The coldspot challenge

The hotspot idea is attractive because it recognizes a real challenge facing conservationists. We have to make choices. It is not possible, it may not even be desirable in terms of human welfare, to prevent large-scale changes is land use in many parts of the world. Moreover, the number of species threatened with extinction is so vast that we cannot possibly devote our attention to saving each one individually. We must identify areas in which they can persist⁸ and leave them to fend for themselves. So we have to identify the areas where we will focus our attention as wisely as possible.

If our goal is to prevent as many species from going extinct as possible, then focusing on biodiversity hotspots is an obvious way to move forward. But is preventing extinction of as many species as possible our only goal? Is it even our primary goal? If it is, why are conservationists so worked up about drilling in the Arctic National Wildlife Refuge? The diversity of bryophytes and lichens may be reasonably great in the Arctic tundra, but for most other groups of organisms, the diversity in the Brazilian Atlantic forest or Madagascar (to pick just a couple of examples) is probably far greater.

Kareiva and Marvier [1] point out several reasons why we preventing extinction of the maximum number of species might not be our only conservation goal. We might be interested in:

• Maintaining functioning ecosystems,

• Providing the greatest variety of plant, animal, and microorganism lineages for evolutionary innovations in the future,

• Preserving spectacular wild landscapes that inspire the human spirit, or

• Protecting biodiversity values in a way that complements and sustains human welfare.

These interests are not contradictory with preventing species extinctions, but they are not identical with preventing species extinctions, nor are they identical to one another. Consider the example of Montana and Ecuador that Kareiva and Marvier use:

• Montana and Ecuador are of roughly equal size.

• Ecuador: 19,362 vascular plant species and 2466 vertebrate species - total 21,828

• Montana: about 2,600 species

• Suppose we focus only on the number of species and set 20,000 as a target, and consider three scenarios:
  1. Ecuador 18,000 species; Montana 2000 species

  2. Ecuador 19,000 species; Montana 1000 species

  3. Ecuador 20,000 species; Montana 0 species

All have the same outcome in terms of total number of species, but the fraction of Ecuador's diversity that is protected ranges from a low of 82% to a high of 92% while the fraction of Montana's diversity protected ranges from 0% to 77%. Are those outcomes really equivalent?

If you answer that question ``No'',⁹ it means that there are some other aspects of biodiversity or wild systems that you value beyond simply the number of species that they contain. Notice, however, that this answer involves a judgement of value, i.e., it involves bringing in some ethical or aesthetic judgment that isn't subject to experimental verification.

To see this, imagine that you went through the above calculations with me and I told you at the end ``I think all three scenarios are equivalent. There's no reason to prefer one to the other (unless one costs a lot less money, and saving species in Ecuador is probably cheaper than saving them in Montana, so forget Montana).'' How would you go about convincing me I'm wrong?