Abstract：
Seascape connectivity increases carbon and nitrogen exchange across coastal ecosystems through flow of particulate organic matter (POM). However, there are still critical gaps in knowledge about the drivers that mediate these processes, especially at regional seascape scales. The aim of this study was to associate three seascape-level drivers which could influence carbon and nitrogen stocks in intertidal coastal seascape: connectivity between ecosystems, ecosystem surface area, and standing vegetation biomass of ecosystems. Firstly, we compared whether connected mangrove and seagrass ecosystems contain larger carbon and nitrogen storage than isolated mangrove and seagrass ecosystems. Secondly, we compared autochthonous and allochthonous POM in mangrove patches and seagrass beds, simultaneously estimating the area and biomass relative contribution to POM of the different coastal vegetated ecosystem. Connected vs isolated mangrove and seagrass ecosystems were studied at six locations in a temperate seascape, and their carbon and nitrogen content in the standing vegetation biomass and sediments were measured. POM contributions of these and surrounding ecosystems were determined using stable isotopic tracers. In connected mangrove-seagrass seascapes, mangroves occupied 3 % of total coastal ecosystem surface area, however, their standing biomass carbon content and nitrogen per unit area was 9-12 times higher than seagrasses and twice as high as macroalgal beds (both in connected and isolated seascapes). Additionally in connected mangrove-seagrass seascapes, the largest contributors to POM were mangroves (10-50 %) and macroalgal beds (20-50 %). In isolated seagrasses, seagrass (37-77 %) and macroalgal thalli (9-43 %) contributed the most, whilst in the isolated mangrove, salt marshes were the main contributor (17-47 %). Seagrass connectivity enhances mangrove carbon sequestration per unit area, whilst internal attributes enhance seagrass carbon sequestration. Mangroves and macroalgal beds are potential critical contributors of nitrogen and carbon to other ecosystems. Considering all ecosystems as a continuing system with seascape-level connectivity will support management and improve knowledge of critical ecosystem services.
摘要：
海景连通性通过颗粒有机物（POM）的流动增加了沿海生态系统的碳和氮交换。然而,关于调解这些过程的驱动因素的知识仍然存在关键差距，尤其是在区域海景尺度上。这项研究的目的是将三个可能影响潮间带沿海海景碳和氮储量的海景水平驱动因素联系起来：生态系统之间的连通性，生态系统表面积，和生态系统的现存植被生物量。首先,我们比较了连接的红树林和海草生态系统是否比孤立的红树林和海草生态系统包含更大的碳和氮储量。其次,我们比较了红树林斑块和海草床中的本地和异源POM，同时估计不同沿海植被生态系统的面积和生物量对POM的相对贡献。在温带海景的六个地点研究了连接与孤立的红树林和海草生态系统，并测量了它们在站立植被生物量和沉积物中的碳和氮含量。使用稳定的同位素示踪剂确定了这些和周围生态系统的POM贡献。在相连的红树林海草海景中，红树林占沿海生态系统总面积的3%，然而,它们的单位面积上的生物量碳含量和氮比海草高9-12倍，是大型藻类床的两倍（在连通和隔离的海景中）。此外，在连接的红树林-海草海景中，POM的最大贡献者是红树林（10-50％）和大型藻类床（20-50％）。在孤立的海草中，海草(37-77%)和巨藻(9-43%)贡献最大，在孤立的红树林中，盐沼是主要贡献者(17-47%)。海草连通性增强了红树林单位面积的碳固存，而内部属性增强了海草的碳固存。红树林和大型藻类床是氮和碳对其他生态系统的潜在关键贡献者。将所有生态系统视为具有海景级连通性的持续系统，将支持管理并提高对关键生态系统服务的了解。
