A. Olchev

Modeling of the carbon dioxide fluxes in European Russia peat bogs

A process-based model (Forest-DNDC) was applied to describe the possible impacts of climate change on carbon dioxide (CO2) fluxes from a peat bog in European Russia. In the first step, Forest-DNDC was tested against CO2 fluxes measured by the eddy covariance method on an oligotrophic bog in a representative region of the southern taiga (56 ◦ N3 3 ◦ E). The results of model validations show that Forest-DNDC is capable of quantifying the CO2 fluxes from the bog ecosystem. In the second step, the validated model was used to estimate how the expected future changes of the air temperature and water table depth could affect the C dynamics in the bogs. It was shown that a decrease in the water table and an increase in temperature influence significantly the CO2 exchange between our bog ecosystem and the atmosphere. Under elevated temperature and deepened water table the bog ecosystems could become a significant source of atmospheric CO2.

Application of a 2D Model for Describing the Turbulent Transfer of CO2 in a Spatially Heterogeneous Vegetation Cover

A numerical 2D model of the turbulent transfer of CO2 in the air between a spatially heterogeneous vegetation cover and the atmospheric surface layer was developed. The model is based on the one-and-a-half closure scheme for averaged equations of hydrodynamics and diffusion of CO2 in the air. The model was applied to assess the possible influence of forest canopy heterogeneity on the turbulent regime and CO2 fluxes in the atmospheric surface layer. CO2 exchange was simulated both at the windward forest edge and around a forest clearing.

Climatic conditions of the south part of Valday Hills, Russia, and their projected changes during the 21st century

Modern climate conditions and their possible future changes in the southern part of Valday Hills, Russia, were analyzed using 40-years of meteorological data observations and global model projections. It was shown that the annual, January and July temperatures in the area increased during the last 40 years by about 0.7°, 4.0°C and 0.3°C, respectively. Annual precipitation also increased by about 60 mm. Climate simulations for the period up to 2100 provided by a general circulation model ECHAM5 (MPI Hamburg, Germany) according to B1, A1B and A2 IPCC emission scenarios propose significant changes in meteorological conditions for the study area in the future. The mean annual temperature at the end of the century may rise by 2.2-3.9°C. Increase of January temperatures under different scenarios can range between 3.3 and 6.7°C. Projected increase of annual precipitation can reach 105 mm and it is mainly manifested in growth of winter values.

Growing season variability of net ecosystem CO2 exchange and evapotranspiration of a sphagnum mire?in?the?broad-leaved forest zone of European?Russia

The spatial and temporal variability of net ecosystem exchange (NEE) of CO2 and evapotranspiration (ET) of a karst-hole sphagnum peat mire situated at the boundary between broad-leaved and forest‐steppe zones in the central part of European Russia in the Tula region was described using results from field measurements. NEE and ET were measured using a portable measuring system consisting of a transparent ventilated chamber combined with an infrared CO2/H2O analyzer, LI-840A (Li-Cor, USA) along a transect from the southern peripheral part of the mire to its center under sunny clear-sky weather conditions in the period from May to September of 2012 and in May 2013. The results of the field measurements showed significant spatial and temporal variability of NEE and ET that was mainly influenced by incoming solar radiation and ground water level. The seasonal patterns of NEE and ET within the mire were quite different. During the entire growing season the central part of the mire was a sink of CO2 for the atmosphere. NEE reached maximal values in June‐July. 6:8 4:2 mol m 2 s 1 /. The southern peripheral part of the mire, due to strong shading by the surrounding forest, was a sink of CO2 for the atmosphere in June‐July only. ET reached maximal values in the well-lighted central parts of the mire in May (0:34 0:20 mm h 1 ) mainly because of high air and surface temperatures and the very wet upper peat horizon and sphagnum moss. Herbaceous species made the maximum contribution to the total gross primary production (GPP) in both the central and the peripheral parts of the mire. The contribution of sphagnum to the total GPP of these plant communities was relatively small and ranged on sunny days of July‐August from 1:1 1:1 mgC g 1 of dry weight (DW) per hour in the peripheral zone of the mire to 0:6 0:2 mgC g 1 DW h 1 at the mire center. The sphagnum layer made the maximum contribution to total ET at the mire center.0:25 0:10 mm h 1 / and the herbaceous species on the peripheral part of the mire (0:03 0:03 mm h 1 ).

