Australian acacias across eastern Adriatic – abundant but not aggressive

Background and Purpose: Biological invasions are considered among the main factors of global changes and the identification of future invaders may help in taking effective steps to prevent their dispersal and/or establishment. For some Australian Acacia species, especially Acacia dealbata Link, an invasive status has been already described in some European countries. The aim of this work was surveying the actual spatial pattern of Australian acacias across the eastern Adriatic, and, by applying GIS techniques, to learn more about their ecology and distribution. Materials and Methods: We carried on two field surveys during the flowering season of the year 2014, and recorded the locations of Acacia species, their flowering state, floral characteristics, and the insects present on the inflorescences. We georeferenced any plant detected, and collected soils samples under the plant crowns and in close natural or semi-natural areas. Results and Conclusions: Very few species were recorded and mostly in private gardens, A. dealbata being the preferred ornamental. Records referring to plants grown in abandoned or unattended gardens demonstrate the potential of this species to expand if not properly controlled. In addition, we detected no plants outside gardens in natural habitats. Results on soil characteristics, with higher pH values than those usually found under trees of this genus elsewhere, may partly explain our findings. The surveys took place during a spring following an unusually warm winter: this may have influenced both phenology and pollinator activity, finally reducing observations of the latter. Descriptive statistics and MaxEnt analysis have shown the importance of the warmer areas in determining the presence of Acacia species. At present, acacias are not to be considered aggressive invaders along the eastern Adriatic according to our observations; they can be classified as alien, with a local trend toward becoming casual