Mangrove habitats are complex systems, which are subjected to both natural and human external forces such as tidal variations, sediment supply, deforestation, and climate change, which in many locations are causing mangroves to decline and even disappear. Global measurements of surface elevations have been conducted at many locations to understand if sedimentation rates in mangrove areas will keep pace with sea level rise. However, extending results to other areas requires a detailed understanding of subsidence processes in mangrove areas. Here, we provide a detailed geotechnical investigation (sediment cone resistance and friction, coefficient of consolidation, grain size, normalised tip resistance and friction ratio, etc.), critical for understanding surficial sediment dynamics and vertical sediment accretion rates, of the mangrove forest edge and its surrounding mud flat in the Firth of Thames, New Zealand. Eight in situ samples were collected and tested in oedometer experiments to evaluate the coefficient of consolidation. Furthermore, a kinematic penetrometer, NIMROD, was used to estimate the resistance forces of the mud flat and mangrove forest, from which soil properties were evaluated. Our results show that mangroves are able to change soil properties to enhance sediment resistance towards erosion. An increase of sediment strength correlated with an increase of mangrove tree density as well as a decrease in the coefficient of consolidation. Hence, the increase of tree density to a decrease of the coefficient of consolidation correlates as well. In this study, our results suggest that the Firth of Thames mangroves are able to accrete enough sediment to keep up with local sea level rises if sediment supplies remain similar in the future. The correlation of tree density to the coefficient of consolidation can be used to assess future mangrove-soil interaction and mud flat progression. Finally, the applicability of literature soil classifications for the kinematic penetrometer was realized for the first time and applied to mangrove and mud flat areas.

中文翻译：

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新西兰泰晤士湾不断扩大的红树林边缘沉积物固结的快速转变

红树林栖息地是一个复杂的系统，受到潮汐变化、沉积物供应、森林砍伐和气候变化等自然和人类外力的影响，在许多地方导致红树林数量减少甚至消失。已在许多地点进行了全球地表海拔测量，以了解红树林地区的沉积速率是否会与海平面上升保持同步。然而，将结果扩展到其他地区需要详细了解红树林地区的沉降过程。在这里，我们提供了详细的岩土工程调查（沉积物锥体阻力和摩擦力、固结系数、粒度、标准化尖端阻力和摩擦比等），对于了解地表沉积物动力学和垂直沉积物沉积速率至关重要，新西兰泰晤士湾的红树林边缘及其周围的泥滩。收集了八个原位样品并在固结仪实验中进行测试以评估固结系数。此外，运动渗透仪 NIMROD 用于估计泥滩和红树林的阻力，从中评估土壤特性。我们的研究结果表明，红树林能够改变土壤特性，以增强沉积物对侵蚀的抵抗力。沉积物强度的增加与红树林密度的增加以及固结系数的降低相关。因此，树木密度的增加与固结系数的降低也相关。在这项研究中，我们的结果表明，如果未来沉积物供应保持相似，泰晤士河红树林能够积累足够的沉积物，以跟上当地海平面的上升。树木密度与固结系数的相关性可用于评估未来的红树林-土壤相互作用和泥滩进展。最后，首次实现了文献土壤分类对运动渗透仪的适用性，并应用于红树林和泥滩地区。