CO2 and H2O exchange in the forest ecosystems of Southern Taiga under climate changes

173 The structure, species composition, and productivv ity of forest ecosystems are determined by a number of factors, with climatic conditions as the major one. Incoming solar radiation, air temperature and humidd ity, and soil moisture conditions regulate plant photoo synthesis, respiration and transpiration, determining the growth and developmental patterns of plant comm munities. The modern climate changes appeared mainly in increase of the air temperature, alterations in the gas composition of the air and land surface moistenning conditions may evidently influence the dynamics and rate of biophysical and biochemical processes in plants and soil and, as a consequence, lead to changes in the intensity of CO 2 and H 2 O exchange between plants and ambient air. In a longg term perspective, this may influence sustainable development of forests and lead to changes in their species composition and spatial distribution of varii ous species [1]. Possessing by a high sensitivity to changes in envii ronmental conditions, forests also have a significant feedback effect on the climate system. Actively absorb CO 2 from the atmosphere during photosynthesis, accumulating carbon in the aboveground and underr ground biomass, and retaining it in a fixed state during a considerable time period, they enhance the maintee nance of natural CO 2 balance in the atmosphere, mitt igating the possible negative ecological consequences of the increasing greenhouse effect. Directly influencc ing the radiation, heat, and water regimes of the ground surface and atmospheric surface layer, forests protect the ground surface from overheating in summ mer as well as regulate evaporation processes. Preservv ing moisture incoming to the ground surface with pree cipitations, they enhance the formation of a stable river discharge. The study of climate and forest vegetation interacc tions requires integrated experimental and modelling studies, first and foremost, aimed at analysis of the natural variation and sensitivity of different forest types to environmental changes, stability of the forest systems, and assessment of the effects of the changes in the structure and species composition of forest plant communities on climate. In this study, the sensitivity of the CO 2 and H 2 O exchange components in forest ecosystems to pro jected climate changes by the end of the 21st century has been estimated in a case study of southern taiga spruce forests of European Russia using results of modelling experiments. A modellbased approach allows not only to estimate the spatial and temporal variability of the …

Application of the paleoanalog method for prediction of vegetation dynamics under climate changes

228 The problem of climate and vegetation dynamics in the past epochs attracts much attention of the researchers because these data can help to predict pos sible changes in plant communities under various sce narios of climate changes in the future. Analysis of the paleoclimate data suggests that, during the thermal maxima of the last Interglacial (about 125 thousand calendar years before present (ka BP)) and the Holocene (about 5.5 ka BP), the air temperature in the northern hemisphere was 1.7–1.8°C and 1°C higher than the modern values, respectively [1, 2]. Consider ing current trends in climate changes, which are pri marily expressed in a rapid increase in the global air temperature [9], analysis of the climatic conditions and vegetation for selected time slices is of crucial importance for the reliable prediction of changes in plant communities. The method of paleographic reconstruction (the method of so called paleogeographic analogs) has been developed about 20 years ago to evaluate the response of plant species to climate changes [1]. How ever, until recently, the researchers used this method to study vegetation dynamics only at the global level, e.g., for the entire northern hemisphere, Northern Eurasia, Western Siberia, or East European Plain [2]. In our study, the method of paleo analogs was used to predict possible changes in vegetation on a regional scale at the south of the Valdai Hills under different scenarios of the future climatic changes. The main objects of our study were the coniferous forests of the Central Forest State Nature Biosphere Reserve (CFS NBR) in the southwestern part of the Valdai Hills (56.4°–56.6° N, 32.7°–33.1° E). Located near the southern boundary of taiga zone, in a transitional area from the south taiga to mixed broad leaved–conifer ous forests, the CFSNBR forest ecosystems can be very sensitive to the global warming projected in 21 century [2, 12]. To reconstruct the climatic conditions in the past epochs, we used paleobotanical data and the results of radiocarbon dating of a number of sections through organogenic deposits of the late Pleistocene and Holocene in the CFSNBR area [6, 10, 11]. The mean temperatures of the coldest and warmest months during the Mikulino Interglacial (January and July, respectively) were calculated using Grinchuk’s method of climatograms [4] and the data of palyno logical and paleocarpological studies. Climatic recon structions for the Holocene (temperatures of the cold est/warmest months, annual mean temperature, and annual precipitation) were conducted by “the best analog” method [14] using available palynological data.

