and Swietenia macrophylla were characterized and studied to find out and discover their potential utilization as suitable feedstocks for biofuel (ethanol) production. Characterization was done by evaluation of lignin, holocellulose and cellulose contents of woody biomass including the yield of reducing sugar (saccharification) after pretreated with alkaline (NaOH) at moderate temperature. Among 15 species of tropical forest wood biomass evaluated, our findings showed that M. gigantea was gave the highest yield of saccharified sugar (42.22%, weight of original wood dry basis) and also yield of theoretical ethanol (± 273 L/ton). We also found growth of M. gigantea was very fast to produce approximately 26,119 kg ha-1 dry biomass within 3 years. In general, the tropical wood biomass such as M. gigantea, A. moluccana, G. arborea, A. cadamba, and P. falcataria are suitable and potentially to be used as feedstocks for ethanol production due to their fast growing ability, availability and attractive chemical composition to produce high saccharified sugar and yield of ethanol.

Abstract. Amirta R, Haqiqi MT, Saparwadi, Septia E, Mujiasih D, Setiawan KA, Sekedang MA, Yuliansyah, Wijaya A, Setiyono B, Suwinarti W. 2019. Searching for potential wood biomass for green energy feedstock: A study in tropical swamp-peat forest of Kutai Kertanegara, Indonesia. Biodiversitas 20: 1516-1523. Recently, much attention has been focused on finding suitable plant species, from different forest ecosystems, having the potential to be used as sources of renewable energy. Most of such information was reported from the lowland forest area and only limited information is available regarding swamp-peat forest species, including their energy potency. Therefore, in this paper, plant diversity and energy potency of swamp-peat forest wood biomass were studied to reveal their potential as green energy feedstock. Physico-chemical characterization of wood biomass was performed using the American Society for Testing and Material (ASTM) protocols. Twenty-seven species of plants, consisting of 23 trees and 4 shrubs, belonging to 19 families were identified, amongst which Shorea balangeran had the highest importance value index (87.72%). The results showed that T. obovata exhibit the highest suitability to be used as energy feedstock indicated by the highest energy production of 4.60 MWh per ton of dry biomass, followed by L. indica (4.56 MWh/ton), D. excelsa (5.52 MWh/ton), F. rukam (4.20 MWh/ton), P. galeata (3.66 MWh/ton), S. caudatilimbum (3.61 MWh/ton), A. elmeri (3.59 MWh/ton), G. nervosa (3.49 MWh/ton) and G. bancana (3.42 MWh/ton). The high density of wood species correlated with the high value of energy potency. In contrast, the fast-growing tree and shrub species, such as K. hospita (1.76 MWh/ton), C. odorata (1.36 MWh/ton) and O. sumatrana (1.17 MWh/ton), showed lower energy potency. The most dominant plant species, S. balangeran gave only 2.96 MWh energy per ton of dry biomass and it was classified in the middle group of plant species suitable as green energy feedstock, along with other species, such as C. brachiata, C. rotundatus, P. javanicum, V. umbonata, L. speciosa, V. pinnata, and A. longifolius. Due to suitable energy properties, growth rate and also adaptability of this woody biomass, they can be exploited to support sustainable supply of biomass feedstock for the green electricity program in the study area.

Abstract. Yuliansyah, Haqiqi MT, Septia E, Mujiasih D, Septiana HA, Setiawan KA, Setiyono B, Angi EM, Saparwadi, Sari NM, Kusuma IW, Rujehan, Suwinarti W, Amirta R. 2019. Short Communication: Diversity of plant species growing during fallow period of shifting cultivation and potential of its biomass for sustainable energy production in Mahakam Ulu, East Kalimantan, Indonesia. Biodiversitas 20: 2236-2242. Fallow period is a time gap, as long as 15 years, for improving natural soil fertility of land used for traditional shifting cultivation, in the tropical areas commonly used by Dayak People in Borneo Island. During this period, many biomass plant species naturally grow and develop a new forest vegetation community with shrub and medium trees, dominated by fast-growing pioneer species. In this study, we investigated the plant diversity in fallowed shifting cultivation area in Batu Majang Village, Mahakam Ulu District, East Kalimantan Province, followed by analysis of the suitability of wood characteristics for energy production. We classified the study area according to the age of fallow period as: 1-3 years, 4-6 years, 7-9 years and 10-15 years. We found 29 species among which 13 were identified as the top species according to the highest value for important value index. Potential wood biomass production increased from 3.01 m3 ha-1 to 399.62 m3 ha-1. V. pinnata and M. pearsonii showed the highest dominance which is present in almost all area based on age classification groups. Wood from V. pinnata achieved the highest calorific valueof18.00 MJ kg-1 whereas N. cadamba and M. sericea were in the second and third places with the value of 17.30 MJ kg-1 and 17.28 MJ kg-1, respectively. Therefore, V. pinnata was an important species among all other species observed because of high adaptability and high energy content. In addition, possible energy production at the end of the fallow period of 15 years was 2.92 GJ ha-1.

Abstract. Adie MM, Krisnawati A. 2016. Identification of soybean genotypes adaptive and productive to acid soil . Optimalization of acidic land for soybean development can be performed through the provision of soybean variety adapted to low pH. A total of 13 soybean genotypes was identified for its performance on three acid soil sites in Lampung Province, Indonesia, from February to June 2015. Soybean variety adapted to acid soil (Tanggamus and Demas 1) were used as check varieties. The experiment was using Randomized Block Design, 15 traits and four replicates. The concentration of pH (H 2 O) in locations L1, L2 and L3 were 5.87, 5.04, and 4.73, respectively. The average yield in L1, L2 and L3 were 1.96 t/ha, 2.17 t/ha, and 1.92 t/ha, respectively. This showed that yield decrease as soil pH value decline. Genotype G4AB was consistently produced highest yield at pH 5.04 as well as at pH 4.73, hence the genotype G4AB was not only adaptive at low pH but also relatively productive. Based on yield in three locations, G4AB categorized as less stable. On the contrary, genotype G115H/Kaba//Kaba///Kaba-8-6 produced average yield of 2.23 t/ha, and categorized as stable in three sites of acid soil. Soybean genotype adaptive to acid soil was characterized by its ability to maintain the plant height, and followed by a high number of node per plant and pod per plant.