Data from: Dynamics of marsh-mangrove ecotone since the mid-Holocene: a palynological study of mangrove encroachment and sea level rise in the Shark River Estuary, Florida

Sea level rise and the associated inland shift of the marsh-mangrove ecotone in south Florida have raised many scientific and management concerns in recent years. Holocene paleoecological records can provide an important baseline to shed light on the long-term dynamics of vegetation changes across this ecotone in the past, which is needed to predict the future. In this study, we present palynological, X-ray fluorescence, and loss-on ignition data from four sedimentary cores recovered from a 20-km marine-to-freshwater transect along the Shark River Estuary, southwest Everglades, to document the patterns and processes of coastal vegetation changes in response to sea level rise since the mid-Holocene. Our record indicates that freshwater marsh progressively replaced marl prairies at the Shark River Estuary between 5700 and 4400 cal yr BP. As marine transgression continued, marine influence reached the threshold necessary for mangroves to establish at the current mouth of the Shark River Slough at 3800 cal yr BP. During the next 3000 years, although sea level rise in the Western North Atlantic slowed down to 0.4 mm/yr, a spatial and temporal gradient was evident as the marsh-mangrove ecotone shifted inland by 20 km from 3800 to 800 cal yr BP, accompanied by a gradual landward replacement of freshwater marsh by mangrove forest. If sea level continues to rise at 2.33 mm/yr in the 21st century in south Florida, it is possible that marine influence will reach the threshold for mangroves to establish in the central Everglades, and we could expect a much more aggressive mangrove encroachment toward the northern and interior parts of south Florida in the next few centuries.

近年来，佛罗里达州南部的海平面上升以及伴随发生的盐沼-红树林交错带（marsh-mangrove ecotone）向内陆迁移的现象，引发了诸多科学与管理层面的担忧。全新世古生态记录可为揭示该交错带过去植被变化的长期动态提供关键基准，而这一信息对未来预测至关重要。本研究针对大沼泽地西南部鲨鱼河河口（Shark River Estuary）沿线20公里海相-淡水相断面采集的4根沉积岩芯（sedimentary cores），获取了孢粉数据、X射线荧光（X-ray fluorescence）数据及烧失量（loss-on ignition）数据，旨在记录全新世中期以来响应海平面上升的海岸植被变化模式与过程。本研究记录显示，在距今5700至4400个校准年（cal yr BP）期间，鲨鱼河河口的淡水盐沼逐渐取代了泥灰岩草原（marl prairies）。随着海侵持续进行，在距今3800个校准年时，海洋影响达到了红树林在现今鲨鱼河泥沼（Shark River Slough）口定植所需的阈值。在随后的3000年间，尽管西北大西洋的海平面上升速率放缓至0.4毫米/年，但仍呈现出显著的时空梯度：盐沼-红树林交错带在距今3800至800个校准年期间向内陆迁移了20公里，同时红树林逐步向内陆取代淡水盐沼。倘若21世纪佛罗里达州南部的海平面仍以2.33毫米/年的速率上升，那么海洋影响将可能达到红树林在大沼泽地中部定植的阈值，未来数百年内，红树林对佛罗里达州南部北部及内陆区域的扩张入侵态势将更为剧烈。