Climate and Livability Initiative, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
Climate and Livability Initiative, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
Sci Total Environ. 2022 Oct 15;843:157098. doi: 10.1016/j.scitotenv.2022.157098. Epub 2022 Jun 30.
Mangrove ecosystems represent one of the most effective natural environments for fixing and storing carbon (C). Mangroves also offer significant co-benefits, serving as nurseries for marine species, providing nutrients and food to support marine ecosystems, and stabilizing coastlines from erosion and extreme events. Given these considerations, mangrove afforestation and associated C sequestration has gained considerable attention as a nature-based solution to climate adaptation (e.g., protect against more frequent storm surges) and mitigation (e.g. offsetting other C-producing activities). To advance our understanding and description of these important ecosystems, we leverage Landsat-8 and Sentinel-2 satellite data to provide a current assessment of mangrove extent within the Red Sea region and also explore the effect of spatial resolution on mapping accuracy. We establish that Sentinel-2 provides a more precise spatial record of extent and subsequently use these data together with a maximum entropy (MaxEnt) modeling approach to: i) map the distribution of Red Sea mangrove systems, and ii) identify potential areas for future afforestation. From these current and potential mangrove distribution maps, we then estimate the carbon sequestration rate for the Red Sea (as well as for each bordering country) using a meta-analysis of sequestration values surveyed from the available literature. For the mangrove classification, we obtained mapping accuracies of 98 %, with a total Red Sea mangrove extent estimated at approximately 175 km. Based on the MaxEnt approach, which used soil physical and environmental variables to identify the key factors limiting mangrove growth and distribution, an area of nearly 410 km was identified for potential mangrove afforestation expansion. The factors constraining the potential distribution of mangroves were related to soil physical properties, likely reflecting the low sediment load and limited nutrient input of the Red Sea. The current rate of carbon sequestration was calculated as 1034.09 ± 180.53 Mg C yr, and the potential sequestration rate as 2424.49 ± 423.26 Mg C yr. While our results confirm the maintenance of a positive trend in mangrove growth over the last few decades, they also provide the upper bounds on above ground carbon sequestration potential for the Red Sea mangroves.
红树林生态系统是固定和储存碳 (C) 的最有效自然环境之一。红树林还具有显著的协同效益，它们是海洋物种的苗圃，为支持海洋生态系统提供养分和食物，并防止海岸线受到侵蚀和极端事件的影响。考虑到这些因素，红树林造林和相关的碳封存作为一种基于自然的气候适应（例如，防止更频繁的风暴潮）和缓解（例如，抵消其他产生碳的活动）解决方案得到了广泛关注。为了提高我们对这些重要生态系统的理解和描述，我们利用 Landsat-8 和 Sentinel-2 卫星数据，对红海地区的红树林范围进行了当前评估，并探讨了空间分辨率对制图精度的影响。我们发现 Sentinel-2 提供了更精确的范围空间记录，随后使用这些数据和最大熵 (MaxEnt) 建模方法来：i）绘制红海红树林系统的分布地图，ii）确定未来造林的潜在区域。从这些当前和潜在的红树林分布地图中，我们使用来自现有文献中调查的封存值的荟萃分析，估算了红海（以及每个邻国）的碳封存率。对于红树林分类，我们获得了 98%的制图精度，估计红海的红树林总面积约为 175 公里。基于 MaxEnt 方法，该方法使用土壤物理和环境变量来确定限制红树林生长和分布的关键因素，确定了近 410 公里的潜在红树林造林扩展区域。限制红树林潜在分布的因素与土壤物理特性有关，这可能反映了红海的低沉积物负荷和有限的养分输入。当前的碳封存率计算为 1034.09 ± 180.53 Mg C yr，潜在封存率计算为 2424.49 ± 423.26 Mg C yr。虽然我们的结果证实了过去几十年红树林生长呈正增长趋势，但也为红海红树林的地上碳封存潜力提供了上限。
