Fig. 4

UF and UB curves of farmland (a) and grassland (b) based on the M-K mutation test; and the accumulative anomaly curves of farmland (c) and grassland (d). The intersection points of the UF and UK curves and the inflection points of the accumulative anomaly curves were considered as the time nodes, which indicated that significant changes occurred. The changes in the LUT area were judged on the basis of the UF and accumulative anomaly curves.