Naturalization of Paulownia tomentosa in Sicily (Italy)
Paulownia tomentosa (Paulowniaceae) is native to China and is recorded as an invasive species in Australia and the USA where in the case of the latter, it is reported as invasive from Pennsylvania south to Georgia and west to Missouri. Within the EPPO region, P. tomentosa has had a long use as a garden ornamental and a tree species grown in towns and cities. Within the EPPO region, the species has been reported as escaping cultivation and colonising disturbed urban habitats. In Switzerland, the species has been included on the Watch List since 2014 (EPPO RS 2014/176) and in Germany it is one of 42 potentially invasive alien species included on the Grey List (EPPO RS 2013/251). In Sicily (Italy), over the last few decades, the number of casual or naturalised alien tree species has steadily increased. Since 2015, periodic observations of mature P. tomentosa trees were carried out in green areas (parks and gardens) of Palermo. During this period, approximately 10 self-sown individuals were found. Natural regeneration exclusively occurred at the base of walls or on pavements where some water and nutrients may accumulate. The authors highlight that in the case of P. tomentosa, its future behaviour in Mediterranean-climate remains uncertain, especially as the species is grown in urban situations and thus spread into natural environments is difficult. In addition, the species seems to be limited by its lack of ability to cope with drought, which may also prevent its colonisation of new areas. The authors suggest that P. tomentosa should be considered as a casual alien species in Sicily.
Sources
Badalamenti E (2019) Notes about the naturalization in Sicily of Paulownia tomentosa (Paulowniaceae) and remarks about its global spread. Flora Mediterranea 29, 67-70.