This is the first in a series of posts in which I plan to examine one of the fundamental concepts in ecology - the species-area relationship

Species conservation has always been intimately linked with the idea of habitat conservation. While habitat quality determines the amount of habitat required to protect a viable population of a given species, it’s only a modifier - the determining factor is area. Habitat quality can determine whether you need more or less area, but area is still the critical factor. While protected areas can be set aside for specific species, more commonly protected areas seek to protect as many species as possible. More land is likely to protect more species, but there are other factors that influence conservation decisions like the cost of land acquisition and the competing interests such as agriculture, mining or housing development.

One way to maximise the number of species in a protected area is to include as many habitat types as possible. If you include a forest, a meadow, a marsh and a lake in your protected area, you are likely to get a lot more species than you would if you only had forest habitat. The heterogeneity of the area increases the number of species. (After all, you don’t find a lot of fish in a pine forest, or field mice in a lake.) But again, this overlays a simple factor of area. A larger tract of forest will probably have more species than a smaller tract of forest. A larger section of a marsh will probably have more species than a smaller section of marsh. This fact, known as the species-area relationship is fundamental in both ecology and conservation biology. The existence of a relationship between species richness and area is obvious to anyone who has taken the time to think about it, but it is still interesting enough that it has attracted the attention of generations of ecologists.