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We applied thermogravimetric analysis to ten successive growth rings of Siberian larch and the same number of mountain birch individuals sampled in the alpine forest-tundra ecotone of Kuznetsk Ala Tau mountain ridge to compare physical and chemical responses of the species wood to climate change. Our analysis of the correlation of the wood thermal parameters with air temperature and precipitation revealed that early and latewood cellulose and lignin in the birch were more sensitive to climatic changes as compared to the larch. June–August weather conditions appeared to largely control the chemical composition of the birch early and latewood. Air temperature had a marked influence during synthesis of both early and latewood cell walls, whereas precipitation influenced only latewood. Thermogravimetric analysis of growth rings formed in alpine forest-tundra proved to be an effective tool to study the influence of climatic and weather variability on lignin-carbohydrate complex of deciduous and conifer tree species. [ABSTRACT FROM AUTHOR]

This paper deals with the results of a study of the thermodestruction of the earlywood and latewood in the 1988-1998 growth rings of Gmelin larch ( Larix gmelinii (Rupr.) Rupr.) trees growing along the polar tree line (7052′53″N, 102°58′26″E, Taimyr Peninsula). The study used methods of thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). Thermogravimetric data obtained were analyzed by Ozawa-Flynn-Wall kinetic model. We determined macrokinetic parameters of thermodestruction. Earlywood and latewood showed no significant difference in cellulose/hemicellulose/lignin ratio, whereas they differed significantly in destruction average value of activation energy (197.55 and 55.90 kJ mol, respectively). Our analysis of the correlation of thermodestruction values with mean monthly air temperature and precipitation revealed that component composition of both earlywood and latewood was influenced more by the weather conditions at the beginning of the growing season (April-June). Air temperature had markable influence on the wood component composition during cell wall synthesis only in latewood, whereas precipitation influenced the composition in both latewood and earlywood. TG/DTG and DSC methods were found to be promising for developing information on biochemical composition of early and latewood tracheids in stems and for identifying the extent of the influence of climatic changes on cell wall synthesis. [ABSTRACT FROM AUTHOR]