Spatiotemporal relationships between ash tree plantings and EAB infestations
To determine the relationship between ash tree plantings and EAB infestations in China, we gathered information on ash tree introductions and plantings from literature sources published from 1900 to 2019. We used the search terms of “Fraxinus and China” in Web of Science and “trees, introduction, Fraxinus ” to retrieve publications in the National Science Data of Forestry (www.lknet.ac.cn/sztsg.htm) from 1900 to 2019. These searches generated 548 and 100 results, of which 25 publications (Table S2) included details about introduced exotic ash trees including ash tree species, planting year, name of province, provincial city or region with ash tree plantation, number of these provinces, provincial cities or regions, number of planting, and total area of plantations. Data on five variables were obtained from these 25 publications, including plantings of non-Asian ash trees; planting year; planting provinces, provincial cities, or regions; planting times; and planting areas. Planting years were divided into eight 10-year-periods from 1900 to 2019 (Table S3) and all data on ash tree species, times, and areas of plantings were accumulated for each time period. Data on the distribution of native ash species were obtained from Flora of China (The Chinese Academy of Sciences Editorial Board of Flora 1992). Finally, we mapped the geographic distributions of native and non-Asian ash trees in China. Different non-Asian ash species were marked with different colors and ash trees native to China were marked with the green background color. The regions with EAB present were simultaneously marked to illustrate the spatial relationships between ash plantations and EAB occurrence. The planting areas of non-Asian ash species, number of provinces, provincial cities or regions with non-Asian ash plantations, and numbers of cities with EAB present were accumulated during each 10-year-period from 1900 to 2019 to determine the temporal distribution characteristics of EAB in China.