关键词: 生态位模型, 最优模型, 水盾草, 潜在分布, 中国

Abstract

Uncertainty is inherent in ecological niche model predictions and different models yield different predictions. Based on the niche conservatism hypothesis, classic niche models that are calibrated on native areas and transferred to introduced areas for evaluation and prediction have advantages. Cabomba caroliniana is a notorious invasive aquatic weed native to South America that has established populations in China. In this study, independent testing points from China were used to validate and select the best individual model to predict the potential distribution, offering reliable and valuable information for risk analyses of C. caroliniana. The distributional records of C. caroliniana in China were sorted in chronological order, and climate niche dynamics and niche conservatism of C. caroliniana invasions across major continents were investigated using environmental variables associated with observed records. A total of 10 models were then calibrated in native area using two environmental datasets and five model algorithms. The best individual model was used to predict distribution, which was tested and selected based on the criteria of low omission and commission errors of independent introduced points. Results showed that present distribution of C. caroliniana occurs mainly along the eastern coastal areas of China. It has also dispersed northward in rivers and lakes system along Beijing-Hangzhou Grand Canal or South-to-North water diversions. The climate conditions occupied by different continental populations overlap broadly suggesting its climate niche was conserved during the invasion in China. There were many climate spaces that were unfilled when compared to its native niche spaces, suggesting a high invasion potential in these areas. Areas of potential distributions identified by best native individual model include Beijing, Shanghai, Shandong, Zhejiang, Jiangsu, Anhui, Hubei and Hunan provinces. These potential areas were mainly distributed in the southeastern rivers, lakes, canals and channels all with high human activity and no effective natural enemy, which could assist C. caroliniana expansion. Our research demonstrates the need for rigorous surveys in these areas, together with an integrative management action to control further expansion of C. caroliniana.

Key words: ecological niche model, fine-tuned model, Cabomba caroliniana, potential distribution, China