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Journal of Resources and Ecology >

2019 , Vol. 10 >Issue 6: 598 - 604

DOI: https://doi.org/10.5814/j.issn.1674-764X.2019.06.004

Ecological Carrying Capacity

Ecological Carrying Capacity of Grasslands and Animal Husbandry Sustainability in Central Asia

  • ZOU Xiuping 1 ,
  • SONG Dunjiang 1 ,
  • CHEN Shaofeng , 1, 2, *
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  • 1. Institutes of Science and Development, Chinese Academy of Sciences, Beijing 100190, China
  • 2. School of Public Policy and Management, University of Chinese Academy of Sciences, Beijing 100049, China
CHEN Shaofeng, E-mail:

Received date: 2019-08-23

  Accepted date: 2019-09-23

  Online published: 2019-12-09

Supported by

The Second Comprehensive Scientific Investigation of Tibet Plateau—Regional Function Types and Zoning Plans(2019QZKK0406)

The Research on Resource Bottleneck and Security Guarantees for One-hundred strategic Targets(Y9X0722601)

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Abstract

Grassland ecosystems are one of the most important terrestrial ecosystems on the earth. Central Asia has the largest contiguous grazing area in the world and good conditions for the development of animal husbandry. However, in the past 30 years, the grassland ecosystem in Central Asia has experienced significant degradation, and the livestock industry has also experienced an overall decline to the point that livestock products are now dependent on imports. The ecological footprint method was used to analyze the change trend and characteristics of grassland ecological carrying capacity and ecological occupation in Central Asia. The grassland ecological capacity in Central Asia was found to be much higher than the global level, and great potential still remains for further development and utilization. The international trade of livestock products in Central Asian countries showed a deficit, and the net import of livestock products increased year by year. Net imports reached 9.5% in 1992-2016, and the dependence on foreign countries increased significantly, which is not conducive to the sustainable development of animal husbandry in Central Asia. In the future, the counties of Central Asia should optimize the aspects of policy, management and technology to improve the productivity of grassland animal husbandry, strengthen grassland ecological protection, and realize the coordinated and sustainable development of their grassland ecological economic systems.

Key words： Central Asia; grassland resources; ecological footprint; animal husbandry

Cite this article

ZOU Xiuping , SONG Dunjiang , CHEN Shaofeng . Ecological Carrying Capacity of Grasslands and Animal Husbandry Sustainability in Central Asia[J]. Journal of Resources and Ecology, 2019 , 10(6) : 598 -604 . DOI: 10.5814/j.issn.1674-764X.2019.06.004

1 Introduction

Grasslands serve important economic and ecological functions, such as material production, climate regulation, soil and water conservation, sand stabilization, soil improvement, biodiversity preservation, and livestock and poultry farming (Huang et al., 2017; Eichelmann et al., 2016). The total area of grassland on the earth is about 2.4×109 ha, which is one-sixth of the total land area. Grassland ecosystems can convert atmospheric carbon dioxide into stable carbon sequestered into plants and soils, helping to mitigate the effects of climate change. Grassland ecosystem carbon storage accounts for more than 33% of global terrestrial carbon storage and plays an important role in the global carbon cycle. Grassland is also an important grazing animal husbandry base for human societies. The productivity of natural grassland ecosystems accounts for more than 20% of the total productivity of terrestrial ecosystems.
Central Asia has the largest contiguous grazing area in the world and the grassland area is about 2.6×108 ha, which occupies 65% of the total land area of Central Asia (Gintzburger, 2004; Winckler et al., 2012; Mirzabaev et al., 2016). With abundant sunshine and heat in Central Asia, grassland grows well, and this region has good conditions for developing animal husbandry production (Chen et al., 2019). Therefore, animal husbandry has traditionally been the leading industry in Central Asian countries. However, in the last three decades, the grassland ecosystem in Central Asia has experienced significant degradation (Chen et al., 2019), such as the reduction of biodiversity, the decline of soil fertility, the reduction of high-quality pasture, and the decline in grass yield. Rangeland degradation is mainly driven by overgrazing, cutting of shrubs, abandonment, and lack of maintenance of the rangeland infrastructure (Mirzabaev et al., 2016). Moreover, effective pasture management mechanisms are often absent, pasture leasing is not clearly regulated in most countries in the region, and institutional mechanisms to sustainably manage rangelands are weak (CACILM, 2006a, 2006b, 2006c, 2006d, 2006e). In the past two decades, the livestock industry in Central Asia has also experienced an overall recession trend. The domestic supply of livestock products is seriously insufficient and now relies heavily on imports. Due to the lack of scientific support, capital investment and the flawed management system, the livestock industry in these countries has been at a low level for a long time. Therefore, exploring the policy measures for the development, protection and sustainable management of grassland resources in Central Asian countries has important theoretical and practical significance for realizing the sustainable development of animal husbandry.
Previous research reported that grasslands in Central Asia were undergoing degradation and desertification (Zhang et al., 2018). Numerous quantitative assessment methods have been employed to assess the relative roles of climate change and human activities on grassland ecosystems (Yang et al., 2016), while research is lacking on the relationship between the international trade of livestock products in Central Asian countries and the protection and development of grassland resources.
Therefore, this paper aims to: 1) explore the spatial and temporal variations in the grazing land ecological footprint and ecological capacity in Central Asia from 1992 to 2014; 2) analyze the impact of international trade in livestock products on the ecological capacity of grazing land in Central Asia; 3) assess the relationships between international trade and grassland carrying capacity and ecosystem services; and 4) explore policy measures for the development, conservation and sustainable management of grassland resources in Central Asian countries.

