Terrestrial herb communities of tropical submontane and tropical montane forests in Central Sulawesi, Indonesia

Abstract

Although the diversity of terrestrial herbs is high tropical forests and although herbs may play important roles, e.g., as competitors of tree seedlings, most tropical botanical research to date has focused on trees. We studied the diversity, taxonomic composition, and biogeographical relationships of terrestrial forest herbs at two sites of tropical mountain forest at different elevations (Pono: 1000 m, Bariri: 1400 m) in Central Sulawesi. The study was conducted in 400 plots of 5 × 5 m2 (200 for each site). At Pono, we recorded 91 angiosperm herb species in 28 families, and 112 ferns and lycophytes in 15 families whereas at Bariri we found 77 angiosperms in 25 families and 94 ferns and lycophytes in 20 families. At both sites, the most species-rich angiosperm families were Araceae, Orchidaceae, and Zingiberaceae. The species numbers recorded by us are much higher than those reported in any previous tropical forest herb inventories and point to a previously underappreciated richness of plant assemblages on Sulawesi. Biogeographically, significantly more fern species reached their western than eastern distributional limits on Sulawesi, showing that the zoogeographical Wallaces line separating continental Asia and its shelf islands from the Moluccan region also holds for spore-dispersed plants.