Response of Spruce Forest Ecosystem CO2 Fluxes to Inter-Annual Climate Anomalies in the Southern Taiga

Climate extremes and anomalies modify the CO2 ecosystem–atmosphere exchange of the boreal forests and consequently alter the terrestrial carbon stocks and the atmospheric greenhouse gas concentrations. The effects of the anomalous weather conditions on the CO2 net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) of the typical southern taiga nemorose spruce forest were analyzed using continuous eddy covariance flux measurements in the 2015–2020 period. The forest was found to be a source of atmospheric CO2 in 2016, 2017, 2019, and 2020 (the mean annual GPP/TER ratio was between 0.87 and 0.97). In 2018, the forest was found to act as a CO2 sink (GPP/TER = 1.47) when a positive temperature anomaly in the growing season was accompanied by a negative precipitation anomaly and increased global radiation. The early start of the CO2 uptake in the anomalously warm winter of 2019/2020 did not result in an increase in the annual GPP/TER ratio (0.90). The comparison of the flux data obtained from the nemorose spruce forest on the well-drained soils with the data obtained from paludified spruce forest in the same landscape showed that the mean annual GPP/TER ratio of the sites alternatively responded to the mentioned anomalies. This study suggests that a variety of soil moisture regimes across the southern taiga spruce forests provide a non-uniformity in the response reactions of the CO2 ecosystem–atmosphere exchange on the climate anomalies

Response of Spruce Forest Ecosystem CO₂ Fluxes to Inter-Annual Climate Anomalies in the Southern Taiga

Climate extremes and anomalies modify the CO2 ecosystem–atmosphere exchange of the boreal forests and consequently alter the terrestrial carbon stocks and the atmospheric greenhouse gas concentrations. The effects of the anomalous weather conditions on the CO2 net ecosystem exchange (NEE), total ecosystem respiration (TER), and gross primary production (GPP) of the typical southern taiga nemorose spruce forest were analyzed using continuous eddy covariance flux measurements in the 2015–2020 period. The forest was found to be a source of atmospheric CO2 in 2016, 2017, 2019, and 2020 (the mean annual GPP/TER ratio was between 0.87 and 0.97). In 2018, the forest was found to act as a CO2 sink (GPP/TER = 1.47) when a positive temperature anomaly in the growing season was accompanied by a negative precipitation anomaly and increased global radiation. The early start of the CO2 uptake in the anomalously warm winter of 2019/2020 did not result in an increase in the annual GPP/TER ratio (0.90). The comparison of the flux data obtained from the nemorose spruce forest on the well-drained soils with the data obtained from paludified spruce forest in the same landscape showed that the mean annual GPP/TER ratio of the sites alternatively responded to the mentioned anomalies. This study suggests that a variety of soil moisture regimes across the southern taiga spruce forests provide a non-uniformity in the response reactions of the CO2 ecosystem–atmosphere exchange on the climate anomalies

Elemental composition of human hair in different territories of the Crimean peninsula

The chemical homeostasis of humans has changed due to global and local anthropogenic impacts on biogeochemical cycles. Their degree is mediated by natural geochemical character of local environments. The elemental composition of human hair and quantitative relation between elements is summary characteristic of biogeochemical environmental conditions. To determine the biogeochemical situation 78 inhabitants from different geographic regions across the Crimean peninsula, cities and rural areas were investigated through the analysis of 28 elements by neutron activation analysis and determination of mercury by atomic absorption spectroscopy. High variety of elemental composition in inhabitants’ hair on different types of territories in the Crimean peninsula was revealed. Comparison with different territories of Russian Federation and Belarus shows both common and specific features. On most part of Russian and the Crimean territories a deficiency of essential elements (Zn, Cu) in human hair is characteristic. At the same time there are significant differences in content of some essential elements (Ca, Fe) and other ones (Th, Ce, Au, U, Ag, Cs) even in the limited Crimean territory. It requires further investigation of factors, which determine the revealed variability

Energy and CO2 exchange in an undisturbed spruce forest and clear-cut in the Southern Taiga

•Clear-cutting strongly influence energy and CO2 fluxes of forest ecosystems.•Clear –cut is characterized by decreased energy fluxes comparing with mature forest.•Similar Bowen ratio at the mature and clear-cut forest ecosystems.•The recently clear-cut area was a consistent source of CO2 for the atmosphere. Effects of clear cutting and other forest disturbances on surface radiative properties and the energy and CO2 fluxes between land surface and the atmosphere can vary significantly depending on local climatic and moisture conditions, forest structure and species composition, soil properties and many other factors. In this study we analyzed the influence of clear-cutting on the energy, water vapor and CO2 fluxes in the still very poorly investigated part of the boreal forest community in the European part of Russia. This issue has become particularly relevant due to intensified logging in the region during recent decades. The sensible (H) and latent (LE) heat, as well as CO2 fluxes were continuously measured at recently clear-cut and undisturbed mature spruce forest sites using eddy covariance technique during the first growing season following harvest. Because of their close location they are characterized by similar meteorological conditions. The results of our field measurements showed that the clear-cut strongly influenced the energy balance and CO2 fluxes between the land surface and atmosphere. Energy fluxes (LE and H) at the undisturbed forest site were consistently larger than at the clear-cut throughout the period of measurements. The Bowen ratio (β=H/LE) varied significantly over time, though was similar at both sites. Whereas H was almost equal to LE at both sites in spring, the LE significantly exceeded H over the summer (β≈0.2 - for mature spruce forest and β = 0.4 - for clear-cut). The mean β for the entire period was similar (β≈0.5) at both sites. Analysis of CO2 fluxes showed that the clear-cut was a consistent source of CO2 to the atmosphere. Net ecosystem exchange (NEE) at the clear-cut averaged 3.3 ± 1.3 gC∙m−2∙d-1 (±1 SD), while average NEE at the undisturbed mature forest was close to zero (0.1 ± 1.9 gC∙m−2∙d-1). Differences in NEE were mainly governed by differences in gross primary productivity (GPP) between sites (7.0 ± 4.1 gC∙m−2∙d-1 and 4.1 ± 3.0 gC∙m−2∙d-1, for the undisturbed forest and clear-cut, respectively). Total ecosystem respiration (TER) did not significantly (p < 0.05) differ between sites (7.1 ± 3.6 gC∙m−2∙d-1 at the undisturbed mature forest and 7.4 ± 3.4 gC∙m−2∙d-1 at clear-cut). TER at the undisturbed forest showed higher sensitivity to changes in soil temperature, whereas GPP at the clear-cut was characterized by higher light-use efficiency. Our measurements showed that TER rates were relatively high in the southern taiga in comparison with other boreal sites where CO2 fluxes were previously investigated