Abstract:

【Objective】Sudden oak death caused by Phytophthora ramorum is known as the destructive disease which is usually found on trees and ornamental plants. It has very wide range of host species, mostly broad leaved trees, and kills them very quickly. This disease has not been found in China, but already being listed as the quarantine species by Chinese government based on its potential risk and prevention difficulty. It may become a big threat to our ecological environment security once it has been introduced someday. Thus, it is particularly important to predict the potential distribution and analyse the invasion risk of P. ramorum in China, which will help us to make a pertinent prevention and quarantine measures.【Method】The maximum entropy (MaxEnt) model based on environmental variables of the existing distribution areas was used to generate the suitable prediction map of P. ramorum with the geographic information system ArcGIS. The invasion risk analysis was performed using a multi-index comprehensive evaluation system, including 5 hierarchies (possibility of incoming, colonization, diffusion, the victim host economic importance and difficulty of risk management) and 18 indicators. 【Result】The test omission rate of MaxEnt model was in accordance with the predicted omission rate, which indicated the accuracy of this model and it could be used as the evaluation benchmark. The results showed that the potential distribution of P. ramorum was mainly located in the southern China. The geographical coordinates were ranged from 101.9 °-122.9 °E, 18.9 °-38.0 °N, including Jiangsu, Anhui, Shanghai, Henan, Hubei, Chongqing, Hunan, Guizhou, Jiangxi, Zhejiang, Fujian, Guangdong, Guangxi, Hainan, Hongkong, Macao, Taiwan and some areas of Shandong, Sichuan, Shanxi and Tibet, accounting for about 19.6% of administrative area of China. The invasion risk index value (R) of P. ramorum was 2.64 which suggested it should belong to an extreme high risk grade of harmful species. 【Conclusion】Due to no national record of P. ramorum and its high risk level in China, we believed that strict quarantine measures and more than 2 years isolated planting were mandatory to prevent the disease.

Key words: Phytophthora ramorum, potential distribution, maximum entropy model (MaxEnt), Integrated multi-index evaluation system, invasion risk analysis