Corridor Concerns

It is important to take into account the possibility of negative, unintended consequences of corridor creation in their design. In the same ways that corridors may facilitate movement of rare, endangered, or declining species, they may also increase dispersal of unwanted species, such as invasive species, or antagonists (predators or diseases) of conservation targets. For the most part, researchers have not encountered negative effects of corridors in conservation. Yet, work is still needed to understand when and where corridors can have negative effects.

Edge Effects

edge_effects_srsPerhaps the most 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.

Predation

predation_pokeweedAnother 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.

Disease

plant_diseaseRelated to effects of corridors on predation, diseases and other parasites may also utilize corridors to enhance dispersal and transmission. 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.

Invasive species

invasive_speciesThere has been no evidence that corridors created in conservation or restoration increase the spread of invasive species. These species are generally excellent colonizers, regardless of whether there are corridors.

Below are examples from corridor research that show the specific effects corridors can have, both in positive and negative ways.