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GCE IV - Key Finding in 2021

    Comparisons with Chinese Wetlands Provide Insight into Salt Marsh Ecology

    Spartina alterniflora was introduced into China in 1979 and now covers almost all of the Chinese coastline. This invasion presents powerful opportunities for comparative research, and GCE scientists Pennings and Craft have ongoing collaborations on several topics. 1) Soil development. Carbon sequestration is driven by both salinity and plant species composition (Xue et al. 2020; Yuan et al. 2020), but S. alterniflora traps sediment and sequesters substantial carbon in both China and the U.S. (Li et al. 2013; He et al. 2016). These gains, however, may be offset by conversion of marshes to aquaculture and other land uses (Li et al. 2018). 2) Interactions between mangroves and salt marsh plants. Exotic mangroves, Sonneratia apetala, that have also been introduced to China are likely to suppress S. alterniflora, replacing one exotic species with another (Peng et al. 2018; Peng et al. in press). 3) S. alterniflora traits. S. alterniflora displays latitudinal clines in height, biomass and phenology (Liu et al. 2020a; Chen et al. 2021). In the US these clines are largely genetically based (Chen et al. 2021; Liu et al. 2016, 2017, 2020b), whereas in China they are due to phenotypic plasticity. The main exceptions are clines in seed set and phenology in China that are genetically based, reflecting strong selection at high latitudes (Chen et al. 2021, Fig. 1). 4) Marsh community structure. In the native ranges of S. alterniflora in the US and Phragmites australis in China the diversity of soil nematodes decreases at high latitudes (Zhang et al. 2019, 2020). Where S. alterniflora has been introduced in China, however, these latitudinal patterns are absent, and nematode diversity is relatively low (Zhang et al. 2019). 5. Habitat restoration. Coastal habitat restoration projects have focused on different habitats in the two countries, have been funded in different years, and use different techniques. In both countries, public information about these projects is incomplete, and it is unclear to what extent projects are achieving their goals or using optimal techniques (Shanze et al. 2019).

    2021_Accomplishments_Fig4

    Fig. 1 (a) In China, Spartina alterniflora displays striking latitudinal variation in seed set, which ranges from ~10% at low latitudes to >80% at high latitudes. (b) In three common gardens, seed set increased with latitude of the garden, indicating an environmental effect on seed set. (c) Within the high- and mid-latitude gardens, seed set also increased with the latitude from which the plants were collected, indicating genetic control of seed set. Source: Liu et al. 2017.



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This material is based upon work supported by the National Science Foundation under grants OCE-9982133, OCE-0620959, OCE-1237140 and OCE-1832178. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.