Measurements of gases desorbed by the vacuum method from the disc ring wood of deciduous trees were carried out. The analysis of gases was performed using a photoacoustic gas-analyzer with a tunable CO2 laser. The chronologies of residual CO2 and (CO2+H2O) gases of some trees that grew in and around Tomsk (West Siberia) have been obtained. Correlation coefficients of chronologies with temperatures and precipitations for the vegetation period are determined. All the chronologies have cycles with period of 2-4 years. We suppose that the distribution of the residual gases in the discs reflects the annual release of the gases from the stems of the deciduous trees into the atmosphere.
Analysis was performed of the gas samples vacuum-extracted from the discs of the larches that had survived the explosion of a space body in the region of Podkamennaya Tunguska in 1908. The specificity of the CO2 accumulation in the tree rings after the catastrophe was revealed, which could affect the dynamics of the CO2 released by the stems into the atmosphere.
Analysis of the annual CO2 distribution in the gas samples vacuum - extracted from the tree - ring wood of several conifer discs has been performed. The results indicate that part of the CO2 released by forest communities into the atmosphere can vary with a period of about 4 years. The published series of the atmospheric CO2 content with the variations of close periods have been analyzed.
Stem wood is known to contain significant amounts of gases. However, literature data on the functional role of the gases are lacking. The results of our experiments show that porous wood structure is capable of annual accumulation (sorption) of the stem gas components that include H2O vapor and plant cell-respired CO2. This allows for development of additional chronologies to be used for gaining a deeper insight into the behavior of the stem gases. An analysis of the vacuum-extracted wood tree ring CO2 and H2O has revealed that the CO2 and H2O chronologies are associated with interannual variations in the total pressure of the gas components in the tree rings and are characterized by short-period cycles independent of tree age and by long-period variations with tree age. Our investigations led us to propose a procedure for using the CO2 content as a marker of year-to-year variations in the total pressure of the residual gas components found in wood tree rings.
Extensive literature devoted to investigations into the influence of environmental conditions on the plant respiration and respiration rate. It is generally accepted that the respired CO2 generated in a stem completely diffuses into the atmosphere. Results obtained from explorations into the CO2 content in disc tree rings by the method proposed in this work shows that a major part of CO2 remains in tree stems and exhibits inter-annual variability. Different methods are used to describe of CO2 and H2O distributions in disc tree rings. The relation of CO2 and H2O variations in a Siberian stone pine disc to meteorological parameters are analyzed with use of wavelet, spectral and cross-spectral techniques. According to a multiple linear regression model, the time evolution of the width of Siberian stone pine rings can be partly explained by a combined influence of air temperature, precipitation, cloudiness and solar activity. Conclusions are made regarding the response of the CO2 and H2O content in coniferous tree disc rings to various climatic factors. Suggested method of CO2, (CO2+H2O) detection can be used for studying of a stem respiration in ecological risk areas.
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