BIOTROPIA Vol . 27 No . 2, 2020 : 125 - 133 DOI: 10.11598 / btb. 2020.27. 2.1176 SOIL PROPERTIES AND TREE COMPOSITION IN A 27- YEAR OLD Acacia mangium Willd. PLANTATION ON ABANDONED MINING AREA AT PHANGNGA FORESTRY RESEARCH STATION ** JETSADA WONGPROM 1 ' , ROONGREANG POOLSIRI 2 , SAPIT DILOKSUMPUN 2 AND CHATCHAI NGERNSAENGSARUAY 3 1 Faculty of Forestry, Kasetsarf University ' , Bangkok 10900, Thailand 2 F ) epartment ofSilviclture, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand ^ Corresponding author, e-mail : fforjdw@ku.ac.th Received 19 December 2018 / Accepted 04 April 2019 ABSTRACT In order to validate the important role of Acacia mangium plantation in mining rehabilitation, a study was conducted on the soil properties and tree composition in a 27-year-old A. mangium plantation growing on sandy ( S27) and clay (C27) soil types, as well as a mixed plantation ( MP) growing on clay soil type. The results were compared with those grown on an abandoned mining area ( AB), a secondary forest ( SF ) and a primary forest ( PF), at the Phangnga Forestry Research Station, Thailand. Three 40 x 40 m permanent plots were established and soil samples were randomly collected from depths of 0- 10, 10-20, 20-30, and 30-50 cm, in each of the S27, C27, MP, AB, SF, and PF. The bulk density values in the S27, C27, and MP were lower than that in AB and was similar to those in SF and PF, particularly, the top soil . Total nitrogen, available phosphorus, organic matter, exchangeable potassium, and magnesium contents in the S27, C27, and MP were higher than that in AB, but were lower than those in SF and PF, indicating that the soil development in the S27, C27, and MP was slower than in the SF and PF. This lower bulk density values and higher soil nutrient contents were positively contributed by the A . mangium plantation. The Shannon-Wiener index obtained for S27 ( 1.43 ) , C27 (2.51), and MP ( 2.77) were lower than that for the SF (3.86). The similarity indices of the tree species found in S27, C27, MP, and PF were low, ranging from 5.83 - 8.00, indicating that the development of the forest community was slow compared to SF (31.03 ) . Enrichment planting with poorly dispersed shade tolerant trees has increased the diversity and improved the forest structure in the mined out areas and other similarly degraded lands. Keywords: Acacia mangium, mining area, soil properties, tree composition INTRODUCTION Ever since mining has been widely operational all over Thailand, the local environment and ecosystem conditions have been severely impacted by the mining activities ( Macdonald et al . 2015 ). Vegetations were destroyed and soil properties were changed from ^ Corresponding author, e-mail: fforjdw@ku.ac.th ** This paper was presented at the 3 rd International Conference on Tropical Biology 2018, 20-21 September 2018, Bogor, West Java , Indonesia the originally rich to currently poor soil . Soil textures have become unsuitable for planting ( Oktavia et al 2015 ) . In some areas, the soil has turned extremely acidic and the soil moisture went very low during the dry season ( Tripathi et al . 2016) . As a result, soil improvement and forest restoration in mining areas has taken a long time. Invariably, changes in such important factors as soil properties like soil texture, organic matter, pH, nitrogen, phosphorus and potassium have negatively affected the development of a forest community in 125