Spatiotemporal relationships between plantings of non-Asian ash species and EAB infestations in China
Field surveys and reports of ash species distribution, introductions, and plantings in literature sources indicated that native Asian ash species, typically Chinese (F. chinensis ) and Manchurian ash, were widely distributed in China. However, white, green, velvet and other non-Asian ash species were also frequently found in northern China and some cities of central and southern China (Fig. 4a). In northern China, EAB infestations were detected in eight of 14 provinces, provincial cities, or regions where non-Asian ash species were present (Fig. 4a). Non-Asian ash trees have been introduced into China since the early 1900s over an increasingly wide geographic range (Fig. 4b). For example, 14,000 ha of non-Asian ash trees were planted in the 1980s and more than 20,000 ha of non-Asian ash plantations were established in the 2010s according to data collected from the literature used in this study. However, EAB outbreaks did not immediately coincide with wide-spread plantings of these non-Asian ash species; rather, there were time lags of at least 30-50 years between ash plantings and increased EAB outbreaks (Fig. 4b).