Stocks of phytodetrite and its biogenic elements in larch forests in small watershead basin of Central Evenkia

Abstract

The article notes the main sources of phytodetritus in undisturbed cryolithic larch forests of Central Evenkia. The features of the distribution of phytodetritus stocks and its individual components depending on the age of forest stands (young, mature and overmature) and forest types are considered. All these stands were formed on the territory of a small drainage basin in Central Evenkia after intensive ground fires in the early and last decades of the 20th century. An uneven distribution of litter stocks was revealed both in age groups and forest types. Significant annual fluctuations in litter stocks over 7-year observation period were also noted. The composition of the litter is dominated by needles – 84.8–93.2% of the total mass, while the branches and bark of larch (Larix Mill.) and birch (Betula L.) leaves account for only 3.0–3.2, 4.5–2.6, and 7.7–< 1 %, respectively. It was established that according to the degree of accumulation of phytodetritus in the main types of larch forests of the basin under consideration, they are arranged in the following descending order: ledum green moss, red berry green moss, shrub green moss. Litter stocks in them vary from 2.4 to 76.3 t/ha. The total stock of litter in the territory of the basin is 133038 tons, of which 103916 tons fall on larch forests, with a predominance of mature and overmature – 4966 and 61188 tons, respectively. In larch forests of the permafrost zone, phytodetritus is formed mainly due to the litter of the moss-lichen cover. The role of litter from aboveground organs and root mortmass is insignificant. In all cases, with an increase in the age of forest stands, an increase in the mass of the litter is observed. The role of individual components of phytodetritus in the deposition of biogenic elements was revealed, with a significant predominance of carbon and nitrogen in them and an insignificant content of phosphorus and potassium as additional sources of mineral nutrition in forest biogeocenoses of the permafrost zone, and a low rate of their entry into the soil in the process of detritus mineralization was noted.

Keywords

• larch forests of cryolithic zone
• forest types
• litter mortmass
• components
• biogenic elements