Table 1.
List of model variables and parameters
| Symbol | Meaning |
|---|---|
| Variables | |
| A | Size of observation area |
| N(A) | Number of individuals in observation area A |
| S(A) | Number of species in observation area A |
| P(A) | Total productivity of individuals in observation area A |
| I(A) | Invariability of productivity P(A), that is, the reciprocal of the squared coefficient of variation of P(A) |
| Parameters | |
| λI | Density of individuals within species range, that is, for a given species the density of individuals belonging to this species in the range of this species; units of area–1 |
| λS | Density of species range centres; units of area–1 |
| Q | Size of species range |
| λIQ | Average number of individuals per species |
| λSQ | For a given point of the landscape the average number of species ranges containing this point |
| λIλSQ | Total density of individuals, that is, the density of individuals all species confounded; units of area–1 |
| mp | Mean productivity of an individual |
| Variance of productivity of an individual | |
| ρintra(d) | Correlation coefficient of the productivity fluctuations of two individuals belonging to the same species, that is, intraspecific correlation |
| ρinter(d) | Correlation coefficient of the productivity fluctuations of two individuals belonging to different species, that is, interspecific correlation |
| ρo | Correlation coefficient of the productivity fluctuations of two nearby individuals; specific to IAR-DD |
| Do | Correlation area, that is, for a given individual the area in which other individuals have productivity fluctuations correlated with this individual; specific to IAR-DD |
IAR-DD = invariability–area relationship with decorrelation by distance.