Recent decrease in carbon sink to Russian forests.

Regional Evaluation of Carbon Budget of Forests (RECBF), was used to study the dynamics of carbon balance in Russian forests in 1988-2015. The carbon sink (excess of absorption over losses) to forests was minimal in 1988. Since the first half of the 1990s, its increase has started. This increase was associated with the reduction of logging volume in connection with socioeconomic reforms. Since 2008, the carbon sink was gradually reduced due to increasing losses in logging operations, forest fires, and decreased carbon absorption.

Unconsidered sporadic sources of carbon dioxide emission from soils in taiga forests.

Long-term monitoring in the Russian taiga zone has shown that all known extreme destructive effects resulting in the weakening and death of tree stands (windfalls, pest attacks, drought events, etc.) can be sporadic, but significant sources of CO2 soil emission. Among them are (i) a recently found effect of the multiyear CO2 emission from soil at the bottom of deadwood of spruce trees that died due to climate warming and subsequent pest outbreaks, (ii) increased soil CO2 emissions due to to the fall of tree trunks during massive windfalls, and (iii) pulse CO2 emission as a result of the so-called Birch effect after drought events in the taiga zone. According to the modeling, while depending on the spatial and temporal scales of their manifestation, the impact of these sporadic effects on the regional and global soil respiration fluxes could be significant and should be taken into consideration. This is due to continuing Climate Change, and further increase of local, regional and Global human impacts on the atmospheric greenhouse gases balance, and land use, as well.

[The influence of local anthropogenic factors on soil emission of biogenic greenhouse gases in cryogenic ecosystems].

For the first time were the results of studies on influence of main kinds of local anthropogenic factors on soil emission of biogenic greenhouse gases (CO2, CH4, and N2O) in permafrost ecosystems of Arctic and North-Boreal zones of the Russian Federation, and also of the Spitsbergen Archipelag summarized. Different types of land use can, depending on their manner, lead to significant enhancing or suppression of soil CO2 emission. On average, anthropogenic factors (AFs), acting in concert, favor the enhancement of local CO2 soil emission, promoting, at the same time, an increase in its dispersion. AFs directly influence the microbial-root respiration in soil, modify the soil itself, and indirectly affect important natural respiration regulators, phytomass reserves in particular, which makes them primary factors with relation to respiration pattern. AFs influence also the emission of other biogenic greenhouse gases (CH4 and N2O), though this influence can be exercised in different ways. Methane emission is mediated by degree of the territory drainage. However, in all studied cases, AFs have led to source reduction or sink intensification of this gas from the atmosphere. Unlike methane emission, N2O emission increased under the influence of AFs considered. As for the whole complex of AFs that impacts the carbon balance and fluxes of CO2 in cryogenic ecosystems, its role is expressed through the enhancement of soil respiration at the beginning of the cold season, when AFs are capable of soil emission increasing, at the level of meso-landscape, almost by 50%.

[CO2-exchange in tundra ecosystems of Vaygach Island during the unusually warm and dry vegetation season].

In summer of 2013, field studies of CO2-exchange in tundra ecosystems of Vaygach Island have been conducted using the chamber method. The models are developed that establish relationships between CO2 fluxes and key ecological factors such as temperature, photosynthetic active radiation, leaf mass of vascular plants, and depth of thawing. According to the model estimates, in 2013 vegetation season tundra ecosystems of Vaygach Island have been appearing to be a CO2 source to the atmosphere (31.9 ± 17.1 g C m(-2) season(-1)) with gross primary production equal to 136.6 ± 18.9 g C m(-2) season(-1) and ecosystem respiration of 168.5 ± ± 18.4 g C m(-2) season(-1). Emission of CO2 from the soil surface (soil respiration) has been equal, on the average, to 67.3% of the ecosystem respiration. The reason behind carbon losses by tundra ecosystems seems to be unusually warm and dry weather conditions in 2013 summer. The air temperature during summer months has been twice as high as the climatic norm for 1961-1990. Last decades, researches in the circumpolar Arctic revealed a growing trend to the carbon sink from the atmosphere to tundra ecosystems. This trend can be interrupted by unusually warm weather situations becoming more frequent and of larger scale.

[Interannual changes in PAR and soil moisture during the warm season may be more important for directing of annual carbon balance in tundra than temperature fluctuations].

A lot of studies on the impact of global climate changes on natural communities deal with cryogenic ecosystems, tundra in particular, since they are delimited by low air temperature and permafrost, thus being extremely sensitive to long-term climate fluctuations. Continuous warming in Northern Hemisphere is unmasking all the more details concerning complex system of direct relationships, feedbacks, and interactions of carbon balance factors as the main response function. While the set of such factors may be viewed as more or less complete, their relative contribution to C-balance, as is becoming clear with accumulating results of field observations, directly depends on temporal scale of observations and is not constant. As the results of field observations and modeling of tundra ecosystems show, any one of significant factors can become the leading one within the boundaries determined by the given scale of observations. Even the least significant factor can become the determining one for direction of carbon annual net flux in an ecosystem, if contributions of more significant factors canceled each other during the period of observations. In the most general situation, the greater is the variation of a significant factor during the period of observations, the larger is its partial contribution. The complete set of independent variables of C-balance is not limited by abiotic factors but should include such an important factor as a stock of plants living top mass, which can be treated as not only the natural product of C-balance but also as its independent parameter.

[Microbiological characteristic of anthills of Lasius niger].

The characteristics of microbial communities of the anthills of Lasius niger compared to the soil beyond the area of the strong effect of ants is given.

[Geoinformational model of the carbon reserve of the Russian tundra zone]. / Geoinformatsionnaia model' biudzheta ugleroda tundrovoi zony Rossii.

We present a summary of our own gas measurement data on biogenic fluxes of CO2 in various ecosystems of the Russian tundra zone, using seasonal and geographical extrapolations based on mathematical simulation modeling. The model follows construction principles of geoinformational systems and consists of (1) a computer map of tundra landscape boundaries; (2) a meterological database; (3) a model of changes of the phytomass; and (4) the actual model of carbon fluxes. The model, which uses a 10-day step, allows estimates of regional and landscape-associated macroscopic carbon fluxes and predicts the response of the tundras to climatic changes. The data obtained are in good agreement with independently obtained estimates of the major characteristics of tundra carbon balance.