ISSN 1875-3728, Geography and Natural Resources, 2011, Vol. 32, No. 2, pp. 195-203. © Pleiades Publishing, Ltd., 2011. Original Russian Text © I.A. Belozertseva, D. Enkhtaivan, 2011, published in Geography and Natural Resources, 2011, Vol. 32, No. 2, pp. 173-182
GEOGRAPHY ABROAD
Soils in the Northern Hovsgol Region and Their Transformation in the Process of Land Use a
I. A. Belozertsevaa and D. Enkhtaivanb
Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia b Institute of Geography, Mongolian Academy of Sciences, Ulan Bator, Mongolia e-mail:
[email protected] Received October 28, 2010
Abstract—The formation features of soil cover in conditions of the Northern Hovsgol Region are considered. A standardization of pasture loads on the region’s steppe landscapes has been carried out on the basis of the soil transformation indices identified for land use. DOI: 10.1134/S1875372811020168 Keywords: soil cover, physicochemical indices, pasture load, transformation, standardization.
PRESENT STATE OF KNOWLEDGE OF THE TERRITORY AND INVESTIGATIVE TECHNIQUES The uniqueness of nature of Mongolia is reflected in the definition of its territory as the East SiberianCentral Asian system of nontropical Eurasia [1]. Pioneering investigations on the territory of Mongolia were undertaken at the beginning of the 20th century by the noted Russian scientists L.I. Prasolov [2], B.B. Polynov [3], and others. Subsequently, N.D. Bespalov [4], I.P. Gerasimov and E.M. Lavrenko [5] studied the peculiarities of nature throughout the entire territory of the MPR, including soils, and compiled its first-ever soil map at a scale of 1:5 000 000 [4]. At the beginning of the latter half of the 20th century, intense soil-melioration investigations were made in Mongolia in connection with economic development of land resources. During the 1970s, the International Comprehensive Hovsgol Expedition published the results from studying the soil cover in the Hovsgol Region and within the Selenga river basin [6–8]. An impressive contribution to a better understanding of the soil cover in Mongolia was made by N.A. Nogina and D. Dorzhgotov [9–11]. In 1980, in collaboration with other specialists, they prepared and published the 1:2 500 000 soil map of the country [12], and the Atlas of Lake Hovsgol was issued in 1989 [13]; it was created on the basis of many years of research on the territory of Northern Mongolia. To date the least studied soils correspond to the Darkhat depression, waterlogged grasslands and lake-bog complexes as well as to the high-mountain tundra belt of the Hovsgol Region. During 2003–2007 the V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences (IG SB RAS), and the Institute of Geography, Mongolian Academy of Sciences (IG MAS), carried out comprehensive geomorphological, geobotanical
and soil investigations in order to assess the present dynamical state of landscapes on the study territory, and to standardize the anthropogenic loads on geosystems. The results obtained from those studies, aimed at substantiating a rational and sustainable economic utilization of the natural resources in the Hovsgol Region, were presented in Russian and Mongolian scientific publications [14–18]. Expedition field work was done within 15 experimental areas and catenas intersecting spatially conjugated geosystems characteristic for this territory, with due regard for the conditions of intrasoil-ground migration of matter and its accumulation on landscapegeochemical barriers. A total of more than 80 soil sections was established, and about 300 samples were collected from genetic soil horizons. A contemporary classification was used in their identification [19]. The physicochemical properties of soils were determined by conventional methods [20] at the licensed chemicalanalytical center operated by IG SB RAS. The soils were analyzed for total contents of macro- and micronutrient elements by quantitative spectrometric methods with the DFS–8 and atomic-emission Optima 2000DV instruments. Razing livestock were taken into consideration on the basis of statistical bulletins [21] and information made available by the district and sum (county subdivision) administrations as well as using local population poling data. NATURAL CONDITIONS FOR THE DEVELOPMENT OF SOIL-FORMING PROCESSES The soils of the Northern Hovsgol Region are in a frozen state over a long period of time in a year, which constrains the development of biochemical processes in them as well as the differentiation of the soil profile. 195
196
BELOZERTSEVA, ENKHTAIVAN
