Amazonian White-Sand Forest
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BOIS ET FORÊTS DES TROPIQUES, 2013, N° 315 (1) 63 FORÊTS SUR SABLES BLANCS Ruth de Oñate-Calvín1 Alfonso San Miguel-Ayanz1 Juan Orensanz-García2 Angel A. Salazar-Vega3 1 Sonia Roig-Gómez Amazonian White-Sand Forest: 1 Universidad Politécnica de Madrid A Black Future? ETSI Montes Ciudad Universitaria s/n. E-28040 Madrid Spain 2 Departamento de Agricultura Ganadería y Medioambiente Diputación General de Aragón Plaza San Pedro Nolasco, 7 E-50071 Zaragoza Spain 3 Instituto de Investigaciones de la Amazonía Peruana (IIAP) Av. Abelardo Quiñones km 2,5 Iquitos, Dpto. Loreto Perú Photograph 1. Typical aspect of a Peruvian white-sand forest (varillal) showing a high density of small diameter stems. Photograph R. de Oñate. BOIS ET FORÊTS DES TROPIQUES, 2013, N° 315 (1) 64 WHITE SAND FORESTS R. de Oñate-Calvín, A. San Miguel-Ayanz, J. Orensanz-García, A. A. Salazar-Vega, S. Roig-Gómez RÉSUMÉ ABSTRACT RESUMEN LA FORÊT AMAZONIENNE SUR SABLES AMAZONIAN WHITE-SAND FOREST: EL BOSQUE SOBRE ARENAS BLANCAS BLANCS : UN SOMBRE FUTUR ? A BLACK FUTURE? AMAZÓNICO: ¿UN FUTURO SOMBRÍO? Les forêts amazoniennes sur sables Amazonian white-sand forest, a distinc- Los bosques sobre arena blanca amazó- blancs sont des peuplements arborés tive and fragile type of lowland rainforest, nicos son un tipo singular y frágil de bos- très particuliers et fragiles, dispersés en usually occurs on scattered highly olig- que tropical húmedo de selva de zonas zones basses humides sur des dalles de otrophic soil patches and holds a high bajas, que aparecen dispersos sobre sols fortement oligotrophes, qui recèlent number of endemism species. It is nei- teselas de suelo muy oligotrófico y alber- un fort endémisme végétal. Ces surfaces ther suitable for agriculture nor for timber gan un alto porcentaje de endemismos. boisées sont dédaignées pour leur mise production. However, it is a valuable No son susceptibles de aprovechamiento en culture ou l’exploitation du bois, mais resource for local communities since its maderero ni de uso agrícola, pero su néanmoins leurs tiges de faible diamètre, small diameter (5-15 cm) straight round madera redonda de pequeño diámetro compris entre 5 et 15 centimètres, détien- wood shows long durability and is widely (5-15 cm) posee gran durabilidad y es un nent une forte durabilité et constituent used for house building. Despite that, recurso extraído tradicionalmente por los une ressource traditionnellement extraite local management remains invisible to pobladores locales para construir sus par les populations locales pour forestry regulation and it might blacken viviendas. A pesar de ello, este aprove- construire leurs logements. Toutefois, the future of Amazonian white-sand chamiento local permanece invisible cette valorisation locale reste invisible forests. The purpose of this work is to para la reglamentación forestal, lo que vis-à-vis de la réglementation forestière, provide basic knowledge on white-sand puede perjudicar el futuro de estos bos- ce qui pourrait aller à l’encontre de l’ave- forest stand structure and floristic com- ques sobre arena blanca. Este trabajo nir de ces forêts sur sables blancs. Cette position, which is essential for sustain- tiene por objetivo aportar conocimientos étude a pour objectif d’apporter les able management planning. It shows básicos sobre la estructura forestal y la connaissances de base de structure that, in spite of its fragility, white-sand composición florística de estos bosques, forestière et de composition floristique, forests also show some strengths regard- lo que es esencial para poder planificar essentielles pour mener à bien la gestion ing sustainable management possibili- un gestión sustentable. Los resultados durable de ces massifs forestiers. Les ties, as compared to other rainforests: muestran que, a pesar de su fragilidad, résultats montrent que, malgré leur fragi- the high percentage of valuable species los bosques sobre arena blanca también lité, ces forêts sur sables blancs présen- (26 %), the striking dominance of a small presentan ciertas ventajas en vista de tent aussi certains atouts du point de vue set of species most of them (67 %) with sus posibilidades de gestión sustentable de leurs possibilités d’aménagement par commercial interest and the fact that en comparación con otro tipo de bosques rapport aux autres types de forêts tropi- potentially harvestable stems only tropicales húmedos: debido a un alto cales humides : il s’agit d’une forte fré- account for seventeen percent of the porcentaje de especies comerciales quence (26 %) d’espèces de valeur, de la total basal area, induce that technical (26 %), a la clara dominancia de un remarquable dominance d’un petit requirements like “Reduced Impact Log- pequeño grupo de