The Pyrological Situation in the Steppe Regions of North Eurasia and Adjacent Territories: FIRMS Data Analysis for the Multi-year Period

Abstract

Grass fires are typical phenomena in the vast region of North Eurasia, including the landscapes of the steppes and adjacent natural areas. Insufficient knowledge of the geography of forest fires, their activation over the past decades, and the increased impact on various groups of steppe biota determine the research relevance. The study aims to identify the spatial and temporal patterns of grass fire development at the macro-regional level. As the primary source of data on fires and analyzed parameters, we used the global archive of FIRMS thermal anomalies. We established that the steppe zone of North Eurasia is characterized by the most significant variability in the long-term dynamics of fires. The spatial distribution of thermal anomalies did not correlate with decoding the burned areas from the satellite images. We found the highest density of hot spots in the most agriculturally developed regions (the West-Black Sea part of the steppes and adjacent territories), where agricultural incineration was a traditional method of nature management. Thus, a specific feature of the archives of thermal anomalies of FIRMS was the ability to record live fires on arable land, which was almost impossible to implement directly based on satellite images for objective reasons. The paper considers the long-term dynamics and evaluates the relationship between agricultural fires on arable land and fires on pasture and hay lands on the example of the steppe zone of Russia. These results implicitly confirmed that uncontrolled agricultural fires on arable land caused a significant part of the steppe fires. This fact was also supported by analyzing the seasonal distribution of thermal anomalies, the absolute maximum of which falls at the beginning of agricultural work (April–early May). Also, we revealed the specifics of the formation of pyrogenic conditions in azonal and intrazonal landscapes. We found that steppe fires are phenomena based on spatial and temporal patterns revealed in the complex interaction of natural and anthropogenic factors.