Station-based observations1 [10, 11] established that a severe overcooling of the upper soil horizons causes drying of mineral substrate and coagulation of colloids, and speed up crystallization of amorphous compounds. The low biological activity of the region’s soils is due not only to the short-lasting summer season but also to the dryness of its first half. Given a relatively small annual amount of atmospheric precipitation (less than 250 mm in the depressions, and 300–500 mm on the mountain slopes), the pedogenesis conditions are altered drastically at the occurrence of the rainfall maximum in the latter half of summer with the highest air temperatures (> 30ºС) [13, 21]. An increase in biological activity of soils in conditions of their sufficient humidification at that period is combined with vertical (downward the profile) matter migration. The region’s chestnut soils with light particle-size composition undergo intermittent wetting from top to bottom. An enhanced development of root systems with their shallow penetration into the layer of soil and earth materials is taking place in complicated habitat conditions for plants. As a result, the soils are characterized by small thicknesses of organogenic horizons, and by an abrupt decrease of the amount of humus downward the profile, which is responsible for their vulnerability and low resistance to erosion and deflation processes, leading to a decline in bioproductivity. The aforementioned characteristic features of the natural conditions, and also the region-wide occurrence of parent materials with high water permeability create the preconditions for the transition of chemical elements from the biological interchange of matter to the geological sphere of migration. Under favorable hydrothermal conditions of the summer-autumn seasons, an intensification of biochemical processes promotes an increase in carbon dioxide concentration in the soil air, which, in turn, improves solubility of calcium carbonates thus rendering them mobile even in steppe soils. Because of this, a special subtype of soils, namely carbonatefree chernozems develop there. In the lower part of the humus soil horizon, the reaction of the medium is shifted toward acidic pH values. Chestnut soils occurring on eluvium of native carbonate-free rocks do not show any appreciable accumulation of calcium. In chernozems and chestnut soils on sandified earth materials, the calcium content is minimal in some cases. In the Northern Hovsgol Region, the parent materials have a light particle-size composition with the inclusion of detritus, gravel and pebbles in which readily-soluble salts and gypsum are leached. This is also true of the desert part of Mongolia where the salt composition of friable accumulated drifts is similar to the one in its northern part [10], although the contemporary climatic conditions of these territories 1
The investigations were made with the participation of researchers from pedological institutions of the Russian Federation and Kazakhstan.
are fundamentally different. Such a phenomenon is due to active migration of matter in earth materials with light particle-size composition, no matter what the temperature regime. On the other hand, the presence of carbonate-enriched calcium in these desalinizated deposits is inherited from the former matter-dynamical development stage of geosystems that formed in different climatic conditions. The calcareous horizon that was revealed in friable accumulated drifts is not homogeneous; sometimes it reaches a considerable thickness and undergoes degradation. The depth of its HCl-caused effervescence in the soil profile depends to a greater extent on the character of the friable drifts than on the contemporary soilforming processes. Hence the effervescence index can not always serve as a diagnostic subtype attribute of the soil, as is customary for steppe soils of other regions. The light particle-size composition and high contents of detritus matter in parent materials, and the low content of fine clay fractions and humus in soils which are unable to ensure the raising of moisture from the lower part of the profile are responsible for the high air and water permeability, and the low water-retaining and absorbing capacity. These physical properties are the main factors of matter migration in the soil-ground layer and important indicators of the conditions of the water regime of migration. DISTINCTIVE FEATURES OF SPATIAL DIFFERENTIATION OF SOIL COVER The formation of a structurally complicated soil cover on the study territory is attributed to the great diversity of its natural-ecological conditions. According to Mongolia’s soil-geographical regionalization [9], the soils of the Northern Hovsgol Region are defined as mountain-taiga soils with the humid type of vertical zonality which, in conditions of extra-continental climate, is characterized by an abrupt transition from taiga geosystems to dry-steppe geosystems. These geographical features are integrally