especies, la mayoría groupe d’espèces, dont la plupart (67 %) ging” are not necessary since harvested de ellas (67%) con interés comercial y al sont d’intérêt commercial, et du fait que stems are thin, no machinery is involved hecho de que los fustes potencialmente les tiges potentiellement utiles ne comp- and transportation is carried out only on aprovechables sólo suponen el diecisiete tent que pour dix-sept pour cent de la sur- foot and/or by river. porciento de la área basimétrica total, face terrière ; et il en résulte que dans la resulta que en la situación actual, no es situation actuelle, il n’est pas nécessaire Keywords: white-sand forest, round necesario aplicar técnicas de aprovecha- d‘appliquer des techniques telles que wood, species diversity, stand structure, miento de impacto reducido, puesto que l’exploitation à faible impact, puisque les tropical forest, round varillal. los pies aprovechados son de pequeño pieds exploités sont de faible taille, que diámetro, que no se utiliza maquinaria y les engins mécaniques ne sont pas utiles que el transporte se realiza únicamente a et que le transport est réalisé à dos hombros y/o por flotación. d’homme et/ou par flottaison. Palabras clave: bosque sobre arena Mots-clés : forêt sur sables blancs, bois blanca, madera redonda, diversidad de rond, diversité d’espèces, structure du especies, estructura forestal, bosque tro- peuplement, forêt tropicale, bois varillal. pical, madera varillal. BOIS ET FORÊTS DES TROPIQUES, 2013, N° 315 (1) 65 FORÊTS SUR SABLES BLANCS Introduction Sustainable Forestry (SF) has been a major topic for scientific debate since the XIXth century. Achieving SF is particularly difficult in tropical moist forests due to their extremely high levels of structural and biological diversity, the complexity and intensity of their deficiently known webs of plant-animal relation- ships and social implications, espe- cially regarding local communities (GÜNTER et al., 2011). Most scientific literature dealing with SF concen- trates on Sustainable Timber Yield (STY) of valuable species and Sustain- able Forest Management (SFM). Like- wise, the forestry and environmental institutional control concentrates on timber yield in most tropical coun- tries. However, there is usually neither control nor management regulation on other renewable products which Photograph 2. Wooden house structure made with small diameter round are not suitable for exportation but wood coming from white-sand forests. are often highly valuable for local Photograph R. de Oñate. communities (SHACKLETON et al., 2011). That is the case of edible and medicinal plants (HERRERO-JAUREGUI et al., 2009), some 1996; PROCTOR, 1999; FINE et al., 2006, 2010). Maybe due palm species, such as Irapay, Lepidocaryum tenue Martius, to the same reasons, they show a rather low biodiversity lev- whose leaves are used for thatching rural houses, or small els but a high number of plant and animal endemisms and diameter round-wood, an essential material for wooden thus should be prioritized for conservation (AUBRÉVILLE, house structures. Their exploitation and trade is either 1958; DUIVENVOORDEN, 1996; FINE et al., 2010). unregulated or usually escapes regulation and thus remains White-Sand forest is neither suitable for agriculture nor hidden or invisible to regional Institutions. The achievement for timber harvesting. However, it is a highly valuable of the long-term maintenance of the ecosystems providing resource for local communities, since the small diameter (5- those useful resources (the so-called coarse-grain or sys- 15 cm) straight round wood of many of its typical species temic conservation approach) requires the incorporation of shows long durability for house building (photograph 2). human needs as a conditioning factor of management strate- That is why its trade is also a major source of money for rural gies (MEFFE et al., 2002; GUARIGUATA et al., 2010; POKORNY families (VALDERRAMA, 2003; PYHÄLÄ et al., 2006). et al., 2010) and hence the implementation of an integrated, Although harvesting usually concentrates only on commer- adaptive, community-based management approach. cial species and sizes (diameter and length) the increasing White-Sand (WS) forest, or heath forest, a distinctive demand of WS forest products might lead to unsustainable and fragile type of lowland rainforest (photograph 1), usually management mostly in the environs of rivers, towns, villages occurs on highly oligotrophic siliceous-sand soil patches and other human settlements. Since in the outsides of scattered throughout other extensive types of lowland rain urban centres, slums are built basically with small diameter forest (AUBRÉVILLE, 1958; ANDERSON, 1981; PROCTOR, round wood. On the other hand, the white sand of these 1999). It has been found in South America