2 Methods and data

2.1 Study area

Central Asia includes five countries, Kazakhstan, Uzbekistan, Turkmenistan, Kyrgyzstan and Tajikistan. The total area is about 3.9×106 km2, and the total population in 2017 was about 71 million. Central Asia is deeply rooted in the hinterland of the Eurasian continent. The southeastern mountain blocks the water vapor from the Indian Ocean and the Pacific Ocean. It is a typical temperate continental arid climate zone. Central Asia has diverse landscapes, of which nearly half show a natural landscape of desert and semi-desert, with high vegetation coverage in the north and southeast, waters distributed in the middle, and agricultural and residential areas concentrated on both sides of the rivers. The grassland area in Central Asia accounts for more than 65% of the total land area. Large-scale grassland resources have laid a solid foundation for the development of animal husbandry in Central Asia.
Since the 1990s, the socio-economic development in Central Asia has experienced a period of stagnation and decline (1991-1995), a recovery phase (1996-2000), and a steady growth phase (after 2001). In recent years, the economies of Central Asian countries have continued to grow. During 2008-2015, the economic growth rates of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan reached 7.0%, 5.6%, 7.9%, 17% and 12%, respectively, which were much higher than the world’s average 2.6% growth level.

2.2 Methods

Ecological Footprint (EF) was first proposed by William Rees. From the perspective of a biophysical quantity, this method converts various resources and energy consumption into land area to judge whether the ecosystem is in a loadable state (Siche et al., 2010).
Grazing ecological footprint includes the demand for grazing land to feed livestock and the embodied demand for grazing land in traded goods, which can be calculated as (Lin et al., 2018):
EFc = EFP + (EFI - EFE)
where EFc represents the footprint of consumption associated with grazing land, EFP represents the footprint of production associated with grazing, EFI represents the footprint of imports associated with grazing, EFE represents the footprint of exports associated with grazing.
Ecological capacity is a concept that is based on the ecological footprint. Grazing ecological capacity refers to the amount of biologically productive land, which can be calculated as (Lin et al., 2018):
BC = A × YF × IYF ×EOF
where BC represents the biocapacity of grazing land, A represents the area of grazing land within a country, YF represents the yield factor of grazing land within a country, IYF represents the Intertemporal yield factor of grazing land for that year, and EOF represents the equivalence factor for grazing land.
NS is the occupation rate of ecological footprint for ecological carrying capacity, which can be calculated as:
NS= EFc / BC
when the ecological carrying capacity is greater than the ecological footprint, namely, NS<1, there is an ecological reserve, indicating that the resource usage is in a sustainable development state. In contrast, when NS>1 it is in an ecological deficit state, which indicates that the demand for resources exceeds the ecological carrying capacity of the region, and the development of the region is unsustainable.
NSD is the occupation rate of domestic production footprint for ecological capacity, which can be calculated as:
NSD = EFP / BC
If the international trade of animal products is not considered, then the consumption of livestock products depends only on domestic production, and the ecological footprint in this case accounts for the proportion of ecological capacity. The use of NSD found that the grassland ecological capacity occupancy rate in Central Asia is very low, which means that the grassland resource development utilization rate in Central Asia is low and the technical level is also low.

