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Is habitat fragmentation bad for biodiversity?

Is habitat fragmentation bad for biodiversity?
Is habitat fragmentation bad for biodiversity?

In a review of landscape-scale empirical studies, Fahrig (2017a) found that ecological responses to habitat fragmentation per se (fragmentation independent of habitat amount) were usually non-significant (>70% of responses) and that 76% of significant relationships were positive, with species abundance, occurrence, richness, and other response variables increasing with habitat fragmentation per se. Fahrig concluded that to date there is no empirical evidence supporting the widespread assumption that a group of small habitat patches generally has lower ecological value than large patches of the same total area. Fletcher et al. (2018) dispute this conclusion, arguing that the literature to date indicates generally negative ecological effects of habitat fragmentation per se. They base their argument largely on extrapolation from patch-scale patterns and mechanisms (effects of patch size and isolation, and edge effects) to landscape-scale effects of habitat fragmentation. We argue that such extrapolation is unreliable because: (1) it ignores other mechanisms, especially those acting at landscape scales (e.g., increased habitat diversity, spreading of risk, landscape complementation) that can counteract effects of the documented patch-scale mechanisms; and (2) extrapolation of a small-scale mechanism to a large-scale pattern is not evidence of that pattern but, rather a prediction that must be tested at the larger scale. Such tests were the subject of Fahrig's review. We find no support for Fletcher et al.'s claim that biases in Fahrig's review would alter its conclusions. We encourage further landscape-scale empirical studies of effects of habitat fragmentation per se, and research aimed at uncovering the mechanisms that underlie positive fragmentation effects.

Corridors, Cross-scale extrapolation, Edge effect, Habitat diversity, Habitat fragmentation per se, Habitat loss, Landscape configuration, Landscape heterogeneity, Patch isolation, Patch size, SLOSS, Spatial scale
0006-3207
179-186
Fahrig, Lenore
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Arroyo-Rodríguez, Víctor
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Bennett, Joseph R.
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Boucher-Lalonde, Véronique
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Cazetta, Eliana
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Currie, David J.
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Eigenbrod, Felix
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Ford, Adam T.
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Harrison, Susan P.
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Jaeger, Jochen A.G.
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Koper, Nicola
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Martin, Amanda E.
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Martin, Jean Louis
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Metzger, Jean Paul
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Morrison, Peter
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Rhodes, Jonathan R.
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Saunders, Denis A.
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Simberloff, Daniel
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Smith, Adam C.
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Tischendorf, Lutz
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Vellend, Mark
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Watling, James I.
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Fahrig, Lenore
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Arroyo-Rodríguez, Víctor
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Bennett, Joseph R.
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Boucher-Lalonde, Véronique
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Cazetta, Eliana
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Currie, David J.
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Eigenbrod, Felix
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Ford, Adam T.
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Harrison, Susan P.
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Jaeger, Jochen A.G.
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Koper, Nicola
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Martin, Amanda E.
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Martin, Jean Louis
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Metzger, Jean Paul
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Morrison, Peter
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Rhodes, Jonathan R.
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Saunders, Denis A.
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Simberloff, Daniel
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Smith, Adam C.
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Tischendorf, Lutz
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Vellend, Mark
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Watling, James I.
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Fahrig, Lenore, Arroyo-Rodríguez, Víctor, Bennett, Joseph R., Boucher-Lalonde, Véronique, Cazetta, Eliana, Currie, David J., Eigenbrod, Felix, Ford, Adam T., Harrison, Susan P., Jaeger, Jochen A.G., Koper, Nicola, Martin, Amanda E., Martin, Jean Louis, Metzger, Jean Paul, Morrison, Peter, Rhodes, Jonathan R., Saunders, Denis A., Simberloff, Daniel, Smith, Adam C., Tischendorf, Lutz, Vellend, Mark and Watling, James I. (2019) Is habitat fragmentation bad for biodiversity? Biological Conservation, 230, 179-186. (doi:10.1016/j.biocon.2018.12.026).

Record type: Review

Abstract

In a review of landscape-scale empirical studies, Fahrig (2017a) found that ecological responses to habitat fragmentation per se (fragmentation independent of habitat amount) were usually non-significant (>70% of responses) and that 76% of significant relationships were positive, with species abundance, occurrence, richness, and other response variables increasing with habitat fragmentation per se. Fahrig concluded that to date there is no empirical evidence supporting the widespread assumption that a group of small habitat patches generally has lower ecological value than large patches of the same total area. Fletcher et al. (2018) dispute this conclusion, arguing that the literature to date indicates generally negative ecological effects of habitat fragmentation per se. They base their argument largely on extrapolation from patch-scale patterns and mechanisms (effects of patch size and isolation, and edge effects) to landscape-scale effects of habitat fragmentation. We argue that such extrapolation is unreliable because: (1) it ignores other mechanisms, especially those acting at landscape scales (e.g., increased habitat diversity, spreading of risk, landscape complementation) that can counteract effects of the documented patch-scale mechanisms; and (2) extrapolation of a small-scale mechanism to a large-scale pattern is not evidence of that pattern but, rather a prediction that must be tested at the larger scale. Such tests were the subject of Fahrig's review. We find no support for Fletcher et al.'s claim that biases in Fahrig's review would alter its conclusions. We encourage further landscape-scale empirical studies of effects of habitat fragmentation per se, and research aimed at uncovering the mechanisms that underlie positive fragmentation effects.

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Fahrig et al Is Fragmentation Bad Fo rBiodiversity 2018 Biol Conserv - Author's Original
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More information

Accepted/In Press date: 19 December 2018
e-pub ahead of print date: 31 December 2018
Published date: 1 February 2019
Keywords: Corridors, Cross-scale extrapolation, Edge effect, Habitat diversity, Habitat fragmentation per se, Habitat loss, Landscape configuration, Landscape heterogeneity, Patch isolation, Patch size, SLOSS, Spatial scale

Identifiers

Local EPrints ID: 429589
URI: http://eprints.soton.ac.uk/id/eprint/429589
ISSN: 0006-3207
PURE UUID: c5f4fb6e-fbcf-470c-a143-12dd771c93f4
ORCID for Felix Eigenbrod: ORCID iD orcid.org/0000-0001-8982-824X

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Date deposited: 29 Mar 2019 17:30
Last modified: 07 Oct 2020 01:58

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Contributors

Author: Lenore Fahrig
Author: Víctor Arroyo-Rodríguez
Author: Joseph R. Bennett
Author: Véronique Boucher-Lalonde
Author: Eliana Cazetta
Author: David J. Currie
Author: Felix Eigenbrod ORCID iD
Author: Adam T. Ford
Author: Susan P. Harrison
Author: Jochen A.G. Jaeger
Author: Nicola Koper
Author: Amanda E. Martin
Author: Jean Louis Martin
Author: Jean Paul Metzger
Author: Peter Morrison
Author: Jonathan R. Rhodes
Author: Denis A. Saunders
Author: Daniel Simberloff
Author: Adam C. Smith
Author: Lutz Tischendorf
Author: Mark Vellend
Author: James I. Watling

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