Abstract How past environments and communities responded to episodes of coastal inundation can inform preparations for future resilience to predicted rises in sea level. Southeast Asia’s extensive coastlines and expanding coastal populations mean vast natural and human capital is at risk from future sea level rise. Regional mangroves provide many ecosystem services that can help mitigate such risks, but deforestation has left them threatened and compromised. The present study examines the Holocene development and human use of mangrove forest in northern Vietnam, where existing palaeo-records derive from sedimentary archives in tidal flat, estuarine and deltaic settings. Here, we expand that coverage by describing conditions at an enclosed doline within the Trang An limestone karst in Ninh Binh province that would have been sheltered from deltaic and marine processes. We present a multi-proxy assessment incorporating pollen analysis of the 8125-year-old discontinuous sediment core obtained from the doline floor, combined with inferences from erosional tidal notches in the enclosing limestone, and analyses of phytolith, vertebrate and mollusc assemblages from an adjacent archaeological cave site with deposits of comparable age. The results provide a detailed example of how enclosed coastal environments and communities responded to Middle Holocene marine inundation. High percentages of pollen from mangroves (17–57%) suggest their colonisation of the doline from ∼8100 cal. BP and persistence until ∼250 cal. BP, well after the intertidal zone regressed seaward beyond the massif. Archaeological assemblages dating to ∼5500 cal. BP and containing palm and woody eudicot phytoliths and sponge spicules, neurocrania of the fish genus Pomadasys (‘grunts’, ‘grunters’ or ‘javelins’) and brackish-water molluscs Sermyla riqueti and Neripteron violaceum support the persistence of mangrove environments through the Middle Holocene high-stand, a period of hiatus within the core, and indicate human foraging and fishing activities took place in mangrove and lagoonal habitats alongside hunting in the surrounding limestone forest. Subsequent structural opening of this latter forest formation from ∼1075 cal. BP (875 CE), evident in the pollen record, coincides with the Medieval Climate Anomaly and with the adjacent development of the ancient capital at Hoa Lu. We propose that given the long-term persistence of mangrove habitats and associated resources documented in this study, regional initiatives aimed at rehabilitating mangroves (with the positive consequences that this holds for biodiversity and socio-economic conditions) may wish to consider selective restorative measures within Trang An and similar sheltered sub-coastal karst settings.

中文翻译：

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越南宁平 Tràng An 喀斯特古洪泻湖中红树林和石灰岩森林的全新世开发和人类利用

摘要 过去的环境和社区如何对沿海洪水事件作出反应，可以为未来对预测的海平面上升的复原力做准备。东南亚广阔的海岸线和不断扩大的沿海人口意味着未来海平面上升将面临巨大的自然和人力资本风险。区域红树林提供了许多有助于减轻此类风险的生态系统服务，但森林砍伐使它们受到威胁和危害。本研究考察了越南北部红树林的全新世发展和人类利用，那里现有的古记录来自潮滩、河口和三角洲环境中的沉积档案。这里，我们通过描述宁平省 Trang An 石灰岩岩溶内封闭漏斗的条件来扩大覆盖范围，该漏斗本来可以避免三角洲和海洋过程。我们提出了一个多代理评估，其中包括对从漏斗底获得的 8125 年历史的不连续沉积物核心的花粉分析，结合对封闭石灰岩中侵蚀潮汐槽口的推断，以及对来自邻近地区的植硅体、脊椎动物和软体动物组合的分析。考古洞穴遗址，具有可比年龄的沉积物。结果提供了一个详细的例子，说明封闭的沿海环境和社区如何应对全新世中期海洋淹没。来自红树林的高百分比花粉（17-57%）表明它们在大约 8100 卡路里的沟渠中定植。BP 和持久性直到 ~250 cal。血压计，在潮间带向海退去地块之后很久。考古组合可追溯到~5500 cal。BP 和含有棕榈和木质双子叶植物植硅体和海绵针状体、Pomadasys 鱼属的神经头骨（“咕噜声”、“咕噜声”或“标枪”）和咸水软体动物 Sermyla riqueti 和 Neripteron violaceum 支持中红树林环境的持久性全新世高位，核心内的一段中断期，表明人类在红树林和泻湖栖息地进行觅食和捕鱼活动，同时在周围的石灰岩森林中进行狩猎。后一种森林形成的后续结构开放从~1075 cal。BP（公元875年），在花粉记录中很明显，恰逢中世纪气候异常和古都华卢的邻近发展。