The typical form of the species-area relationship in arithmetic (A) and logarithmic (B) axes. The increase of the number of species is progressively decelerating in arithmetic space, but close to linear in logarithmic space, although particular measurements deviate from perfect linearity, and thus the straight line must always be taken as an approximation. Since the line can be expressed by the equation y = ax + b where a is the slope of the line and b is the intercept, in this case it can be written as log(S) = Zlog(A) + log(c), where S is the number of species, A is area, Z is the slope of the line, and c is a constant related to mean number of species per unit area. This equation in non-logarithmic form is expressed as S = cAZ, i.e. the slope of the line in the logarithmically plotted SAR becomes the exponent of the power-law.

  Part of: Henle K, Potts S, Kunin W, Matsinos Y, Simila J, Pantis J, Grobelnik V, Penev L, Settele J (Eds) (2014) Scaling in Ecology and Biodiversity Conservation. Advanced Books: e1169.