STUDI PALINOLOGI FORMASI MENTAWIR, SUB CEKUNGAN KUTAI BAWAH, KALIMANTAN TIMUR

Palynological study of the Mentawir Formation, Lower Kutai Basin, East Kalimantan has been conducted on the 27 selected cutting samples of the 'X' Well in the depth of interval 100'-4.140 'which is situated in 'DNA' Field The purpose of this study is to determine the age and depositional environment and biostratigraphic sequence of the sediment. The age of the sediment is primarily marked by the last appearance of Florschuetzia trilobata at 850', range from Middle Miocene to Late Miocene. The Middle Miocene age occupies sediments from interval 850'-4.140 , whilst the Late Miocene  age covers sediments from interval 100'-850'. Delta environment of the interval samples were deposited in lower delta plain (distal) to the delta front (distal). Based on the changes on the amount of the taxa group in the mangrove and freshwater ecology as well as the changes in the sedimentation, thus the biostratigraphic sequence of the 2 X2 Well with depth of interval 100'- 4.140' in 2 DNA2 field lies in the Transgressive System Tract to the Highstand System Tract. 

Forest Dynamics and Agroforestry History since AD 200 in the Highland of Sumatra, Indonesia

Understanding past forest dynamics and human influence is essential for future forest management and ecosystem conservation. This study aims to provide insights into the forest dynamics and agroforestry history in the highlands of Sumatra for the last 1800 years. We carried out palaeoecological multi-proxy analyses of pollen, spores, non-pollen palynomorphs, macro-charcoal, and X-ray fluorescence on a limnic sediment core taken from Danau Kecil in the submontane area of Kerinci Seblat National Park in Sumatra, Indonesia. Our results provide an 1800-year record of forest dynamics under climate change and human influence including the transition from forest opening to shifting cultivation and eventually permanent agroforestry. Indicators for forest openings and secondary forest formation have been present since the beginning of records (AD 200). This is followed by the possible initiation of sugar palm (Arenga) cultivation (AD 400). Since AD 500, potential agroforestry and forest gardening practices have promoted major timber trees such as Lithocarpus/Castanopsis, Bischofia, and Dipterocarpaceae combined with sugar palm (Arenga). Permanent agroforestry systems were possibly established since AD 1760, evinced by an increase in commodity trees such as Dipterocarpaceae for resin production. With the Dutch invasion ca. AD 1900, agroforestry intensified and expanded to the Kerinci Valley. This was followed by land use intensification and potential rice cultivation around Danau Kecil since the 1940s. This study provides the first details on past forest dynamics around Danau Kecil since AD 200, showing among others how appropriate forest management and a closed canopy could reduce fire vulnerability in submontane rainforest