Global ore trade is an important gateway for non-native species: a case study of alien plants in Chinese ports.
Aim: Biological invasion has become one of the most important environmental concerns in many countries, with considerable time, money and effort being spent in the prevention and eradication of invasive species. Since mineral ores tend to harbour seeds from the local plants, our aim was to study the non-native plants collected in Chinese ports to understand the influence of global ore trade on biological invasion. Location: China. Methods: We surveyed 75 ore heaps across six types of ore in 22 Chinese port cities from 2010 to 2016 and collected 737 voucher specimens of non-native plants, out of which 709 specimens were traced to the country of origin. Using the software Maxent, we evaluated the risk of invasion from these non-native plants based on the global ore trade flow, traced their route and predicted the regions in China most vulnerable to invasion by these plants. Results: Of the 407 non-native plant species identified, most were from India, followed by Malaysia, Swaziland, Mexico, and Iran. Taxonomically, there were representations from 49 families, notably Fabaceae, Poaceae, Asteraceae and Solanaceae. The non-native plant species were represented by varying number of species, from a single specimen to 179. Analysis of the invasion risk indicated that the entire coast of China was at high risk. Furthermore, two major potential introduction pathways were also identified, namely the Yangtze drainage basin and the land from the Gulf of Tonkin to Sichuan Basin. Main conclusion: An important pathway for the invasion of non-native plants is the inadvertent transportation of seeds through global ore trade networks. Based on this study, we suggest greater monitoring and cooperation in the international ore trade for better management, and creating public awareness of the dangers of non-native species to help minimize the risk of transporting non-native plants by the global ore trade network.