2.3 Data sources

National biocapacity and Ecological Footprint data come from the Global Footprint Network (https://www.footprintnetwork.org/).
Import and export data for livestock products and live animals come from FAO Trade STAT Statistical Databases (http://www.fao.org/faostat/en/#home). The scope of animal products in this study is defined by the HS classification system, and the scope of livestock products is divided into four categories: 1) meat and products; 2) animal fats; 3) animal furs; and 4) other animal products. All the grazers were converted into sheep units according to the standard of animal unit equivalence provided by the Ministry of Agriculture of the People’s Republic of China: one goat equals 0.9 sheep, one horse equals 6 sheep, one camel equals 8 sheep, and one bovine equals 6 sheep, and one buffalo equals 6.5 sheep.

3 Results

3.1 Grassland ecological carrying capacity and consumption footprint in Central Asia

The grassland consumption footprint in Central Asia in 2014 was 26% of its ecological capacity (Fig. 1), far below the world average of 69.2%, indicating that the ecological capacity of grassland ecosystems in Central Asia has great potential. As the consumption level of residents in Central Asian countries continues to increase, the resulting grassland ecological footprint is also growing. In 1992-2014, the grassland ecological capacity in Central Asia increased by 19%, and the grassland consumption footprint increased by 88%, but the differences between various Central Asian countries were very obvious.
3.1.1 Per capita grassland ecological capacity is higher than the global average
In the five countries of Central Asia, the per capita ecological capacity of grassland and the per capita grassland consumption footprint are higher than the world averages. In 2014, the per capita grassland ecological carrying capacity in Central Asia was 0.77 gha, 3.7 times the world average (0.21 gha per person), and the per capita ecological footprint was 0.21 global hectares, 1.5 times the world average (0.14 gha). However, the five countries in Central Asia differ greatly. The per capita ecological carrying capacity and per capita consumption of Turkmenistan are the highest in Central Asia, with 1.93 gha per person and 0.58 gha per person, respectively, while the per capita ecological carrying capacity and per capita consumption of Tajikistan are the lowest in Central Asia, with 0.13 gha per person and 0.14 gha per person, respectively. Tajikistan the only grassland ecological deficit country among the five Central Asian countries (Fig. 2).
3.1.2 The growth rate of the animal product ecological footprint is much higher
From 1992 to 2014, the global grassland bio-productive areadecreased by 2.3%, and the grassland consumption footprint decreased by 0.03%. The grassland bio-productive area (ecological carrying capacity) in Central Asia increased by 19%, but the total grassland consumption footprint in the
Fig. 1 Grassland ecological capacity and livestock product ecological footprint in Central Asia (million GHA) during1992-2014
Fig. 2 Per capita grassland ecological capacity and per capita grassland ecological footprint in Central Asian countries in 2014
region increased by 88%, far exceeding the growth rate of its ecological capacity. For the ecological footprint of grassland consumption in the five countries in Central Asia, the growth rate is much higher than the growth rate of grassland ecological capacity, the most prominent of which are Turkmenistan and Kyrgyzstan, which have the fastest growth in grassland consumption footprints (Fig. 3), while the grassland ecological capacity of these two countries show negative growth.
3.1.3 The differences in the occupational capacity of gras land ecological capacity between Central Asian countries are large
Among the five Central Asian countries, Kazakhstan has the largest ecological capacity surplus and the great potential for grassland resource development. The grassland consumption footprints of Kyrgyzstan and Turkmenistan are about half of the world average. Tajikistan is overloaded and Uzbekistan is on the verge of overload (Fig. 4). In the future, as the consumption levels of residents in Central Asian countries continue to increase, the grassland ecological footprints will continue to expand, and the sustainability of the grassland economic systems will decline.

