Assessing the impacts of climate change on suitable distribution areas and ecological risks of the invasive grass (Spartina alterniflora) in China

Anthropogenic climate change significantly influences the distribution of species, reshaping habitats for invasive species to adapt to. Studying the effects of climate change on the distribution patterns of Spartina alterniflora is crucial for developing more scientific and rational coastal wetland management policies. Therefore, we have taken the future climate, Topography factor and soil properties of Spartina alterniflora under two shared socioeconomic pathways. The species distribution model MaxEnt has been used to predict the suitability of Spartina alterniflora in China, and a risk level has been established based on the suitability index. The predictive model showed a significant correspondence between the test and expected omission rates, boasting AUC metrics of 0.962 (+0.001) and 0.955 (+0.003). The study indicates that under the SSP 5-8.5 scenario, the distribution of Spartina alterniflora is jointly influenced by elevation and bioclimatic variables (bio2: mean diurnal range; bio14: precipitation of the wettest quarter; bio19: precipitation of the coldest quarter), with a concentration in areas at 0 m above sea level and a mean diurnal range of 3-7 degrees C. However, under the SSP 1-2.6 scenario, its distribution is primarily dominated by bioclimatic variables (bio2, bio14, bio19), the restrictive effect of elevation is significantly reduced, leading to a substantially higher invasion risk. Preventing secondary invasion is critical in ecological engineering. Hence, we have mapped the risk of secondary invasion under two climate scenarios and discussed the possibility of Spartina alterniflora invading into the inland and more northern regions of China. These findings emphasize the necessity of developing targeted prevention strategies across diverse climatic conditions, offering a scientific foundation for policy formulation and conservation planning to reduce secondary invasion risks.