2.4.2. PLEF identification index system

Taking into account the multifunctional properties, spatial variability, and systemic nature of land, the development and current situation of the UACY, county-level administrative districts as the identification unit [16,41,42], and after consulting with experts in land, geography, urban and rural planning, agriculture, and ecology, and taking into account the accessibility of data, 21 indices were selected to build the evaluation index system of the PLEFs in the study area (Table 2). The weights of the indices were determined by the entropy method after dimensionless by the polar method [43]. The value of the PLEF was calculated by Eq. (2).

where F_a represents the PLEF index value of the ath cell, y_ab represents the standardized value of the PLEF evaluation index. W_b is the weight of the bth evaluation index. the PLEF values were calculated and divided into high-, relatively high-, medium-, relatively low-, and low-value areas using the natural breakpoint method.

Multi-function evaluation index system of PLEFs.