Органическое земледелие в лесостепи западной Сибири: оценка повторяемости атмосферных засух на основе SPI

Abstract

This paper presents the findings of a study to assess the recurrence of moisture/drought conditions on the territory of the forest-steppe zone of Western Siberia for the period from 1971 to 2021. The degree of moistening was investigated on the basis of the Standardized Precipitation Index (SPI). Calculations were made for 4 areas (Altai Territory, Kemerovo, Novosibirsk and Omsk regions) with meteorological stations located on the territory of the forest-steppe zone of Western Siberia. In the studied areas, it was found that the drought conditions of different categories were manifested with a certain periodicity. SPI categories "moderately dry", "severely dry" and "extremely dry" for the studied period in May-July in Altai Territory account for 15,68% of years, in Novosibirsk Region for 13,72%, in Kemerovo Region for 19,6% and in Omsk Region for 13,72% of years. Local manifestation of extreme droughts for the time interval under study in the forest-steppe zone of Western Siberia was observed 7 times. Frequency of occurrence of deficiency of atmospheric precipitation during a part of vegetative period from May till July in territories of subjects in forest-steppe zone of Western Siberia is on the average 15,68%. The years with atmospheric precipitation shortage during the 51-year period in May accounted for 6 to 10 years, and 6 to 8 years in June. For Altai Territory, Novosibirsk and Kemerovo regions in the dynamics revealed trends in improving wetting conditions, characteristic both for most of the growing season of May-July, and separately for May and June. For territory of the Omsk region the trend indicating decrease in quantity of atmospheric precipitation in June is established. Frequency of occurrence of the dry events connected with deficiency of atmospheric precipitation remains high enough (once in 7-8 years). The results of studies on the degree of moisture/drought of the territory, carried out by SPI calculations, can be used for risk analysis and assessment of the effectiveness of crop production, as well as for the development and adaptation of farming systems, including organic agriculture to changing climatic conditions, where the role of natural factors in the crop production process becomes much more prominent. Keywords: ATMOSPHERIC DROUGHT, STANDARDIZED PRECIPITATION INDEX, SPI, FOREST-SEPHERE ZONE, WESTERN SIBERIA