embodied in the soil cover that is represented by a broad gamut of soil types ranging from cryozems to chestnut soils. The main key study areas were established in 2004 and 2007 in the Northern Hovsgol Region (the interfluve and the valleys of the Tanyn-Gol, Goin-Gol, Khankh-Gol, Bayan-Gol, Dzhargalant-Gol, Ikh-KhoroGol, Khongor-Boyan-Gol, Tomkhog-Gol, Shurgag-Gol and Mungarag-Gol rivers, and the southern macroslope of the Greater Sayan Range). The other routes of investigations were located in the Eastern Hovsgol Region, the southern termination of Lake Hovsgol, and in the Darkhat, Mondinskaya and Tunkinskaya depressions in 2003–2007 [14]. The question as to the particular classes into which the soils of Mongolia must be categorized genetically still remains debatable. In the references cited above for the 1970s, the soils of forest landscapes are classified, according to the results obtained by the
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
No. 2
2011
SOILS IN THE NORTHERN HOVSGOL REGION AND THEIR TRANSFORMATION
comprehensive expedition, with podzolic, gray forest unpodzolized [6] and soddy-gray forest soils [7]. The weak pronouncedness or the absence of manifestations of podzolization in the eastern and southern parts of the Hovsgol Region, combined with the widespread occurrence of gray forest soils is typically accounted for by the open canopy, and by the role played by the grass cover in soil formation. An earlier publication [4] rejected the possibility that the soils of the larch taiga of Mongolia can be assigned to the type of gray forest soils. Sazovo-calcareous soils were identified in the middle part of the Selenga river basin [8]. Similar (in physicochemical properties) soils of Northern Mongolia were termed previously the dark-gray forest soils with the chernozem-like profile [3]. In our opinion, they all are different soils. In the mountain-forest landscape of the Hovsgol Region, we identified, according to a new classification [19], cryometamorphic coarse-humus, organo-cryometamorphic and gray-humus soils. No manifestations of podzolization was revealed in these soils. The familiar “depression effect” is clearly pronounced in the Hovsgol Region [11]; it manifests itself as an increase in dryness of the climate in the extensive intermontane depressions when compared with the mountain slopes and adjoining plains. In the central, the lowest, part of the Darkhat depression, this effect is signaled by the chernozems and chestnut soils that formed in this area. As pointed out by D. Dorzhgotov [11], along the intermontane depressions these soils produce a significantly more northern occurrence area of relatively flat territories of Mongolia and are zonal ones. Because of the high hypsometric level (from 1645 to 3491 m) of this territory and due to the depression effect, the latitudinal zonality here is disturbed but there are conspicuous differences in soil-forming processes on slopes with different aspects. On the northern slopes there occur cryometamorphic coarse-humus, organocryometamorphic and gray-humus soils, while chernozems and chestnut soils correspond to the southern slopes. The peculiar feature of the most widespread soils on the study territory are reflected in their properties and matter composition (see table and Fig. 1). In most of the samples of different soil types used in our analysis, the pH value in the upper and lower parts of the profile corresponds to a neutral and weakly alkaline medium, respectively, which is testimony to the calcareousness of the region’s parent materials. On the other hand, the decline in absorbed bases (except for the chestnut soil) downward the slope is due to the lighter particle-size composition of its lower part (the fractions of fine sand and coarse silt make up 60– 80% of the entire soil) from which the mobile form of alkali-earth elements is removed with intrasoil flows. The tundra and mountain-taiga soils on acidic rocks (granitoids, etc.) have a weakly acidic medium (see table). While humus accumulation in the upper soil GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
197
