Andrey Sirin

Rising methane emissions in response to climate change in Northern Eurasia during the 21st century

We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to examine the methane (CH4) exchanges between terrestrial ecosystems and the atmosphere in Northern Eurasia from 1971 to 2100. Multiple model simulations using various wetland extent datasets and climate change scenarios were conducted to assess the uncertainty of CH4 fluxes, including emissions and consumption. On the basis of these simulations we estimate the current net emissions in the region to be 20–24 Tg CH4 yr − 1 (1 Tg = 1012 g), two-thirds of which are emitted during the summer. In response to climate change over the 21st century, the annual CH4 emissions in the region are projected to increase at a rate of 0.06 Tg CH4 yr − 1, which is an order of magnitude greater than that of annual CH4 consumption. Further, the annual net CH4 emissions are projected to increase by 6–51% under various wetland extent datasets and climate scenarios by the end of the 21st century, relative to present conditions. Spatial patterns of net CH4 emissions were determined by wetland extent. Net CH4 emissions were dominated by wetlands within boreal forests, grasslands and wet tundra areas in the region. Correlation analyses indicated that water table depth and soil temperature were the two most important environmental controls on both CH4 emissions and consumption in the region. Our uncertainty analyses indicated that the uncertainty in wetland extent had a larger effect on future CH4 emissions than the uncertainty in future climate. This study suggests that better characterization of the spatial distribution and the natural diversity of wetlands should be a research priority for quantifying CH4 fluxes in this region.

Possible decline of the carbon sink in the Mongolian Plateau during the 21st century

The Mongolian Plateau is dominated by grassland ecosystems. It frequently experiences drought and is underlain by permafrost in the north. Its complex responses of plant carbon uptake and soil carbon release to climate change are considered to have affected the global carbon cycle during the 21st century. Here we combine spatially explicit information on vegetation, soils, topography and climate with a process-based biogeochemistry model to assess the carbon responses for the 20th and 21st centuries. We estimate the region acted as a C sink of 31 Tg C yr −1 in the 1990s, but that this sink will likely decline in both magnitude and extent under future climate conditions. This change is due to the relatively larger enhancement of soil organic matter decomposition, which releases carbon to the atmosphere, than the corresponding enhancement of plant C uptake, by rising temperatures and atmospheric CO2 concentrations. Future plant C uptake rates are expected to become more limited due to drier soils caused by increasing evapotranspiration rates. Complex soil thermal and moisture dynamics result in large interannual and spatial variability as a consequence of the different rates of change of air temperature and precipitation in this region.

Evapotranspiration in Northern Eurasia: Impact of forcing uncertainties on terrestrial ecosystem model estimates

The ecosystems in Northern Eurasia (NE) play an important role in the global water cycle and the climate system. While evapotranspiration (ET) is a critical variable to understand this role, ET over this region remains largely unstudied. Using an improved version of the Terrestrial Ecosystem Model with five widely used forcing data sets, we examine the impact that uncertainties in climate forcing data have on the magnitude, variability, and dominant climatic drivers of ET for the period 1979–2008. Estimates of regional average ET vary in the range of 241.4–335.7 mm yr−1 depending on the choice of forcing data. This range corresponds to as much as 32% of the mean ET. Meanwhile, the spatial patterns of long-term average ET across NE are generally consistent for all forcing data sets. Our ET estimates in NE are largely affected by uncertainties in precipitation (P), air temperature (T), incoming shortwave radiation (R), and vapor pressure deficit (VPD). During the growing season, the correlations between ET and each forcing variable indicate that T is the dominant factor in the north and P in the south. Unsurprisingly, the uncertainties in climate forcing data propagate as well to estimates of the volume of water available for runoff (here defined as P-ET). While the Climate Research Unit data set is overall the best choice of forcing data in NE according to our assessment, the quality of these forcing data sets remains a major challenge to accurately quantify the regional water balance in NE.

Carbon accumulation in soils of forest and bog ecosystems of southern Valdai in the Holocene

Carbon stocks and accumulation rates in humus and peat horizons of the contiguous soil series of forest and bog ecosystems have been studied in the Central Forest State Biosphere Reserve, Tver Region. Upland soil types (soddy podzolic, brown, and white podzolic) have been compared to paludified (peat-enriched gley podzolic and peaty gley) and bog soils differing in trophic status, including those of upland, transitional, and lowland bogs. The results show that carbon stocks in mineral soils are many times smaller than in waterlogged soils and an order of magnitude smaller than in bog soils. Mineral and bog soils are characterized by similar rates of carbon accumulation averaged over the entire period of their existence. The highest rate of carbon accumulation has been noted for the soils of waterlogged habitats, although this process may be periodically disturbed by fires and other stress influences.

