Boreal Plant Species within the Kazakh Small Hills: Ecological–Cenotic Characteristics and Distribution Features

On the territory of the Kazakh small hills, boreal plant species have been preserved, growing far beyond the boundaries of their typical taiga ecosystems since the widespread expansion of coniferous forests during the Pleistocene period. These species are an important component of the region’s phytodiversity and require comprehensive study. In the course of this study, based on field observation data and analyses of literary sources, information was obtained on the taxonomic composition of this group of species, their coenotic occurrence, and the ecological and geographical characteristics. In the composition of the plant communities of the Kazakh small hills, 30 species of vascular plants were identified that belong to the boreal ecological–coenotic group of plants, differing in ecology and coenotic affiliation from plants of zonal steppe vegetation. In conditions of a sharply continental arid climate, the studied boreal species grow in special habitats—in mountain forest–steppe landscapes and moist habitats along rivers and along the shores of lakes. The largest number grows on the slopes of hills with granite outcrops as part of island pine forests. In places of increased moisture at the foot of the slopes and in depressions, which are associated with azonal forest communities, mainly small-leaved plants of this group are also found. In addition, finds of boreal plants were noted in the intrazonal meadow and swamp cenoses and on rocky slopes. As an analysis of the distribution across the territory of the small hills has shown, the maximum diversity of boreal species is concentrated in the Kokshetau and Karkaraly floristic regions, where 23 and 29 species of these plants grow, respectively. Three species of boreal plants are included in the Red Book of the Republic of Kazakhstan (2006) due to the small number and vulnerability of their populations; however, as the study showed, a number of other boreal species also require protection. The main threats to the conservation of populations of boreal plant species are excessive recreation and fires. Thoughtful measures are needed to preserve rare and vulnerable plant communities, including plant species growing at the border of the range.