Summary
Larger areas contain more species, commonly following a power law.
In depth
S = cA^z with z usually 0.15 to 0.35. A tenfold decrease in habitat area leads to roughly 50 percent loss of species at equilibrium. Used to predict extinction from habitat loss.
The slope depends on isolation and taxa. Used to estimate extinction after habitat loss.
Example: halving forest cover could eliminate about 10 to 15 percent of species eventually.
Larger areas contain more species. The relationship is usually described by the power law S = cA^z, where S is the number of species, A is area, c is a constant and z is typically 0.15 to 0.35, so plotted on log scales it is linear.
Reasons include larger areas having more habitats, larger populations that are less likely to go extinct and more chance of colonisation. MacArthur and Wilson's theory of island biogeography uses it with distance: islands that are large and near the mainland hold the most species. It predicts that losing 90 percent of an area removes about half the species, and is used to estimate extinctions from habitat loss.
Example: a rule of thumb is that a tenfold increase in island area doubles the species.
Frequently asked questions
What is Species-Area Relationship?
Larger areas contain more species, commonly following a power law.
Which area of biology covers Species-Area Relationship, and how advanced is it?
Species-Area Relationship is one of the 52 topics in Taxonomy & Biodiversity. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Habitat Loss, Protected Areas, Endemic Species.
Why does Species-Area Relationship matter?
It informs the design of reserves.
Can you give an example of Species-Area Relationship?
Islands and habitat fragments follow it.
What should I learn before Species-Area Relationship?
Work through the Beginner topics in Taxonomy & Biodiversity first, such as Taxonomy, Binomial Nomenclature, Taxonomic Hierarchy, then return to Species-Area Relationship. Intermediate topics assume the Beginner vocabulary.
What topics are related to Species-Area Relationship?
The closest topics to Species-Area Relationship are Habitat Loss, Protected Areas, Endemic Species, Biodiversity Hotspots. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Species-Area Relationship?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Species-Area Relationship. To practise the whole of Taxonomy & Biodiversity, use the Taxonomy & Biodiversity quiz.
How is Species-Area Relationship different from Habitat Loss?
Species-Area Relationship: Larger areas contain more species, commonly following a power law. Habitat Loss: Destruction of natural habitats by farming, logging and urbanisation, the leading threat to species. Read both side by side and note what each one explains.
How should I study Species-Area Relationship step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Habitat Loss and explain the difference aloud. Finally, take the Taxonomy & Biodiversity quiz and come back to this page for any question you miss.