3.2 Characteristics of international trade flows of livestock products in Central Asian countries

In the vast grasslands of Central Asia, sufficient sunshine provides a good foundation for the development of animal husbandry. The livestock products are mainly beef and mutton, skin, wool and milk products. In recent years, animal husbandry has had many problems such as reduced stocks, low yields, and outdated technology. The high prices of livestock products in the domestic market have led to these countries becoming net importers of meat and meat products.
Fig. 3 Changes in grassland carrying capacity and consumption footprint of the five countries in Central Asia from 1998 to 2014
Fig. 4 Percentage of grassland ecological footprint in biocapacity originating from grassland in Central Asian countries in 2014
3.2.1 The international trade of livestock products in Central Asia is mainly characterized by net imports.
The international trade in livestock products in Central Asia is characterized by net imports. For example, in 2014, the export volume of livestock products in Central Asia was 115,000 tons, and the import volume was 741,000 tons. From 1992 to 2014, the import of livestock products increased by 341%, while the export volume only increased by 267%, so the growth of imports was 1.27 times the growth of exports, but the difference between countries was great. Net imports increased year by year, with an average annual growth rate of 9.5% (Fig. 5).
Fig. 5 International trade volume of livestock products in Central Asia from 1992 to 2014 (million tonnes)
3.2.2 Characteristics of import and export trade of livestock products in Central Asian countries
Kazakhstan, Kyrgyzstan and Turkmenistan are the countries with the largest exports of livestock products in Central Asia. In 2014, exports from these three countries accounted for 47%, 42% and 7.3% of the total exports of livestock products in Central Asia (Fig. 6). Kazakhstan has changed from a meat exporting country to a meat importing country, and it imports not only meat and dairy products from abroad, but also cattle. In 2012, imports of fresh meat, frozen meat, chilled meat and edible chopped meat totaled 235,400 tons, while the export of meat did not exceed 2,000 tons. Kyrgyzstan's share of livestock exports is much larger than its imports. From 1992 to 2007, Kyrgyzstan maintained a net export of livestock products, but since 2008 it has also changed to a net importing country.
Fig. 6 The import and export trade of livestock products in Central Asian countries accounts for the proportions shown above of the import and export trade in the whole of Central Asia (2014)

3.3 Protection and utilization of grassland resources and sustainable development of animal husbandry

3.3.1 Protection and utilization of grassland resources in Central Asia
From the changes in livestock stocks in Central Asian countries (Fig. 7), Uzbekistan, Turkmenistan, and Tajikistan have maintained steady growth in livestock stocks for nearly 20 years, even in the midst of economic depression and recession. After gaining independence, Uzbekistan carried out a series of changes to the traditional animal husbandry practices, using artificial breeding, bar breeding and other methods to improve the intensity level of animal husbandry. Uzbekistan has an annual output of about 1.5 million high- quality Karakul lambs, ranking second in the world. Animal husbandry plays an important role in the economy of Turkmenistan, with sheep farming as the mainstay. Karakul lamb skin has a very good reputation in the international market. Animal husbandry is one of the more important industries in the Tajikistan’s agricultural sector, including cattle farming, sheep farming, pig farming, poultry farming, rabbit farming, beekeeping and fish farming. The livestock stocks in the two countries of Kazakhstan and Kyrgyzstan decreased significantly in the late 1990s, and while they began to increase gradually after 2000, they have not yet reached the levels of the 1990s. Kazakhstan has a vast range of pastures and innate natural conditions for the development of animal husbandry.
Fig. 7 Livestock stocks in Central Asian countries in 1992, 1999, 2014
During the period of the Soviet Union, large areas of grassland in northern Kazakhstan were converted to farmland, but these croplands were largely abandoned owing to the decrease in the population after the collapse of the Soviet Union. In addition, grazing activities and livestock numbers have had significant impacts on the grasslands in this region since 1990. Kyrgyzstan's pastures are mostly natural pastures which have good natural conditions for the development of animal husbandry, and Kyrgyzstan was once a major exporter of meat, milk and dairy products in Central Asia.
In the past two decades, the quantity and quality of grassland in Central Asia have been declining, its carrying capacity has been greatly reduced, and the conflict between grass and livestock has intensified, due to long-term re-use and over-grazing. Unreasonable use of grassland resources has seriously damaged the productivity of grassland in Central Asia, and the economic growth of grassland animal husbandry has also been affected. Most of the grassland in Central Asia is in arid areas with harsh natural conditions. The grassland animal husbandry mainly relies on the method of raising livestock by day, the sustainable management of grassland ecosystems is poorly executed, and the ability to protect animal husbandry against disasters is weak.
3.3.2 Sustainable development of animal husbandry in Central Asia
The natural and geographical conditions in Central Asia are very suitable for the development of animal husbandry, and the pastoral farming industry is a traditional pillar industry. It has accumulated a lot of experience in livestock breeding and improvement, and has cultivated many improved livestock breeds. The development of animal husbandry has made great contributions to the economic development of Central Asia. Since the disintegration of the former Soviet Union, the economies of Central Asian countries have been hit hard. The fiscal revenues of these countries have been very low, and the proportion of financial expenditures on agriculture has been decreasing. This decline has led to the massive loss of agricultural and animal husbandry researchers in various countries, which has seriously hindered the development of animal husbandry in the various countries. Since 2000, with the continuous improvement of the consumption level of Central Asian residents, the demand for animal products such as meat and milk has been increasing, which has brought new development opportunities for the revitalization of the grassland animal husbandry economy in Central Asia. The implementation of intensive housing or factory-based raising of livestock is the key to making animal husbandry internationally competitive. Initiatives along three lines with further improve the situation.
(1) Improving the grassland management policy system, increasing investment, improving management technology, and strengthening the supervision and management functions of the government's pastoral ecological environment protection are the fundamental guarantees for promoting the sustainable development of grassland animal husbandry. In addition, so will strengthening the management of natural grassland and the construction of artificial forage materials. Through the rehabilitation of post-grazing lands, fertilization, artificial grassland improvement, grazing and grassland and fence enclosures, and the implementation of agricultural subsidies and other protection policies, the ecological function of degraded grassland will be gradually restored, allowing these countries to fully tap into the production potential of their grasslands and putting grassland animal husbandry on a sustainable development track.
(2) Take the road of grass-fixing animals, achieve a balance between livestock and grass, and increase grass and animals. Grazing is also an important means of improving grassland. Appropriate grazing can not only reduce grassland but also promote grassland productivity. Especially by using the best methods for grazing grassland resources in the desert steppe in Central Asia, proper grazing will be more conducive to the growth of pastures. In addition, the introduction and cultivation of excellent livestock is also the key to improving the international competitiveness of Central Asia’s animal husbandry.
(3) Increase investment in grassland animal husbandry. The economic level of grassland animal husbandry in Central Asia is relatively low and dependence on infrastructure is high, so if infrastructure is improved, the development of animal husbandry will be promoted. At the same time, the scale of funds will be expanded to promote industrial upgrading and transformation, from an extensive to an intensive mode.

