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 H<sub>2</sub>O vapor and plant cell-respired CO<sub>2</sub>. 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 CO<sub>2</sub> and H<sub>2</sub>O has revealed that the CO<sub>2</sub> and H<sub>2</sub>O 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 CO<sub>2</sub> 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 CO<sub>2 </sub>generated in a stem completely diffuses into the atmosphere. Results obtained from explorations into the CO<sub>2</sub> content in disc tree rings by the method proposed in this work shows that a major part of CO<sub>2</sub> remains in tree stems and exhibits inter-annual variability. Different methods are used to describe of CO<sub>2</sub> and H<sub>2</sub>O distributions in disc tree rings. The relation of CO<sub>2</sub> and H<sub>2</sub>O 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 CO<sub>2</sub> and H<sub>2</sub>O content in coniferous tree disc rings to various climatic factors. Suggested method of CO<sub>2</sub>, (CO<sub>2</sub>+H<sub>2</sub>O) detection can be used for studying of a stem respiration in ecological risk areas.