Nikita Alexandrovich Alexandrov

In the context of global climate transformation and the implementation of national low-carbon development strategies, precise assessment of the sequestration potential of agroecosystems is a critical task. This study analyzes the interannual dynamics of carbon dioxide fluxes (NEE, GPP, Reco) in spring barley (Hordeum vulgare L.) agroecosystems on sod-podzolic soils in the southern taiga zone (Moscow region). The research is based on Eddy Covariance measurements obtained during growing seasons with contrasting hydrothermal conditions (2013, 2016, and 2023). A non-linear response of carbon exchange to climatic drivers was revealed: while the maximum gross primary production was recorded in the warmest year, 2016 (GPP=775 g Cm−2), the record net uptake occurred in 2013 (NEE=−245 g Cm−2) under optimal moisture conditions. It was established that the determining factors for productivity are the moisture regime and the proportion of diffuse radiation, rather than heat supply alone. A pattern of decreasing carbon exchange efficiency (GPP:Reco ratio) from 2.27 in moderately productive years to 1.25 in highly productive seasons was discovered, indicating an outstripping growth of ecosystem respiration during the intensification of assimilation processes. The results are of fundamental importance for the verification of carbon cycle models and the development of regional greenhouse gas monitoring systems

The article presents an algorithmic approach for separation of integral CO2 fluxes, allowing for a quantitative assessment of the contribution of field areas with different topsoil bulk densities to the overall carbon balance. The methodology is based on integrating eddy covariance data, dynamic footprint modeling, and digital soil mapping. The experiment was conducted in 2023 on spring barley crops under conditions of pronounced soil bulk density heterogeneity (1.45–1.80 g cm⁻³). The developed approach enabled the partitioning of the total net ecosystem exchange (NEE) into gross primary production (GPP) and ecosystem respiration (Reco) components, specific to the identified zones with contrasting densities. It was established that under the dry conditions of June 2023, overcompacted areas (>1.65 gcm⁻³) were characterized by higher values of gross primary production (up to 14 μmolm⁻2s⁻1) and water use efficiency compared to less compacted areas (<1.65 gcm⁻³), where these values did not exceed 10 μmol Cm⁻2s⁻1. In the second half of the growing season, during the ripening stage and with an increase in precipitation in August, an inversion was observed: GPP values in the overcompacted areas were 2.8 μmol C m⁻2s⁻1, and Reco intensity was 2.1 μmol C m⁻² s⁻¹, which is half the values recorded in areas with lower bulk density (4.2 μmolm⁻2s⁻1). The proposed approach made it possible to quantitatively capture the within-field variability of carbon balance components without using spatial averaging.