Ailanthus altissima(tree of heaven): Spread and harmfulness in a case-study urban area

Among the woody and shrubby weeds colonising non-crop areas in the Apulia Region (South Italy), Ailanthus altissima (tree of heaven), an exotic invasive species, is one of the worst, because of its fast growth and root-sucker production. It reaches the heart of protected areas and spreads everywhere in urban and peri-urban areas creating dense stands. As there are no official monitoring protocols for weed mapping, a method based on real-time global positioning system (GPS) on satellite maps was set up. Due to this method, the distribution, spread, size, density and harmfulness of A. altissima were assessed across the wide urban area of Bari (South Italy) by mapping all the individual plants and areas/stands of plants. In Bari, along a total of 76 km of roads mapped, 170 very large (diameter >18 cm), 231 large (diameter 8–18 cm), 130 medium (diameter 3–8 cm), 53 small (diameter < 3 cm) single plants, and 70 high, 63 medium and 13 low density areas were detected. This indicated that A. altissima (tree of heaven) was very widespread in the study area. Moreover, 35 types of damage or potential risks were recorded covering functional, environmental, health and safety and aesthetic aspects and then classified according to frequency and location. The real-time GPS method proved to be very useful for providing a speedy and accurate record of the data.