing these systems: farmers’ expectations, in contexts that are determined at once by social, economic and political factors, must not be ignored, and agroforestry systems should not be exclusively geared to productivity. Agroforestry cannot evolve as an environmental concept if it is voided of its most fundamental goal, which is to bring sustainable improvements to farming livelihoods.

Keywords: agroforestry, environment, biodiversity, agroecology, conservation, smallholder.


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PHYSICAL, MECHANICAL AND NATURAL DURABILITY PROPERTIES OF WOOD FROM REFORESTATION PINUS HALEPENSIS MILL. IN THE MEDITERRANEAN BASIN

M. T. Elaieb, F. Shel, S. Elouellani, T. Janah, M. Rahouti, M.-F. Thévenon, K. Candelier

Pinus halepensis Mill. was introduced into regions with a Mediterranean climate as an ornamental tree, and is now often found in parks and gardens. At present, Aleppo pine (Pinus halepensis Mill.) forests cover approximately 2,500,000 ha in the Mediterranean Basin, mostly at low altitudes (less than 500 m) and along the coast. It has become naturalized outside cities in North Africa to the extent that it is now listed as an invasive species there. Because of its size (over 15 m in height and 30 cm in diameter), Pinus halepensis could be a good potential green resource for structural material in Tunisia. The focus of this study was to assess rot resistance and the physical and mechanical properties of reforestation Aleppo pine from the Mediterranean basin. The Pinus halepensis wood samples studied were collected from 6 tree provenances in Tunisia for physical and mechanical characterization and from Morocco for decay and termite resistance tests. Densities and shrinkage were determined and mechanical and rot resistance tests performed. Preliminary results showed that Tunisian Pinus halepensis wood has great dimensional stability. Although the compressive strength of Pinus halepensis wood is high, its bending strength is rather low for each of the provenances. MOR in bending is lower than in other Tunisian softwood species. Finally, Pinus halepensis sapwood has low resistance to fungi and termites. This timber species could be valuable for furniture and/or as a building material provided that a wood preservation method is applied before it is used.

Keywords: Pinus halepensis, Aleppo Pine, rot resistance, Maghreb reforestation areas, mechanical properties, physical properties, tree stand density.


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LOCAL PERCEPTIONS OF INTERACTIONS BETWEEN ELEPHANTS AND BORASSUS AETHIOPUM MART. (ARECACEAE) IN THE PENDJARI NATIONAL PARK IN BENIN

J. S. H. Houndonougbo, V. K. Salako, R. Idohou, F. A. Azihou, A. E. Assogbadjo, R. Glèlè Kakaï

Elephants are reported to have a dramatic impact on woody vegetation in protected areas. Careful control of elephant and wood species populations is therefore crucial to successful biodiversity management in such ecosystems. The perceptions of local people and protected areas managers could very usefully supplement classic ecological surveys and monitoring to achieve this goal. This study assessed the perceptions of managers and local people regarding the causes, damage, consequences and management options of elephant pressure on the declining dioecious palm Borassus aethiopum. The study was conducted in the Pendjari National Park, which is part of the W-Arly-Pendjari transboundary complex of reserves in West Africa. Semi-structured interviews were conducted with 53 respondents belonging to three socio-professional categories: administrators, ecoguards and local professional hunters. Relative frequency of citation and the Pearson correlation were used to assess the consensus and concordance of their perceptions, respectively. The respondents reported a steep increase in the number of elephants in the Pendjari National Park, which they attributed to significant elephant migration from transboundary parks where poaching pressure was perceived as high. This has resulted in high pressure on tree species including B. aethiopum. Despite differences in professional outlook, consensual and concordant opinions were noted among administrators, ecoguards and local professional hunters on the relationship between B. aethiopum and elephants. A regional approach aiming to protect the elephant population (low poaching) in the W-Arly-Pendjari complex and other neighbouring reserves was suggested in order to limit elephant migration.

Keywords: African fan palm, elephant, pressure, reserve managers, savannah, West Africa.


