Seasonal Growth of Scots Pine under the Conditions of Water-Logged Soils of the North

The seasonal rhythm of height growth of young shoots of Scots pine growing in a 33-year-old shrubby-sphagnum pine forest of the northern taiga natural-climatic zone has been studied in a complex with the main physiological processes. The possibility of regulating their intensity by additional introduction of nitrogen fertilizer has been determined. It has been found that on hydromorphic excessively wet soils of the North, seasonal height growth of pine occurs with a maximum rate in late June and early July, when air temperature rises and the root system is released from excessive moisture. Unlike lichen pine forests, in which pine roots are not affected by flooding, on hydromorphic peat soils pine grows much slower and during the growing season has less intensive physiological processes. The low rate of shoot growth and physiological processes in pine in sphagnum forest site conditions is explained by dysfunction of its root system as a result of soil anoxia caused by flooding, as well as by insufficient supply of growing shoots with acronutrients from the crown as a result of violation of their normal outflow and movement in the tree. Nitrogen fertilizers positively affect growth and physiological processes in pine trees in sphagnum forest types. However, their effect in these forest site conditions is much weaker than in the dry lichen forests of the Far North. On water-logged peat soils under the influence of nitrogen fertilizer seasonal height growth of pine trees increases by 20 %, the duration of seasonal shoot growth increases by 8–10 days, the intensity of photosynthesis increases significantly, and, as a result of reduced water onsumption for transpiration, the tree water regime normalizes and the transpiration productivity increases. These positive nitrogen-induced changes ultimately improve the viability and productivity of sphagnum pine forests. For citation: Zarubina L.V., Khamitov R.S. Seasonal Growth of Scots Pine under the Conditions of Water-Logged Soils of the North. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 3, pp. 86–100. DOI: 10.37482/0536-1036-2021-3-86-100