Global tidal marshes 2020 dataset

Tidal marsh ecosystems are heavily impacted by human activities, highlighting a pressing need to address gaps in our knowledge of their distribution. To better understand the global distribution and changes in tidal marsh extent, and identify opportunities for their conservation and restoration, it is critical to develop a spatial knowledge base of their global occurrence. Here, we develop a globally consistent tidal marsh distribution map for the year 2020 at 10-m resolution. To map the location of the world’s tidal marshes we applied a random forest classification model to earth observation data from the year 2020. We trained the classification model with a reference dataset developed to support distribution mapping of coastal ecosystems, and predicted the spatial distribution of tidal marshes between 60°N to 60°S. We validated the tidal marsh map using standard accuracy assessment methods, with our final map having an overall accuracy score of 0.852. We estimate the global extent of tidal marshes in 2020 to be 52,880 km² (95% CI: 32,030 to 59,780 km²) distributed across 120 countries and territories. Tidal marsh distribution is centred in temperate and Arctic regions, with nearly half of the global extent of tidal marshes occurring in the temperate Northern Atlantic (45%) region. At the national scale, over a third of the global extent (18,510 km²; CI: 11,200 – 20,900) occurs within the USA. Our analysis provides the most detailed spatial data on global tidal marsh distribution to date and shows that tidal marshes occur in more countries and across a greater proportion of the world’s coastline than previous mapping studies. Our map fills a major knowledge gap regarding the distribution of the world’s coastal ecosystems and provides the baseline needed for measuring changes in tidal marsh extent and estimating their value in terms of ecosystem services. This dataset accompanies the preprint https://doi.org/10.1101/2023.05.26.542433潮汐沼泽（Tidal Marsh）生态系统深受人类活动的强烈影响，凸显出填补当前对其分布认知空白的迫切需求。为更好地掌握全球潮汐沼泽的分布格局与面积变化情况，并确定其保护与修复的可行路径，构建涵盖其全球分布的空间知识库至关重要。 本研究针对2020年构建了一套全球统一的10米分辨率潮汐沼泽分布地图。为绘制全球潮汐沼泽的空间位置，我们将随机森林分类模型应用于2020年的地球观测数据；采用专为海岸生态系统分布制图开发的参考数据集对该分类模型进行训练，并对北纬60°至南纬60°范围内的潮汐沼泽空间分布进行了预测。 我们通过标准精度评估方法对该潮汐沼泽地图进行了验证，最终地图的总体精度得分为0.852。经估算，2020年全球潮汐沼泽总面积为52880 km²（95%置信区间（Confidence Interval, CI）：32030～59780 km²），分布于全球120个国家与地区。 潮汐沼泽的分布集中于温带与北极地区，全球近半数的潮汐沼泽面积分布在温带北大西洋区域（占比45%）。在国家尺度上，全球超过三分之一的潮汐沼泽面积（18510 km²；置信区间：11200～20900 km²）分布于美国境内。 本研究的分析结果提供了迄今为止最为详尽的全球潮汐沼泽空间分布数据，且相较于以往的制图研究，本研究发现潮汐沼泽分布于更多国家，覆盖了全球更长比例的海岸线。本研究绘制的地图填补了全球海岸生态系统分布认知中的重大空白，并为监测潮汐沼泽面积变化、评估其生态系统服务价值提供了必要的基准数据。 本数据集配套的预印本链接为https://doi.org/10.1101/2023.05.26.542433