New measures for evaluation of environmental perturbations using Before-After-Control-Impact analyses.

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Show simple item record Chevalier, Mathieu en Russell, James en Knape, Jonas en 2020-02-17T22:18:57Z en 2019-03 en
dc.identifier.citation Ecological applications 29(2):e01838 Mar 2019 en
dc.identifier.issn 1051-0761 en
dc.identifier.uri en
dc.description.abstract Before-After-Control-Impact (BACI) designs are powerful tools to derive inferences about environmental perturbations (e.g., hurricanes, restoration programs) when controlled experimental designs are unfeasible. Applications of BACI designs mostly rely on testing for a significant interaction between periods and treatments (so-called BACI contrast) to demonstrate the effects of the perturbation. However, significant interactions can emerge for several reasons, including when changes are larger in control sites, such that additional diagnostics must be performed to determine the full complexity of system changes. We propose two measures that detail the nature of change implied by BACI contrasts, along with its uncertainty. CI-divergence (Control-Impact divergence) quantifies to what extent control and impact sites have diverged between the after and the before period, whereas CI-contribution (Control-Impact contribution) quantifies to what extent the change between periods is stronger in impact sites relative to control sites. To illustrate how these two CI measures can be combined with BACI contrast to gain insights about effects of environmental perturbations, we used count data from the Swedish Breeding Bird Survey to investigate how hurricane Gudrun affected the long-term abundances of four bird species in forested areas of southern Sweden. Before-After-Control-Impact contrasts suggested the hurricane affected all four species. However, the values of the two CI measures strongly differed, even among species showing similar BACI contrasts. Those differences highlight qualitatively distinct population trajectories between periods and treatments requiring different ecological explanations. Overall, we show that BACI contrasts do not provide the full story in assessing the effects of environmental perturbations. The two CI measures can be used to assist ecological interpretations, or to specify detailed hypotheses about effects of restoration actions to allow stronger confirmatory inference about their outcomes. By providing a framework to develop more detailed explanations and hypotheses about ecological changes, the two CI measures can improve conclusions and strengthen evidence of effects of conservation actions and impact assessments under BACI designs. en
dc.format.medium Print-Electronic en
dc.language eng en
dc.relation.ispartofseries Ecological applications : a publication of the Ecological Society of America en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.subject Animals en
dc.subject Birds en
dc.subject Ecology en
dc.subject Sweden en
dc.subject Cyclonic Storms en
dc.subject Forests en
dc.title New measures for evaluation of environmental perturbations using Before-After-Control-Impact analyses. en
dc.type Journal Article en
dc.identifier.doi 10.1002/eap.1838 en
pubs.issue 2 en
pubs.begin-page e01838 en
pubs.volume 29 en
dc.rights.holder Copyright: The author en
pubs.publication-status Published en
dc.rights.accessrights en
pubs.subtype Research Support, Non-U.S. Gov't en
pubs.subtype Journal Article en
pubs.elements-id 765955 en Science en Biological Sciences en
pubs.record-created-at-source-date 2018-12-15 en
pubs.dimensions-id 30549390 en

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