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The Anthropocene Epoch is characterized by novel and increasingly complex dependencies between the environment and human civilization, with many challenges of biodiversity management emerging as wicked problems. Problems arising from the management of biological invasions can be either tame (with simple or obvious solutions) or wicked, where difficulty in appropriately defining the problem can make complete solutions impossible to find. We review four case studies that reflect the main goals in the management of biological invasions – prevention, eradication, and impact reduction – assessing the drivers and extent of wickedness in each. We find that a disconnect between the perception and reality of how wicked a problem is can profoundly influence the likelihood of successful management. For example, managing species introductions can be wicked, but shifting from species-focused to vector-focused risk management can greatly reduce the complexity, making it a tame problem. The scope and scale of the overall management goal will also dictate the wickedness of the problem and the achievability of management solutions (cf. eradication and ecosystem restoration). Finally, managing species that have both positive and negative impacts requires engagement with all stakeholders and scenario-based planning. Effective management of invasions requires either recognizing unavoidable wickedness, or circumventing it by seeking alternative management perspectives.
Since first of January 2015, the EU-regulation 1143/2014 obligates all member states to conduct costbenefit 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. mantagezzianum 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.
Successful invasion is often due to a combination of species characteristics (or invasiveness) and habitat suitability (or invasibility). Our objective was to identify preferred habitats and suitable environmental conditions for the African tulip tree Spathodea campanulata (Bignoniaceae), one of the most invasive alien trees on the tropical island of French Polynesia (South Pacific Ocean), in relation to its distribution and photosynthesis capacity. Spathodea abundance and leaf chlorophyll fluorescence Fo’, ETRmax, and Y(II) effective were examined in relation to topography and micro-climate along elevational transects between 140 m and 1,300 m. Results showed that Spathodea is (1) present up to 1,240 m with lowest maximum July–October (cool season) temperature of 9.4 °C and an average July-October temperature of 14.6 °C, (2) is able to colonize slope steepness of more than 45°, (3) is well represented in the elevational range of 140–540 m as well as in the native forests between 940 m and 1,040 m, suggesting a high threat for native and endemic plants species. Along one of the transects, in the elevation range of 541–940 m, Spathodea was under-represented, Chl fluorescence Fo’ increased significantly while Y(II)effective decreased significantly supporting the hypothesis that this range is a non-preferred environment, probably due to microclimate conditions characterized by punctual air dryness. Among Spathodea plants surveyed along a wetter transect, Y(II)effective and ETRmax were comparable from low elevation to mid-high elevation indicating that the potential photosynthesis rate of Spathodea may be similar from sea level until mid-high elevation. Major infestations on the island of Tahiti were reported on the leeward (drier and urbanized) west coast, but Spathodea has also been recently found on the slopes of the windward (wetter) east coast. Chlorophyll fluorescence measurements indicate a high photosynthetic capacity among Spathodea in wet environments suggesting that Spathodea will become invasive across most of the island of Tahiti.
Background: Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe.
Methods: In the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements.
Results: Both species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus.
Conclusions: Species distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies.