Revue d’Ecologie (Terre et Vie), Vol. 73 (3), 2018 : 283-292

283 SECONDARY SUCCESSION AND ROOT BIOMASS CHANGES IN MADAGASCAR DRY DECIDUOUS FOREST (MIKEA FOREST)

Tropical dry forest (TDF) can be characterized by a pattern of seasonal rainfall with dry periods of variable frequency, timing and extent. They are the most threatened terrestrial ecosystems in the tropics (Vieira & Scariot, 2006). Seventy percent of remaining TDF are considered to be at high risk and among the numerous threats, human activities and climate change (Miles et al., 2006). In southwestern Madagascar, due to land use conversion to slash and burn agriculture called locally hatsaky, 55 % of the dry deciduous forest of Mikea was cleared between 1971 and 2001 (Lasry et al., 2004). The Mikea, forest people, hunter-gatherers, a little-known group of between 1000 and 3000 people live in the deciduous forest of southwestern Madagascar called Mikea forest (Stiles, 1998). In contrast to the high degree of resilience of the eastern rain forest of Madagascar (Randriamalala

et al., 2007), post-cropping dynamics in southwestern Madagascar are characterized by transformation into savanna (Leprun et al., 2009; Raharimalala et al., 2010). After 30 years of fallow, the vegetation becomes a mixed assemblage of herbaceous and woody species characteristic of savanna (Leprun et al., 2009). Change in root biomass during tropical secondary