PROGRESSIVE, NORMAL AND DIGRESSIONAL SECONDARY SUCCESSIONS OF FOREIGN LANDS IN THE BORDERS OF SYSTEMS OF USEFUL PROTECTIVE FOREST STRIPES OF THE REPUBLIC OF KHAKASIA
To prevent the occurrence of undesirable vegetation during further agricultural use of fallow lands, it is necessary to control the processes of secondary successions. Studies were carried out in the steppe zone in the Republic of Khakassia on fallow lands with different conservation periods. Ulmus pumila L. gives good natural regeneration, and the inter-strip fields in the systems of field-protecting forest strips, when they transition to the category of fallow lands, are simultaneously overgrown with grassy and woody vegetation. For the first time, a scale has been proposed for assessing the rate of demutation of fallow lands by three gradations: normal, progressive, digression. Demutation processes are progressive if there are closely spaced areas of the virgin steppe and if the territory is poorly or completely not used as pasture. The dynamics of secondary vegetation on medium-degraded fallow lands with forest reclamation is characterized. An intense pasture load determines the digression rate of succession. The type of soil, the degree of its degradation does not have an active effect on the variability of succession processes. A study of the dynamics of vegetation on fallow lands over a 7-year period shows significant changes in vegetation cover. The number of squat elm increases by 3-7 times; the crown density is 1.25-6 times, a mossy layer appears, weedy, weedy plants dominate. During the 18 years preceding the study, there was an active invasion of tree and shrub vegetation, which ensured a large number of individuals in the territory adjacent to the forest protection zone, reaching 186.0 thousand units per hectare. The data obtained can be used to develop measures to improve pastures and when returning land to agricultural circulation.