Floristics and structure of a lowland dipterocarp forest at Wanariset Samboja, East Kalimantan, Indonesia

KARTAWINATA, K., PURWANINGSIH, PARTOMIHARDJO, T., YUSUF, R., ABDULHADI, R. & RISWAN, S. 2008.Floristics and structure of a lowland dipterocarp forest at Wanariset Samboja, East Kalimantan, Indonesia. Reinwardtia12(4): 301– 323. — The results of a floristic inventory of trees with DBH < 10 cm in a lowland dipterocarp forest in EastKalimantan show that 553 species of 192 genera in 62 families, represented by 5847 individuals, with the total basalarea of 350.01 m2 occurred in the plot of 10.5 hectare sampled. The two leading families in terms of number of specieswere Myrtaceae and Lauraceae while according to the total sum of importance values for families wereDipterocarpaceae and Euphorbiaceae. The forest had the second highest species richness in Indonesia. We recorded25 species of dipterocarps , constituting 4.53 % of total species with basal area of 85.53 m2. or 24.44 % of the totalbasal area in the plot. Shorea laevis (a diptererocarp) and Pholidocarpus majadum, (a palm) were the most prominentspecies occurring here and were two of the ten leading species. The species-area curve rose steadily even up to anarea of 10.5 hectare, with a very slight indication of levelling off at about five hectares, indicating high heterogeneityof the forest. Three largest trees were Shorea pauciflora (DBH = 196.50 cm) Dipterocarpus cornutus (DBH = 170.90cm), and Alstonia scholaris (DBH = 170.00 cm) , Some species could be identified as fruit trees and medicinal plants.