The impact of human activities on tropical ecosystems has increased dramatically in recent decades leading to a global reduction of primary forests (Laurance 1999, Morris 2010). For tree species, fragmentation of forests into patches has led to degradation of both their habitat and

1Laboratoire de Microbiologie de l’Environnement, Centre National de Recherches sur l’Environnement BP 1739 Fiadanana Antananarivo 101, Madagascar. 2Laboratoire des Symbioses Tropicales et Méditerranéennes (LSTM), UMR 113 CIRAD/INRA/ IRD/SupAgro/UM2, Campus International de Baillarguet, TA A-82/J, Montpellier, France. *Corresponding author: [email protected]

ecological processes such as biogeochemical cycling and community dynamics (Weaver and Kellman 1981). The forest ecosystems of Madagascar are recognized as being among the most species-rich around the world (Myers et al. 2000). Approximately 80% of the plant species of Madagascar are endemic and the island contains a wealth of fauna and fl ora (Mittermeier et al. 2004), but they have been seriously impacted by a combination of agricultural practices such as slash and burn culture, livestock production and logging, and ancient climate changes. More recently, during the last two centuries, the extent of the Malagasy forest has decreased dramatically. Today, primary vegetation probably covers only about 10% of the original area and dense forest has been reduced to a fragmented landscape (Myers et al. 2000). Similarly, in the highland of Madagascar, sclerophylous woodland dominated by Uapaca bojeri (Tapia forest) is the last remnant of primary forest. The main components of this formation are small endemic trees of Uapaca bojeri (family Euphorbiaceae), in some patches endemic shrubs such as Sarcolaena sp. (family Sarcolaenaceae), or Asteropeia sp. (family Asteropeiaceae) which also grow as subdominants. The Tapia forest plays an important role in local community livelihood as it provides fuel, wood and timber, medicinal plants, non-timber forest products, and many other sources of food and income (Kull et al. 2002). Additionally, Tapia forest provides important environmental services: e.g., protection against erosion, protection of water sources, and carbon sequestration. However, Tapia trees are threatened by human destruction through bush fi res, fi rewood collection, and charcoal production, and restoration efforts using native trees of this forest formation should be undertaken to preserve the entire ecosystem.