A multi-point aggregation trend of the outbreak of pine wilt disease in China over the past 20 years

Abstract

Pine wilt disease is a worldwide forest disease, caused by an invasive species in China that is highly dangerous. It caused huge losses to the Chinese ecological environment, natural landscape and social economy. The existing studies on the spread of pine wilt disease have been limited in scope and duration and have been fragmented. This study aims to apply macroscopic analysis to reveal the spatiotemporal spread of pine wilt disease in mainland China and provide a scientific basis for the control of pine wilt disease. According to statistical pine wilt disease data from 1998 to 2017 and NDVI data for China, we showed relevant information concerning the disease graphically, mapped the distribution of the infected area in ArcGIS and performed scan statistics in SaTScan to detect spatiotemporal clusters. This study applied macroscopic analysis of the evolution of pine wilt disease over a long duration, revealing the occurrence, spatial distribution and aggregation of infections and the spatial and temporal patterns of the disease. The results show that the pine wilt disease is concentrated in southeastern China and has a strong spatial correlation. The trend of spread of the infected area was examined using 2013 as the node. Pine wilt disease spread in a pattern of “spread - stabilization – outbreak – full outbreak” throughout the country. The direction of spread was from south to north, coast to inland, developed to developing areas, and multiple areas were affected with multiple outbreaks. According to the spatiotemporal scan results, disease occurrence in the long-infested areas of Jiangsu, Anhui, Zhejiang, Shanghai and Guangdong Provinces showed high clustering, and new clusters were formed in Sichuan, Chongqing and there surrounding areas with the spread of the disease. The spread of pine wilt disease was distributed across multiple areas with multiple outbreaks and showed significant characteristics of spatiotemporal aggregation.