Nitrogen Reserves and Balance in Phytocenoses of the High-Mountain Subprovincia of Dagestan

Abstract

The purpose of the work is to determine the content and reserves of nitrogen, its balance in the ecosystems of the northern and southern expositions of the Mayak Mountain in the Highlands of Dagestan. For the first time, calculations of nitrogen reserves and balance in phytocenoses were performed for the High-mountain subprovincion of Dagestan. Methods. The study was conducted in 2012-2019 on the territory of the Gunib base of the Mountain Botanical Garden of the Russian Academy of Sciences. A protected regime was introduced at the experimental sites to exclude anthropogenic impact. The plots are located on the slopes of Mount Mayak: south (2100 m above sea level with a slope of 350), north (2070 m above sea level with a slope of 100). The nitrogen content in the phytomass was determined by wet salting. Nitrogen reserves and balance in phytocenoses were determined by the method of A. A. Titlyanova. Results. The productivity of phytomass on the slopes of Mount Mayak was at the northern and southern exposures: in the aboveground mass-69.62 and 66.50 c/ha * year; in the underground mass-2.07-2.10 times more. Most of the nitrogen reserves were on the slope of the northern exposure, which was probably due to the leaching of nitrogen from the soil, due to the great steepness of the southern slopes. The input part of the nitrogen balance in the phytocenoses of the Highlands of Dagestan during the decomposition of the underground mass was from 68.57 to 68.80%, depending on the slope exposure. During the decomposition of aboveground phytomass, 27.29-27.64% were received. Nitrogen fixation and intake with atmospheric precipitation amounted to a total of 3.69-4.32%. The main part of the expenditure item of the nitrogen balance accounts for the creation of net primary production of phytocenoses – 98.25-98.50%. Denitrification was 0.94-1.10%, leaching from the soil was 0.56-0.66%. In the studied protected areas, a positive nitrogen balance of + 8.47 and + 6.2 was found on the northern and southern slopes.