Simulation of Spartina alterniflora invasion trends in the coastal areas of Fujian Province based on PLUS model

The invasion of Spartina alterniflora, an exotic invasive plant species, has inflicted severe degradation and irreversible structural damage to coastal wetland ecosystems, including the loss of native species habitats, the disruption of hydrological processes, and the degradation of wetland ecological functions. Investigating the future diffusion and expansion trends of S. alterniflora is of profound theoretical and practical significance for formulating scientific and targeted prevention and control strategies, effectively curbing its invasive spread, and conserving the ecological integrity and stability of coastal wetland ecosystems. Based on the remote sensing extraction of spatiotemporal distribution information of S. alterniflora in Fujian Province, this study systematically analyzed the spatiotemporal dynamic characteristics of its invasion process, including the temporal variation of invasion area, spatial distribution pattern, and expansion rate in different regions. Taking the extraction results of wetland landscape patterns in 2010, 2016, and 2022 as the basic data, the Patch-generating Land Use Simulation (PLUS) model was employed to simulate the diffusion trend of S. alterniflora in the coastal zone of Fujian Province in 2028. In the simulation process, multiple key driving factors were comprehensively considered, including climatic conditions (air temperature and precipitation), topographic features (elevation), and soil properties, so as to improve the accuracy and reliability of the simulation results. The validation results of the model demonstrate that the PLUS model has high reliability and applicability in simulating the future wetland landscape pattern. By comparing the wetland landscape pattern simulated by the PLUS model in 2022 with the actual remote sensing interpretation data, the results show that the Kappa coefficients for the overall wetland feature simulation in Zhangjiang Estuary, Quanzhou Bay, Luoyuan Bay, and Sansha Bay are 0.76, 0.81, 0.82, and 0.91 respectively, and the overall simulation accuracies are all above 85%. These quantitative evaluation indices fully verify the effectiveness of the PLUS model in predicting the long-term dynamic changes of coastal wetland landscapes. The simulation results indicate that the future expansion of S. alterniflora in Fujian Province exhibits pronounced regional heterogeneity. The main invasion areas of S. alterniflora in the future will be low-lying tidal flats and mangrove areas, where the hydrothermal conditions and soil environment are highly suitable for its growth and spread. It is projected that by 2028, the area of S. alterniflora in Quanzhou Bay, Luoyuan Bay, and Zhangjiang Estuary will increase rapidly, with annual average growth rates all surpassing 30%, while the expansion in Sansha Bay will be relatively slow, mainly relying on the proliferation and diffusion of existing populations. Further analysis shows that the diffusion process of S. alterniflora is significantly driven by environmental factors such as elevation, air temperature, precipitation, and soil conditions. Accordingly, it is recommended that relevant competent departments strengthen targeted monitoring, early warning, and integrated manage-ment measures in high-risk invasion zones, so as to effectively control the spread of S. alterniflora and safeguard the structural stability and functional sustainability of coastal wetland ecosystems. The findings of this research can provide reliable scientific basis and decision-making references for relevant departments to carry out S. alterniflora eradication actions and formulate long-term conservation and management strategies for coastal wetland ecosystems.