Cautions on using the Before-After-Control-Impact design in environmental effects monitoring programs

Smokorowski, Karen E.; Randall, Robert G.

doi:10.1139/facets-2016-0058

Cited by 133 publications

(108 citation statements)

References 30 publications

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“…Indeed, the short time involved in our study–considering relevant generation time scales for birds–could represent a static picture of local population dynamics. If we could have analyzed more than a single generation, we could have better considered whether the changes we observed were transient or permanent (Smokorowski & Randall ).…”

Section: Discussionmentioning

confidence: 99%

Effects of crowding due to habitat loss on species assemblage patterns

Vallejos

Padial

Vitule

et al. 2019

Conservation Biology

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Terrestrial animals are negatively affected by habitat loss, which is assessed on a landscape scale, whereas secondary effects of habitat loss, such as crowding, are usually disregarded. Such impacts are inherently hard to address and poorly understood, and there is a growing concern that they could have dire consequences. We sampled birds throughout a deforestation process to assess crowding stress in an adjacent habitat remnant in the southern Brazilian Atlantic Forest. Crowding is expected of highly mobile taxa, especially given the microhabitat heterogeneity of Neotropical forests, and we hypothesized that the arrival of new individuals or species in refuges shifts assemblage patterns. We used point counts to obtain bird abundances in a before‐after‐control‐impact design sampling of a deforestation event. Temporal changes in taxonomic and functional diversity were examined with metrics used to assess alpha and beta diversity, turnover of taxonomic and functional similarity, and taxonomic and functional composition. Over time increased abundance of some species altered the Simpson index and affected the abundance‐distribution of traits in the habitat remnant. Taxonomic composition and functional composition changed in the remnant, and thus bird assemblages changed over time. Taxonomic and functional metrics indicated that fugitives affected resident assemblages in refuges, and effects endured >2 years after the deforestation processes had ceased. Dissimilarity of taxonomic composition between pre‐ and postdeforestation assemblages increased, whereas functional composition reverted to preimpact conditions. We found that ecological disruptions resulted from crowding and escalated into disruptions of species’ assemblages and potentially compromising ecosystem functioning. It is important to consider crowding effects of highly mobile taxa during impact assessments, especially in large‐scale infrastructure projects that may affect larger areas than is assumed.

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Section: Discussionmentioning

confidence: 99%

Effects of crowding due to habitat loss on species assemblage patterns

Vallejos

Padial

Vitule

et al. 2019

Conservation Biology

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“…Successfully detecting environmental change with monitoring is affected by many factors, including the availability of data from an undisturbed baseline period and the study designs selected (Smokorowski and Randall 2017). Where a baseline data set is missing or deficient, the capability to detect change is compromised and alternative approaches are required.…”

Section: Discussionmentioning

confidence: 99%

“…A primary difficulty in ecological monitoring is the lack of information describing the undisturbed baseline conditions. This information is necessary for a widely discussed and ideal design, before-after-control-impact (BACI; Smokorowski and Randall 2017). Where data to fulfill the BACI design or its variants are not available, other study types such as paleolimnology may be employed (Kurek et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Increased size and relative abundance of migratory fishes observed near the Athabasca oil sands

Arciszewski

Munkittrick

Kilgour

et al. 2017

FACETS

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Responses to chemical and physical stressors are commonly expected among organisms residing near the Athabasca oil sands. Physiological effects have been observed in fishes during field studies; but further effects associated with development are not clear or consistent among species. For instance, data from a fish fence in 2009 show declines in the relative abundances of some species, including Arctic grayling (Thymallus arcticus). In contrast, increases were seen in white sucker (Catostomus commersoni). This divergence suggests incomplete understanding of the status of fishes residing near the oil sands. However, an important challenge limiting understanding is the lack of reliable baseline or reference data. To overcome this challenge, we used iterative normal ranges and a historical data set (electrofishing surveys done from 1987 to 2014) to determine if changes have occurred in fishes captured in the lower Athabasca River. These analyses revealed clear increases in the lengths of white sucker and walleye (Sander vitreus) and their relative abundances during the spawning season. The occurrence of these changes may be associated with overwintering location, but reduced fishing pressure in Lake Athabasca, eutrophication, or a cumulative effect may explain the form of changes detected in this study.

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“…The ideal scenario is to have a BACI (before‐after‐control‐impact) study design (Ogren & Huckins ; Tummers et al ) that controls for both spatial and temporal variation. However, few studies achieve this despite that it has been shown to be the overall superior method for monitoring (Smokorowski & Randall ).…”

Section: Introductionmentioning

confidence: 99%

Does restoration work? It depends on how we measure success

Mahlum

Côté

Wiersma

et al. 2017

Restoration Ecology

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The restoration of 4 partial stream barriers was evaluated in watersheds of Terra Nova National Park, Newfoundland, Canada from 2009 to 2011. Brook trout (n = 462) were tagged and tracked moving through our study sites using passive‐integrated transponder telemetry and the restoration actions were assessed using 3 different measures: passage success rates; the range of passable flows; and the availability of passable flows. We considered the observed results within a before‐after‐control‐impact (BACI) design that included reference reaches and pre‐restoration observations. The conclusions of BACI analyses were also contrasted with those that would have been obtained from commonly used before‐after (B‐A) or control‐impact (C‐I) study designs. While the restoration actions changed hydrological conditions in a way that should facilitate fish passage, our biological measures indicated that success was variable across culverts and within culverts depending on the measure evaluated. Furthermore, the natural temporal and spatial variability of fish movements often resulted in different conclusions between the more robust BACI design and the more commonly used B‐A and C‐I designs. Our results demonstrate that restoration of partial barriers may not always yield dramatic improvements. Furthermore, without suitable controls, the chances of drawing false conclusions regarding restorations in temporally and spatially dynamic systems are substantial.

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Cautions on using the Before-After-Control-Impact design in environmental effects monitoring programs

Cited by 133 publications

References 30 publications

Effects of crowding due to habitat loss on species assemblage patterns

Effects of crowding due to habitat loss on species assemblage patterns

Increased size and relative abundance of migratory fishes observed near the Athabasca oil sands

Does restoration work? It depends on how we measure success

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