4 Discussion

4.1 Grassland ecological degradation and moderate grazing

In the past 20 years, important changes have taken place in the livestock industry in Central Asia. Grassland ecosystems in Central Asia are sensitive to global climate change and human activities due to their relatively sparse vegetation and poor soil. Under the impact of modern agriculture and industrial activities, the structure and function of grassland ecosystems have undergone major changes. Central Asia is rich in land resources and has great potential for animal husbandry development. After establishing the independence of the countries, due to economic difficulties and lack of funds, most of the natural pastures were gradually abandoned, resulting in a rapid decline in the productivity of the livestock industry in Central Asia. As governments increase their support for animal husbandry, these natural pastures provide new space for animal husbandry. A reasonable grassland grazing system in arid areas can effectively prevent the degradation of grassland ecosystems in Central Asia and promote the sustainable development of grassland ecosystems (Han et al., 2016).

4.2 International trade of livestock products and grassland ecological degradation

In the past 20 years, the overall competitiveness of livestock products exports in Central Asia has been gradually declining, the supply of domestic livestock products is insufficient, and the expansion of supply capacity in the international market has caused the trade deficit of livestock products in Central Asia to continue to rise. The advantages and potential of grassland resources in Central Asia have not been well developed. The trade deficit represents a disadvantage in the development of animal husbandry in the world market. The increase in regional external dependence has affected the economic independence of the region, and is not conducive to the sustainable development of Central Asia. It is necessary to alleviate the pressure caused by rapid growth in the trade deficit of livestock products and maximize the advantages of the grasslands. As a renewable natural resource, grassland can be used for scientific management and rational use under appropriate natural conditions or artificial environments, allowing Central Asia to tap the huge potential of its grasslands. To make the grassland livestock production grow steadily, the key is to change the antiquated grazing production mode, restore the grassland ecological balance, and improve the utilization efficiency of grassland resources.