horizon varies over a broad range (from 3 to 18%), its amount at a depth of 0.5 m decreases to 0.5–1%, except in hydromorphic soils where 4–7% of humus is contained at the same depth. In the mineral component of the region’s soils, the concentration of a number of chemical elements is below the percent abundance for the lithosphere and above the percent abundance of acidic rocks (Fig. 2). The oxygen barrier of the upper part of hydromorphic soils and the horizons enriched with clayey matter show an accumulation of iron and of elements from its group. The peaty horizon of alluvial soils is also enriched with barium, lead and manganese. Manganese concentration here is by factors of 2–5 higher when compared with the humus horizon of the other soils. Nickel, copper and lead levels in the peaty layer are twice as large as the MPC (Maximum Permissible Concentration). Biogenous accumulation of calcium is clearly pronounced in the soils. Strontium accumulates on the carbonate barrier. On the whole, the distribution of chemical elements throughout the entire soil profile does not show any alluvial-illuvial differentiation of them, which must be recognized as the characteristic natural-regional property largely attributable to the climate of the Northern Hovsgol Region. Since the early 20th century the forest landscapes of the territory under consideration have experienced time and again fires and cuttings; to date they have been replaced by steppe plant communities. A large number of tracts in the Hovsgol and Darkhat depressions exhibit the ongoing processes of anthropogenic steppization. The steppe landscapes were described in the early 20th century by B.B. Polynov as forest landscapes [3]. Our field investigations into the soils of steppizated tracts in the neighborhoods of the settlements of Khankh, Khukh-Must and Khatgal, in the interfluve of the Tanyn-Gol and Tain-Gol, on the eastern slope of the Bayan-Ula Range, and in the valleys of the KhankhGol and Tokhmog-Gol, revealed post-fire wood remains at a depth of 11–18 cm [22]. A.A. Sirin et al. [23] in their investigations into the boggy landscapes of Mongolia recorded clear trends to desertification evolving over the past several decades. Data of analytical investigations indicate that burnt-over areas show a decline in soil acidity and content of organic matter, and its mineralization results in an increase of the number of mobile forms of phosphorus, and alkaline and alkaline-earth elements. Thus, the concentration of the water-soluble form of Na, K, Ca and Mg increases by a factor of 7–48 in the wake of a fire [24]. At the same time the burnt-over areas with a shallow (20– 30 cm) occurrence of permafrost are experiencing swamping in the region’s northern part, on the territory bordering upon Russia, in the neighborhoods of the southern slope of the Munku-Sardyk Range. With further anthropogenic disturbances to the forests in the Northern Hovsgol Region, the aforementioned changes will encompass increasingly larger territories thereby affecting the evolution of landscapes. No. 2
2011
Fig. 1. Content of chemical elements in soils of the Northern Hovsgol Region for genetic horizons. Soils: Cz – cryozem, CMch – cryometamorphic coarse-humus, Hud – dark-humus, ACh – agrochernozem, Chm – chestnut hydrometamorphized, Alpg – alluvial peaty-gley. (a) macronutrient elements, (b) micronutrient elements.
198
BELOZERTSEVA, ENKHTAIVAN
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
No. 2
2011
199
SOILS IN THE NORTHERN HOVSGOL REGION AND THEIR TRANSFORMATION Physicochemical characteristic of soils in the Northern Hovsgol Region Soil
Са2+
Mg2+
Depth, cm
Water, рН
Humus, %
0–27
6.0
–
56.8
15.3
CR
27–35
6.1
6.1
10.2
2.5
С
35–42
6.2
2.3
6.1
2.6
0–13
6.1
17.8
37.4
4.7
CRM
13–32
7.1
3.1
15.6
2.1
С
32–45
7.8
0.9
7.2
0.9
Organo-cryometamorphic (CМо)
О
0–12
6.1
15.1
31.9
3.7
CRM
12–30
7.1
2.7
13.6
0.8
С
30–60
7.8
0.5
4.8
1.2
Dark-humus (Hud)
AU
0–22
7.4
16.3
26.8
12.0
22–60
8.4
0.7
11.6
5.5
PUd
0–17
6.7
6.7
17.2
6.8
AU
17–26
7.7
2.6
13.6
7.6
ВСА
26–41
8.3
1.8
11.6
3.6
Сса
41–60
8.8
0.4
6.2
2.5
Cryozem (Cz)
Cryometamorphic coarsehumus (CМch)
Horizon О
АО
С Agrochernozem (АCh)
Cryogenic-mycelial chernozen (Chcmc)
AU
Mg eq./100 g of soil
0–10
8.2
10.1
20.3
9.2
А
10–26
8.1
8.1
18.4
5.4
ВСАmc
26–30
8.0
3,5
14.7
5.2
BCAg
30–42
8.6
1.9
14.0
6.4
Cca,g
42–65
8.9
0.9
8.9
3.2
3.2
6.9
4.0
Light-humus (Hult)
AJ
0–24
8.5
Сса
24–52
8.8
0.8
9.0
3.0
Chestnut hydrometamorphized (Chm)
AJ
0–9
7.1
11.2
13.4
3.5
ВМК
9–18
7.1
5.2
18.4
3.5
CATg
18–35
8.6
2.9
19.4
9.3
Cca,g
35–65
8.5
0.9
22.4
11.5
AU
0–30
8.5
12.2
14.4
8.4
Сса
30–90
8.9
0.6
6.4
3.1
Н
0–36
8.2
–
–
–
Q
36–47
8.5
9.1
45.6
18.4
CQ
47–70
8.5
6.9
15.4
6.3
Tmr
0–20
8.3
–
–
–
G
20–34
8.5
–
56.9
13.6
CG
34–46
8.6
4.2
12.2
4.5
Т
0–33
6.9
–
–
–
G
33–45
6.9
–
66.4
15.6
CG
45–60
6.9
5.1
9.2
2.4
Alluvial dark-humus (Ald) Mull-hydrometamorphic (HMm) Alluvial peaty-mineral (Almn) Alluvial peaty-gley (Alpg)
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
No. 2
2011
200
BELOZERTSEVA, ENKHTAIVAN
Fig. 2. State indices of soil medium on the territory of Northern Mongolia under animal husbandry conditions. (а) natural state of landscape; pasture load: (b) weak (< 200 head/km2), (c) moderate (200–400 head/km2); (d) intensive (400–1000 head/km2). Soils: (1) chernozems and chestnut, (2) hydrometamorphized and chestnut hydrometamorphized, (3) alluvial peaty-gley, (4) mull-hydrometamorphic.
