ИСТИНА

Despite the significance ascribed to lignin in the humus formation our knowledge on the really amount and degradation pathway of natural lignin in the different zonal soils of Russia is rather fragmentary. Characterization of lignin compounds in the zonal mountainous soils is very rare. The aim of our investigation is to study in detail the ¬ composition and profile distribution of lignin parameters in soils under different types of vegetation and different biochemical conditions. Amount and composition of lignin phenols (vanillin, syringaldehyde and vanillic, syringic, p-coumaric, ferulic acids) are investigated in Chemozems Haplic, Cambisols Humic, Greyzems Haplic, Gleysols Mollic, Leptosols Umbric, Leptosols Mollic, Gleysols Mollic. Ecosystems with different types of vegetation were studied: pine, spruce, birch, aspen, larch, cedar, junipers forests, arab le land, steppe, alpine and sub alpine meadows. Lignin phenols were determined in plant tissues, in root and plant litter, in soils and in humic acids. The amount and stage of oxidative decomposition of lignin was estimated using the system of lignin parameters obtained from alkaline CuO oxidation. It was established, that the main source of lignin in all ecosystems studied is a root litter. Sum of lignin-oxidative products in the soils studied reflects different biochemical conditions of humification. In chemozems, as in soils with high biochemical activity, the more possible pathway of humification is the deep and quick fermentative degradation of high-molecular compounds to the monomers. Besides, the role of humic ac ids abiotic condansation from simple free monomers is more considerable. In lowlands hydromorphic and in high mountain soils, where microbial activity is more lower and ferment amounts is also low, high-molecula compounds preserve and gradually change into humic acids by the way ofbiopolimer degradation. Due to the biochemical specificity of plant lignin compounds and high sustainability it can be used as a molecular traces of organic matter in the paleolandscape studies.