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Options for reducing uncertainty in impact classification for alien species

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posted on 01.06.2021, 05:15 by DA Clarke, DJ Palmer, C McGrannachan, TI Burgess, SL Chown, RH Clarke, S Kumschick, L Lach, AM Liebhold, HE Roy, ME Saunders, DK Yeates, MP Zalucki, Melodie McGeochMelodie McGeoch
Impact assessment is an important and cost-effective tool for assisting in the identification and prioritization of invasive alien species. With the number of alien and invasive alien species expected to increase, reliance on impact assessment tools for the identification of species that pose the greatest threats will continue to grow. Given the importance of such assessments for management and resource allocation, it is critical to understand the uncertainty involved and what effect this may have on the outcome. Using an uncertainty typology and insects as a model taxon, we identified and classified the causes and types of uncertainty when performing impact assessments on alien species. We assessed 100 alien insect species across two rounds of assessments with each species independently assessed by two assessors. Agreement between assessors was relatively low for all three impact classification components (mechanism, severity, and confidence) after the first round of assessments. For the second round, we revised guidelines and gave assessors access to each other’s assessments which improved agreement by between 20% and 30% for impact mechanism, severity, and confidence. Of the 12 potential reasons for assessment discrepancies identified a priori, 11 were found to occur. The most frequent causes (and types) of uncertainty (i.e., differences between assessment outcomes for the same species) were as follows: incomplete information searches (systematic error), unclear mechanism and/or extent of impact (subjective judgment due to a lack of knowledge), and limitations of the assessment framework (context dependence). In response to these findings, we identify actions that may reduce uncertainty in the impact assessment process, particularly for assessing speciose taxa with diverse life histories such as Insects. Evidence of environmental impact was available for most insect species, and (of the non-random original subset of species assessed) 14 of those with evidence were identified as high impact species (with either major or massive impact). Although uncertainty in risk assessment, including impact assessments, can never be eliminated, identifying, and communicating its cause and variety is a first step toward its reduction and a more reliable assessment outcome, regardless of the taxa being assessed.

Funding

Ian Potter Foundation; National Science Foundation. Grant Numbers: 1241932, 1638702; European Union; Australian Government; Natural Environment Research Council. Grant Number: NE/R016429/1; Queensland Department of Environment; Invasive Species Council; Australian Department of Agriculture; Australian Antarctic Science Grant. Grant Number: 4482; Australian Research Council. Grant Number: DP200101680; South African National Department of Environment Affairs.

History

Publication Date

23/04/2021

Journal

Ecosphere

Volume

12

Issue

4

Article Number

e03461

Pagination

(p. 1-12)

Publisher

Wiley

ISSN

2150-8925

Rights Statement

The Author reserves all moral rights over the deposited text and must be credited if any re-use occurs. Documents deposited in OPAL are the Open Access versions of outputs published elsewhere. Changes resulting from the publishing process may therefore not be reflected in this document. The final published version may be obtained via the publisher’s DOI. Please note that additional copyright and access restrictions may apply to the published version.

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