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This book presents state-of-the-art scientific evidence and technological innovations to restore lands on the Loess Plateau of China, known worldwide for its serious land degradation and desertification problems. Supported by a rapidly developing Chinese economy and the dissemination of effective technology, the Grain-for-Green Project and Western Development Action launched by the Chinese government have resulted in successful ecological restoration and protection over the past 30 years. These programs have contributed not only to conservation of soil and water, but also to economic development. At the same time, however, these developmental interventions have brought new challenges that have not yet been fully addressed. The book describes (1) case studies of success and failure in practice, including rare success stories of combating desertification; (2) technical issues such as erosion control and breeding of stress-tolerant plant species, and socioeconomic measures taken by the Chinese government and lending policies with support from the World Bank; and (3) comprehensive measures against desertification, such as water and wind erosion, salinization, and deforestation. This volume is recommended for researchers and students above the undergraduate level in diverse fields including soil science, rural engineering, social technology and civil engineering, biology, ecology, climatology, physical and human geography, and developmental economics, among others. It also serves as a valuable resource for engineers, government officials, and NPOs and NGOs involved in afforestation, ecological restoration, combating desertification, disaster prevention, and sustainable rural development.



Nature of the Loess Plateau


Chapter 1. Location, Geology and Landforms of the Loess Plateau

The Loess Plateau is a highland region in north-central China with average elevation about 1,200 m. It has the thickest known loess deposits in the world. Although there are several definitions in the literature for the plateau boundary and area, two definitions are the most commonly reported. The first of these defines the plateau from the standpoint of physical geography. As a large geographical unit, “Loess Plateau” is defined as the highland area with thick loess deposit, covering about 380,000 km2. Another commonly accepted definition, is that of the “Loess Plateau region”, which refers to a larger loess-distribution area with loess landscape and related environmental characteristics, covering about 640,000 km2. Formation of the plateau began about 2.6 million years ago. Information about past global climate change has been derived from samples taken from deep layers of loess deposit. Since loess is highly subject to erosion, a unique morphology has developed in the region. Typical landforms are loess Yuan, Liang, and Mao and various valleys of different erosion magnitudes. Loess hills and gullies are very common and are symbolic landscapes of the plateau region.
Mei-Jie Yan, Qiu-Yue He, Norikazu Yamanaka, Sheng Du

Chapter 2. Climate of the Loess Plateau

The Loess Plateau in China covers an area of ca. 640,000 km2, extending between 34° N and 40° N/100° E and 115° E, which is the middle region of China’s Yellow River. The climate of Loess Plateau is strongly influenced by latitude, longitude, and topography. It has a typical continental monsoon climate. Winters are cold and dry, and most rainfall occurs during the summer (June to September). Annual precipitation is approximately 400 mm (minimum 150 mm, maximum 750 mm). Under China’s physical geography classification, the Loess Plateau is classified as the Loess Plateau sub-region in the North China region. The most significant aspect of its climatological characteristics is the distinct seasonality of temperature and precipitation distribution. According to the aridity index (the value obtained when dividing annual precipitation by potential evapotranspiration) (Millennium Ecosystem Assessment (2005) Ecosystems and human well-being: desertification synthesis. World Resource Institute, Washington, DC), the Loess Plateau belongs to a semiarid area.
Reiji Kimura, Naru Takayama

Chapter 3. Soils on the Loess Plateau

Morphological characteristics of soils on the Loess Plateau are products of its distinctive physical properties and behavior of water and salt in soil profiles. Various types of soils are distributed across the plateau, where rapid environmental changes occur because of long-term artificial contributors to loessial sediments. Soil health in this region has declined, owing to the fragile environment. In a case study of the Luohui Irrigation Scheme, soil morphological characteristics and soil salinization were related to the topographic sequence of the soils. Soil salinization differed within this scheme and subsoil texture was a useful indicator of the state of salt accumulation. This information may help develop guidelines for agricultural soil management that are based on underground water dynamics and soil morphological properties. A proper conservation strategy is necessary to achieve an optimal combination of land use for soils on the Loess Plateau.
Sadahiro Yamamoto, Tsuneyoshi Endo

Chapter 4. Vegetation of the Loess Plateau

Natural vegetation on the Loess Plateau has been suffering gradual degradation over a long period, owing to human activities. As a result, hardly any original vegetation remains.
The potential natural vegetation is divided into five vegetation zones—forest, forest steppe, steppe, desert steppe and desert. These vegetation zones change from forest to desert with a declining precipitation gradient from southeast to northwest on the plateau.
In the forest and forest steppe zones, the dominant tree species is Quercus liaotungensis, which is considered the climax species in this area.
In terms of artificial forest, the most important and widely planted tree species on the plateau is Robinia pseudoacacia, a deciduous tree species belonging to the family of Leguminosae. Another such species is the conifer Pinus tabulaeformis. In contrast to R. pseudoacacia, which is alien to China, P. tabulaeformis is indigenous and its natural forests are widely distributed in central and northern China.
This chapter describes the features of natural and artificial vegetation on the Loess Plateau.
Norikazu Yamanaka, Qing-Chun Hou, Sheng Du

