ASIAN JOURNAL OF FORESTRY Volume 2, Number 1, June 2018 E-ISSN: 2580-2844 Pages: 12-19 DOI: 10.13057/asianjfor/r020102 Nutrient distribution on soil and aboveground biomass of Macaranga gigantea five years after planting DWI SUSANTO 1, , RATNA KUSUMA 2 , RUDIANTO AMIRTA 3 1,2 Department of Biology, Faculty of Mathematics and Natural Sciences, Mulawarman University. Jl. Barong Tongkok No. 4, Gunung Kelua, Samarinda Ulu, Samarinda-75123, East Kalimantan, Indonesia. Tel./fax.: +62-541-749140, 749152, 749153, ♥ email: susantodwiki@yahoo.com 3 Faculty of Forestry, Mulawarman University. Jl. Ki Hajar Dewantara, Kampus Gunung Kelua, Samarinda 75123, East Kalimantan, Indonesia Manuscript received: 27 September 2017. Revision accepted: 2 April 2018. Abstract. Susanto D, Kusuma R, Amirta R. 2018. Nutrient distribution on soil and aboveground biomass of Macaranga gigantea five years after planting. Asian J For 2: 12-19. The aims of this study were to evaluate growth of M. gigantea and to calculate nutrient distribution in the soil and 5-year-old M. gigantea. Soil sampling was conducted in all research plots with drill ground at a depth of 0-30 cm and 30-60 cm. The tree biomass was sampled within one stand to calculate the biomass of all the trees within a particular plot. The research findings revealed that plot 5 produces the best growth performance and the plant accumulates 2 times of N, P, K, Ca, Mg nutrients on wood, bark, branches, and leaves, compared to the plants in plots 1. The most distributed nutrients in the soil were magnesium, nitrogen, calcium, and phosphorus. Whereas the most accumulated nutrient in plant was potassium. The relative portion of K nutrients accumulates in the soil is quite small that is 44.18% but in stand was higher that is between 55.82%. It concluded that if the M. gigantea harvested at 5 years, it needs to give attention to potassium nutrient for the next of planting cycles. Keywords: Biomass, Macaranga gigantea, distribution nutrient, soil INTRODUCTION Macaranga gigantea is tree species that grows naturally in the lowland of tropical rainforest gaps after shifting cultivation (Susanto et al. 2016b), forest fires (Silk 2008) and timber harvestings (Susanto et al. 2017a). This species also potentially as a bioethanol feedstock (Amirta et al. 2016). The plant reproduces by forming flower buds initiated in the dry season and the fruits ripened in the rainy season. The seeds that fell under the tree germinated in approximately 24 days (Susanto et al. 2016a). Bentos et al. (2008) also reported that the flowering of pioneer trees happening at the end of the dry season and fruiting happening at the beginning of the wet season. M. gigantea seeds have low water content, classified into orthodox seeds and produce low seed germination of 2-10% when using dry seed extraction treatment (Suita and Nurhasiby 2009). Mindawati et al. (2010) also reported that soaking the seeds into 0.2% potassium nitrate solution for 20 minutes before germinate on sand medium able increasing seed germination rates up to 20%. On the other hand, Susanto et al. 2016a reported that wet extraction without fruit drying treatment, able increased seeds germination (65%), with germination time first seeds (GTFS) 7.67 ± 1.15 days, germination time last seeds (GTLS) 17.33 ± 4.04, and mean germination times (MGT) 11.97 ± 1.93 days. In the germination process of M. gigantea seedlings showed that the highest relative growth rate obtained by seedlings planted on mushroom spawn waste media, followed by compost media, top soil media, and sand media. Lawrence 2001, reported that seedlings of M. gigantea grow rapidly over the first of 18 weeks when planted in polybags if enough supplied with a combination of nitrogen and phosphorus fertilizers. While, M. gigantea 6 months after planting in degraded land from unused log piles in Malaysia, indicates that nutritional deficiency is an important factor that inhibits early growth of this plant (Nussbaum in al. 1995). Susanto et al. (2016b) reported that in secondary forests after shifting cultivation, M. gigantea plants accumulate phosphorus and potassium nutrient mostly in the leaves part. On the other hand, in secondary forest after selective logging, M. gigantea most accumulated nutrients potassium, calcium, and magnesium. It suggested that bases nutrients, potassium, calcium, and magnesium, large quantities absorbed by M. gigantea and extremely important to its growth (Susanto et al. 2017a). In monoculture system, M. gigantea was fertilized with NPK fertilizer treatment (age of 1 year), and the most nutrient element accumulated were potassium, followed by phosphorus and then nitrogen (Susanto et al. 2017b). There is lack information about nutrients content distribution in the soil and aboveground biomass of M. gigantea. Therefore, our research focuses on the growth evaluation and soil nutrients and aboveground biomass distribution on 5 years M. gigantea planted using monoculture system. This information is very important in the sustainable of M. gigantea plantation.