Rain Forest Fragmentation and Environmental Dynamics on Nosy Be Island (NW Madagascar) at 1300 cal BP Is Attributable to Intensified Human Impact

Madagascar houses one of the Earth’s biologically richest, but also most endangered, terrestrial ecoregions. Although it is obvious that humans substantially altered natural ecosystems during past decades, timing arrival early inhabitants on as well their environmental impact still intensively debated. This research aims to study beginning human Malagasy ecosystems, specifically Nosy Be island (NW Madagascar) by targeting sedimentary archive Lake Amparihibe, an ancient volcanic crater. Based pollen, fungal spore, other non-pollen palynomorph, charcoal particle and diatom analyses combined with high-resolution sediment-physical (in)organic geochemical data, paleoenvironmental dynamics three millennia were reconstructed. Results indicate a major change at ca. 1300 cal BP characterized abrupt development grass (C 4 ) dominated fire disturbed landscape showing alteration rain forest. Further, increased soil erodibility suggested distinct increase in sediment accumulation rates, strong pulse nutrient input, higher water turbidity contemporaneous spores mycorrhizal fungi. These parameters are interpreted show anthropogenic transformation from forest open grassland. After 1000 BP, fires remain frequent vegetation forest/grassland mosaic. While should be Be, these last results continuously impacted landscapes surrounding lake. At local scale, our data support “subsistence shift hypothesis” which proposed population expansion herding/farming ecosystems. However, precise regional synthesis challenging, since multi-proxy records continuous archives located further north hinterland scarce Madagascar. The lack such prevents comparison between different regions detect potential (dis)similarities climate dynamics, ecosystem responses influences island’s scale (late) Holocene.