Anja Bindewald1,2, Uwe Starfinger3, Etienne Branquart4, Giuseppe Brundu5 and Jürgen Bauhus2
1Department of Forest Conservation, Forest Research Institute of Baden-Württemberg (FVA), Freiburg 79100, Germany
2Chair of Silviculture, University of Freiburg, Freiburg 79085, Germany
3Research Department for natural and agricultural areas, Service Public de Wallonie, Gembloux, 5030, Belgium
4Julius Kühn Institute, Institute for Plant Health, Braunschweig, 38104, Germany
5Department of Agriculture, University of Sassari, 07100 Sassari, Italy
Existing risk assessment tools are often used at the country level and rank introduced species based on their detrimental impact for the early detection of “invasive alien species” (IAS) of most concern. Yet, it is necessary to move beyond these IAS lists that are based on broad geographic areas and assess the risk in a way that addresses various management aspects. So far, the use of widely cultivated introduced trees was not supported by a Pan-European standardized risk assessment and it is likely that the management of the risk of invasion was not included in forestry planning and management practices by default. For the majority of introduced tree species used in forestry and considered as IAS, complete eradication is neither desired nor can it be achieved at reasonable costs. Instead, controlling further spread and the protection of ecosystems most sensitive to tree invasion should be considered more important. We propose a comprehensive risk analysis framework based on the quantification of site-specific environmental risks associated with these species. To underpin the assessment, we recommend using systematically sampled data from national forest inventories and regional selected habitat maps covering areas of high conservation value. To support this approach, regular (forest) monitoring should be improved, for example, by recording all tree species separately. Our proposed framework can be simply applied by the responsible forest authorities and is considered cost-effective. With respect to risk management, it provides on-site assistance regarding introduced tree species control, eradication or prevention measures. Furthermore, a solid standardized evaluation provides reliable invasiveness assessments and thus facilitates meaningful comparisons among ecosystem types in various regions or jurisdictions.