Context Agricultural land abandonment across the steppe belt of Eurasia has provided an opportunity for the restoration of steppe landscapes in recent decades. However, global food demands are about to revert this trajectory and put restored steppe landscapes at risk. Objectives We analysed steppe development in southern Russia in the last 40 years, assessed its spatial patterns and drivers of change for several periods. Methods Using Landsat imagery, we mapped the permanent steppe and steppe restoration from 1990 to 2018. Based on regression tree models, we evaluate and explain its dynamics. Results were compared with district-level trends in land-use intensities of cropland. Results We found 70% of the steppe in 2018 represented permanent steppe and 30% of former cropland dominantly abandoned in the postsocialism (1990–2000). The permanent steppe and steppe restored in the postsocialism (1990–2000) were located far from settlements, on rough terrain and in districts of the Virgin Land Campaign (1954–1963). In recent decades, the patterns of steppe restoration (2000–2018) were mostly determined by unfavourable agroclimatic conditions and distance from grain storage facilities. The restoration pattern reflects regional differences in land-use intensities, e.g., isolated steppe patches mostly appeared in areas of intensive agricultural land-use. Conclusions Steppe restoration has appeared in areas marginal for agricultural production, with poor natural conditions and little human footprint. Consequently, the permanent steppe became less fragmented and a more continuous steppe landscape resulted. The remaining isolated steppe patches require attention in restoration programs as they are mostly located in areas of intensive agricultural land-use.

This study aimed to define an optimal sowing date of winter wheat in the steppe zone of South Ural and West Siberia. The effects of climatic factors were determined by analyzing modern climatic resources and experimentally testing in the conditions of the central zone in Orenburgskaya oblast. Research from the All-Russian Scientific- Research Institute of Hydro-meteorological Information – World Data Center (RSRIHI-WDC) served as a source of archival meteorological data for 2009-2019. Experimental data were collected through field work on the south chernozem in the Central zone of Orenburgskaya oblast for 2019-2020. Digital material was processed using statistical analysis. It was confirmed that in the Central zone of Orenburgskaya oblast under modern climatic conditions, the period between 25-30 August is the most acceptable date to sow winter wheat. If sowing occurs at later dates, there is a risk of not obtaining the required amount of effective temperatures, which can result in disunited sparse shoots, bushes that are not fully formed, and low phytometric parameters, and therefore a low realization of climatically secured productivity. These results could be more widely tested in other steppe regions of Ural and West Siberia with a prospect to introduce the results into zonal recommendations for production. Keywords: climatic resources, productivity reserves, winter wheat

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