Mixed messages from multiple information sources on invasive species: a case of too much of a good thing?

Abstract

Aim The increasing number and availability of online databases of alien species beg a question of their comparability given most do not adopt standard criteria in the definition of species status or taxonomic treatment and vary in their comprehensiveness. In this study, we compare the consistency of two major European databases for the regions they have in common. We assess whether they use consistent terminology to classify species status, provide similar taxonomic classification and coverage, deliver comparable estimates of alien richness per country and identify comparable correlates of alien richness. Location Northern Europe.Methods Data on the total number of alien species as well as the number of established alien species were extracted from the online databases DAISIE and NOBANIS for 13 European countries and classified into comparable taxonomic groups. Analyses across countries examined trends in alien species richness, correlations among taxonomic groups and the explanatory power of population density, country area and per capita GDP on alien species richness.Results Alien species richness, intertaxon correlations and the significance of individual drivers of invasion were all strongly database dependent. Differences were more marked for total numbers of aliens than established aliens. Over all taxonomic groups, DAISIE had lower species richness and fewer significant intertaxon correlations but presented a greater number of significant explanatory models of alien species richness. Trends in species richness were not generally correlated between the two databases with human population density being a more important driver in DAISIE while country area had greater explanatory power in NOBANIS.Main conclusions Considerable caution should be applied when collating data from different databases because often their underlying structure and content may differ markedly. For Europe, the analysis indicates that having two contrasting databases is not an ideal basis for implementing invasive species policy and moves should be made soon to establish a central pan-European database.

Naturalized alien flora of the world

“…The last decade has thus seen rapid development of numerous alien species databases, ranging in extent from regional to continental, built with the aim of collecting information on alien species status, distribution, pathways, impacts and other characteristics (Hulme & Weser 2011). One such effort was the European DAISIE project, which at the time was exceptional in terms of covering all major taxa and biomes for a whole continent and because the data were purposely collected based on standardized criteria (DAISIE 2009.…”

“…Based on the DAISIE database, Lambdon et al (2008) provided a comprehensive analysis of the species composition and structure of regional floras in Europe, but such a detailed account has until now remained available only for this continent. Another major European alien species inventory compiled over the last decades is the North European and Baltic Network on Invasive Alien Species (NOBANIS; www.nobanis.org), a joint effort of 18 European countries (Hulme & Weser 2011). For other continents, a comprehensive database, primarily focused on native taxa but also including the distribution of a complete alien flora, is the regularly updated BONAP database (Kartesz & Meacham 1999, which has been used in a number of intercontinental analyses of plant invasions , Kalusová et al 2013, van Kleunen et al 2015.…”

Taxonomic perils and pitfalls of dataset assembly in ecology: a case study of the naturalized Asteraceae in Australia

“…For instance, the 21% of taxa in the FD that were either found only in GD or only in RD under their currently accepted name demonstrate that using more than one source dataset when possible is likely to lead to a higher number of relevant taxa in the FD and that disparate source datasets are likely to differ in their taxonomic content (e.g. Hulme and Weser 2011). At this stage, it is unclear why our two source datasets each contained taxa that the other did not.…”

“…The value of such datasets for addressing research questions is first and foremost determined by the quality of taxonomic accuracy underpinning their plant names. The task of merging multiple source datasets into one plant ecological dataset that is clean of taxonomic errors is seldom straightforward because lists that have not been actively maintained become outdated and riddled with incorrect or obsolete taxonomy (Soberón andPeterson 2004, Hulme andWeser 2011). This can lead to a lack of taxonomic congruence among existing lists and ultimately the assembly of a taxonomically unreliable dataset (Jansen and Dengler 2010).…”

“…These journals periodically publish lists and records of plants newly recorded or identified as naturalized within Australia. We located three sources documenting new naturalizations in Australia, Hosking et al (2007), Hosking et al (2011) andParsons (2012).…”