The Response of Coniferous Trees to Industrial Pollution in North-Western Russia

The response of two dominant coniferous species (Picea obovata Ledeb. and Pinus sylvestris L.) of east- European taiga to industrial pollution in the impact zone of the Severonickel metallurgical combine (Murmansk Region, Kola Peninsula) was investigated. The water deficit of the needles and shoots described by shoot water potential () was used as indicator of the pollution level in the area. The vitality status of the trees was assessed by visual traits (crown shape, life span and degree of needle damage). It was shown that industrial pollution results in injuring the spruce and pine trees, damaging their conducting system and increasing the water deficit of the needles. Correlation between the visually determined health status of the trees (including needle yellowing and die-back) and their water deficit was higher for spruce than for pine trees. High sensitivity of spruce trees to air pollution may be used in forest ecology for e.g. remote detecting the forest areas with high levels of industrial pollution.

Evidence of temperature and precipitation change over the past 100 years in a high-resolution pollen record from the boreal forest of Central European Russia

Near-annual pollen records for the last 100 years were obtained from a 65-cm peat monolith from a raised peat bog in the Central Forest State Natural Biosphere Reserve (southern part of the Valdai Hills, European Russia) and compared with the available long-term meteorological observations. An age–depth model for the peat monolith was constructed by 210Pb and 137Cs dating. Cross-correlation and the Granger causality analysis indicated a broad range of statistically significant correlations between the pollen accumulation rate (PAR) of the main forest-forming trees and shrubs (Picea, Pinus, Betula, Tilia, Quercus, Ulmus, Alnus, and Corylus) and the air temperature and precipitation during the previous 3 years. Results showed that high air temperatures during the growing season (May–September) in the year prior to the flowering led to an increase in pollen productivity of the main tree species. The statistically significant correlation between the PAR of trees and shrubs and winter precipitation of the current and previous years could reflect the influence of winter precipitation on soil water availability and as a result on tree growth and functioning in the spring.

An impact assessment of forest belts on the SO2 transport within the atmospheric boundary layer using a hydrodynamic model

A numerical two-dimensional hydrodynamic model was used to describe the influence of forest belts of different sizes on turbulent transport of SO2 within the atmospheric surface layer. The results of the model calculations showed that the presence of a forest belt results in an substantial reduction of the horizontal SO2 flux due to the decrease of the wind speed and the absorption of SO2 by tree crowns. The extinction coefficient of SO2 flux increases with an increase in the forest belt size and decrease with the pollution source height.

Influence of forest cover changes on regional weather conditions: estimations using the mesoscale model COSMO

This modeling study intends to estimate the possible influence of forest cover change on regional weather conditions using the non-hydrostatic model COSMO. The central part of the East European Plain was selected as the ‘model region’ for the study. The results of numerical experiments conducted for the warm period of 2010 for the modeling domain covering almost the whole East European Plain showed that deforestation and afforestation processes within the selected model region of the area about 105 km2 can lead to significant changes in regional weather conditions. The deforestation processes have resulted in an increase of the air temperature and a reduction in the amount of precipitation. The afforestation processes can produce the opposite effects, as manifested in decreased air temperature and increased precipitation. Whereas a change of the air temperature is observed mainly inside of the model region, the changes of the precipitation are evident within the entire East European Plain, even in regions situated far away from the external boundaries of the model region.