EPPO Global Database

EPPO Reporting Service no. 07 - 2018 Num. article: 2018/149

Citizen science as a tool for recording the alien tree species Ailanthus altissima

Ailanthus altissima (Simaroubaceae: EPPO List of Invasive Alien Plants) is a tree species native to Asia and invasive within the EPPO region.  The species can outcompete native plant species and negatively impact ecosystem processes.  In Croatia A. altissima is established throughout the country especially in coastal regions and it is spreading within urban areas and protected sites.  Invasive tree species are often more conspicuous than other invasive alien plants, or other invasive pests and therefore they make a good case study for citizen science monitoring and recording.  Citizen scientists were recruited via personal contacts, social networks, emails or telephone calls and to be accepted they had to be willing to undertake surveys through hiking, biking or by car.  Each participant was required to attend a half-day training session which included theoretical and practical information related to a freely available app and a smartphone equipped with GPS and a camera.  Each citizen was assigned a specific trail or road on which to record the presence and abundance of A. altissima.  Due to the high level of infestation of A. altissima in the region, recording individual trees was not appropriate and data was simplified by using polygons.A total of 90.61 km of road and trails were mapped using citizen scientists and included the detection of 20 single plants and 19 multi-plant clusters.  A total infested area of 2 610 m2 was recorded during the exercise. The study concludes that citizen science can operate over large scales and has many positive effects including raising awareness of the negative impacts of invasive alien plants.  


Sladonja B, Poljuha D (2018) Citizen science as in biological recording – A case study of Ailanthus altissima (Mill.) Swingle, Forests DOI:10.3390/f9010031.