Unraveling the change of land-use regimes with satellite and ground surveys in the steppe belt of Russia from 1990 to 2018

One of the recent phenomena in land-change history in the steppe belt of Russia after 1990 is the formation of unclaimed or partially claimed agricultural lands, their periodic and fragmented use, suggesting the change of land-use regimes compared to intensive cropping in the Soviet period (pre 1991). Therefore, there is a strong need for the systematic field and remotely-sensed monitoring of shifts of land-use regimes, because they may impact various socio-ecological processes, such as the spread of wildfires, degradation and recovery of vegetation on spared agricultural lands. Here we present an elaboration on monitoring with satellite observations and field surveys of land-cover dynamic in the steppe belt of Orenburg Province and with more detailed focus on the districts (rayons) of Orenburg Province, which were once a part of Virgin Lands Campaign (1954-1963), when croplands expanded at the expense of agro-environmental frontiers. Our remote-sensing observations and ground surveys revealed widespread abandonment from 1990 to 2018. The calculation of Shannon's Diversity Index confirmed the change in the typology of land-use regimes in Orenburg Province-transition from stable cultivation back to 1990 to new land regimes, such as stable cultivated areas with minor abandonment (typology #1)-e.g., Asekeevskij district; complete cropland contraction without recultivation (typology#2)-e.g., Akbulakskij district; strong fluctuation of cultivated and abandoned croplands from year to year (typology #3)-e.g., Pervomajskij district. Former Virgin Lands Campain areas were more exposed to typology #3. Shannon's diversity index was useful to evaluate the changing land regimes and areas prone to socio-economic and environmental shocks. We hypothesize a new stage of land regimes may provide opportunities for biodiversity conservation, but also threats such as the spread of wildfires, particularly under the projection of an increase of aridity.