2010). Above 2000 m a.s.l., there is also an increasing quantity of mosses (Frahm and Gradstein 1991). Southeast Asian forests of the montane zone have been broadly characterised as evergreen Lauro-Fagaceous forests with high diversity and abundance of tropical Fagaceae (Ashton 1988, 2003; Ohsawa 1993; Soepadmo 1972; Corlett 2007). In mountain

forests of Central Sulawesi, the Fagaceae make up to >50% of the aboveground biomass; tree family abundances associated with biogeographical and phylodiversity patterns steadily change along the elevational gradient (Culmsee et al. 2010). As part of Wallacea, the island of Sulawesi is positioned at the biogeographical crossroads between East Asia and Australasia (Wallace AZ 628 mouse 1869),

and between the Laurasian and Gondwanan continents (Primack and Corlett 2006). It has a long history as a large oceanic island. Extremely high rates of plate convergence resulted in the island’s configuration of partly southeast Asian and partly southwest Pacific origin (Hall 2009). Roos et al. (2004) attributed the unusual biogeographical composition of the flora of Sulawesi, comprising eastern and western Malesian centred floristic elements, to its complex geological history, but found relatively low species richness and endemism rates in comparison to the bigger Malesian islands which had land connections on the Sunda and Sahul shelves. In this article, the tree diversity of mountain rain forests was studied at Mt Nokilalaki and Mt Rorekautimbu, two peaks situated within Lore Lindu National Park,

Central Sulawesi. This is the find more first study in Sulawesi that includes both thorough floristic and quantitative, plot-based tree diversity data from high montane old-growth forests. The purpose of this study is to contribute to a better knowledge of the composition and origin of the high mountain tree flora of Sulawesi. The lack of taxonomic Calpain data from this region suggest a high see more number of new species distribution records to be discovered. Specifically, we analysed the tree species richness, species composition and tree family importance values (FIV) based on quantitative plot data comparing forests from two different elevational belts. In addition, phytogeographical patterns were investigated by comparing the forests at different elevations and by considering endemism rates and biogeographical distribution patterns of the tree species in the Malesian context. Methods Study area The study sites were located in primary forests on the slopes of Mt Nokilalaki (S 01°14.6′, E 120°09.2′, GC-WGS 84) and Mt Rorekautimbu (S 01°16.8′, E 120°18.5′, GC-WGS 84), which are among the highest peaks in the Lore Lindu National Park, Central Sulawesi, Indonesia (Fig. 1). The forest conditions have been classified as good to old-growth (Cannon et al. 2007). Mid-montane forests were investigated at Mt Nokilalaki at c.