Moscow State University

About: Moscow State University is a education organization based out in Moscow, Russia. It is known for research contribution in the topics: Catalysis & Laser. The organization has 66747 authors who have published 123358 publications receiving 1753995 citations. The organization is also known as: MSU & Lomonosov Moscow State University.

Mapping the extent of abandoned farmland in Central and Eastern Europe using MODIS time series satellite data

Abstract: The demand for agricultural products continues to grow rapidly, but further agricultural expansion entails substantial environmental costs, making recultivating currently unused farmland an interesting alternative. The collapse of the Soviet Union in 1991 led to widespread abandonment of agricultural lands, but the extent and spatial patterns of abandonment are unclear. We quantified the extent of abandoned farmland, both croplands and pastures, across the region using MODIS NDVI satellite image time series from 2004 to 2006 and support vector machine classifications. Abandoned farmland was widespread, totaling 52.5 Mha, particularly in temperate European Russia (32 Mha), northern and western Ukraine, and Belarus. Differences in abandonment rates among countries were striking, suggesting that institutional and socio-economic factors were more important in determining the amount of abandonment than biophysical conditions. Indeed, much abandoned farmland occurred in areas without major constraints for agriculture. Our map provides a basis for assessing the potential of Central and Eastern Europe’s abandoned agricultural lands to contribute to food or bioenergy production, or carbon storage, as well as the environmental trade-offs and social constraints of recultivation.

Variable chlorophyll fluorescence and its use for assessing physiological condition of plant photosynthetic apparatus

Abstract: Analysis of plant behavior under diverse environmental conditions would be impossible without the methods for adequate assessment of the processes occurring in plants. The photosynthetic apparatus and its reaction to stress factors provide a reliable source of information on plant condition. One of the most informative methods based on monitoring the plant biophysical characteristics consists in detection and analysis of chlorophyll a fluorescence. Fluorescence is mainly emitted by chlorophyll a from the antenna complexes of photosystem II (PSII). However, fluorescence depends not only on the processes in the pigment matrix or PSII reaction centers but also on the redox reactions at the PSII donor and acceptor sides and even in the entire electron transport chain. Presently, a large variety of fluorometers from various manufacturers are available. Although application of such fluorometers does not require specialized training, the correct interpretation of the results would need sufficient knowledge for converting the instrumental data into the information on the condition of analyzed plants. This review is intended for a wide range of specialists employing fluorescence techniques for monitoring the physiological plant condition. It describes in a comprehensible way the theoretical basis of light emission by chlorophyll molecules, the origin of variable fluorescence, as well as relations between the fluorescence parameters, the redox state of electron carriers, and the light reactions of photosynthesis. Approaches to processing and analyzing the fluorescence induction curves are considered in detail on the basis of energy flux theory in the photosynthetic apparatus developed by Prof. Reto J. Strasser and known as a “JIP-test.” The physical meaning and relation of each calculated parameter to certain photosynthetic characteristics are presented, and examples of using these parameters for the assessment of plant physiological condition are outlined.

Tomography of temperature gradient metamorphism of snow and associated changes in heat conductivity

Abstract: Temperature gradient metamorphism is one of the dominant processes changing the structure of natural dry snow. The structure of snow regulates the thermal and mechanical properties. Physical models and numerical simulations of the evolution of the snow cover require a thorough understanding of the interplay between structure and physical properties. The structure of snow and the heat conductivity were measured simultaneously without disturbance in a miniature snow breeder. The structure was measured by microtomography, and heat conductivity by measuring heat fluxes and temperatures. A temperature gradient from 25 to 100 K m−1 was applied to the snow. The snow density range of the samples varied from 150 to 500 kg m−3. The density in the observed volume remained constant during the experiments under temperature gradient conditions. The structure was analysed with respect to the size of typical ice structures and air pores, specific surface area, curvature and anisotropy of the ice matrix. The temporal changes in structure and heat conductivity are compared. The heat conductivity changed by as much as twice its initial value, caused by changes in structure and texture, but not due to changes in density. This shows the enormous importance of structure in the evolution of the heat conductivity. The observed changes are not in good agreement with the current understanding of the metamorphic process, because heat conductivity increased during temperature gradient metamorphism, instead of the expected decrease due to a shrinking of the bonds. We also observed a plateau in the evolution of the heat conductivity coefficient, which indicates a quasi-steady state of the structural evolution with respect to thermophysical properties of snow. Copyright © 2004 John Wiley & Sons, Ltd.