Type Index Formula Value range and significance Area index PLAND (Proportion of Landscape Types) $\text{PLAND}=\frac{\sum _{j=1}^{n}{a}_{ij}}{A}×100%$ 0 ≤ PLAND ≤ 100. The value tends to 0, indicating that plaque types in this landscape become very scarce. If the value is equal to 100, it indicates that the total landscape is composed of only one type of plaque. It is one of the important indexes of landscape structure. TCA (Total Area of Core Plaque) $\text{TCA}=\sum _{i=1}^{m}\sum _{j=1}^{n}{a}_{ij}^{c}\left(\frac{1}{10000}\right)$ TCA ≥ 0, no ceiling. When all positions within the plaque are specified in the margin depth of the patch circumference, TCA = 0; when the plaque shape is simplified and the edge depth distance decreases, TCA approaches the total landscape area. Edge index TE (Edge Total Length) $\text{TE}=\sum _{k=1}^{m}{e}_{iK}$ TE ≥ 0, no ceiling. The edge total length of landscape type. The edge index can reflect the degree of substance and energy exchange of the landscape type. It has special value in research and conservation of biodiversity. ED (Edge Density) ${\text{ED}}_{i}=\frac{{p}_{i}}{A}$ ED ≥ 0, no ceiling. The ratio of total edge length (Pi) of plaque type i and its area (Ai) in the landscape. It reveals the degree of landscape or type, which has been divided by edge. It is also a direct reflection of landscape fragmentation. Shape index LSI (Landscape Shape Index) $\text{LSI}=\frac{0.25\sum _{k=1}^{m}{e}_{iK}^{*}}{\sqrt{A}}$ LSI ≥ 1. It is the standard measure of landscape edge shape. For a very simple perimeter (such as square), LS is close to 1; for a complex shape, it has no ceiling. PAFRAC (Fractal Dimension) $\text{PAFRAC}=\frac{2}{\frac{\left[N\sum _{i=1}^{m}\sum _{j=1}^{n}\left(\mathrm{ln}{p}_{ij}-\mathrm{ln}{a}_{ij}\right)\right]-\left[\sum _{i=1}^{m}\sum _{j=1}^{n}\mathrm{ln}{p}_{ij}-\sum _{i=1}^{m}\sum _{j=1}^{n}\mathrm{ln}{a}_{ij}\right]}{\left[N\sum _{i=1}^{m}\sum _{j=1}^{n}\mathrm{ln}{p}_{ij}^{2}\right]-\left[\sum _{i=1}^{m}\sum _{j=1}^{n}\mathrm{ln}{p}_{ij}\right]}}$ 1 ≤ PAFRAC ≤ 2. A fractal dimension greater than 1 means a separation of 2D landscape mosaic and Euclidean geometry. The complexity of patch shape increases, and for highly complex edge shape, it is closer to 2. Density index PD (Plaque Density) $\text{PD}=\frac{{n}_{i}}{A}\left(10000\right)\left(100\right)$ PD ≥ 0, no ceiling. Plaque density refers to the number of plaques per unit area. It benefits the comparison between different landscapes. If the total landscape area is determined, then the density and number of plaque convey the same information. MPS (Mean Plaque Size) $\text{MPS}=\frac{\sum _{i=1}^{n}{a}_{ij}}{n}×\left(\frac{1}{10000}\right)$ MPS ≥ 0. The distribution range of the MPS value in landscapes restricts the image or map scope and the selection of the smallest plaque size of the landscape. In addition, MPS can refer to the degree of landscape fragmentation. ENN (Mean Nearest Distance) $\text{ENN}={h}_{ij}$ ENN > 0, no ceiling. It is equal to the distance of the nearest and the same type of plaque, based on the shortest distance between edge and edge. When the nearest neighbour distance decreases, the value of ENN tends towards 0. It reflects the isolation and distribution degree of landscape type. Stability index LSBI (Landscape stability index) $\text{LSBI}=\frac{\text{PLAND}+\text{TCA}+\text{TE}+\text{PAFRAC}+\text{ENN}}{5}×100%$ 0 ≤ LSBI ≤ 100. Summarizes the ecological significance of all the selected indices. When the landscape area is greater, the edge perimeter is longer, and the shape is more complex. When the isolation degree of landscape is smaller, it means the landscape pattern is more stable.