DYNAMICS OF PRODUCTIVITY OF RESTORED VEGETATION OF THE IZYKHSKY SURFACE MINE (TERRA MODIS)

. The subject of the study is the course of the dynamics of vegetation productivity on the dumps of the surface mine «Izykhsky» (2000-2019), using Terra Modis. The aim is to identify patterns of seasonal and long-term dynamics of restored vegetation as a result of succession according to images. The methodology included processing information on gross primary production and evapotranspiration, as well as identifying the relationship with meteorological data for 2018-2019. There is a positive trend in the long-term dynamics – in terms of total gross primary production from 1.7 to 5.5 kg/m 2 /8 days and in evapotranspiration from 1142 to 2784 kg/m 2 /8 days. The evapotranspiration correlated with the productivity. Since 2016, productivity has reached a plateau, which indicates the development of ecological niches by plants. The phytomass of the restored vegetation was in 1.5 times greater, than the mass of the steppe site. Seasonal dynamics in 2019 showed that communities on dumps have higher productivity, in contrast to the steppe, and one peak in the first ten days of July. The sum of temperatures and productivity had a high relationship (R 2 = 0.7) in comparison with the steppe (R 2 = 0.2). Terra Modis data can be applied in the field of ecological monitoring of vegetation of coal dumps.

A monitoring of restored lands, the vegetation cover disturbances and the pollution is carried out also according to remote sensing data [1,2]. The coal industry in Khakasia has increased dramatically since 2015 (7 surface mines, 5222 hectares of disturbed territories) [2]. Vegetation reconstruction efforts were becoming increasingly difficult in the areas affected by coal mining. The lack of moisture, high temperatures, with a short period of temperatures above 10° C leads to the fact that organic matter have started to mummify for a long time, and not its decomposition [3,4].
The aim of the work is to identify patterns of seasonal and long-term dynamics of vegetation productivity as a result of succession after reconstruction of the Izykhsky surface mine (Khakasia) according to Terra Modis data.
The sum of temperatures was obtained from the site rp5.ru. For integral productivity and evapotranspiration (half-sum of bases, multiplied by 8 days of the composite), the sum and standard deviation were calculated, and the regression was additionally calculated (Excel).
The Izykhsky coal surface mine has been developed since the 1960s. During this time, the natural landscape was transformed into the mining one in the form of a residual Corresponding author: zhukov.khsu@gmail.com quarry and an external coal dump on the land surface of 131 and 322 hectares, respectively ( Fig. 1). In the 2000s. its reclamation has begun [1].
The climate is continental, the radiation balance is 33-34 kcal per cm 2 , water (65%) is spent on evaporation. The sum of temperatures for the warm season is 1800-1950 о С. The amount of precipitation is 320 mm [3].
Chestnut soils, common or southern chernozems are widespread [3]. The layer up to 2 m is formed by Quaternary rocks. Humus in a layer up to 40 cm is 1.5-3.4% [1]. The evolution of steppe soils on coal dumps has been stopping for a long time only on the organo-accumulative stage, less often on the sod stage [7]. Due to the lamellar shape and angularity of embryozems, soil compaction occurs [4]. Erosion, deflation and aeolian weathering in the dry steppe zone can lead to a desertification and impeded a recovery [8].
From the point of view of studying of successions, the Terra Modis data are of interest primarily due to their significant archive (Fig. 2).
There There is a positive trend for all sites, especially for the eastern, northern and central parts.
High performance coincides with ground data. Evapotranspiration correlates with productivity (Fig. 3).
In the central part, evapotranspiration ranked first due to the accumulation of water (physical evaporation). Consider the seasonal dynamics for 2019 (Fig. 4). In contrast to the steppe with low productivity, the phytocoenoses on the dumps had a high productivity and a peak coinciding with the temperature peak. The maximum values were observed in the eastern and northern parts, the minimum values were in the south, where herbaceous vegetation is widespread.
The dependences of the GPP indicator on the sum of positive temperatures (regression) for the vegetative season from 2018 to 2020 were studied. The results showed that natural vegetation has a weak positive dependence on the sum of temperatures (R 2 = 0.16, 4 degree polynomial). This shows that the vegetation of such communities is better adapted from the point of ecological view to the semiarid climate. Consequently, the coal dump vegetation is more dependent on meteorological conditions than the steppe background During the work, the following conclusions were made: 1.

Evapotranspiration, kg/m2/8 day
There is a positive trend -in terms of total gross primary production from 1.7 to 5.51.7 kg / m 2 / 8 days and for evapotranspiration from 1142 to 2784 kg / m 2 / 8 days in the long-term dynamics of Terra Modis satellite data in the period from 2000 (2001) to 2019. The dynamics of evapotranspiration correlates with gross productivity in general. Since 2016, the GPP index has reached a plateau, which indicates the closure of the vegetation cover and the occupation of accessible ecological niches by plants.

2.
The GPP parameter for the restored vegetation was 1.5 times higher than the natural steppe vegetation. Consequently, for plants on the coal dump, in general, the growing conditions (moisture, nutrients) are favorable. This is confirmed by a higher projective cover and larger sizes of species. This makes the territory promising for the restoration of biological diversity, even for trees and shrubs. 3.
The analysis of seasonal dynamics for 2019 showed that, in contrast to the steppe community, the communities on the restored coal dumps had high productivity (up to 0.07 kg / m 2 / 8 days) and one peak of the seasonal development in the first ten days of July. The maximum values throughout the season were observed in the more humid eastern and northern parts of the coal dump, and the minimum values were in the southern part.

4.
Regression analysis showed that GPP and the sum of positive temperatures had a high level of relationship (R 2 = 0.7) compared to the steppe site (R 2 = 0.2).