Ecological and Social Issues Availability and Uses of Four Timber Tree Species in Menabe, Madagascar
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BOIS ET FORÊTS DES TROPIQUES, 2009, N° 302 (4) FORÊTS SÈCHES 33 PROBLÈMES ÉCOLOGIQUES ET SOCIAUX Ecological and social issues Availability and uses of four timber tree species in Menabe, Madagascar Eliane Graf1 Lanto Herilala Andriambelo2 Jean-Pierre Sorg1 1 ETH Zurich Department of Environmental Sciences Universitätsstrasse 22 8092 Zürich Switzerland 2 ESSA Département des Eaux et Forêts BP 3044 Antananarivo 101 Madagascar Photograph 1. The supporting structure of this house under construction in Mandraotra is made of Cedrelopsis gracilis, one of the preferred species for this purpose. Photograph E. Graf. BOIS ET FORÊTS DES TROPIQUES, 2009, N° 302 (4) 34 DRY FORESTS ECOLOGICAL AND SOCIAL ISSUES E. Graf, L. H. Andriambelo, J.-P. Sorg RÉSUMÉ ABSTRACT RESUMEN DISPONIBILITÉ ET UTILISATIONS DE AVAILABILITY AND USES OF FOUR DISPONIBILIDAD Y USOS QUATRE ESSENCES À BOIS D’ŒUVRE TIMBER TREE SPECIES IN MENABE, DE CUATRO ESPECIES DE MADERA DANS LA RÉGION DE MÉNABÉ, MADAGASCAR DE CONSTRUCCIÓN EN LA REGIÓN MADAGASCAR DE MENABE, MADAGASCAR Les forêts sèches de l’Ouest de Mada- The western dry forests of Madagascar Los bosques secos de Madagascar gascar ont une grande valeur écolo- are highly valuable both ecologically occidental poseen un alto valor ecoló- gique et sociale. D’une grande diversité and socially. They are very rich in biodi- gico y social. Encierran una gran diver- biologique, elles sont une source versity and are an important source of sidad biológica y son una importante importante de produits forestiers timber and non-timber forest products fuente de productos forestales made- ligneux et non ligneux pour les popula- for people in rural areas. In Central rables y no maderables para las pobla- tions rurales. Au Ménabé central, Menabe, selective logging is increas- ciones rurales. En el centro de la región l’abattage sélectif accroît la pression ing pressure on a number of valued de Menabe, la tala selectiva aumenta sur plusieurs essences appréciées, qui species, which seem to be increasingly la presión sobre algunas especies semblent se raréfier. Cela pose des scarce. This is raising ecological and especialmente apreciadas y cuya pre- problèmes à la fois écologiques et social problems, since the species are sencia es cada vez más escasa. Esto sociaux, car la raréfaction de ces becoming endangered and people are plantea una serie de problemas ecoló- essences contraint les populations à having to switch to other less appropri- gicos y sociales, ya que la rarefacción prélever d’autres essences moins ate species. This study investigated de dichas especies lleva a la población adaptées. Cette étude est centrée sur the availability and uses of the four a buscar otras especies menos adap- la disponibilité et les utilisations des most important species used to build tadas. Este estudio analiza la disponi- quatre essences privilégiées pour le housing in Central Menabe, i.e. bilidad y usos de las cuatro especies bois d’œuvre dans le Ménabé central, Securinega seyrigii, Cedrelopsis preferidas para madera de construc- Securinega seyrigii, Cedrelopsis grevei, grevei, C. gracilis and C. microfoliolata. ción en el Menabe central, Securinega C. gracilis et C. microfoliolata. Plus pré- Specifically, we determined available seyrigii, Cedrelopsis grevei, C. gracilis cisément, il a été déterminé les stocks stocks and annual use in the two vil- y C. microfoliolata. Más concreta- disponibles et leur utilisation annuelle lages of Ampataka and Mandraotra. mente, hemos determinado las exis- dans deux villages, Ampataka et Man- The main question needing an answer tencias disponibles y su utilización draotra. La question principale était de was whether demand in the villages anual en dos pueblos: Ampataka y savoir si la demande villageoise peut can be satisfied in the long term. It Mandraotra. El principal interrogante être satisfaite à long terme. Il apparaît appears that there is an overall lack of consistía en saber si la demanda cam- que la régénération fait globalement regeneration. In Ampataka, Cedrelop- pesina podía verse satisfecha a largo défaut. À Ampataka, l’essence Cedre- sis grevei did not occur in the shoot plazo. Los resultados muestran una lopsis grevei est absente dans l’étage layer and in Mandraotra, all four ausencia global de regeneración. En végétatif tandis qu’à Mandraotra les species were absent. It is therefore Ampataka, Cedrelopsis grevei está quatre essences étaient absentes. Il likely that the availability of the four ausente en el piso vegetativo, mien- est donc vraisemblable que la disponi- species cannot satisfy demand in the tras que en Mandraotra las cuatro bilité des quatre essences est insuffi- villages in the long term. To reduce the especies están ausentes. Parece por sante pour satisfaire la demande villa- deficit in future, forest management tanto verosímil que la disponibilidad geoise à long terme. Afin de réduire ce schemes and uses should be adapted de las cuatro especies sea insuficiente déficit à