Losses of salt marsh in China: Trends, threats and management

Abstract

Coastal salt marsh, one of the blue carbon ecosystems that can adapt and mitigate climate change influence, is drawing global attention due to its high carbon sequestration capability. In China, however, coastal salt marsh has suffered great losses. Nation-wide analysis of salt marsh trends and management is critical to ecosystem protection and restoration. Thus, by analyzing previous coastal salt marsh studies, we found that the extent of coastal salt marsh varied greatly among the Liao River Delta, the Yellow River Delta, the middle coast of Jiangsu Province, Chongming Dongtan and Jiuduansha in Shanghai, with a 59% overall loss of salt marsh extent from the 1980s to the 2010s. The rate of salt marsh loss slowed down after the year 2000. Coastal land-claim (reclamation) is the most dominant driver of salt marsh loss. Climate change and coastal erosion, invasive species, and vegetation dynamics driven by competition and succession have also led to various effects on salt marsh extent and the ecological services they provide. Sea level rise, reclamation pressure and environmental pollution are the main factors, as negative drivers, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 2 together with conservation and restoration policies, as positive ones, affecting future trends in salt marshes. China has implemented several measures to protect and restore salt marshes, such as setting up protected areas, drawing marine ecological redline, and making strict regulations on reclamation. However, stronger legal protection for wetlands, more effective enforcement, and participation by local communities can further enhance salt marsh restoration, conservation and management.

Modeling long‐term salt marsh response to sea level rise in the sediment‐deficient Plum Island Estuary, MA

“…Recent observations of marsh submergence have prompted concern for salt marsh persistence worldwide (Reed 1995;FitzGerald et al 2008;Kirwan and Megonigal 2013;Crosby et al 2016). Extensive marsh loss from subsidence, accretion deficits, and human impacts has occurred in the world's largest estuaries, including the Mississippi River Delta, Yellow River Delta, and Venice Lagoon (Carniello et al 2009;Murray et al 2014;Jankowski et al 2017;Gu et al 2018). However, several marshes in northwest Europe and North America have shown resilience to SLR (French 2006;Kirwan et al 2016a).…”

Coastal environmental changes under increasing anthropogenic impacts: an introduction

“…It was estimated that globally 50% of saltmarsh, 35% of mangrove, 30% of coral reef, and 29% of seagrass have already been lost in the past few decades (Barbier et al 2012). In China, about 58% of coastal wetlands were lost between 1950 and 2014 (Gu et al 2018), and only 40% of the mainland coastline remains in a relatively natural state.…”

Mapping the Rapid Decline of the Intertidal Wetlands of China Over the Past Half Century Based on Remote Sensing

“…The majority of studies have focused on coastal parameters, like the coastline, ecosystem, or coastal land use pattern, while the intertidal wetland has not received sufficient investigation. National-wide research on the intertidal zone in China highlighted the social-economic role of the coastal system and mainly focused on description and estimation of the ecological service, biodiversity, management strategy, and countermeasures for the degradation of the coastal wetland, based on statistical information and published reports (Ma et al, 2014;Cui et al, 2016;Gu et al, 2018). Estimation of Chinese intertidal flats and wetland based on remote sensing data has attracted a large amount of attention in recent years, especially at local scale (Wei et al, 2015;Chen et al, 2016;Wu X. et al, 2017).…”