TRANSFORMATION DUE TO LAND USE AND STANDARDIZATION OF PASTURE LOADS Natural pastures for sustaining livestock husbandry which, traditionally, constitute the main object of economic utilization in the Hovsgol Region (over 80%), are represented by steppe, meadow-steppe and meadow plant communities on chernozems, chestnut (hydrometamorphized) and alluvial soils. The vast majority of the pastures is a combination of areas disturbed to a different extent. Their irregular utilization for grazing purposes with excessive pasture loads causes changes in the structure and a decline in productivity of the vegetation cover, mechanical destruction of the vegetable layer and compaction of the upper soil horizon, microterracing of slopes, and hummocking of top soil. Under the unfavorable natural-climatic conditions of the Hovsgol region, tillage agriculture has had a negative influence on the soil cover, so that it has not been promoted further. The high-mountain territory not easily accessible and not exploited by humans is classed with arbitrarily undisturbed areas. It is dominated by nival meadows and barren places, mountain tundras, and by fields of screes and taluses. The sparsely populated middlemountain belt is only weakly disturbed by the economic activities. The preservation of its natural environment is favored by elevated humidity and ruggedness of relief. Most of the territory of the Darkhat and Hovsgol
depressions is weakly or moderately disturbed. The natural environment on the bottoms of the depressions is represented largely by steppe and forest-steppe geosystems, including anthropogenically derivative ones. This area is the home to large human settlements, district and sum centers, motor roads, and countrytracks. The study territory has no industrial facilities, so that the economic influence occurs only locally. The transboundary territory of the Hovsgol Region and Southwestern Baikal Region is the home to all main forms of animal husbandry, namely nomadic, seminomadic, semisedentary, and sedentary [25]. On the Mongolian territory, steppe tracts of lands are mainly used as pastures, while meadow-steppe and meadow lands serves as pastures, although in either case the aforementioned geosystems are all being exploited. The nomadic form of animal husbandry, a traditional pursuit on the territory of Mongolia, is not always rewarding ecologically. Given persistent overgrazing, combined with great numbers of livestock staying for long in one place, low-productivity steppe tracts in the Hovsgol Region may well evolve into barren soils. Given the traditional economic management practices, the results from investigating on the model tracts of land suggest that the geosystems are essentially in a relatively stable state. The degree of their disturbance is dependent on the numbers of livestock grazing on pastures (see Figs 2 and 3). In the case of optimal
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
No. 2
2011
SOILS IN THE NORTHERN HOVSGOL REGION AND THEIR TRANSFORMATION
grazing (up to 200 head/km2), the pastures sow a weak degree of disturbance to the soil cover, which manifests itself as a reduction in productivity of the subsurface vegetable mass by a factor of 1.6, and as a compaction of the soil according to standard (1.1 g/cm3 for steppe soils in a natural state). In these circumstances, the measures on regeneration and preservation of the natural state of geosystems would be appropriate. The moderate degree of disturbance to geosystems (with a pasture load of 200–400 head/km2) is characterized by a compaction of the soil to 1.21 g/cm3, and a decrease in the plant root mass by a factor of 4.7. To regenerate such tracts of land requires a decrease of the livestock number or a temporary suspension of grazing. For the case of intensive grazing (400– 1000 head/km2) and, accordingly, a severe degree of disturbance to geosystems, our study revealed a decrease in plant root productivity by a factor of 22, a soil compaction to 1.46 g/cm3, and destruction of the soddy horizon. For regenerating the soil cover, it is advisable to impose a partial ban on the utilization of such lands as pastures, and to carry out environmental protection measures. A number of parameters of the dynamical state of the geosystems under investigation were used to determine the nonlinear