Multiple trajectories of grassland fragmentation, degradation, and recovery in Russia's steppes

Over the 20th century, the Eurasian steppes underwent drastic land-cover changes. Much progress was made studying cropland expansion and the post-1990 (i.e., post-Soviet) agricultural land abandonment in Eurasia. However, the alteration of steppe landscapes may include other disturbances, such as oil and gas development, formal and informal roads and garbage dumps, which were not systematically documented. Considering the example of the steppe Orenburg Province in Russia, we reconstructed agricultural land-cover change dynamics using Landsat and Sentinel-2 imagery from 1990 to 2018. Furthermore, we used very high-resolution imagery and assessed the patterns and determinants of other steppe landscape anthropogenic disturbances. Our study showed that, despite steppe recovery due to widespread cropland abandonment from 1990 to 2018, the steppes, including the recovered steppe patches, underwent fragmentation due to informal roads, oil and gas development, shrub encroachment, garbage dumps and quarries, as well as abandonment of settlements and buildings. Only 6.4% of the sampled 7859 1×1 km blocks in 2018 showing grassland extent had no documented disturbances. The mapped disturbances occurred primarily near settlements and roads, while some disturbances occurred in remote areas. Given the accessibility of steppes, our study calls for a urgent need to systematically document alternatives to agricultural land uses in the steppes of Eurasia and other parts of the global grassland biome.