To determine whether mangrove soil accretion can keep up with increasing rates of sea level rise, we modeled the theoretical, steady-state (i.e., excluding hurricane impacts) limits to vertical soil accretion in riverine mangrove forests on the southwest coast of Florida, USA. We measured dry bulk density (BD) and loss on ignition (LOI) from mangrove soils collected over a period of 12 years along an estuarine transect of the Shark River. The plotted relationship between BD and LOI was fit to an idealized mixing model equation that provided estimates of organic and inorganic packing densities in the soils. We used these estimates in combination with measures of root production and mineral deposition to calculate their combined contribution to steady-state, vertical soil accretion. On average, the modeled rates of accretion (0.9 to 2.4 mm year⁻¹) were lower than other measured rates of soil accretion at these sites and far less than a recent estimate of sea level rise in south Florida (7.7 mm year⁻¹). To date, however, no evidence of mangrove “drowning” has been observed in this region of the Everglades, indicating that assumptions of the linear accretion model are invalid and/or other contributions to soil accretion (e.g., additional sources of organic matter; feedbacks between physical sedimentation processes and biological responses to short-term environmental change) make up the accretion deficit. This exercise highlights the potential positive impacts of hurricanes on non-steady-state soil accretion that contribute to the persistence of neotropical mangroves in regions of high disturbance frequency such as the Gulf of Mexico and the Caribbean region.

为了确定红树林的土壤积聚是否能跟上海平面上升的速度，我们对美国佛罗里达州西南海岸的河流红树林中垂直土壤积聚的理论，稳态（即，不包括飓风影响）进行了建模。我们测量了沿鲨鱼河河口样地在过去12年中收集的红树林土壤的干容重（BD）和灼烧损失（LOI）。BD和LOI之间的绘制关系适合于理想化的混合模型方程式，该方程式提供了土壤中有机和无机堆积密度的估计值。我们将这些估算值与根系产量和矿物质沉积量度结合起来使用，以计算它们对稳态垂直土壤积聚的综合贡献。平均而言，模型化的吸积率（0.9至2.4毫米/年^-1）低于这些地点的其他测得的土壤增生速率，也远低于最近对南佛罗里达州海平面上升的最新估计（7.7毫米，- ^1年））。然而，迄今为止，在大沼泽地的这一地区还没有观察到红树林“溺水”的迹象，这表明线性增生模型的假设是无效的和/或对土壤增生的其他贡献（例如，其他有机物来源；反馈物理沉降过程和对短期环境变化的生物学响应之间的差距）弥补了增生赤字。这项工作突显了飓风对非稳态土壤积聚的潜在积极影响，这有助于在干扰频繁的地区（如墨西哥湾和加勒比海地区）使新热带红树林持续存在。