Non-native tree species (NNT) that pose risks to biodiversity are classified as ‘invasive’ in some European countries. However, country-specific risk assessment methods may lead to different results for the same NNT between countries of comparable growth conditions, raising doubts about the reliability of risk classifications. Here, we analysed six risk assessment tools used in Germany and adjacent countries for their practical applicability and consistency using four NNT (Fraxinus pennsylvanica Marsh., Paulownia tomentosa (Thunb. ex Murray), Pseudotsuga menziesii (Mirb.) Franco and Quercus rubra L.) as case studies. Using these tools to classify risks for the same NNT and reference area (Germany) yielded inconsistent results for all NNT. The reasons for this were (1) differences in classification and weighting of criteria, (2) a lack of data to quantify invasion risks and (3) uncertainties related to assessment methodologies. Moreover, the tools fail to distinguish between risks posed by NNT in different sites. We suggest that instead the risks should be assessed for different ecosystem types by using site-specific inventory data covering the establishment, spread and potential impact of NNT. Our recommendations provide a foundation for developing a consistent, systematic Pan-European approach to assess invasiveness while addressing both risk and forest management aspects.

中文翻译：

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风险在评估者的眼中：比较德国四种非本土树种的风险评估

对生物多样性构成威胁的非本地树种（NNT）在某些欧洲国家被归类为“入侵”。但是，针对特定国家/地区的风险评估方法可能会在增长条件相当的国家/地区之间对同一NNT得出不同的结果，这使人们对风险分类的可靠性产生了怀疑。在这里，我们使用四种NNT（Fraxinus pennsylvanica Marsh。，Paulownia tomentosa（Thunb。ex Murray），Pseudotsuga menziesii（Mirb。）Franco和Quercus rubra）分析了德国和邻国使用的六种风险评估工具，以评估其实用性和一致性。L.）作为案例研究。使用这些工具对同一NNT和参考区域（德国）的风险进行分类时，对所有NNT得出的结果不一致。造成这种情况的原因是：（1）标准的分类和权重不同；（2）缺乏量化入侵风险的数据；（3）与评估方法有关的不确定性。而且，这些工具无法区分NNT在不同站点中带来的风险。我们建议，应使用涵盖NNT的建立，传播和潜在影响的特定地点清单数据来评估不同生态系统类型的风险。我们的建议为开发一致，系统的泛欧洲方法以评估侵害性同时解决风险和森林管理两方面的问题奠定了基础。