Federal Biological Research Centre for Agriculture and Forestrywww.bba.de Economic and environmental impact assessment for ornamental and forest plants – the case of P. ramorum  Long-term growth of perennials – substitution of damaged plants hardly to calculate / problem of appropriate discount rates  Ideal values of ornamentals or forests may not be accounted with market prices and are hardly to be estimated  Different use-values of forests (current and future) like recrea- tional land use, aesthetic, production or ecological value  Difficult evaluation of (impacts on) biodiversity Phytophthora ramorum damages a broad range of ornamentals and forest trees (examples in table 1) and is actually being evalua- ted within the European Union framework 6 project on Risk Analysis for P. ramorum threat to Europe (RAPRA, ). Impacts of the fungus in Europe are mostly on crop production in nurseries and to a limited extent outside nurseries in plant societies where Rhododendron are present. Details on possible impacts and methods for their assessment shows table 1. Foto: S. Werres Fig. 3: Branch dyback and foliar lesions on Rhododendron caused by P. ramorum Foto: S. Werres Fig. 4: Stem canker on Quercus agrifolia Fig. 1: What is the recreational value of a rhododendron park? Foto: Axel Oehler Hella Kehlenbeck Federal Biological Research Centre for Agriculture and Forestry, Department for National and International Plant Health Stahnsdorfer Damm 81, D Kleinmachnow, Germany; The example of P. ramorum shows that the economic and environmental impact assessment for ornamental and forest plants as needed within Pest Risk Analysis requires a broad range of economic methods and tools. Since economic and environmental con- sequences depend on a number of biological, environmental and ecological data, these disciplines have all to be linked together. Example: Phytophthora ramorum in Europe Problem Pests and diseases cause a variety of direct and indirect impacts. The assessment of these impacts on perennial ornamental and forest plants as needed for a decision on measures (SPS agreement) and their evaluation with cost-benefit analysis differs very much from the assessment for annual crops (wheat, corn). It remains very often with a high degree of uncertainty. Important points are: 1 concept of willingness to pay: is based on the estimate how much people would be willing to pay for specific environ- mental services. 2 market price method: applicable to products or services (of ecosystems) that are bought and sold in commercial markets. 3 travel cost method: assumes that the value of a site is reflected in how much people are willing to pay to travel to visit the site. Conclusion Fig. 5: Shoot dyback on Vi- burnum caused by P. ramorum Foto: S. Werres Foto: Fig. 2: What is the use-value of an old tree? A proper impact assessment for ornamental and forest plants requires:  Experience in practical application of the complex and very special methods  Consultation with experts in economics  More interdisciplinary investigations and projects  Use of qualitative data where quantification of monetary terms is not possible