Influence of Picea Abies (L.) H. Karst. Logs on Soil Morphological Properties

Relevance and objectives. Deadwood is an integral component of natural forest ecosystems, ensuring their sustainability. In Russian soil science, the role of large woody debris as a component of the soil profile is practically not taken into account, despite the fact that buried deadwood is widely represented in boreal forests. The purpose of the study is to characterize the morphological properties changes (color and soil profile structure) of illuvial-iron podzol (Ferric Albic Podzol Arenic) and gray-humus (sod) metamorphosed soil (Umbrisol Loamic) under the influence of Picea abies logs 3-5 decay classes in local conditions in the middle taiga spruce forest. Materials and methods. The study was carried out in the summer of 2023 and 2024 in the Republic of Karelia on the territory of the Kivach State Nature Reserve on two sample plots. The influence of the deadwood was studied from the 3rd to the 5th decomposition class. Soil profiles are dug in each direction from the deadwood to 1 m. The morphological description of the profile is carried out directly under the deadwood, at distances of 0-25 cm, 25-50 cm, and 50-100 cm from the log according to generally accepted methods. This work shows the influence of deadwood on the soil within a local area, and there is no extrapolation of the obtained results to the entire area of the soil type. Results. The schemes of changes in the morphological structure of the upper horizons under the deadwood trunk and at a distance from it are compiled. Under the deadwood trunks in the conditions of gray-humus soil, the AY1 horizon, intensely colored with humus, is absent. In Podzol the fermented-humus horizon OFHh is diagnosed under the log. In Umbrisol, at a distance of 25 cm from the log, a change in the composition of the forest litter is observed. In Podzol a bleached horizon E is diagnosed under the log of the last decomposition class and at a distance of up to 25 cm from it. A litter is formed directly on the fallen wood, which gradually merges with the soil litter as the log decomposes. Conclusion. Logs of 3-5 decay classes create heterogeneity in the surface horizons. The effect on morphological properties is manifested in a change in color, as well as in the appearance or, conversely, the absence of some soil horizons. The effect of log of late decay classes (classes 3, 4, 5a for Umbrisol and classes 3, 4 for Podzol) is manifested directly under the log. The effect of the log extends to the surrounding space only at the last decomposition class of the log (class 5b for Umbrisol soil and class 5 for Podzol).