UMT 11 th International Annual Symposium on Sustainability Science and Management 09 th – 11 th July 2012, Terengganu, Malaysia e-ISBN 978-967-5366-93-2 1212 Underground Microbial Biodiversity during Conversion of Secondary Logged Over Forest for Oil Palm Plantation in Belaga, Sarawak Siti Ramlah Ahmad Ali, Nor Shalina Ahmad Tajuddin and Shamsilawani Ahamed Bakeri Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia Corresponding author’s e-mail: ramlah@mpob.gov.my Abstract Conversion of secondary forest to oil palm plantations will in one way or another have an impact on the environment. Soil microbes play an important role in conserving soil productivity and are sensitive to the changes in soil. Therefore, microbial biodiversity can be used as an indicator for soil quality. Hence, study to detect changes in soil microbial community in Belaga, Sarawak is required to investigate the diversity of the soil bacteria prior to and at various stages of the planting activities. Soil taken from the site was analyzed to identify the genus and species of microbes using molecular techniques and sequencing. Biodiversity indices were calculated to detect the changes in the soil. After two years of study, Shannon-Weaver biodiversity index showed that the index reduced from before clean cleared to during clean cleared and the early stages of planting, from 3.278 to 2.996 and 1.648, respectively. However, biodiversity index increased when the oil palm age increased to two and a half and three years old, 3.443 and 3.394, respectively, which almost similar to that of biodiversity strips. This result was also shown using the Simpson Index, where the index value of area with oil palm was practically similar to the biodiversity strips. Prevalence of the prokaryotic taxonomy, genus, species and strains detected from the sites showed that after two years of planting, the number of prokaryotic taxonomy, genus, species and strains in the oil palm planted area was comparable to the biodiversity strips. The biodiversity of culturable prokaryotes in Belaga, Sarawak showed that in area cultivated with oil palm, the microbial biodiversity increased with the increased on palm age to 3 years. Keywords: biodiversity, microbes, secondary forest, oil palm plantation Introduction Agricultural activities often associate with land clearing and intensive application of chemicals such as pesticides and fertilizers which can lead to changes in soil microbial community and biodiversity loss [8]. Like all the other plantations such as rubber, oil palm plantation has been thought to have impacts on the environment and ecosystem [9]. Clearance of tropical forests is estimated at between 16.4 and 20.4 x 10 6 hectares per year [5]. Microorganisms in the soil are reckoned sensitive to such agricultural activities. The term biodiversity according to Erwin [7], is related to the number of species, or species richness, along with ‘the richness of activity each species undergoes during its existence through events in the life of its members, plus the non-phenotypic expression of its genome’. Microorganisms has their role, they are decomposers, converting nutrients in organic wastes and from dead organisms into molecules that are reused within ecosystems. Many of them live as symbiotic. Microorganisms include agents that cause disease and also may function as biological pest and disease control agents. The development of molecular techniques to detect microorganisms was an aid to the requirement that microorganisms must grow on lab based media so they could be isolated and identified. Molecular technologies like PCR-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, 16S rRNA, phylogenic tree, fatty acids analysis and protein sequencing have increased the knowledge of microbial life that exist [6]. This study was conducted to investigate whether below ground microbial biodiversity are affected during conversion of secondary logged over forest on mineral soil to oil palm plantation.