Parameterization of mires in a numerical weather prediction model

Mires (peat-accumulating wetlands) occupy 8.1% of Russian territory and are especially numerous in the western Siberian Lowlands, where they can significantly modify atmospheric heat and water balances. They also influence air temperatures and humidity in the boundary layers closest to the earths surface. The purpose of our study was to incorporate the influence of mires into the SL-AV numerical weather prediction model, which is used operationally in the Hydrometeorological Center of Russia. This was done by adjusting the multilayer soil component (by modifying the peat thermal conductivity in the heat diffusion equation and reformulating the lower boundary condition for Richards equation), and reformulating both the evapotranspiration and runoff from mires. When evaporation from mires was incorporated into the SL-AV model, the latent heat flux in the areas dominated by mires increased strongly, resulting in surface cooling and hence reductions in the sensible heat flux and outgoing terrestrial long-wave radiation. Presented results show that including mires significantly decreased the bias and RMSE of predictions of temperature and relative humidity 2 m above the ground for lead times of 12, 36, and 60 h from 00 h Coordinated Universal Time (evening conditions), but did not eliminate the bias in forecasts for lead times of 24, 48, and 72 h (morning conditions) in Siberia. Different parameterizations of mire evapotranspiration are also compared.

Quantifying historical and future net exchanges of greenhouse gases of CO 2 , CH 4 and N 2 O between land and the atmosphere in Northern Eurasia

Qianlai Zhuang1, Tong Yu1, David W Kicklighter2, Jerry Melillo2, Yongxia Cai3, John Reilly3, Andrei Sokolov3, Erwan Monier3, Andrey Sirin3 Nadja Tchebakova4, V.N. Sukachev4, Shamil Maksyutov5 and Anatoly Shvidenko6 1Purdue University, USA 2The Ecosystems Center of the Marine Biological Laboratory, USA 3Massachusetts Institute of Technology, USA 4Russian Academy of Sciences, Russia 5National Institute for Environmental Studies, Japan 6International Institute for Applied Systems Analysis (IIASA), AustriaT study was aimed at assessing the profitability and constraints faced by fish farmers in the southern sector of Ghana. Four regions in the southern sector were selected, namely, Greater Accra, Volta, Western and Ashanti region. A standardized structured questionnaire were distributed among 320 respondents. A multiple linear regression analytical tool was employed to estimate the factors which affect profitability of fish farming while the Net Farm Income (NFI) analytical tool was used to analyse the cost and returns of fish farming. The weighted average formula was used together with the Kendall’s Coefficient of Concordance to analyse the constraints of fish farming. The data was analysed using SPSS (version 24) and STATA (version 14) software. Results from the study showed that farm ownership, educational level, access to market, FBO membership, and extension service significantly affect the profits of fish farming. However, the age, gender, form of sale of fish and type of market were not significant in influencing profit. The mean total cost, revenue and profit of GH₵ 6293.37, GH₵ 12859.44 and GH₵ 6566.07 were obtained respectively. The return on investment was 104.33%. The constraints analysis showed that, high cost of inputs and lack of clear government policies and incentives were the most pressing constraints faced. Aquaculture in the southern sector of Ghana is a profitable business venture, but it is normally on a small scale, and hence the need for commercialization. Aquaculture can greatly contribute to the total reduction in the short falls of demand and supply of fish products in the country and be a potential source of animal protein, income generation and employment. More extension officers should be deployed to the southern sector to educate fish farmers on the best fish farming practices. Government should build processing factories to facilitate fish storage, processing and marketing.T based approach are widely used in the study of different process (dispersal limitation, habitat filtering and limitation similarity) underlying community assembly. However, most researches are based on trait mean value, which only consider interspecific trait variation. Due to the genetic and environmental difference, functional trait can also exhibit significant intraspecific trait variation (ITV). Thus disentangle whether and how will the detection of relative importance of ecological process be influenced by the inclusion of ITV is of significant meaning for our understanding of community assembly. Here, we collected community composition data and 8 functional traits in a young (24-ha) and old (25-ha) growth forest plot. We analyzed the relative importance of different process based a recent developed modeling technique (STEPCAM). Moreover, we detect the effect of ITV on the relative importance with and without ITV. We found that dispersal limitation are most important at 20 m in two forest plot, followed by habitat filtering, and limiting similarity had minor effect. When taking ITV into consideration, the proportion of deterministic process (habitat filtering and limiting similarity) improved at early successional stage, while such effect was not found at late successional stage. Moreover, based on single trait, we found the deterministic process only improved for the nutrition absorb related trait when we consider of ITV at late successional stage, which imply the importance of soil condition on community assembly at this scale. In conclusion, our study highlights the importance of ITV for the detection of trait based ecological process in this temperate forest across successional stage.

Influence of Hydrological Conditions on the Formation of Forested Peatlands and Shallow-Peat Forests at Watersheds in the Central Forest Nature Reserve

The spatial variability of the water regime determined by peat-deposit structure and surface slope is characteristic of watershed forested peatlands and shallow-peat forests that belong to similar forest types The specific features of the water regime determine the tree-stand structure, the composition of the herb–shrub and moss tiers, and the reaction to climatic changes of the past. The history of forested peatlands formation is comparable in duration to that of large peatbog massifs formation. An increase in wood-macrofossils content in peat is characteristic of warm periods of the Holocene. Conversely, a decrease in wood-macrofossils content accompanied by an increase in sphagnum moss remains, intensive growth of the deposit, and paludification of the adjacent forests were timed to the cold periods. The climatic factor was shown to determine the general direction of forested peatlands development, whereas the hydrological features of the site determined the variety of scenarios and resistance to environmental changes.