Академическое издательство «Гео»

Keywords: grass fires, burns, latitudinal zonality, intensification, periodicity, agricultural use.


The conditions for the spread of grass fires and the periodicity of their occurrence in the Transvolga-Ural region

V.M. Pavleichik

Steppe Institute, UB RAS,
ul. Pionerskaya, 11, Orenburg, 460000, Russia, pavleychik@rambler.ru

Analysis of archival data from satellite monitoring services for the fire situation and results from visual interpretation of satellite images of the Earth’s revealed characteristic features and spatiotemporal patterns of the spread of steppe fires in the Transvolga-Ural region. It is pointed out that fires are of ubiquitous occurrence on the study territory but are most characteristic for the steppe zone. Furthermore, arable lands constitute the main limiting factor for fire occurrence in the northern steppe subzone and in forest-steppe. The study revealed a tendency for a ubiquitous intensification of grass fires, and for an increase in their areas, number and periodicity. This negative ecological process is caused by a drastic reduction in livestock population, and in pressures on pasture lands in the later 20 th century which were subsequently accompanied by the recovery of steppe phytocenoses, and by an accumulation of plant litter and debris. In the absence of clearly pronounced climatic changes, it is this factor that became a central determining factor, while the long-term variations in the spread of fires are governed by the weather conditions in separate years. The mean, maximum and minimum values of the periodicity of fires were determined for the key areas of the Ural-Ilek interfluve. The mean recurrence frequency of fires is once every five years, which points to a constant post-pyrogenic progressive succession of steppe vegetation as a whole. Differences in the periodicity of fires were revealed for previously developed and protected territories. The characteristic features of occurrence of steppe fires, and the favorable and limiting factors for their spread are determined. Long-term data are used to summarize information concerning the seasonality of fire events as well as a predominance of late-summer fires. An assessment is made of the influence of weather conditions on the occurrence of separate fires. It is concluded that there is a need to organize agricultural production on the basis of the fire-prevention principles.

Keywords: grass fires, burns, latitudinal zonality, intensification, periodicity, agricultural use.

DOI: 10.21782/GiPR0206-1619-2017-2(56-65)