Abstract: Landscape heterogeneity is the basis for maintaining biodiversity and ecosystem services in cultivated land system. To explore the effect of non-cultivated land on landscape heterogeneity of cultivated land system, taking Changtu county of Liaoning Province as the study area, Rao quadratic entropy index (Q) was used to characterize landscape heterogeneity based on grid units, and the effect of non-arable patches on landscape heterogeneity was investigated by redundancy analysis, independent sample T test, regression analysis and other methods. The results indicate that: (1) when the proportion of non-arable land of the sample grid units was similar, there was a significant difference in landscape heterogeneity. When the proportion of non-arable land of the sample grid units was 8%, the difference of landscape heterogeneity between the units was the largest. (2) Forest land, grassland, rural road, water area and ditch had significant positive effects on landscape heterogeneity (P<0.01), and forest land had the greatest effect. (3) The mean nearest neighbor distance index (ENN-MN) of non-arable land patches in grid units with different landscape heterogeneity was significantly different (P<0.05). The stronger the non-arable patch connectivity was, the stronger the landscape heterogeneity was. This paper can provide reference for the ecological management and protection of cultivated land in the context of strictly protecting the red line of cultivated land.

Key words: cultivated land system, landscape heterogeneity, proportion of non-cultivated land, connectivity