Corridor Concerns - Conservation Corridor (2024)

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Edge Effects | Predation | Disease | Invasive Species | Population Synchrony | Social Concerns

Publications Table

• Gilbert-Norton, L., et al. 2010. A meta-analytic review of corridor effectiveness. Conservation Biology 24: 660-668.
• Haddad, N.M., et al. 2014. Potential negative ecological effects of corridors. Conservation Biology 28: 1178-1187.

• Resasco, J. 2019. Meta-analysis on a decade of testing corridor efficacy: What new have we learned? Current Landscape Ecology Reports 4: 61-69.

One important negative effect of corridors is introduced because of their long and narrow shape. This shape creates boundaries between conservation and degraded areas. Species tend to behave differently at these boundaries, or edges, of habitat fragments, and there is concern that in creating habitat patches such as corridors, the high ratio of edge to area might be detrimental to species using the corridor.

This concern is somewhat supported by research; because of edge effects, some species do experience corridors as habitat sinks or ecological traps. When edge effects are negative, they should be planned for and mitigated against when designing corridors.

• Travers, E., Härdtle, W. and Matthies, D. 2021. Corridors as a tool for linking habitats–Shortcomings and perspectives for plant conservation. Journal for Nature Conservation 60: 125974.

• Åström, J., and T. Pärt. 2013. Negative and matrix‐dependent effects of dispersal corridors in an experimental metacommunity. Ecology 94: 72-82.
• Johnson, B.L., and N.M. Haddad. 2011. Edge effects, not connectivity, determine the incidence and development of a foliar fungal plant disease. Ecology 92:1551-1558.
• King, D.I., et al. 2009. Effects of width, edge and habitat on the abundance and nesting success of scrub-shrub birds in powerline corridors. Biological Conservation 142: 2672-2680.

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Another concern about corridors is that they may increase predation rates. If prey are dispersing through corridors, this may provide the perfect bottleneck of which a predator can take advantage.

This, also, is a valid concern that is not strongly supported by scientific evidence. There is no clear evidence that predation rates universally increase in a negative way due to corridors, although the relationship between predation and corridors is complex.

• Saxena, A. and Habib, B. 2022. Safe passage or hunting ground? A test of the prey-trap hypothesis at wildlife crossing structures on NH 44, Pench Tiger Reserve, Maharashtra, India. Diversity 14: 312.

• Hawn, C.L., et al. 2018. Connectivity increases trophic subsidies in fragmented landscapes. Ecology Letters 21: 1620-1628.

• Orrock, J.L., et al. 2003. Spatial ecology of predator-prey interactions: corridors and patch shape influence seed predation. Ecology 84: 2589-2599.
• Gilliam J. F. and D.F. Fraser. 2001. Movement in corridors: enhancement by predation threat, disturbance and habitat structure. Ecology 82: 258-273.

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Related to effects of corridors on predation, diseases and other parasites may also utilize corridors to enhance dispersal and transmission. If corridors connect individuals more effectively, then pathogens or individual parasites may also spread more rapidly through connected patches.

Evidence to date suggests that some parasites, particularly those that are dispersed by animals, move more frequently between patches connected by corridors. But there has been no evidence that this reduces the persistence of species in restoration or conservation.

• Sullivan, L.L., et al. 2011. Can dispersal mode predict corridor effects on plant parasites? Ecology 92: 1559-1564.
• Johnson, B.L., and N.M. Haddad. 2011. Edge effects, not connectivity, determine the incidence and development of a foliar fungal plant disease. Ecology 92:1551-1558.

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There has been little evidence that corridors alone, created in conservation or restoration, increase the spread of invasive species. These species are generally excellent colonizers, regardless of whether there are corridors. Their ability to spread rapidly and displace native species is an inherent characteristic rather than a sole feature of the landscape.

Some research has suggested that corridors may influence the spread of some invasives, although the effects may be transient.

• Resasco, J., et al. 2014. Landscape corridors can increase invasion by an exotic species and reduce diversity of native species. Ecology 95(8): 2033-2039.
• Vila, M. and I. Ibanez. 2011. Plant invasions in the landscape. Landscape Ecology 26(4): 461-472.

• Minor, E.S., et al. 2009. The role of landscape connectivity in assembling exotic plant communities: a network analysis. Ecology 90: 1802-1809.

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One potential impact of corridors is to synchronize population dynamics and increase the likelihood of metapopulation extinction. Populations that are connected by corridors could have similar changes in abundance, and therefore be more vulnerable to an antagonistic event such as disturbance or invasion.

Research shows that corridors do have the potential to synchronize populations, but the long-term consequences of this synchronization are untested for a diversity of species traits and likely to be complex.

• Cooper, J.K., et al. 2012. Intermediate fragmentation per se provides stable predator‐prey metapopulation dynamics. Ecology Letters 15: 856-863.

• Hudgens, B.R. and Haddad, N.M. 2003. Predicting which species will benefit from corridors in fragmented landscapes from population growth models. The American Naturalist 161: 808-820.

• Holyoak, M. 2000. Habitat patch arrangement and metapopulation persistence of predators and prey. The American Naturalist 156: 378-389.

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Social concerns about the creation and maintenance of corridors often echo concerns about conservation lands in general. Will this change negatively impact landowners and communities by threatening economic livelihoods, private land ownership rights, or environmental stability? Will local needs be ignored in favor of protecting land for “the greater good”?

Research continues to address these concerns and further dialogue about corridors and connectivity.

• Zafra-Calvo, N. and Moreno-Peñaranda, R. 2018. Exploring local people’s views on the livelihood impacts of privately versus community managed conservation strategies in the Ruvuma landscape of North Mozambique-South Tanzania. Journal of Environmental Management 206: 853-862.

• Bluwstein, J. and Lund, J.F. 2018. Territoriality by conservation in the Selous–Niassa Corridor in Tanzania. World Development 101: 453-465.

• Wyrick, J.R., Rischman, B.A., Burke, C.A., McGee, C. and Williams, C. 2009. Using hydraulic modeling to address social impacts of small dam removals in southern New Jersey. Journal of Environmental Management 90:S270-S278.

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