Study areas and Methods

The objects of study served as agricultural land of Tuva. Steppes occupy taking intermontane basins with elevations 550-1200 m above sea level, the lower part of the mountains slopes and high terraces of the river valleys. Large tracts of the steppes, which are farmland, typical of the Ulug-Chemskoy and Ubsunur basins. Our own government studies on desertification land of Tuva was conducted on land improvements moistened the Turan-Uyuk (5 key plots) and Todja depressions, dry Central Tuvinian hollow, and in the most arid - Ubsunur hollow in 1996-2014. Field studies were conducted mainly the rout method. Analyzed materials on desertification Tuvinian research Institute of agriculture, State reports "On the state of environment of the Republic of Tuva" [1].

For the study of vegetation using conventional techniques. Geobotanical descriptions of ecosystems conducted at each site on five sites of 100 m². To determine the biomass at each site were laid randomly 8 pilot sites. At all sites above-ground phytomass were cut at soil level and the soil was collected litter. Rags were collected separately from green phytomass and the last element analyzed by species [2].

According to the "Subregional national action program to combat desertification for the South of Middle Siberia of the Russian Federation" [3] as key indicators of desertification of lands taken the degree of deflorimonte, erosion (water erosion), salinization and degradation of pastures, which lead to natural and anthropogenic disturbance of ecosystems. So, it was revealed that four of the degree of land desertification: 1 - background, 2 - weak, 3 - average, 4 - strong.

Results

The main natural factor contributing to the development of desertification processes in Tuva, is a landlocked position, which determines the continentality and the situation in the Central Asia, the uneven distribution of water resources. Conditions for development of land degradation processes are created and in violation of the seasonal peculiarities of the formation of soils when exposed to drought. Prerequisite desertification is also a weak soil formation and land cover and its dynamics. These natural features of Tuva condition the weak sustainability of the natural environment to human impacts.

Anthropogenic factors leading to the emergence and development processes pustynia deposits in Tuva, related, mainly, with such activities as grazing, agriculture, mining, construction and exploitation of industrial, military and civil facilities, irrigation and linear structures. Desertification is also a result of illegal logging, shrubs and dwarf shrubs, forest and steppe fires, haphazard recreation, organization dumps around human settlements, pollution of soils and groundwater with toxic substances, the effects of transport.

When assessing the transformation of agricultural lands of the Republic we compared the status of land from 1965 to 2014. Particularly strong suffer whether from the degradation of farmland steppe intermountain basins. The most elevated of the North-Eastern part of the territory of Tuva is included in subforest zone, so erosion processes themselves are affected slightly. The total degradation indices (ID) of farmland for 2014 in the administrative districts of the Republic are displayed in table 1. With use of the calculated index shows the spread of desertification varying degrees. Overall a strong degree of degradation of farmland tends to be southern and Central areas of the Republic of the aridity index of 0.16 to 0.40 (Table 1, 2).

Table 1. The mean and summary indexes of the degradation (ID) of the general kinds agricultural lands, t.h to 2014

Table 2. Area of dedeserted agricultural lands of Tuva, t. h to 2014

As a result of plowing of light granulometric composition 90 % of arable lands subjected to degradation, and more deflation. Average transformation land in Tuva is 90.5 % when in Khakassia it is 75,4, in the southern districts of the Krasnoyarsk territory - 4,2 [3].

Eroded and saline soils are relatively few. So, the area of saline farmland in 1995 was 178.5 thousand hectares, including arable land - 15.7 thousand hectares; eroded farmland - 17.0 thousand ha, including arable land - 11.1 thousand ha. A clear distribution of the breadth and extent of desertification of certain areas-holders, due to natural (climatic zonation, geomorphology, etc.) and an anthropogenic (economic activity) factors. Thus, the index of erosion degradation of natural increases from arid to sub-humid bioclimatic zone, and the index of deflation and salinity, on the contrary [4].

From all forms of land degradation in Tuva most developed deflation, which affected of the territory 30% agricultural lands, of them deflated to 50-75% of farmland in the southern and Central parts of the Republic. Average degree of deflorimonte lands it has been commented in eight districts. The rest of the territory of the Republic of the index deflorimonte all farmland does not exceed 8.5% (0.99-8.5).

Conclusions

The overall effect of anthropogenic pressure on steppe ecosystems of Tuva are a violation of the existing energy turnover, reduced productivity of converted ecosystems, increasing the degree of nakedness of the earth's surface and, as a consequence, General manifestations of desertification of the territory.

2. Titlyanova A.A. The biological succession of carbon in the grassland ecosystems. Novosi-birsk: Science. Sib. Branch. - 1977. - 219 p.

3. Subnational action programmers to combat desertification to the South of Central Siberia in the Russian Federation. Abakan. - 2000. - 294 p.

4. Sambuu A.D., A. B. Dapyldie, A. N. Kuular, N. G. Khomushku. Problems of Desertifica-tion in the Tuva Republic. Arid Ecosystems. - 2012, Vol. 2, No. 4. - P. 225-231.