Dispersal risk of Alternanthera philoxeroides in Hainan Tropical Rainforest National Park under climate change postprint

Abstract: Alternanthera philoxeroides, a globally invasive species, poses a significant threat to local ecosystems due to its rapid spread and adaptability to diverse environmental conditions. Hainan Tropical Rainforest National Park, a critical area for biodiversity conservation, is increasingly at risk from the spread of A. philoxeroides. Therefore, accurately mapping its distribution and conducting dynamic monitoring are essential for effective management. This study utilized field survey data and employed the Biomod2 package in the R programming language to develop species distribution models, analyzing the spatial distribution of A. philoxeroides in the national park under current and future climate scenarios, as well as identifying key environmental factors influencing its habitat suitability. The results were as follows: (1) The suitable areas for A. philoxeroides in the national park were categorized into low, medium, high, and very suitable zones. Under current conditions, the highly suitable area covered approximately 180.75 km², concentrated primarily in the Yinggeling, Diaoluoshan, and Limushan areas. (2) Among the various factors influencing habitat suitability, climatic variables were found to have the most significant impact on the species’ distribution. Specifically, the mean annual temperature change (bio7), normalized difference vegetation index (ndvi), maximum temperature in the warmest month (bio5), and precipitation in the warmest quarter (bio18) were identified as the key factors influencing habitat suitability. (3) The trends in the total habitat suitability area of A. philoxeroides under different future climate scenarios revealed two distinct patterns. In both scenarios, the centroid of suitable habitat shifted eastward. Under the high emissions, extreme climate intensification scenario (SSP585), the expansion of suitable habitat was more rapid compared to the moderate sustainable development scenario (SSP126). In conclusion, the projected habitat of A. philoxeroides under current climate conditions is primarily located on the periphery of the national park. However, due to the expected dramatic changes in global climate, the risk of its spread within the national park is significantly heightened. Continuous monitoring and proactive management are crucial to prevent the large-scale invasion of A. philoxeroides and mitigate its ecological impacts.