An example of SDI calculation for streetside tree populations.
| Species | Number of trees (Nj) | Nj · (Nj - 1) |
|---|---|---|
| Longyan County, Fujian, China | ||
| Platanus x acerifolia | 297 | 77562 |
| Michelia alba | 269 | 72092 |
| Salix babylonica | 171 | 29070 |
| Aleurites moluccnan | 75 | 5550 |
| Ficus religiosa | 67 | 4422 |
| Casssia surattensis | 62 | 3782 |
| Grevillea robusta | 44 | 1892 |
| Ligustrum lucieum | 40 | 1560 |
| Ficus microcarpa | 12 | 132 |
| Acacia confusa | 10 | 90 |
| Eucalyptus citriodora | 9 | 72 |
| Delonix regia | 8 | 56 |
| Cinnamonomum camphora | 7 | 42 |
| Callistemon rigidus | 6 | 30 |
| Trachycarpus fortunei | 6 | 30 |
| Bauhinia variegata | 5 | 20 |
| Bombax malabricum | 4 | 12 |
| Eucalyptus robusta | 4 | 12 |
| Casuarine equisetifolia | 4 | 12 |
| Morus alba | 2 | 2 |
| Total | 1084 | 196440 |
The original data were published by Jim (11). ∑ Nj is the total of streetside trees and ∑ Nj·(∑ Nj - 1) = 1084 x (1084 - 1) = 1173972. SDI =Σ Nj · (∑ Nj -1) / ∑ Nj (Nj - 1) = 1173972 / 196440 = 6.0.