Browsing by Author "Hulme, Philip E."
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- Drivers of future alien species impacts: an expert‐based assessmentPublication . Essl, Franz; Lenzner, Bernd; Bacher, Sven; Bailey, Sarah; Capinha, César; Daehler, Curtis; Dullinger, Stefan; Genovesi, Piero; Hui, Cang; Hulme, Philip E.; Jeschke, Jonathan M.; Katsanevakis, Stelios; Kühn, Ingolf; Leung, Brian; Liebhold, Andrew; Liu, Chunlong; MacIsaac, Hugh J.; Meyerson, Laura A.; Nuñez, Martin A.; Pauchard, Aníbal; Pyšek, Petr; Rabitsch, Wolfgang; Richardson, David M.; Roy, Helen E.; Ruiz, Gregory M.; Russell, James C.; Sanders, Nathan J.; Sax, Dov F.; Scalera, Riccardo; Seebens, Hanno; Springborn, Michael; Turbelin, Anna; Kleunen, Mark; Holle, Betsy; Winter, Marten; Zenni, Rafael D.; Mattsson, Brady J.; Roura‐Pascual, NuriaUnderstanding the likely future impacts of biological invasions is crucial yet highly challenging given the multiple relevant environmental, socio-economic and societal contexts and drivers. In the absence of quantitative models, methods based on expert knowledge are the best option for assessing future invasion trajectories. Here, we present an expert assessment of the drivers of potential alien species impacts under contrasting scenarios and socioecological contexts through the mid-21st century. Based on responses from 36 experts in biological invasions, moderate (20%-30%) increases in invasions, compared to the current conditions, are expected to cause major impacts on biodiversity in most socioecological contexts. Three main drivers of biological invasions-transport, climate change and socio-economic change-were predicted to significantly affect future impacts of alien species on biodiversity even under a best-case scenario. Other drivers (e.g. human demography and migration in tropical and subtropical regions) were also of high importance in specific global contexts (e.g. for individual taxonomic groups or biomes). We show that some best-case scenarios can substantially reduce potential future impacts of biological invasions. However, rapid and comprehensive actions are necessary to use this potential and achieve the goals of the Post-2020 Framework of the Convention on Biological Diversity.
- Projecting the continental accumulation of alien species through to 2050Publication . Seebens, Hanno; Bacher, Sven; Blackburn, Tim M.; Capinha, César; Dawson, Wayne; Dullinger, Stefan; Genovesi, Piero; Hulme, Philip E.; Kleunen, Mark; Kühn, Ingolf; Jeschke, Jonathan M.; Lenzner, Bernd; Liebhold, Andrew M.; Pattison, Zarah; Pergl, Jan; Pyšek, Petr; Winter, Marten; Essl, FranzBiological invasions have steadily increased over recent centuries. However, we still lack a clear expectation about future trends in alien species numbers. In particular, we do not know whether alien species will continue to accumulate in regional floras and faunas, or whether the pace of accumulation will decrease due to the depletion of native source pools. Here, we apply a new model to simulate future numbers of alien species based on estimated sizes of source pools and dynamics of historical invasions, assuming a continuation of processes in the future as observed in the past (a business-as-usual scenario). We first validated performance of different model versions by conducting a back-casting approach, therefore fitting the model to alien species numbers until 1950 and validating predictions on trends from 1950 to 2005. In a second step, we selected the best performing model that provided the most robust predictions to project trajectories of alien species numbers until 2050. Altogether, this resulted in 3,790 stochastic simulation runs for 38 taxon-continent combinations. We provide the first quantitative projections of future trajectories of alien species numbers for seven major taxonomic groups in eight continents, accounting for variation in sampling intensity and uncertainty in projections. Overall, established alien species numbers per continent were predicted to increase from 2005 to 2050 by 36%. Particularly, strong increases were projected for Europe in absolute (+2,543 ± 237 alien species) and relative terms, followed by Temperate Asia (+1,597 ± 197), Northern America (1,484 ± 74) and Southern America (1,391 ± 258). Among individual taxonomic groups, especially strong increases were projected for invertebrates globally. Declining (but still positive) rates were projected only for Australasia. Our projections provide a first baseline for the assessment of future developments of biological invasions, which will help to inform policies to contain the spread of alien species.