There are lots of theories put forward for all aspects of natural resource conservation. One important region involves the design of nature reserves. In 1968 two biologists, MacArthur and Wilcox, published their island biogeography theory, which looked at ecological factors this kind of colonization, extinction and succession on various islands around the world. Many people see strong parallels in between islands and reserves, so their findings were utilized to work out the greatest design for a protected region by many governments and natural resource conservation bodies.

The primary recommendations based on this theory are: a large reserve is better than a small reserve; one big reserve is better than several small reserves from the same total area; the best shape for a reserve is really a circle; it’s better to have reserves close together rather than far apart; and it is preferable to have reserves which are connected by ‘corridors’ than reserves which are isolated. A couple from the recommendations have been the source of conflict in between natural resource conservationists. And also the assumption that reserves are similar to islands surrounded by a sea of development is frequently simply not the case. Some reserves are surrounded entirely by organic habitats.

One from the earliest arguments was whether a single big reserve or several little reserves of the same collective region would maintain much more species. Supporters of single big reserves argue that only these reserves can ensure the long-term survival of wide-ranging species (for example elephants), and of low-density species (species that occur sparsely over a wide region, like eagles). Those in favour of well-placed little reserves insist that they can protect more populations of rare species and a greater variety of habitats. Having several small populations is also good insurance against just one catastrophe, such as disease, wiping out entire populations.

Another major debate is more than the inclusion of ‘corridors’ in between reserves, possibly along existing lines of organic migration, to form just one large reserve system. Some claim these corridors will enable animals to move safely between reserves, giving them a far larger region to roam. This in turn will assist with interbreeding in between previously isolated populations, and plants could be carried by animals to new regions. It would also assist migratory species, which could move seasonally between connected reserves. Others say corridors will assist the spread of illness and pests. There might also be an artificially increased rate of predation along these tunnels, from both animals and humans.