character of their response to the pasture load. The geosystem responds to an increase in the load through a transformation of its parameters. The “load vs. effect” dependence has the form of a “stepped” trend with two levels of mean values of the parameters, and with an abrupt change-over from one to the other. The existence of a threshold in the response of the geosystem serves as the manifestation of the phenomenon of its stability and of the operation of effective self-regulation mechanisms in it. Accordingly, the subthreshold values of the loads are estimated as the reserve of “homeostaticity” where a self-regeneration of the geosystem to its original state is still possible. When the pasture load is higher than the maximum permissible level, the retaining factors which tend to lead to a regeneration of disturbed geosystems are not effective. The ultimate load levels were inferred by identifying critical points on the “load vs. effect” curve that was constructed from sensitive parameters varying in a regular fashion with the livestock number (Fig. 4). A critical point is considered to mean the start of the most rapid change in the parameter. The lower critical point on the plot is regarded as the maximum permissible pasture load at which there are taking place changes in the meaningful indices of the soil but they are still reversible. The impermissible pasture load is indicated by the upper critical point where the changes in the soil parameters that have occurred, are no longer reversible. In calculating the critical points of the function approximating the “load vs. effect” dependence, we availed ourselves of the method suggested by E.L. Vorobeichik, O.F. Sadykov and M.G. Farafontov [26]. The productivity of the subsurface GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
201
Fig. 3. Soil degradation in the Northern Hovsgol Region. (1) arbitrarily undisturbed soils; degree of soil degradation: (2) strong, (3) moderate, (4) weak. (5) motor road; (6) state border.
Fig. 4. Change of soil state under the influence of pasture load. Soil density: (1) chernozem, (2) hydrometamorphized chernozem. (3) mass of roots in chernozem.
mass of plants, and the soil density and turfness were found to be the most sensitive parameters in the zone of pasture load. The maximum permissible ecological load implies the lowest of the high loads on the various natural components. The maximum permissible and impermissible pasture loads on soils were determined from different parameters by analyzing the “load vs. effect” curves. No. 2
2011
202
BELOZERTSEVA, ENKHTAIVAN
The maximum permissible pasture load for hydrometamorphized, chestnut hydrometamorphized, alluvial peaty-gley and mull-hydrometamorphized chernozems is 200 head/km2 (see Fig. 2). For chernozems and chestnut soils of steppe landscapes, the impermissible load of 410 head/km2, was established, otherwise the irreversible processes of soil degradation will start to develop. For the other soil types, no critical load has been ascertained yet, as on the study territory the soil cover has not yet reached the ultimate level of degradation, given moderate grazing by livestock. Calculations of the load took into account the data for pastures experiencing long-term (longer than 10 years) utilization with the most widespread (for the Northern Hovsgol Region) livestock herd composition (sheep: 26–31%, goats: 29–34, sarlyks (yaks): 31–37, horses: 6–10, and camels: less than 1%). Hydrometamorphized chernozems, hydrometamorphized chestnut soils, and alluvial dark-humus soils can be assigned to potentially plowable lands in the Hovsgol Region. Most of the arable lands which are few in number on the territory of Mongolia are in the zone of unstable bogharic agriculture. A case in point are the plowing lands in the area of the middle reaches of the Khugein-Gol river. The plowing up of these lands unfailingly triggers the development of degradation processes: loss of humus, the removal of earthly matter, an enhancement in sandification of the arable horizon, a decline in the absorbing capacity, destruction of soil structure, and an increase in the area of the outcropping calcareous horizon due to its deep plowing [24]. All this leads to the loss of fertility of arable lands, transforming them to unproductive soils. Most soils on