l’avenir, les plans de gestion and improved, and regeneration para satisfacer la demanda campesina forestière et les modes d’utilisation processes need to be studied to a largo plazo. Si, en un futuro, se devront être améliorés et adaptés, et ensure better understanding. quiere reducir dicho déficit, habrá que des études devront être menées sur les mejorar y adaptar los planes de processus de régénération afin d’en Keywords: Cedrelopsis, Securinega, manejo forestal y los modos de utiliza- améliorer la connaissance. construction timber, availability, tim- ción. También habrá que realizar estu- ber uses, sustainability, western dry dios sobre los procesos de regenera- Mots-clés : Cedrelopsis, Securinega, forest, Madagascar. ción para mejorar su conocimiento. bois d’œuvre, disponibilité, utilisa- tions du bois, soutenabilité, forêt Palabras clave: Cedrelopsis, sèche occidentale, Madagascar. Securinega, madera de construcción, disponibilidad, utilización de la madera, sostenibilidad, bosque seco occidental, Madagascar. BOIS ET FORÊTS DES TROPIQUES, 2009, N° 302 (4) FORÊTS SÈCHES 35 PROBLÈMES ÉCOLOGIQUES ET SOCIAUX Introduction Materials Madagascar (together with the The purpose of this study was to and methods Indian Ocean Islands) is one of the 34 examine whether or not the availabil- identified biodiversity hotspots on ity of these four species can satisfy Study area Earth (Conservation International, village demand in the long term. 2007). About 85 % of its 10,000 to Specifically, we conducted a forest The study was carried out in the 12,000 plant species (Direction des inventory to determine available two villages in the Menabe region, Eaux et Forêts, 1996) and 94 % of stocks of these species in the forest Ampataka and Mandroatra (figure 1). its trees and shrubs (Koechlin, 1972) areas used by two villages and com- The study area has a semi-arid cli- are endemic. The biota is forest- pared the results with annual use of mate (Koechlin et al., 1997), with a dependent to a high degree (Dufils, the species. rainy season from November to 2003). Forest cover has been decreas- This study is part of a project on March/April and a dry season from ing at an alarming rate. Between 1990 “Participatory Landscape Manage- April to November. Average annual and 2000, forested areas decreased ment” (PFM) under way in the precipitation is 711 mm, and average by 9 % and covered 20 % of total land Menabe region. The project is aiming annual temperature 25.3°C (Walter, area in 2000 (Earth Trends, 2003). to “set up scientific bases for sustain- Lieth, 1967). Geologically, the terrain Different factors like slash-and-burn able, multifunctional and participa- is sedimentary sandstone and clay. or shifting cultivation have caused tory management of a forest land- Soils are of the tropical ferrous type forest degradation and deforestation. scape in Central Menabe” (Dirac et on sandstone (Le Bourdiec et al., Because of the rapid disappearance al., 2006). 1969). The resident forest is the so- of forested areas, a great many forest- dependent species are now threat- ened. The remaining forest areas are therefore of high ecological value. To conserve natural resources and biodiversity, the government of Madagascar undertook in 2003 to increase the protected area network from the existing 1.7 million hectares to more than 6 million hectares, or 10 % of the country’s area, within the next five years (Conservation International, 2003). Forests also have high social value as they are still an important local resource for rural populations. The four tree species investigated in this study (Securinega seyrigii Leandri, Cedrelopsis grevei Baill., C. gracilis J.- F. Leroy, C. microfoliolata J.-F. Leroy) are the most important species for hous- ing construction in Central Menabe (photographs 1 and 2). They are declining because of increased pres- sure from selective logging and for the local population, they are becoming increasingly hard to find in the forest (Haingomanantsoa, 2007). This is raising an ecological and social prob- lem, as the species are becoming endangered and people are having to switch to other less suitable species. Figure 1. Study area showing the study villages of Ampataka and Mandraotra. Source: adapted from Groupe de foresterie pour le développement (2006). BOIS ET FORÊTS DES TROPIQUES, 2009, N° 302 (4) 36 DRY FORESTS ECOLOGICAL AND SOCIAL ISSUES agricultural and forest products still play a major role (Sorg et al., 2003). Timber is used for different purposes, such as firewood and construction and to make fences, carts, pirogues or tools. But also, a lot of non-timber forest products like medicinal plants, food or honey are gathered by the vil- lagers. Forest areas are also impor- tant for hunting, rituals and cults (Favre, 1996). Species investigated Securinega seyrigii, Cedrelopsis grevei, C. gracilis and C. microfolio- lata are the most important and most valued species for housing construc- tion in Central Menabe. The wood is relatively hard, providing straight logs with high resistance to fungal and insect attacks. This facilitates construction and ensures both dura- bility and stability.