Dynamics of natural regeneration of Betula pendula Roth and Populus tremula L in the Aiyrtau branch of the «Kokshetau» SNNP

Abstract

Background and Aim. The forests of the «Kokshetau» State National Nature Park play a key role in maintaining the ecological balance of the forest-steppe zone of Northern Kazakhstan. Natural regeneration after logging is the basis of their sustainability; however, the spatial patterns and factors of success of this process in the territory of the Aiyrtau branch remain insufficiently studied. The aim of
the research was a comprehensive assessment of the state, spatial differentiation, and leading factors of
natural regeneration of silver birch (Betula pendula Roth.) and European aspen (Populus tremula L.) on sites disturbed by logging.
Materials and methods. The work was carried out in 2025 on the territory of the Aiyrtau branch of the Kokshetau State National Nature Park. On sites subjected to logging in 2018-2022, 36 permanent sample plots of 25 m² were established by systematic sampling in three forestry units (Suly, Syrymbet, Sh. Ualikhan). A complete enumeration of regeneration was carried out with height measurement and
visual assessment of vitality (viable, non-viable, dry). Data processing included calculation of density, proportion of viability, analysis of height structure, as well as the use of analysis of variance (ANOVA) and post-hoc (Tukey) tests in the R 4.3.1 software environment to identify the statistical significance offactors.
Results. It was found that the overall regeneration in the branch is characterized by high intensity: the average density is 12,411 ind./ha with dominance of aspen (54% of the total number of regeneration). Pronounced spatial heterogeneity was revealed. Three contrasting scenarios were diagnosed: 1) in the Syrymbet forestry unit, the maximum density of aspen regeneration (18,467 ind./ha) was recorded, but its low viability (78.5%) indicates processes of natural thinning; 2) Sh. Ualikhan is distinguished by minimal density (7,767 ind./ha) but high quality of regeneration (birch viability 97.8%); 3) Suly
demonstrates balanced average indicators. It was statistically confirmed (p < 0.001) that viable regeneration has greater height, and birch is reliably taller than aspen in all forestry units.
Conclusion. Natural regeneration of birch and aspen in the Aiyrtau branch proceeds successfully; however, its nature and success are determined by local conditions that form different scenarios. For effective management of reforestation processes, a differentiated approach is recommended: in the Syrymbet forestry unit, it is advisable to carry out thinning in dense young aspen stands; in Sh. Ualikhan, to apply measures to promote natural regeneration; and in Suly, to maintain an observational and monitoring regime.