Corridors (and increased landscape connectivity more generally) are the most frequently recommended conservation strategy to protect biodiversity as climate changes. As climate warms, plants and animals are moving to cooler places, either at higher latitudes or up mountains. Yet, their path to cooler places may be blocked by human-created barriers such as cities or fields. Where ranges need to shift, it is important to ensure that individual plants and animals are able to move through landscapes so they can make it to new climates that are now suitable, and corridors can provide a path to those new places. Climate change may also increase population variability and the likelihood of local extinction; corridors provide paths for individuals to recolonize habitats where populations have been lost. Since many species response to climate change is still unpredictable, corridors can provide the necessary outlet for species to expand as needed throughout the landscape and ensure that fewer local populations go extinct.
Are current parks and reserves sufficient to allow range shifts?
Most existing parks and reserves are not wide enough to accommodate range shifts. Recent studies across all plants and animals have shown that the average species has moved nearly 20km per decade poleward, and over 10 m per decade up in elevation. And that is in response to past climate change — future climate change is expected to be faster. Meade Krosby and her colleagues have found that most parks and reserves are relatively narrow, on the scale of 1-10 km wide, not nearly wide enough to accommodate range shifts to higher latitudes. Current reserves encompass larger elevational gradients, but most mountain ranges have a high degree of conservation already, and most of the Earth’s land area is at low elevation, lower than 300m. Thus, connections are needed to conserve range shifts.
What are alternatives to corridors?
The leading alternative to creating corridors is assisted migration or managed relocation. The idea is to physically move species to more suitable climates. Managed relocation has the advantage of not requiring the potentially costly land conservation needed to conserve corridors. But there are risks, such as introducing species to new ranges where they may become invasive, the cost of introductions to get species to establish, or the problem of leaving less charismatic species behind.
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