Foto: S. Werres

1. Hella Kehlenbeck Federal Biological Research Centre for Agriculture and Forestry, Department for National and International Plant Health Stahnsdorfer Damm 81, D-14532 Kleinmachnow, Germany; H.Kehlenbeck@bba.de Foto: S. Werres Fig. 5: Shoot dyback on Vi-burnum caused by P. ramorum Economic and environmental impact assessment for ornamental and forest plants – the case of P. ramorum 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: • 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 Foto: Axel Oehler Foto: www.suentelbuchen.de Fig. 1: What is the recreational value of a rhododendron park? Fig. 2: What is the use-value of an old tree? Example: Phytophthora ramorum in Europe 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,www.rapra.csl.gov.uk). Impacts of the fungus in Europe are mostlyoncropproductioninnurseries 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 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 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. 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