Documenting a thousand years of environmental and anthropogenic changes on mangroves on the Bangkok coast, the upper Gulf of Thailand

• Main Author: Punwong P.
• Other Authors: Mahidol University
• Format: Article
• Published: 2023
• Subjects: Agricultural and Biological Sciences
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/81502

Environmental changes and human activities in a mangrove ecosystem in Bang Khun Thian, south of Bangkok, the upper Gulf of Thailand were reconstructed through the analyses of pollen, charcoal, organic carbon, carbonate, particle size, heavy metals and radiocarbon dating. The results showed that fluctuating sea levels supported mangrove establishment since at least ad 840. From ad 840 to 1240, a delta progradation from the Lower Chao Phraya river was recorded with associated dry conditions. A short period characterized by wetter conditions was recorded from ad 1050–1240. After ad 1240, mangroves were gradually replaced by terrestrial grasses indicative of a period of sea-level fall with relatively drier conditions. There was extension of the intertidal shoreline of Bang Khun Thian farther south allowing open grassland and wetland to form as a young deltaic plain until around ad 1660. During this period, intense agricultural practices, particularly paddy and orchards, expanded in the Lower Chao Phraya delta during this marine regression. From ad 1660, an upper intertidal habitat was gradually re-established, characterised by the presence of back mangroves that possibly result from sea-level rise in the last 300 years. The pollen and heavy metal data also track increasingly intensive human activities such as agriculture, aquaculture, urbanisation and industrial activity in the catchment during the last century.