Chapter 5. Agriculture on the Loess Plateau

The Loess Plateau is considered the cradle of agricultural cultivation in China. The climate, ecology and geography of the area have created a unique farming system on the plateau. Agricultural output in the area increased 25-fold from 1980 to 2008, with more profound increases during the last 5 years because of the adoption of modern farming techniques. However, the rapid advances of technology and drastic societal changes (urbanization) have posed new challenges to agriculture on the plateau, such as shortages of water for irrigation and reductions in cultivable land from urbanization and soil erosion. Hence for sustainable agriculture on the plateau, measures such as terraced farming, use of supplemental irrigation, better farm inputs, crop rotation with legumes, and organic farming are recommended.
Ping An, Tomoe Inoue, Mingqing Zheng, A. Egrinya Eneji, Shinobu Inanaga

Desertification of the Loess Plateau


Chapter 6. Soil Erosion in the Loess Plateau Region of China

The Loess Plateau region has experienced severe soil erosion since the Ming Dynasty, and has become one of the most severe soil erosion regions in the world because of complex landforms, high soil erodibility, concentrated and high-intensity rainfall, and long-term human activity. This chapter outlines the general situation and regional distribution of soil erosion in the region. The soil erosion characteristics are described in detail, including water erosion, wind erosion and wind–water coupling erosion. This chapter also highlights the driving factors of water erosion, wind erosion and dust storms, including climate, soil and parent materials, topography and landforms, vegetation, and human activity. Finally, there is a brief treatment of sediment delivery to the Yellow River and its main tributaries.
Fenli Zheng, Bin Wang

Chapter 7. Irrigated Agriculture and Salinization

The Loess Plateau has complex topography with deep, thick loess, and is poor in water resources. The soil is loose and rich in carbonates, but because these dissolve readily when moistened, the soil is susceptible to subsidence and erosion damage when wet. These natural characteristics have hindered irrigation development on the plateau. Irrigation methods on the plateau can be classified into three categories: (1) gravity irrigation on flat tablelands in the southern region, (2) gravity irrigation on steep topography, and (3) pump irrigation on relatively flat, high plains. Among these three, (1) and a part of (2) have potential salinization hazards, with no such potential for category (3) and most of category (2). We analyzed the relationship between topographic characteristics and potential salinity hazards of irrigated farmlands in the Luohui Irrigation District, a typical large-scale irrigation system located on the southeast Loess Plateau. Based on onsite observation, we summarize current and potential problems of irrigated farmland within a semiarid area. Salinization of irrigated farmland is greatly influenced by water management. The construction, operation, and management of a well-conceived and elaborate water management system is a requirement for sustainable agriculture.
Katsuyuki Shimizu, Shen-Li Yang, Yoshinobu Kitamura

Chapter 8. Land Use Change and Deforestation on the Loess Plateau

Tracing the history of land use and vegetation change to the year 221 BC may help understand the environmental evolution of the Loess Plateau. Research has revealed that vegetation on the plateau maintained a natural state during the Zhou Dynasty and Warring States period. Natural vegetation still accounted for a large proportion during the Qin and Han Dynasties. In the Tang and Song Dynasties, natural forests disappeared from valleys and plains, and vegetation in hills and mountainous regions were also destroyed. The northern desert began to expand and the overall natural environment was in a state of deterioration. Serious deterioration of natural vegetation on the Loess Plateau mainly occurred during the Ming and Qing Dynasties (AD 1368–1911). Reasons for the drastic vegetation changes during this era are associated with both natural and human factors, for example forest cutting, land reclamation and overgrazing. In the last half of twentieth century, artificial plantations have been constructed as the primary means of ecosystem restoration on the plateau. A series of ecological projects implemented in recent decades significantly has changed vegetation cover and the environment there. These projects have eventually changed the trend of historical degradation to one of restoration.
Jing-Feng He, Jin-Hong Guan, Wen-Hui Zhang

Countermeasures for Combating Desertification


Chapter 9. Comprehensive Chinese Government Policies to Combat Desertification

Desertification in China is a serious and mounting environmental problem. Thus, combating it is of great importance to the ecological safety and socioeconomic development of the country. Many laws and regulations have been previously enacted by the Chinese central government. However, implementation of these laws and regulations still requires better management, and successful desertification prevention needs better cooperation between various stakeholders. Moreover, with its rapid growth over the past few decades, China must balance ecological, social and economic development and protection by instigating greater wisdom in decision making. Given the seriousness of the environmental issue, the country has accumulated great experience with prevention and mitigation of desertification. Currently, however, greater effort is required to effectively manage desertification control, including: (1) improving laws and regulations, and perfecting management and monitoring systems; (2) extending investment channels for desertification prevention; (3) strengthening both basic and applied research; (4) improving the ecological compensation mechanism; and (5) strengthening societal awareness of desertification issues and prevention.
Zhan-Bin Li, Peng Li, Ping-Ping Huang, Xiao-Jun Liu

