STATIONARY STUDIES OF THE PRODUCTIVITY OF PLANT MATTER OF STEPPE FACIES OF TRANSECT TESTING AREAS IN SOUTHEAST TRANSBAIKALIA

Abstract

The article focuses on the productivity of plant matter of the steppes in the Onon-Argun District of Southeast Transbaikalia. The
steppes of Transbaikalia represent the main repository of vegetation cover. They are located in the center of the Asian continent and are limited by
coordinates 50oN, 116oE. Two transect testing areas – Kharanorsky and Tsagan-Cholotuysky – were chosen for the study as model sites. This
choice was due to the features of the landscape structure forming landscape-ecological series where facies are interfaced with each other. On the
basis of a long-term stationary study, the dynamics of aboveground and underground plant matter reserves were taken into account. The main
reserves of plant matter of the geosystems were found to be concentrated in the underground mass. Most of the root mass (from 88 to 95% of its
total stock) is concentrated in a half-meter layer of soil. The study revealed specific conditions of the facies of the conservation regime, facies
affected by economic use, and also those in conditionally natural environment. Each facies is characterized by its own dynamics of phytomass
reserves due to the bioclimatic situation of the current year; sharp fluctuations in precipitation at the beginning or end of summer significantly affect
the amount of phytomass created. According to the research results, aboveground mass reserves in the facies of the first transect testing area under
any research regime are arranged in the row III>IV>V>II>VI>I, while on the second testing area with the economic regime they are arranged in the row XVII>XVI>XII>XXI>XIX>XIV>XI. Spatio-temporal models of seasonal dynamics have been created, which can be used to assess
changes in the aboveground and underground mass in the conjugate series of the studied facies during the growing season. It has been established
that for each facies, the maximum accumulation of phytomass during the growing season is achieved within a specific period that is only characteristic of this particular facies and consistent with changes in hydrothermal conditions.