The Loess Plateau in China’s Northwest is home to more than 50 million people. Centuries of overuse led to one of the highest erosion rates in the world and widespread poverty. Two projects set out to restore the Loess Plateau.
The project area covers 15,600 square km of land in nine tributary watersheds of the Yellow River on the Loess Plateau in Shanxi, Shaanxi, and Gansu Provinces, and the Autonomous Region of Inner Mongolia, China.
The Loess Plateau covers an area of some 640,000 sq. km in the upper and middle parts of the drainage basin of the Yellow River. Before the project, most of the project area consisted of severely degraded and barren land and low productivity slope land. The loess soil has good agricultural properties, but drought is a major constraint in crop production. Slope lands in the Loess Plateau produce extremely high levels of sediment runoff per unit area. Broad flat terraces for crops and narrow terraces for trees and shrubs are essential for profitable use of lands in the project areas. Per capita incomes in the project area are mostly below the poverty line.
The objective of the project is to help achieve sustainable development in the Loess Plateau by increasing agricultural production and incomes, and improving ecological conditions in tributary watersheds of the Yellow River, through: (a) the introduction of more efficient and sustainable uses of land and water resources; and (b) reducing erosion and sediment flow into the Yellow River. The project finances the integrated planning and treatment of small watersheds. The project creates high-yielding, level farmland for production of field crops and orchards and thereby replaces areas devoted to crops on erodible slope lands, and (b) plants the slope lands to a range of trees, shrubs and grasses for the production of fuel, timber and fodder. These measures increase per hectare productivity on the improved farmland, raise overall output and incomes, and have positive ecological impact. Comprehensive and integrated planning of individual watersheds in close consultation with the beneficiaries in the villages is a key aspect of the project.
This paper from February 2012 [PLOS PDF] quantitatively evaluates the effects of Grain to Green Program (GTGP) implementation on ecosystem services in the Loess Plateau region (Figure 1)
Prior to the GTGP implementation, the Loess Plateau was dominated by grasslands and farmlands. Between 2000 and 2008 the land cover patterns of the Loess Plateau changed remarkably. Woodland, grassland and residential land cover increased by 4.9%, 6.6% and 8.5%, respectively. Farmland decreased by 10.8% and desertification increased slightly, by 0.3% (Figure 2)
The increases in grassland and woodland were distributed along a northeast to southwest land strip (Figure 3).
The regional climate condition of the Loess Plateau region has exhibited a warming and drying trend. This climate trend was revealed from the analysis of time series data between 1951 and 2008, obtained from 85 weather stations located in the Loess Plateau region (Figure 4). Precipitation was found to decrease annually by an average of 0.97 mm and temperature was found to increase annually by an average of 0.02°C.
Regional water yield decreased after the implementation of the GTGP. Over half of the study area (northeast to southwest of the Loess Plateau) experienced a decrease in runoff (2–37 mm/year) with an average 10.3 mm/year decrease in runoff across the whole Loess Plateau over the 2002–2008 period (Figure 5)
Soil conservation in the Loess Plateau, represented as a decrease in soil erosion, has improved since 2000 as a result of vegetation restoration (Figure 6).
The spatial variation of carbon sequestration in the Loess Plateau is shown in Figure 7.
The time and rate of the gross production change appeared to occur later and more slowly than the grain productivity change (Figure 8). Actual grain production increased across the whole of the Loess Plateau at a rate of 18% between 2000 and 2008.
Table 1. Rainfall erosivity and soil retention characteristics in the Loess Plateau region from 2000 to 2008.
Table 2. Area of cropland converted to forest (grassland) and the carbon sequestration by vegetation, soil and ecosystems in Loess Plateau between 2000 and 2008.
Hope in a Changing Climate
While serving as executive director of the Environmental Education Media Project Jonathan Halperin managed the creation of Hope in a Changing Climate, the award-winning documentary screened in Copenhagen at COP-15 and broadcast globally by BBC World.
The story of successful large-scale ecosystem restoration that is shown in the film, narrated by EEMP founder John D. Liu, continues to inspire audiences around the world and has been translated into French, Russian, Chinese, and numerous other languages.
Origin and Formation of Loessal Soils
Understanding the conditions of the environment that people of the Loess Plateau inhabit is a necessity, and with this acknowledgement comes the need to establish what loess actually is. Containing more nutrients than sand, it is also much finer. Its silt-like nature is noted as being among the most erosion-prone soils known on the planet (Jiang 18). Loess is also extremely sensitive to the forces of wind and water, bearing the dubious honor of being blown or washed away quicker than any other soil type (Pye 125).
Prior to this century, loess was a compelling mystery for geologists seeking to know its origins. Former theories included that loessal deposits were beds of ancient oceans, and even that they were composed of cosmic Saturn-like rings of dust that may have once encircled the globe but somehow rained down in pockets (Pye 237). Into the 19th Century, however, an apparent agreement was shown between the timing of noticeable waves of loessal sedimentation and the glaciation of the northern hemisphere (Smalley 358).
The Loess Plateau was formed in waves between 2.4 and 1.67 million years ago, helped along by the uplift of the Tibetan Plateau, the movements of several huge glaciers across desert
regions, and strong winds maintained by a high-pressure system in a cold and dry continental interior (Meng and Derbyshire 141). It is the world’s largest deposit of loess, approximately the size of France, designated by the large black area in Figure 2 below (Yoong 95).
Of all the factors contributing to soil erosion in the Loess Plateau Region, including desertification, wind erosion, violent rainstorms, and earthquakes, the most significant overall has been irrational land use (Bojie et al. 732). Slopeland, although much less stable than the level “yuan” tables (See Fig. 4), is continuously cultivated out of sheer need for increasing amounts of agriculture. These plowed slopes account for as much as 70% of soil loss in the region (Luk 23). However, it is not enough to simply declare the Loess Plateau inhabitants irrational. Many factors contribute to their use of the land in such a way.
Lev Semenovich Berg was born in Bendery, in Moldova. He had great success as an ichthyologist and geographer; he also proposed, in 1916, an interesting theory of loess formation. As a biologist he was persecuted by Lysenko and the Soviet state in the time of pseudo-science in the 1930s and 1940s. Despite his being persecuted, the loess theory beca- me, in effect, the official Soviet theory of loess formation. This theory had to be compatible with his ‘landscape’ theory which did not find favour in Marxist-Leninist geography. Berg’s loess theory was very much a geographical theory, as opposed to the geological theory of aeolian deposition, which was accepted outside the Soviet Union. Berg was hugely successful in many fields, but his contributions to loess science tend to be neglected. His ‘soil’ theory of loess formation has been widely disparaged but still has some influence in Russia. The concept of loessification may still be relevant to the later stages of deposit formation; the slow transition from metastable to collapsible may be best described as loessification.
The Lessons of the Loess Plateau, part two, part three, part four, part five, part six.