Study on the Spatial and Temporal Changes of Cropland in the Guangdong-Hong Kong-Macao Greater Bay Area from 2010 to 2020

【Objective】Quickly gathering information of accurate cropland distribution and spatial and temporal change is an important technical means for scientific protection and effective management of cropland resources, which is an important guiding significance for ensuring regional food security and formulating cropland protection policies. The study of spatial and temporal change of cropland in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA) can provide data support for local cropland conservation and food security assurance.【Method】Based on the multi-temporal Landsat remote sensing image, the support vector machine method was used to obtain the land cover types and cropland distribution of the GBA from 2010 to 2020. Then, the characteristics of spatial and temporal changes of cropland in the GBA were analyzed from three aspects: quantitative changes, spatial transfer and landscape patterns.【Result】In terms of quantitative changes, from 2010to 2020, the area of cropland in the GBA showed a trend of decreasing first and then increasing, from 16 155.56 km2 in 2010 to 15 740.54 km2 in 2015, and then increasing to 16 473.93 km2 in 2020. At the municipal scale, the net increase of cropland in Jiangmen is the largest, with the net increase area of 176.99 km2, and the net decrease of cropland in Dongguan is the largest, with the net decrease area of 74.68 km2. In terms of spatial transfer, the area of 60.25% of the increased cropland were coming from forest, and the area of 35.85% of the increased cropland were coming from water body. Meanwhile, the area of 49.53%of the decrease cropland were converted to forest, and the area of the 43.51% of the decrease cropland were converted to impervious surface. In terms of landscape patterns, the patch density aggregation index of cropland in the GBA showed a trend of increasing and then decreasing.【Conclusion】In total, the change of cropland resources in the GBA maintained a dynamic balance from 2010 to 2020. The increased areas of cropland were mainly coming from forest and water body, and the decrease areas of cropland were converted to forest and impervious surface. Besides, landscape pattern of cropland generally tended to be less fragmented and more aggregated.