The large proportion of species found by us at single study sites also suggests that further exploration of additional sites in LLNP SB203580 purchase will likely reveal more species, not to speak of other mountain ranges elsewhere in Sulawesi. Future sampling should also be targeted to specific sites, especially

ultramafic and limestone formations due to their unique conditions and demonstrated endemism of rattan flora elsewhere (Dransfield and Manokaran 1994). We found rattan palms in all our study plots in and around the LLNP, with species numbers per site ranging from 3 to 15. In Northern Sulawesi, 13 and 18 species were found in an unharvested lowland region and an exploited montane forest area, respectively (Clayton et al. 2002). On Borneo and Java, Watanabe and Suzuki (2008) found 14 to 17 species in mixed lowland Dipterocarp forests, while 11 species were recorded in a similar habitat in Thailand (Bøgh 1996). These values are notably higher than at our lowland site at Saluki, but this was in a relatively dry and moderately disturbed forest. On Java, Watanabe and Suzuki (2008) found 7 rattan

species at mid-elevation, which is somewhat lower than the diversity found by us at Moa, Palili, and Pono at similar elevations. We conclude that the local species richness of rattan palms in the study region is in the same order of magnitude as that of other areas in Southeast Asia. A comparison of rattan densities between studies is more complex because different studies have MS-275 ic50 applied different cut-off values for the minimum size of the studied rattan individuals. Furthermore, the identification of young rattan plants is often difficult because not all of the important attributes (e.g. features of the stem) are developed. Elevational richness and density patterns The species richness of rattan palms in LLNP shows a humped-shaped elevational pattern with maximum richness at around 1000 m. This pattern contrasts with that usually found in palms (Bachmann et al. 2004, Kessler

Thiamine-diphosphate kinase 2001b), but corresponds to that found in rattan palms in Malaysia (Appanah et al. 1993) as well as in many other plant groups (e.g. Bromeliaceae: Kessler 2001b, ferns: Kluge et al. 2006). While the causes determining elevational richness patterns in plants remain poorly understood, available BIBW2992 ic50 explanations may be grouped into four factor complexes (McCain 2009), namely (1) current climatic variables such as temperature and humidity (Kessler 2001a; Bhattarai et al. 2004), which in turn determine energy availability and ecosystem productivity (Hawkins et al. 2003; Currie et al. 2004), (2) spatial aspects including regional areal size (Rosenzweig and Ziv 1999) and geometric constraints (Bachmann et al. 2004, Grytnes et al.