Using biodiversity offsets to capture moving conservation targets
How do we conserve something when it won’t stand still? It’s a question we are only just beginning to grapple with in conservation science. Fixed protected areas are an example of a classic conservation tool, but traditional interventions like these can be ineffective for ‘moving targets’: for instance, a species that is so mobile that it doesn’t stay within a reserve. Biodiversity offsets, despite the suspicion they are often treated with by conservationists, may provide some answers to this question, as discussed in two new review papers resulting from CEED collaborations (Bull et al. 2013a; 2013b).
Two types of moving target
The moving-target problem that we investigated comes in two forms. The first relates to mobile species and the second to species forced to move by a changing environment.
The problem with mobile species, such as migratory species, is that they are unlikely to be conserved by fixed protected areas that do not cover their entire range. We reviewed potential alternatives to fixed protected areas and found that mobile or temporary protected areas that track species movements have both been proposed for many migratory species. These range from caribou to blue-fin tuna to leatherback turtles. However, apart from efforts made by the Soviet Union to conserve a certain antelope species, there is no evidence of these solutions having been implemented in practice (Bull et al. 2013a).
A second type of moving-target problem involves a threatened habitat that is being modified by environmental change, like climate change. As the habitat moves, the species it supports, even otherwise sedentary species, are forced to move unpredictably across the landscape. This type of moving-target problem is possibly more pernicious and intractable than planning for naturally mobile species because it involves multiple interactions and enormous uncertainty. Extensive habitat modification can change ecological dynamics, affect species both directly and through their interactions with other species, and even modify the human behaviours causing biodiversity loss. Again, we found that numerous solutions had been proposed for this kind of moving target including mobile protected areas and networks of protected areas that are specifically resilient to change. But, again, these proposals remain largely theoretical…