V. A. Sapozhnikova

Variation of H 2 O, CO 2 , and CO 2 Isotope Composition in Tree Rings of Siberian Stone Pine

The experimental measurements of H2O, CO2, and the carbon isotope content of CO2, vacuum-desorbed from tree rings of the Siberian stone pine disc, have been obtained. It is shown that: 1) certain cyclicity exists in annual trends of H2O and CO2; 2) the amplitude of CO2 cycles has markedly risen after 1960; 3) the annual trend of the CO2 concentration in the rings correlates with an increase in atmospheric CO2 concentration; 4) the carbon isotope content varies with the variation of CO2 concentration in a sample.

Variations in gas components and total pressure in stem and root disc wood of conifer species

The content of CO2 and H2O in vacuum-extracted tree-ring wood of stem and root discs of certain conifer species was measured. Annual distributions of these gas components were found to exhibit cyclic behavior. Moreover, distinct cyclicity was also revealed in interannual variations of the total pressure of the vacuum-extracted tree-ring gas samples. It may be safely assumed that diffusion of stem CO2 into the atmosphere will show the same periodic variability. Two hypotheses about the origin of the cyclicity in the treering CO2 distributions are examined.

Variations and trends in CO 2 and H 2 O content in coniferous tree-rings

The experimental values of the variation in the CO2 and H2O content in tree-rings of some conifers from regions with different climate conditions have been obtained. These data are compared with tree-ring widths; some conclusions are made about the climatic response in the annual CO2 and H2O distributions. The hypothesis is proposed that the long-term cyclicity found in the annual CO2 distribution over tree rings is a response of trees to environmental changes.

A trend of the CO2 concentration in tree rings and the atmospheric CO2

Several suppositions about the interpretation of the CO2 content measurements in the rings of old discs of tree stems are put forward. In particular, it is supposed that the trend in the annual CO2 content detected in the rings is related to the rising concentration of the atmospheric CO2.

Dark respiration under low pressure and increased ethylene

Responses of plants seedlings to hypobaria (reduced pressure of air) exposure (up to 8 kPa) and exogenously applied ethylene (10 -4 , 10 -5 , 10 -6 kPa) was studied using a gasometric system based on CO 2 -laser photoacoustic spectrometer. The increase of O 2 -evolution (in the dark) by pea (Pisum sativum L.), wheat (Triticum aestivum L.), maize (Zea mays L.), barley (Hordeum vulgare L.) and pine seedlings (Pinus sylvestris L.) was revealed. Some differences in dynamics of CO 2 -evolution and signal magnitudes are probably stipulated by the objects specificity. The alcohol-dehydrogenase, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, phosphoenolpyruvate carboxylase activity and contents of malate, pyruvate and lactate were studied in pea leaves. It was shown that an anaerobic metabolism increases with time and also when the air pressure is decreased. An increase of CO 2 -evolution from ethylene-treated pea seedlings and alcohol-dehydrogenase activation were observed.

Certain features of gas emission from the wood of annual rings of conifers

Results of our studies of gas content in rings of tree discs have shown that a significant part of the CO2 generated by cell respiration remains in tree stems. The content of this CO2 exceeds the atmospheric CO2 in most cases and forms the distribution over tree rings. In our investigations, we first used photoacoustic gas analysis. In this work, we discuss certain features of the chronologies (year-to-year distribution) of gas samples.

Variations of Residual CO 2 and Pressure in Conifer Woody Roots

In continuation of works on the determination of cyclic tree-stem CO2 efflux, vacuum-extracted gas samples of large woody roots of Siberian stone pine and Scots pine are studied. Laser photoacoustic gas analysis was used to obtain chronologies of CO2 and total pressure of gas components in root rings. Spectral and cross-spectral analyses reveal the cyclic character of variations in the chronologies. Such a behavior of the total pressure and CO2 content in large roots can testify to possible cyclic diffusion of CO2 from the roots into soil and then into the atmosphere, which can be considered as a new feature of autotroph respiration. An attempt is made to analyze results of some previous work on a similar subject based on cyclic CO2 efflux from large roots.

Laser photoacoustic detection of CO2 in biosphere-atmosphere gas exchange and in tree rings

The method and technology of the photoacoustic gas analysis enables highly sensitive investigations of CO2 gas exchange different biosystems. The CO2 evolution by some plants exposed to elevated concentration of pollutants and CO2 emissen from the wood of tree rings at low air pressure is studied. All measurements have been performed using the photoacoustic gas analyzer with the tunable CW CO2-laser.

Dynamics of CO2 evolution by plants at low pressure

Dynamics of CO2 evolution at low pressure was studied in barley, maize, pea, wheat and pine seedlings using the gas exchange system with laser photoacoustic spectrometer. The CO2 evolution from plant surfaces to environment increased with decreasing air pressure. Simultaneously the changes in activities of phosphoenolpyruvate carboxylase, glucose-6-phosphate dehydrogenase, glyceraldehyde phosphate dehydrogenase, alcohol-dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase in pea and maize leaves were observed. The response depended on plant species used as well as on air pressure and period of its action