Invasive Spartina alterniflora marshes in China: a blue carbon sink at the expense of other ecosystem services

Abstract

Coastal (marine) wetlands are recognized as one of the world's most efficient sinks for organic carbon (“blue carbon”), and credits for their restoration and conservation can be obtained from carbon markets. We reviewed 50 studies to compare the climate mitigation potential of the invasive cordgrass Spartina alterniflora to that of native vegetation in marshes along the coast of China. The importance of S alterniflora marshes as a carbon sink varied geographically; however, at all sites soils associated with S alterniflora emitted substantially more methane than soils populated with native plants. Because the species was deliberately introduced, the carbon stored in S alterniflora marshes could qualify for inclusion within China's national inventory of greenhouse‐gas emissions. However, in locations where it significantly increases carbon stocks, its dominance results in the loss of other ecosystem services. Therefore, if included in a national inventory, S alterniflora marshes could conflict with China's action plan for meeting UN Sustainable Development Goals.

Coupling use of stable isotopes and functional genes as indicators for the impacts of artificial restoration on the carbon storage of a coastal wetland invaded by Spartina alterniflora, southeastern China

“…As one of the most productive ecosystems, coastal wetlands contribute greatly to blue carbon and serve as crucial habitats for numerous species, thus playing significant roles in global climate change and coastal biodiversity conservation (Pendleton et al, 2012;Alongi, 2014). However, in the past two decades, the invasion of Spartina alterniflora (S. alterniflora) has caused many problems in coastal wetlands, such as native plant degradation, reduced biological diversity and increased methane emissions (Liu et al, 2021;Qi and Chmura, 2023;Zheng et al, 2023). This highlights the urgent need for the protection of such impaired wetlands.…”

“…This can be attributed to (1) the differences in CO 2 fixation capacity and allocation mechanisms between mangrove plants and S.alterniflora (Regnier et al, 2013;Kuwae et al, 2016;Osland et al, 2018), and (2) the different C: N ratio of photosynthetic products derived from mangrove plants and S.alterniflora (Xia et al, 2021;Li et al, 2023). Currently, many attentions have been paid to the impact of S.alterniflora on SOM (Graca et al, 2000;Feng et al, 2017;Qi and Chmura, 2023). As one of the most productive species in coastal areas, S. alterniflora has been reported to have obvious contribution to SOM (Zhang et al, 2010;Qi and Chmura, 2023).…”

“…Currently, many attentions have been paid to the impact of S.alterniflora on SOM (Graca et al, 2000;Feng et al, 2017;Qi and Chmura, 2023). As one of the most productive species in coastal areas, S. alterniflora has been reported to have obvious contribution to SOM (Zhang et al, 2010;Qi and Chmura, 2023). In addition, the photosynthetic products derived from S.alterniflora is characterized by lower C: N ratio and tannin contents than that derived from mangrove plants (Feng et al, 2015;Wu, 2018;Gao, 2019), thus has higher bioavailability.…”

“…Since 2022, the S.alterniflora here was removed and replaced by mangrove plants, this may provide an ideal site for assessing the effects of wetland restoration. During our investigation, the stable isotopes (d 13 C, d 15 N) were used to determine the potential changes in the source of SOM (Phillips and Gregg, 2003;Philp, 2007;Xia et al, 2021). DNA sequencing and quantitative real-time PCR (qRT-PCR) technologies were used to analyze benthic biomass and composition, as well as the activity of functional genes for benthic microbial CO 2 fixation.…”

Impact of Spartina alterniflora Invasion in Coastal Wetlands of China: Boon or Bane?

“…Studies suggest conflicting results regarding the impact of SA invasion on the carbon sink function of coastal wetlands. While some studies indicate that the invasion of SA enhances the carbon sink function of coastal wetlands [ 23 ], others suggest that it weakens this function [ 24 ]. The positive impacts include erosion control [ 25 ] and nutrient cycling [ 26 ].…”