Подвижные гумусовые вещества в подзолах лесотундровой зоны

• Main Authors: Учаев, Антон, Некрасова, Ольга
• Format: Text
• Language: unknown
• Published: Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования «Национальный исследовательский Томский государственный университет» 2013
• Subjects: ЗАПАДНАЯ СИБИРЬ; ЛЕСОТУНДРА; МЕРЗЛОТНЫЕ ПОЧВЫ; ПОДЗОЛ; ГУМУС; ПОДВИЖНЫЕ ГУМУСОВЫЕ ВЕЩЕСТВА; permafrost; Tundra
• Online Access: http://cyberleninka.ru/article/n/podvizhnye-gumusovye-veschestva-v-podzolah-lesotundrovoy-zony; http://cyberleninka.ru/article_covers/15595134.png

Рассматривается групповой и фракционный состав гумуса и отдельные фи-зико-химические характеристики подзолов криогенно-глеевых Al-Fe-гумусовых на почвообразующих породах, имеющих различный гранулометрический состав, сформировавшихся под разными растительными сообществами лесотундры Западной Сибири. Приведены запасы органического углерода в этих почвах. На основании различных теоретических подходов определен вклад лабильных гумусовых веществ в общий почвенный пул углерода. Показано, что не менее трети запасов органического углерода в подзолах лесотундры находится в составе относительно подвижных гумусовых веществ, которые в первую очередь могут подвергаться минерализации в случае потепления климата. Under stable conditions, the system of soil humic substances is in a state of equilibrium, meaning the dynamic balance between the newly formed and mineralized fragments of macromolecules. In the process of global warming of the climate, which is showing more intensively in the territory of permafrost distribution, the system of soil humic substances can leave its state. In this case primarily mobile humic substances, which are the least stable part will be subjected to additional mineralization, that will increase soil CO2 emissions. The information about stocks of carbon in various humus forms in soils of different forming conditions is required for long-term forecasting of soil behavior. The aim of the work was to establish the contribution of labile humic substances to organic carbon stocks in forest-tundra Podzols. For this reason soil humus characteristics and connected with them physical-chemistry ones were obtained for the purpose of calculating carbon stocks in various humus forms in the typical for West Siberian plain forest-tundra Pod-zols cryogenic gley Al-Fe-humus (Albic Gleyic Podzol). These soils are formed under forest (Section 3.3.1) and lichen plant communities (Section 3.4.1), have various soil textures and the depth of permafrost table ranges in 1.5 times. Both soils have the acid reaction (pHKCl is less than 4.4), pH decreases in the lower soil horizons. The volumes of hydrolytic acid reached 13-25 mmol/kg of the soil in the organic horizons, but in mineral horizons it lowers till average 1-3 mmol/kg of the soil. The distribution character of organic carbon in the studied soils is regressive-accumulative. The maximum content (9-18%) was found in the surface horizons, the minimum on the lower part of the soil profile, where it amounts to 0.04-0.09%. Carbon stocks in the upper 20 cm of studying soils vary in more than 2 times under different vegetation communities, accounting for 950-2090 t/ km2. It corresponds to the very low level. Maximum values occur in Podzol under larch community. The humus content of the studying soils is rather similar. The aggressive fraction of fulvic acids and related with brown humic acids fulvic acids are dominated in the composition of humus, a significant share is also on brown humic acids. According to one theoretically approach, mobile humic substances are those, that can be extracted by 0,1 n NaOH. The average amount of these mobile fractions in the upper 20 cm of studying soils is 38% for Podzol under larch community and 31% for Podzol under lichen community. According to the other view, mobile humic substances are the fulvic acids. The average fulvic acid content in the same soil layers is 41% and 54%, respectively. Thus, more than one third of forest-tundra podzol humus substances exist in less stable, mobile humus fractions, which may cause to the rapid increase of soil CO2 emissions in the case of global warming.