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PHYSICAL AND MECHANICAL PROPERTIES OF TEAK WOOD FROM TANZANIAN AND LOCAL PROVENANCES IN BENIN

M. C. Hounlonon, C. A. Kouchade, B. B. Kounouhewa

Teak (Tectona grandis L. f.) is a tropical timber species which is in great demand. In Benin, the two most commonly planted teak varieties are of Tanzanian and local provenances. To contribute to the characterisation of teak from Benin, we determined and compared, for each provenance, the elasticity and shear modulus, height of the bole, the circumference and bark thickness at felling height, the percentage of heartwood, the circumference 1.30 m from the ground and the density of the wood at a 12 % moisture content. The samples were taken in the Lama plantations from trees of 20 to 25 years of age (6 logs of local provenance 4 of Tanzanian provenance). The results obtained with these samples indicate that for this age class, the values for these properties are higher for the local teak than for the Tanzanian teak, except for the percentage of heartwood. Based on our sample, therefore, the local teak wood is of a fair quality that should be enhanced through biological selection or cloning of the specimens best able to adapt not only to climate change but also to soil structure. This would help to promote teak production across the entire country and even the sub-region. However, establishing a hybrid variety that combines the advantages of both provenances could also be a major step towards improving all tree species used in Benin.

Keywords: teak, Tectona grandis, elasticity modulus, shear modulus, Lama, Benin, Tanzania.


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MEDICINAL PLANTS IN FOREST STANDS AROUND THE BAY OF RIGNYANTSIRANANA IN MADAGASCAR

S. Rakotonandrasana, A. Rakotondrafara, R. Rakotondrajaona, V. Rasamison, M. Ratsimbason

Ethnobotanical surveys were conducted on the forest stands around the Bay of Rigny-Antsiranana in Madagascar. These stands are key zones for Madagascar’s biodiversity and the main source of supply of useful plants for the local population. The survey covered thirtyeight forest stands of 15 to 80 years of age and was conducted with traditional healers and parents familiar with medicinal plants, either during trips into the forest or by showing them herbarium specimens. The survey method chosen was based on individual semi-structured interviews. Fifty-three medicinal plant species belonging to 50 genera and 28 families were identified. Thirty-eight of these (68.6 %) are endemic to Madagascar. The ten most frequently used species had a high loyalty index for treating the ailments for which they are indicated. Nineteen species had a high loyalty index (> 60 %) for several different ailments. Our respondents associated the largest number of medicinal plants with ailments related to the digestive system (stomach aches and diarrhoea), with non-specific health problems (wounds and fatigue), infections and parasitic diseases (malaria) and puerperal problems, as well as with pregnancy and childbirth. The loyalty indices for Adansonia madagascariensis and Senna alata, used to treat weight loss and high blood pressure respectively, were also high. All these health problems are common in Madagascar. The forest stands around the Bay of Rigny-Antsiranana are a medicinal plant reservoir for Madagascar’s northern region. Local knowledge on these plants is passed on orally and not written, and could be lost. The natural vegetation is under threat from human pressure, and because no conservation plan exists. Studies on the chemistry and pharmacology of these endemic species are essential to protect them and develop their use.

Keywords: ethnobotany, medicinal plants, Bay of Rigny-Antsiranana, Madagascar.


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CHEMICAL COMPOSITION AND ETHNOBOTANICAL USES OF ACACIA JACQUEMONTII BENTH. IN THE THAL DESERT IN PAKISTAN

F. Rasool, M. Ishaque, S. Yaqoob, A. Tanveer

This study was conducted in 2014 at the department of botany and the nutritional laboratory of Faisalabad University of Agriculture, in order to assess the chemical composition of Acacia jacquemontii Benth. and its ethnobotanical uses in local communities of the Thal desert in Pakistan. To determine its chemical composition, mature leaves and pods of the species were collected in the field and composite samples were prepared. Their chemical composition was then determined for crude protein, fat, fibre, ash, micro and macro-elements, total phenolics, flavonoids, total tannins, alkaloids and saponin. An interview schedule was developed to assess ethnobotanical uses of A. jacquemontii by local communities for food, shelter and medicine. Thirteen local people and thirteen Hakims involved in traditional uses were interviewed. Our results showed that the leaves and seeds of the species contained respectively 22% and 33% of crude proteins and 49% and 15% of crude fibre. Fats in the leaves and seeds amounted to 17% and 28%. The leaves contained 0.1% phosphorus, 0.6% potassium, 1.2% calcium, 0.1% sodium and 0.6% magnesium and micro-elements: iron (246 ppm), manganese (29.2 ppm), zinc (27.9 ppm) and copper (14.4 ppm). The amounts of alkaloids, flavonoids, saponins, tannins and total phenolics found in the leaves were 5.8, 168, 196, 124 and 137 respectively. Our results for ethnobotanical uses showed that besides using this shrub for shelterbelts, firewood, fodder and medicines, local people have strong religious beliefs, calling A. jacquemontii the ‘shrub of the ghosts’ and believing in its “magic” powers in the practice of necromancy. It was used in the past by Greek practitioners in this area to treat common ailments.

Keywords: chemical compounds, local uses, nutrients, phenolics, Thal desert, Pakistan.


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