Cropland abandonment in a shrinking agricultural landscape: Patch-level measurement of different cropland fragmentation patterns in Central Iran

Abstract

Cropland abandonment (CA) is a growing socio-economic and ecological concern worldwide. CA is formed as a gradual and spatiotemporally complex pattern of agricultural land change that affect accurate measurement of its magnitude and determinants. In this study, different spatial metrics including Attrition, Shrinkage, Fragmentation and Porosity are introduced and developed to better investigate CA in a highly water-deficient agricultural landscape (1964.5 km2) in Central Iran. Annual cropland layers were successfully produced from 1982 to 2022 using Landsat images and areas with more than 5 consecutive years of fallow in 10-year periods were classified as abandoned croplands. In each period, more than 20% of the relict agricultural land areas experienced CA. Moreover, CA represented a highly uneven spatio-temporal distribution. The majority of abandonment occurred on the periphery of active croplands either along the patch edge (Shrinkage) or deep penetration into crop patches (Fragmentation). The area of Porosity, measured as the abandonment holes inside active croplands, increased with increasing conversion of cropland to built-up areas. The complete abandonment of cropland patches (Attrition) was more dominant in resource deficit downstream parts, exhibiting the final stage of the transition from temporal to permanent CA. Results showed that the classification of CA by their spatial configuration shed light on the occurrence process of CA and its driving forces at different spatial and temporal scales.