the territory of Mongolia are in need of irrigation. However, thin layers of soils with light particle-size composition can undergo intense wash work due to irrigation and, hence, experience the removal of nutrient elements, humus and earthly matter. Therefore, a package of agrochemical and agrotechnical measures is requisite for such soils. In the case of excessive watering, loamy soils experience a worsening of the temperature regime, and an enhancement in cryogenic processes, with the salinization process coming into play. The lands suitable for haying on the territory of Mongolia occupy small areas and occur on floodplains and along river valleys, and in intermontane depressions with alluvial mull-hydrometamorphic soils, hydrometamorphized chernozems and hydrometamorphized chestnut soils. More than half of the total reserves of these lands in Mongolia is not in use at present. CONCLUSIONS The natural conditions are of significant importance in the formation of soil cover in the Northern Hovsgol Region: (i) the high overall hypsometric level, combined with complex orography, influencing the circulation of air masses and producing an inhomogeneity of climatic
parameters, even within relatively small territories; (ii) the monsoonic character of atmospheric precipitation redistribution, the severity of winters and the paucity of snow, and deep freezing of soils which, put together, govern the peculiar features of the water regime and matter migration, and the high seasonal contrast of soil-formation processes, and (iii) the development of a vigorous root system with its relatively shallow penetration into the layer of earth materials, which influences the structure of the humus horizon. The study of land use issues showed that the region as a whole is dominated by moderately disturbed pasture lands. The geosystems in an almost unaltered form are situated at rather high elevations and in sparsely populated sums which are distinguished by deferred grazing. Pastures are severely disturbed in the neighborhood of populated localities and nearby temporary stopping places and watering sites. Overgrazing of grasslands by livestock leads to a decline in productivity of the subsurface biomass, soil compactness, and to destruction of the vegetable horizon of soils. The proportion of the severely altered territories in the total area used for pasturing purposes is negligibly small. Pasture lands are able to restore, as before, their original appearance and productivity through continued judicious management of this economic sector, with standard grazing pressure on pasture lands. The landscapes of the Hovsgol Region are experiencing uneven grazing pressures, with their maximum corresponding to steppe tracks. If the pasture load exceeds 410 head/km2, irreversible processes of soil degradation come into play. A load of 200 head/km2 is a maximum permissible value where the geosystem still is capable of restoring its original state. REFERENCES 1. Lavrenko, E.M., On the Vegetation of Steppes and
2.
3.
4. 5. 6.
Deserts of the Mongolian people’s Republic, in Studies of Physical Geography: Collection of Scientific Papers, Ulan Bator: Izd-vo geoekologii MAN, 2006 [in Russian]. Prasolov, L.I., On Frozen Ground in Soils in the Southwestern Part of Zabaikalskaya Oblast and in Mongolia, Trudy Troitsko-Saveno-Kyakhtinskogo obshchestva Priamurskogo otd. GRO, 1912, col. 1, issue 2, pp. 76–84 [in Russian]. Polynov, B.B. and Krasheninnikov, I.M., PhysicalGeographical and Soil-Botanical Investigations Within the Uber-Dzhargalante River and the Upper Reaches of the Ara-Dzhargalante, in Northern Mongolia, Leningrad: Izd-vo AN SSSR, 1926 [in Russian]. Bespalov, N.D., Soils of the Mongolian People’s Republic, Moscow: Izd-vo AN SSSR, 1951 [in Russian]. Gerasimov, I.P. and Lavrenko, E.M., The Main Features of Nature of the MPR, Izv. AN SSSR. Ser. geogr., 1952, no. 1, pp. 27–48 [in Russian]. Martynov, V.P., Ivel’skii, P.K., Batzhargal, B., and Martynova, A.S., Soil Cover Structure in the Mountainous
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
No. 2
2011
SOILS IN THE NORTHERN HOVSGOL REGION AND THEIR TRANSFORMATION
7.
8.
9. 10. 11.
12. 13. 14.
15.
16.
