Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA, USA.
School of Oceanography, University of Washington, Seattle, WA, USA.
Nat Commun. 2023 Mar 13;14(1):1137. doi: 10.1038/s41467-023-36803-7.
Ecosystem connectivity tends to increase the resilience and function of ecosystems responding to stressors. Coastal ecosystems sequester disproportionately large amounts of carbon, but rapid exchange of water, nutrients, and sediment makes them vulnerable to sea level rise and coastal erosion. Individual components of the coastal landscape (i.e., marsh, forest, bay) have contrasting responses to sea level rise, making it difficult to forecast the response of the integrated coastal carbon sink. Here we couple a spatially-explicit geomorphic model with a point-based carbon accumulation model, and show that landscape connectivity, in-situ carbon accumulation rates, and the size of the landscape-scale coastal carbon stock all peak at intermediate sea level rise rates despite divergent responses of individual components. Progressive loss of forest biomass under increasing sea level rise leads to a shift from a system dominated by forest biomass carbon towards one dominated by marsh soil carbon that is maintained by substantial recycling of organic carbon between marshes and bays. These results suggest that climate change strengthens connectivity between adjacent coastal ecosystems, but with tradeoffs that include a shift towards more labile carbon, smaller marsh and forest extents, and the accumulation of carbon in portions of the landscape more vulnerable to sea level rise and erosion.
生态系统连接度往往会增加生态系统对压力的恢复力和功能。沿海生态系统吸收了不成比例的大量碳，但水、养分和沉积物的快速交换使它们容易受到海平面上升和海岸侵蚀的影响。沿海景观的各个组成部分（即沼泽、森林、海湾）对海平面上升的反应不同，这使得难以预测综合沿海碳汇的反应。在这里，我们将一个空间显式地貌模型与一个基于点的碳积累模型相结合，结果表明，尽管各个组成部分的反应不同，但景观连接度、原地碳积累率和景观尺度沿海碳储量的大小都在中等海平面上升率下达到峰值。随着海平面的上升，森林生物量的逐渐丧失导致系统从以森林生物量碳为主向以沼泽土壤碳为主的转变，这是通过沼泽和海湾之间大量有机碳的循环实现的。这些结果表明，气候变化加强了相邻沿海生态系统之间的连接，但也存在权衡，包括向更不稳定的碳、更小的沼泽和森林范围以及更容易受到海平面上升和侵蚀影响的景观部分的碳积累的转变。
