A cost-benefit analysis of controlling giant hogweed (Heracleum mantegazzianum) in Germany using a choice experiment approach

Since first of January 2015, the EU-regulation 1143/2014 obligates all member states to conduct cost-benefit analyses in preparation of control programs for invasive alien species to minimize and mitigate their impacts. In addition, with ratification of the Rio Declaration and the amended Federal Nature Conservation Act, Germany is committed to control any further spread of invasive species. This is the first cost-benefit analysis estimating positive welfare effects and societal importance of H. mantegazzianum invasion control in Germany. The paper analyses possible control options limiting stands of giant hogweeds (H. mantegazzianum) based on survey data of n = 287 German districts. We differentiate between several control options (e.g. root destruction, mechanical cutting or mowing, chemical treatment and grazing) depending on infested area size and protection status. The calculation of benefits is based on stated preference results (choice experiment; n = 282). For the cost side, we calculate two different invasion scenarios (i) no re-infestation after successfully conducted control measures (optimistic) and (ii) re-infestation twice after conducting control measures occurring within ten years (pessimistic). Minimum costs of eradication measures including a time span of ten years and a social discount rate of 1% result in a total of 3,467,640 € for optimistic scenario and 6,254,932 € for pessimistic invasion scenario, where no success of the first eradication attempt is assumed. Benefits of invasion control in Germany result in a total of 238,063,641 € per year and overassessment-factor corrected in 59,515,910 € per year.