5 Conclusions

Central Asia is an important place for the production and export of traditional grassland animal husbandry. However, in the past 30 years, due to climate change, increased intensity of human activities, and political and economic turmoil after the collapse of the Soviet Union, grassland ecological degradation has been evident, and it has impacted animal husbandry production capacity and its technical level. With the increase in population and the increase in consumption levels, net imports of livestock products have increased and external dependence has increased. This study finds that from the perspective of grassland ecological capacity utilization, there is still a certain surplus of grassland ecological capacity in the region, and the potential for further development and utilization of grassland resources is still great. In the future, if policies, management, technology and other factors can be optimized, it is possible to improve the productivity of grassland animal husbandry, strengthen grassland ecological protection, and improve the coordination and sustainability of the grassland ecological economic system. It is conceivable that the Belt and Road Initiative provides a good external environment and historical opportunity for Central Asian countries to improve the sustainability of their grassland ecological economies.

References

Publishing order | Descend order by publishing year | Descend order by cited within
1
CACILM (Central Asian Countries Initiative for Land Management). 2006a. UNCCD National Working Group of the Republic of Kazakhstan. In: Republic of Kazakhstan National Programming Framework.

2
CACILM (Central Asian Countries Initiative for Land Management). 2006b. UNCCD National Working Group of the Republic of Kyrgyzstan. In: Republic of Kyrgyzstan National Programming Framework.

3
CACILM (Central Asian Countries Initiative for Land Management). 2006c. UNCCD National Working Group of the Republic of Tajikistan. In: Republic of Tajikistan National Programming Framework.

4
CACILM (Central Asian Countries Initiative for Land Management). 2006d. UNCCD National Working Group of the Republic of Turkmenistan. In: Republic of Turkmenistan National Programming Framework.

5
CACILM (Central Asian Countries Initiative for Land Management). 2006e. UNCCD National Working Group of the Republic of Uzbekistan. In: Republic of Uzbekistan National Programming Framework.

6
Chen T, Bao A, Jiapaer G , et al. 2019. Disentangling the relative impacts of climate change and human activities on arid and semiarid grasslands in Central Asia during 1982-2015. Science of the Total Environment, 653:1311-1325.

DOI PMID

7
Eichelmann E, Wagner-Riddle C, Warland J , et al. 2016. Evapotranspiration, water use efficiency, and energy partitioning of a mature switch-grass stand. Agricultural and Forest Meteorology, 217:108-119.

8
Gintzburger G. 2004. Agriculture and rangelands in Middle Asian Countries. In: Ryan J, Vlek P, Paroda R. Agriculture in Central Asia: Research for Development. Syria: International Center for Agricultural Research in the Dry Areas (ICARDA):154-175.

9
Han Q, Luo G, Li C , et al. 2016. Simulated grazing effects on carbon emission in Central Asia. Agricultural and Forest Meteorology, 216:203-214

DOI

10
Huang X, Luo G, Lv N . 2017. Temporal patterns of grassland evapotranspiration and water use efficiency in arid areas. Ecological Research, 32(4):523-535.

DOI PMID

11
Lin D, Hanscom L, Martindill J , et al. 2018. Working Guidebook to the National Footprint Accounts. Oakland: Global Footprint Network.

12
Mirzabaev A., Ahmed M., Werner J., Pender J., & Louhaichi M . 2016. Rangelands of Central Asia: challenges and opportunities. Journal of Arid Land, 8(1), 93-108.

DOI

13
Siche R, Pereira L, Agostinho F , et al. 2010. Convergence of ecological footprint and emergy analysis as a sustainability indicator of countries: Peru as case study. Communications in Nonlinear Science and Numerical Simulation, 15(10) : 3182-3192.

DOI

14
Winckler G, Kleinn E, Breckle S W. 2012. The Aralkum situation under climate change related to its broader regional context. In: Breckle S W, Wucherer W, Dimeyeva L A, et al. Aralkum a Man-Made Desert: The Desiccated Floor of the Aral Sea (Central Asia), Ecological Studies. Berlin Heidelberg: Springer-Verlag:431-456.

15
Yang Y, Wang Z, Li J , et al. 2016. Comparative assessment of grassland degradation dynamics in response to climate variation and human activities in China, Mongolia, Pakistan and Uzbekistan from 2000 to 2013. Journal of Arid Environments, 135:164-172.

DOI

16
Zhang G, Biradar C M, Xiao X , et al. 2018. Exacerbated grassland degradation and desertification in Central Asia during 2000-2014. Ecological Applications, 28(2), 442-456.

DOI PMID

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