Hovsgol Region, in Natural Conditions and Resources of the Hovsgol Region (PRM): Trudy Sovetsko-Mongol’skoi kompleksnoi Khubsugul’skoi ekspeditsii, Irkutsk; Ulan Bator, 1973, issue 2, pp. 83–87 [in Russian]. Batzhargal, B., Ivel’skii, P.K., Martynov, V.P., and Martynova, A.S., Soils, in Natural Conditions and Resources of the Hovsgol Region (MPR): Trudy Sovetsko-Mongol’skoi kompleksnoi Khubsugul’skoi ekspeditsii, Moscow: Nedra, 1976, issue 4, pp. 96–113 [in Russian]. Lykov, O.S., Martynov, V.P. and Korzun, M.A., Concerning the Formation of Calcareous Horizon in Some Forest Soils in the Middle Part of the Selenga basin, in Natural Conditions and Resources of the Hovsgol Region (MPR): Trudy Sovetsko-Mongol’skoi kompleksnoi Khubsugul’skoi ekspeditsii, Irkutsk; Ulan Bator, 1977, issue 5, pp. 20–25 [in Russian]. Nogina, N.A. and Dorzhgotov, D., Soil-Geographical Regionalization of Mongolia, Pochvovedenie, 1982, no. 4, pp. 23–31 [in Russian]. Nogina, N.A. and Dorzhgotov, D., The Unique Features of the Soil Cover of Mongolia, Trudy In-ta botaniki AN MNR, 1985, no. 7, pp. 160–167 [in Russian]. Dorzhgotov, D., Soils of Mongolia (Genesis, Systematics, Geography, Resources, and Utilization): Author’s Abstract of Dr. Sci. (Biol.) Dissertation, Moscow, 1992 [in Russian]. Soil Map of the Mongolian People’s Republic, Sc 1:2 500 000, Moscow: GUGK, 1980 [in Russian]. Atlas of Lake Hovsgol. Mongolian People’s Republic, ed. by B.A. Bogoyavlenskii, Moscow: GUGK, 1989 [in Russian]. Vyrkin, V.B., Aleshin, A.G., Belozertseva, I.A., et al., Landscapes of the Northern Termination of Lake Hovsgol (Northern Hovsgol Region), Geografiya i prirod. resursy, 2005, no. 2, pp. 128–135 [in Russian]. Vyrkin, V.B., Belozertseva, I.A. and Mironova, E.N., The State of Natural Landscapes and the Character of Their Transformation in the Asian Border Area, in Border and Transboundary Territories of Asian Russia and Neighboring Countries (Problems and Preconditions of Sustainable Development), Pt. 1, Ch. 4, Novosibirsk: Izdvo SO RAN, 2010, issue 23, pp. 60–77 [in Russian]. Belozertseva, I.A. and Nyamkhuu, M., Structure, Morphology and Chemical Composition of Soils of the Darkhat Depression, in Geologi-Gazarzuin salbaryn
GEOGRAPHY AND NATURAL RESOURCES
Vol. 32
17.
18.
19. 20. 21. 22.
23.
24.
25. 26.
No. 2
203
zaluu “Khurel togoot”, Ulan Bator: Izd-vo In-ta geografii MAN, 2006 [in Russian]. Mironova, E.N., Belozertseva, I.A., Vyrkin, V.B., et al., Assessing the Pasture Transformation of Vegetation and Soil Cover in the Northern Hovsgol Region in Mongol orny gazarzuin assudal, Ulan Bator: Izd-vo Mongol Ulsykh Shinzhlekh Ukhaany Akademi Gazarzuin Khureelen, 2007, no. 6, pp. 39–42 [in Mongolian]. Mironova, E.N., Comparative-Geographical Analysis of Vegetation of the Geosystems of the Darkhat, Hovsgol and Tunkinskaya Depressions: Author’s Abstract of Cand. Sci. (Geogr.) Dissertation, Irkutsk, 2008 [in Russian]. Shishov, L.L., Tonkonogov, V.D., Lebedeva, I.I., and Gerasimova, M.I., Classification and Diagnostics of Soils of Russia, Smolensk: Oikumena, 2004 [in Russian]. Agrochemical methods of Investigating Soils, Moscow: Nauka, 1975 [in Russian]. Monthly Bulletin of Statistics. National Statistical Office of Mongolia, Ulaanbaatar, 2006 (June). Belozertseva, I. A. and Enkhtaivan D., Consequences of Fires and Cuttings Down in Prekhubsugul’e, in Natural Resources and Sustainable Development in Surrounding Regions of the Mongolian Plateau. International Conference, Mongolia, Ulaanbaatar: Mongolian Academy of Sciences Institute of Geography, 2008, pp. 23–25. Sirin, A.A., Minayeva, T.Yu., Gunin, P.D., et al., Between Humid and Arid Environment: Peatland Ecosystems Indicate Desertification Trends in Mongolia, in Ecological Consequences of Biosphere Processes in the Ecotone Zone of Southern Siberian and Central Asia, Ulaanbaatar: Bembi san Publishing House, 2010. Belozertseva, I.A., Structural-Dynamical Features of Soil Cover of Mountain-Depression Landscapes in the Northern Hovsgol Region, in Monitoring and Forecasting of the Matter-Dynamical State of Geosystems of Siberian Regions, Novosibirsk: Nauka, 2010 [in Russian]. Vainshtein, S.I., Historical Ethnography of the Tuvinians, Moscow: Nauka, 1972 [in Russian]. Vorobeichik, E.L., Sadykov, O.F. and Farafontov, M.G., Calculating the Limiting Values of Load, in Ecological Standardization of Technogenic Pollutions of Terrestrial Ecosystems (Local Level), Yekaterinburg: UIF “Nauka”, 1994 [in Russian].
2011
