The generic impact scoring system (GISS): a standardized tool to quantify the impacts of alien species

Abstract

Alien species can exert negative environmental and socio-economic impacts. Therefore, administrations from different sectors are trying to prevent further introductions, stop the spread of established species, and apply or develop programs to mitigate their impact, to contain the most harmful species, or to eradicate them if possible. Often it is not clear which of the numerous alien species are most important in terms of damage, and therefore, impact scoring systems have been developed to allow a comparison and thus prioritization of species. Here, we present the generic impact scoring system (GISS), which relies on published evidence of environmental and socio-economic impact of alien species. We developed a system of 12 impact categories, for environmental and socio-economic impact, comprising all kinds of impacts that an alien species may exert. In each category, the intensity of impact is quantified by a sixlevel scale ranging from 0 (no impact detectable) to 5 (the highest impact possible). Such an approach, where impacts are grouped based on mechanisms for environmental impacts and receiving sectors for socio-economy, allows for cross-taxa comparisons and prioritization of the most damaging species. The GISS is simple and transparent, can be conducted with limited funds, and can be applied to a large number of alien species across taxa and environments. Meanwhile, the system was applied to 349 alien animal and plant species. In a comparison with 22 other impact assessment methods, the combination of environmental and socio-economic impact, as well as the possibility of weighting and

Impact assessment with different scoring tools: How well do alien amphibian assessments match?

“…GISS and EICAT differ in (i) the number of categories (i.e., mechanisms) and (ii) the details of what is required to score a species in any category. The details of both schemes are published elsewhere (Hawkins et al 2015, Nentwig et al 2016) but have been summarised here in Table 1. GISS scores concentrate on the spatial scale at which an alien species is having an impact as well as the number of species that are impacted by the alien.…”

“…However, EICAT assessments assign a confidence level to each assessment ranging from low to high as described in Hawkins et al (2015). The latest guidelines on the GISS system published refers to the EICAT guidelines for confidence assessment (Nentwig et al 2016). However, we did not include these in the analyses as previous publications of GISS did not include them (e.g., Nentwig et al 2010.…”

“…The two impact scoring schemes we chose for the comparison are the Generic Impact Scoring System GISS , Nentwig et al 2016) and the Environmental Impact Classification for Alien Taxa (EICAT) scheme , Hawkins et al 2015. While EICAT was formally adopted by the IUCN as an official system to classify the threat posed by alien species to the native environment (https://portals.iucn.org/congress/motion/014), to be used alongside the Red List for species conservation, to date it has only been systematically applied to one taxonomic group, namely birds (Evans et al 2016).…”

“…While EICAT was formally adopted by the IUCN as an official system to classify the threat posed by alien species to the native environment (https://portals.iucn.org/congress/motion/014), to be used alongside the Red List for species conservation, to date it has only been systematically applied to one taxonomic group, namely birds (Evans et al 2016). The GISS on the other hand is one of the most widely used and adopted impact scoring tools and has been applied to a wide variety of taxa ranging from plants , Novoa et al 2016) to vertebrates (e.g., Evans et al 2014, Martin-Albarracin et al 2015 and invertebrates Nentwig 2014, Nentwig 2015) and spanning many habitats (see Nentwig et al 2016 for an overview of previous applications). A comparison between these impact scoring schemes can be useful in order to assess to what extent GISS scores can be "translated" into EICAT classifications, given the many GISS assessments which were performed before the adoption of EICAT by IUCN.…”

Do local enemies attack alien and native Impatiens alike?

“…Moreover, the evolution of increased competitive ability hypothesis (EICA), which was derived from the ERH, states that the energy and/ or biomass that had to be spent for defense against enemies in the native range can be invested in more effective reproduction in the new areas taken over after introduction [14]. This leads to an increase in the population numbers of the alien species, its spread, and consequently invasiveness, manifested in negative impacts on native biodiversity, ecosystem services, the economy, and human wellbeing (e.g., [15,16]). …”