Chapter 10. Grain-for-Green Policy and Its Achievements

The Chinese Grain-for-Green Policy began in April 1949. The policy was improved and perfected until implementation of the Grain-for-Green Project in 1999. Thus far, forest coverage has increased by an average of 3 % in the region covered by the policy. Trends toward ecological deterioration in some areas have been largely reversed and agricultural restructuring has been promoted. Wuqi County, a representative region of the policy coverage, has shown significant improvement in ecological restoration and agricultural production. Analysis has shown that the Grain-for-Green Policy was a compulsory regulation for required resources. The policy of financial compensation caused production operators to reduce their demand for resources, and the policy directly accelerated evolution of the ecological economic system in the region of implementation.
Ji-Jun Wang, Zhi-De Jiang, Zi-Lan Xia

Chapter 11. Poverty Alleviation Projects Through Integrated Ecological Management Supported by the World Bank: Case Study of the Yanhe River Basin

The Chinese government launched poverty alleviation projects in the 1980s and 1990s, which were supported by loans from the World Bank. One of the projects was organized by the Ministry of Water Resources to control, in an integrated manner, soil and water in the provinces of Shaanxi, Gansu, Shanxi and Inner Mongolia. These provinces include nine tributaries of the Yellow River. One of these tributaries, the Yanhe River in the city of Yan’an, was chosen as a project area. Yan’an City applied for a loan of 28 million USD and provided matching funds of 161 million CNY, amounting to a total project investment of 392 million CNY as of the 1990s. After 8 years of project implementation from 1994 to 2001, living conditions for local residents have greatly improved. Economic, social and ecological benefits were evaluated at the end of project implementation. The World Bank summarized lessons learned from the project, which can be referenced by similar projects.
Puling Liu, Yi Zhang, Yongqing Ma

Chapter 12. Policies and Measures of Chinese Local Government on Grain-for-Green Policy and Desertification Control

To reduce soil erosion and ecological degradation and improve land quality, in 1998 China initiated the state-funded project “Grain-for-Green” in the north, northwest and southwest of the country. This project of converting steep cultivated land to forestland and grassland is one of the most important initiatives for developing western inland regions. To make the project more effective, local governments have established certain policies and measures. These include improvement of existing policies and measures in different regions, establishment of assessment and incentive systems, registration and certification for land use, and development of guidelines for assistance funds and maintenance of past achievements. It was found that the project based on these measures had positive ecological effects (amount of land converted and afforested, ecosystem productivity, water and soil conservation, and pollution reduction) and socioeconomic effects (alleviation of poverty, aid to farmers in changing their income structure by shifting from farming to other activities). These are helpful to both farmers and local governments.
Yin-Li Liang, An-Rong Luo, Lan Mu

Development of Technology to Combat Desertification


Chapter 13. Monitoring Regional Desertification

The monitoring of desertification requires important biological and physical methods. In this chapter, diagnostic methods for regional desertification of the Loess Plateau will be introduced using water balance and water-use efficiency obtained by actual field observation and remote sensing techniques. A wetness index using a numerical simulation soil model (see Chap.​ 2) and meteorological data from 43 observatories was developed for diagnostic methods at the macro scale (across the Loess Plateau). Potential distribution of vegetation cover in the plateau was explored by comparing the distribution as determined by the wetness index with the present-day vegetation cover from satellite imagery.
The index, using a numerical simulation model and remote sensing technology, was developed to estimate the surface wetness of each land surface type at a local scale. The index corresponded with actual seasonal variation of moisture availability over an area of varied land-cover types. This method could be used as aridity and/or drought indices.
Reiji Kimura

Chapter 14. Countermeasures to Prevent Water Erosion in the Loess Plateau of China

The Loess Plateau suffers the most severe soil erosion rates in the world. Great efforts have been made since the 1950s to combat soil erosion and environmental degradation. In this study, the runoff and sediment benefits of major countermeasures including bench terrace, vegetation and check dams are analyzed under different conditions. The development and benefits of integrated management in small watersheds are discussed. We also analyze the variation of sediment yields in the Hekouzhen-Longmen region in the middle reaches of the Yellow River basin. Important considerations that must be addressed for future soil erosion and flood control are discussed. Future management objectives need to be investigated that focus on different soil erosion areas. Future key control areas of the Loess Plateau are mainly regions where there is inadequate management efficiency and high erosion rates (≥5,000 ton km−2 yr−1). Further studies should focus on preventing soil erosion at the source, rather than intercepting sediment yield downstream, and on rational utilization and sustainable development of recovered vegetation.
Juying Jiao

