Professor Ove Hoegh-Guldberg of Queensland University and colleagues have an important article on “Assisted Colonization and Rapid Climate Change” in this week’s issue of Science (pdf). The author’s argue:

Rapid climatic change has already caused changes to the distributions of many plants and animals, leading to severe range contractions and the extinction of some species (1, 2). The geographic ranges of many species are moving toward the poles or to higher altitudes in response to shifts in the habitats to which these species have adapted over relatively longer periods (1-4). It already appears that some species are unable to disperse or adapt fast enough to keep up with the high rates of climate change (5, 6). These organisms face increased extinction risk, and, as a result, whole ecosystems, such as cloud forests and coral reefs, may cease to function in their current form (7-9).

Current conservation practices may not be enough to avert species losses in the face of mid- to upper-level climate projections (>3°C) (10), because the extensive clearing and destruction of natural habitats by humans disrupts processes that underpin species dispersal and establishment. Therefore, resource managers and policy-makers must contemplate moving species to sites where they do not currently occur or have not been known to occur in recent history. This strategy flies in the face of conventional conservation approaches.

The strategy flies in the face of conventional conservation approaches due to the numerous risks associated with the introduction of invasive species. The authors fully acknowledge these risks.

The world is littered with examples where moving species beyond their current range into natural and agricultural landscapes has had negative impacts. Understandably, notions of deliberately moving species are regarded with suspicion. Our contrary view is that an increased understanding of the habitat requirements and distributions of some species allows us to identify low-risk situations where the benefits of such “assisted colonization’” can be realized and adverse outcomes minimized…

…One of the most serious risks associated with assisted colonization is the potential for creating new pest problems at the target site. Introduced organisms can also carry diseases and parasites or can alter the genetic structure and breeding systems of local populations…

…In addition to the ecological risks, socioeconomic concerns must be considered in decisions to move threatened species. Financial or human safety constraints, for example, may make a species’ introduction undesirable. It is likely to be unacceptable to move threatened large carnivores or toxic plants into regions that are important for grazing livestock…

These risks do not invalidate the authors’ major point. If we want to conserve current biodiversity in a changing climate, we will likely need creative alternatives to current conservation approaches. Facilitated dispersal of species is one option that deserves consideration in specific conservation contexts. However, it is far from a silver bullet.