Salt marshes and tidal flats serve as vital habitat for biodiversity and provide extensive and highly valuable ecosystem services. Yet, they have undergone substantial loss and transformation over millennia with impacts increasing in recent decades. Their loss and degradation have impacted species of high conservation concern, including migratory shorebirds and other waterbirds, as well as ecosystem functions and services they provide to humans more broadly. There is increasing recognition of the importance of these systems, and the impact of their loss, and increasing concern and effort in managing and restoring them. These intertidal areas are vital in protecting the coast from erosion, especially during on-shore storm tides, and act as a natural flood defence that can protect built areas such as housing and industry, and other human land uses such as agriculture. As such they can reduce the costs of hard engineering-based coastal protection, and will have an increasing importance as sea levels rise as a result of climate change.
Scope of the document
This document collates evidence-based guidance for site managers and decision makers involved in salt marsh and tidal flat restoration with an ecological focus on shorebirds, a highly threatened group of broad conservation concern. Here, we consider shorebirds in a rather general sense, including all species of the order Charadriiformes. Shorebirds that commonly use or heavily depend on intertidal habitats include waders (e.g. plovers, stilts, oystercatchers, sandpipers), gulls and terns. This document is a collection of smaller stand-alone pieces of guidance, each focusing on a different conservation action. They can therefore be used singularly, or as a collection, depending on the management needs of the user. This document was initiated by concerns about salt marshes and tidal flats in the Yellow Sea region, particularly as habitats for birds. The Yellow Sea is a critical bottleneck for migratory shorebirds and other waterbirds that have suffered extensive loss and degradation of tidal flats and salt marsh (see also Box 1). Therefore, the collated guidance relates to selected actions most relevant to salt marsh and tidal flat restoration, and bird conservation therein, in the Yellow Sea region. The content of each guidance document is, however, global in scope. The guidance does not provide strict protocols that must be followed or detailed practical instructions about how to implement interventions or specific techniques (e.g. how to install a culvert, how to transport sediment, required permits and the application process). Rather, it highlights interventions and restoration techniques that have been demonstrated to be effective in at least some situations. Application and implementation of these techniques requires a thorough understanding of the natural system, both its biotic and abiotic aspects. Interventions that were successful at one site may not be at another because of different local conditions or implementation methods. Evidence for the guidance was gathered primarily from the literature. For evidence on the effects of interventions on biodiversity (focusing on shorebirds, benthic invertebrates and vegetation), we drew from Conservation Evidence syntheses (Sutherland et al. , 2019) where
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