Nitrogen‐Enriched Eutrophication Promotes the Invasion of Spartina alterniflora in Coastal China

Abstract

Pollution‐driven eutrophication is a significant by‐product of rapid economic growth in China. Such environmental changes have huge consequences on local biodiversity and ecosystem functions through the spread of invasive introduced species. Spartina alterniflora has been spreading quickly and extensively throughout China since the mid 1980s, soon after its intentional introduction from the eastern United States. The range expansion of S. alterniflora coincides with a significant increase in the per unit standing biomass of the species in the Chinese coastal wetlands from the 1980s to 2000s. Here we showed that the long term per m2 biomass of S. alternifolia changes are significantly correlated with human‐induced increases of the inorganic nitrogen level in the Chinese coastal water. We established this causal relationship by showing that reproduction, growth, and biomass of individual S. alterniflora, grown in experimental tanks, increased with higher levels of soil inorganic nitrogen. Competition experiments indicated that S. alterniflora out competed Phragmites australis at both low and high soil nitrogen levels. These field and experimental based results support the hypothesis that nitrogen‐enriched eutrophication contributed significantly to the successful invasion of S. alterniflora in China.

The Effect of Submergence and Eutrophication on the Trait’s Performance of Wedelia Trilobata over Its Congener Native Wedelia Chinensis

“…However, nutrients (N) and their interactions, S × N, S × N × C, had significant effects on the morphological traits of both species. This result agrees with our hypothesis, and several researchers have found that increasing nutrient concentrations overcomes the stress of submergence and encourages plants to grow under these conditions, especially for invasive plant species [7,23,27]. Plant heights of both the species were increasing under submergence and nutrients treatments (Table 2, Figure 4a,b).…”

“…Biomasses of many plants was increased or maintained under submergence [46] (Table 1, Figure 2) because plants used the quiescence technique to tolerate submergence [26]. WC maintained a higher root-to-shoot ratio in all treatments under monoculture, which was the plants strategy to cope with submergence and eutrophication [36], while WT maintained a better stem mass ratio under all treatments in monoculture, because adventitious roots were a tolerance stratagem of WT to survive these conditions and also provided structural stability to maintain sexual reproduction [7,24]. Total biomass of both species was increased under both submergence and three nutrient levels' interaction because more than 65% of plants of both species were above the water surface due to plant height elongation [47].…”

“…Many of these species have successfully spread in the introduced ranges and now they occupy large areas because of decreased environment suitability for native plant species [3,4] and increased resource availability due to global change that helps invasive plant species [5,6]. Native diversity is under threat due to increases in precipitation and nutrients enrichment [7], and disturbance in environmental conditions makes invasive plant species more dominant, especially in wetland or a riparian zone [8]. Subsequently, better traits' performance under different environmental conditions makes invasive plant species successful and allows them to spread in the introduced habitat [9][10][11][12].…”

Human eutrophication drives biogeographic salt marsh productivity patterns in China

“…Because the response to nutrient enrichment is species specific, coastal eutrophication might change marsh plant community structure by altering plant competitive balance (Bertness et al 2002, Pennings et al 2005. The strong response of S. alterniflora to exogenous nutrients allows it to outcompete native plants, colonizing bare mudflats and replacing native plants rapidly (including broadly dominant P. australis and other locally dominant species, such as S. mariqueter and S. salsa) throughout the coastal salt marsh ecosystems in China (Zhao et al 2015). Consequently, the distribution of this species has increased exponentially (Davidson et al 2018).…”

Nutrient availability and invasive fish jointly drive community dynamics in an experimental aquatic system

“…, Zhao et al. ), while in other cases nutrients facilitate coexistence between native and introduced species or disproportionately promote natives (e.g., Firn et al. ).…”