Chapter 15. Secondary Salinization and Its Countermeasures

We selected for study the eastern block of the Luohui Irrigation District, which is called the Luodong block. The research area is in the southeast part of the Loess Plateau, which is in a semiarid climate zone. Furrow and border irrigation in the block have been practiced over about 32,000 ha of irrigated area, where crops such as cotton, wheat and fruit are predominant. Based on onsite experiments in the research area, we classify salinization processes, reveal causes of farmland salinization, and propose countermeasures to prevent these phenomena. Lowering groundwater level by improving drainage systems, controlling dumped saline soil, and managing the use of saline irrigation water are recommended.
Yoshinobu Kitamura, Sheng-Li Yang, Katsuyuki Shimizu

Chapter 16. Enhancing Drought Resistance of Plants Using Wheat as a Test Crop

Achieving greater crop yield per unit of rainfall is one of the most important challenges for wheat production in dryland environments. Efficient use of limited water resources may be one means of achieving this goal. This chapter reviews the physiological adaptation to water deficit under variable environmental conditions in wheat. In addition, it reveals the compensatory effect of limited irrigation and fertilizer supplementation on wheat water-use efficiency (WUE) and highlights the breeding of new varieties for high WUE that could improve wheat productivity under water-limited environments. Considerable potential for further improvement in wheat productivity in semiarid areas seems to depend on effective conservation of moisture and efficient use of limited water. Different crops, soil and water management strategies should be adjusted according to the conditions that prevail in the various semiarid areas. Wheat productivity can be significantly improved by integrating the soil and water conservation approach and the regulated cropping system with cultivating drought-tolerance and water-saving cultivars.
Xi-Ping Deng

Chapter 17. Vegetation Restoration on Loess Plateau

Various measures of soil and water conservation on the Loess Plateau since 1950 have increased vegetation coverage and rapidly reduced sediment load to the Yellow River to the middle Holocene level. The Grain-for-Green project, launched in 1999 as part of National Ecological Environmental Construction Plan, has strengthened afforestation/reforestation on the fragile slopes common in the region. However, vegetation recovery has produced both favorable and adverse effects such as soil desiccation and deterioration of indigenous ecosystems. Adverse effects of Robinia pseudoacacia, a major afforestation species native to North America, are the most serious and distinct. Therefore, with a focus on this species, a strategy for vegetation restoration on the plateau is discussed in this chapter. First, ecophysiological and ecohydrological features of Robinia pseudoacacia are addressed by comparing with indigenous Quercus liaotungensis. Then, a strategy to improve existing Robinia pseudoacacia plantations and integrated measures for proper vegetation management are proposed.
Kyoichi Otsuki, Norikazu Yamanaka, Sheng Du

Future of the Loess Plateau


Chapter 18. Recent Changes on the Loess Plateau: Land Resource Development and Rapid Urbanization

The economy of the Loess Plateau of China has been developing rapidly in recent years and therefore the region’s share of the national economy has steadily increased. The plateau is rich in energy resources and their exploitation is the driving factor for economic development of the region. However, this development has come at the expense of the natural environment. Because of implementation of the Grain-for-Green Project, the land resource structure has greatly changed, characterized by a decrease in cultivated land and an increase of forestland. Orchard land has expanded, especially in Weibei Loess Plateau, where the apple fruit industry is enjoying sound development. However, the plateau is characterized by extensive urban sprawl, although the total amount of urbanization is still low by Chinese standards.
Investment in ecological improvement and environmental protection via the Grain-for-Green Project in the Western Regions has greatly developed the society and economy. Even so, the gap between the Loess Plateau region and eastern region continues to widen. Moreover, the degree of coupling between economic and ecological systems is low. Therefore, an ecological compensation system for resource exploitation should be established.
Ming-Quan Lü, Zi-Lan Xia, Ji-Jun Wang

Chapter 19. Future Development-Related Challenges on the Loess Plateau

The vulnerable nature of the environment coupled with monoculture agriculture systems have caused poor land productivity in the Loess Plateau region. Moreover, exploitation of mineral resources for energy may arise negative environmental impacts.
Both the Grain-for-Green project and China Western Development Action, which were launched in the end of 1990s and the beginning of the twenty-first century, respectively, emphasize ecological protection and economic development in this region. In this chapter, we show how ecological restoration and protection have contributed not only to soil and water conservation, but also to regional ecological protection and economic development. Furthermore, we present the challenges faced as a result of such development interventions.
Guobin Liu, Atsushi Tsunekawa, Xiaohu Dang, Sheng Du


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