Tree diversity in sub-montane and lower montane primary rain forests in Central Sulawesi

The tree diversity of sub-montane and lower montane primary forests is studied in plot-based inventories on two sites in Lore Lindu National Park, Central Sulawesi. Out of 166 species in total, 50 % are new records for Sulawesi (19 %) or the Central Sulawesi province (31 %). Species richness decreases with altitude. In the submontane forest, the highest Family Importance Values (FIV) are reached by the Lauraceae, Fagaceae, Sapotaceae, Moraceae and Euphorbiaceae. In the lower montane forest, the Fagaceae are of major importance (FIV 71.9), followed at some distance by the Myrtaceae, Elaeocarpaceae and Lauraceae. For each site, a group of important families is identified that is of minor importance or absent on the other site. The comparison of basal area (BA), number of species and FIV with published plot-based studies in sub-montane and lower montane primary forests in Malesia (Borneo, Sulawesi, Papua New Guinea) reveals: 1) with 35.4 and 37.1 m² ha-1, the BA is comparable to that measured in Borneo and Papua New Guinea, but does not support previous findings of extremely high BA in Sulawesi forests; 2) species richness is comparable to that in Borneo and other Sulawesi forests, but lower than in Papua New Guinea; 3) decrease in diversity with altitude is in accordance with findings in Borneo; 4) in sub-montane forests, the Lauraceae are generally important; the Sulawesi studies are closely related to those from Papua New Guinea; 5) the lower montane forests have the Fagaceae and Myrtaceae as most important families in common.