Table 6 Calculation of landscape ecological risk index.
Index | Formula | Description |
|---|---|---|
Landscape fragmentation (Fi) | \({\text{F}}_{{\text{i}}} = \frac{{{\text{n}}_{{\text{i}}} }}{{{\text{A}}_{{\text{i}}} }}\) | ni denotes the patch count for the landscape i; Ai represents the total area of the landscape i |
Landscape separation (Si) | \({\text{S}}_{{\text{i}}} = \frac{{\text{A}}}{{2{\text{A}}_{{\text{i}}} }}\sqrt {\frac{{{\text{n}}_{{\text{i}}} }}{{\text{A}}}}\) | ni denotes the patch count for the landscape i; Ai represents the total area of the landscape i; A indicates the total area |
Landscape dominance (Di) | \({\text{D}}_{{\text{i}}} = \alpha {\text{L}}_{{\text{i}}} + \beta {\text{M}}_{{\text{i}}}\) | Li denotes the ratio of the area for the landscape i and the total area for the study region; Mirepresents the ratio of the patch count for the landscape i and the total number for all patches; α and β indicate the weights of Li and Mi (0.6 and 0.4, respectively) |
Landscape disturbance (Ei) | \({\text{E}}_{{\text{i}}} {\text{ = aF}}_{{\text{i}}} {\text{ + bS}}_{{\text{i}}} {\text{ + cD}}_{{\text{i}}}\) | a, b, and c denotes the weights of Fi, Si and Di (0.5, 0.3 and 0.2, respectively)25,28,73 |
