Wang Tao and Wu Wei




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6
Combating Desertification in China

Wang Tao and Wu Wei


Institute of Desert Research,

Chinese Academy of Sciences,

Lanzhou, 730000

Introduction

Desertification is one of most serious environmental and social-economic problem in the world, which has been suffering China for a long time. Desertification brought about environmental deterioration and land degradation, which caused heavy losses of economy. Therefore, it is very necessary to carry out project for combating desertification. According to research and practices for nearly 20 years, we consider that the desertification is land degradation mainly resulted from interaction between excessive human activities and vulnerable environment (Zhu Zhenda et al., 1989) The causes leading the land to be desertified may be of varied description, but there are two most important factors can be recognized what we called both ‘natural factor’ and ‘human factor’. The combining actions of those factors are the major causes for sandy desertification, and the human factor is more important than the natural one. So what we have been thinking that it is high possibility to combat desertification just based on the fact that we can manage the human impacts on the process of desertification, because we nearly can do no thing to change the natural impacts. During last 5 decades, the desertified land has expanded continually in the China, which total area has reached over 861,600 km2 by end of 1980's. But some successful models of combating desertification have improved that where the reasonable landuse has been adopted over some years, the sandy desertified land has reversed and can be use again for more effective farming or grassing. Actually, where some preventing and combating measures have been adopted over decade, the desertified land has decreased. For example, according to the remote sensing monitoring result of the Mu Us Sandy Land, the desertified land has decreased from 32,590 km2 in 1987 to 30, 650 km2 in 1993, about 280 km2 had been controlled annually (Wu Wei,1997).


Although the reversing value was rather low compared with its expanded areas in the North China, only about 10% of total spread desertified land, the successful models have illustrated that the desertification can be controlled through appropriated measures. What we need are the confidence and action.


Status and process of desertification

Desertification/land degradation is recognized as environmental and social-economic issues, and attracts attentions from all over the world. Most of the areas to be subject to the desertification are suffered from high pressure of population and intensive human impacts. In China the main types of desertification can be classed as follows: sandy desertification caused by wind erosion, land degradation by water erosion, soil salinization and other land degradation caused by engineering construction of residential areas, communications, coal mine and oil field, etc.


According to the conception of desertification in China, the total desertified land had reached to 861,600 km2 by end of 1980's, accounting for 8.97 % of the total land of China. Table 5 shows the areas of desertified land, which caused by different process in China.

Table 5: Areas of desertified land by different process in China


Types of desertification

Area (km2)

% of total

Wind erosion

Water erosion

Salinization

Engineering construction



379,600

394,000


69,000

19,000


44.1

45.7


8.3

1.9


Total

861,600

100.0



Sandy desertification through wind erosion


In the North China the main land degradation is sandy desertification caused by wind erosion, which covers about 379,600 km2 and mainly distributed in the arid and semi-arid zones where the annual rainfall is below 500 mm. In those areas the land surface is mostly composed of sandy and gritty deposition. Drought season beings synchronously with wind season so that the spread of sandy desertified land will occur immediately so long as the land surface is disturbed by human activities.
On the basis of extensive field investigation and remote sensing data of different period, we established a preliminary degree classes and index system of sandy desertification and developed a suitable method for remote sensing monitoring and assessing on sandy desertification. The results indicate that during last 5 decades the sandy desertification in the North China has been caused mainly by irrational human economic activities, and the growth rate of desertified land has being increased decade by decade like as the annual spread area has increased from 1,560 km2 of during 1950's and middle 1970's to 2,100 km2 of between middle 1970's and late 1980's, to 2,460 km2 of among late 1980's and middle 1990's. From the viewpoint of property, the development during 1950-1970 had been characterized mainly by dune-field formed because the moderate(M) desertified land had developed to very severe(VS) one, while in recent decade it had been characterized by serious wind erosion in new reclaimed land and rangeland because of over-cultivation and over-grassing. The sandy desertified land in the North China are mainly distributed in (a) agro-pastoral areas in the semi-arid region - about 40.5% of total sandy desertified land, (b) desert steppe areas in the semi-arid region - about 36.5% and (c)marginal oases and lower reaches of inland river in the arid region - about 23%. View the situation as a whole, the degree of desertified land has become more serious as the results of development through slight to very severe degree. According to the statistics of desertified land areas with different landuse purposes, the human impacts of contributing to sandy desertification in the North China were as 25% of over-cultivation, 28% of over-grassing, 32% of over gathering firewood and 8% of mis-used water resources and 1% of engineering factors, occupied 94% of causes for the sandy desertification. With the human impacts the limited rainfall and dynamic wind also played a key role, especially during drought.

Desertification through water erosion


This kind of desertification is soil loss through water erosion, which is the most serious land degradation in China. By a rough estimate, annual soil loss caused by water erosion reached to about 5 billion tons, of which about two fifths come into the seas ( Zheng Du,1998 ). According to a national-wide investigation, there were about 1.53 million km2 to be affected by water induced soil erosion at the beginning of 1950's, but increased to 1.79 million km2 of 1990's (accounting for 18.6% of the nation's territory), of which about 394,000 km2 had been desertified by water erosion. Most of those desertified lands distribute eastwards of the boundary from Da Hinggan Ling - Yin Shan - Helan Shan to eastern rim of Qingha - Tibetan Plateau.

Salinization


There are about 20% of total 100 million hm2 farmland of China have been more or less threatened by the salinization at present, and about 69,000 km2 land has been salinized by the end of 1980's in China, which mainly distributed in the arid and semiarid regions of the Northwest China and subhumid regions of North China Plain.

Desertificatin caused by engineering construction


For last 20 years, a new type of desertification has spread very quickly with some large-scale projects like as development of oil field and mining, construction of residential area and communication. A preliminary study indicated that it covers an area of 19,000 km2, which mainly expanded through wind and water erosion.


Principles for combating desertification in China

Based on the summary of research and practice on combating desertification for many years, we would like to suggest that the overall strategic idea on sustainable development carried through to combat desertification in China should follow the guiding principle of "taking prevention first, carrying out overall planning, conducting integrated prevention and treatment, adopting measures suitable to local conditions, strengthening management, and laying stress on efficiency" and implement the following policies.




  1. Taking prevention first. Attention should be paid not only to combat the existing desertified land, but even more important to the prevention of potential desertified land such as to adopt prevention actions to light degraded pastureland and light soil eroded land, enforce supervision and monitoring and minimize desertification resulting from environmental deterioration caused by irrational human activities.




  1. Using key affected points as combating basis to promote work in the entire area, such as in combating water erosion induced desertification, small priority watershed should be taken as a unite (point) to undertake comprehensive management and popularize the work from the unit to large areas. For combating wind erosion induced desertification, priority township should be taken as a unit to promote the work in different batches step by step.




  1. Adopting measures suitable to local conditions and identifying preventive facilities according to type of hazard. Corresponding measures were taken according to local physical, social and economic conditions.




  1. Integrating combating with development and utilization. Desertification combating should be closely combined with economic development, eco-environmental improvement should be integrated with improvement of local people's living standard, combating should be used to ensure development and development should be used to promote combating. For instance, according to the local eco-environmental features favorable either for desertification combating or favorable for economic development, the principle of "protective forestry, commercial animal husbandry and self-sufficient farming" has been suggested to the farming-pastoral areas which experiencing the sandy desertification.




  1. Harmonized ecological benefits with social and economic benefits. When the three benefits are in inconsistency, the need of ecological benefits should be satisfied for it concerns the overall long-term benefits and concerns the sustainable development of desertified area and the immediate economic benefits should not be taken into account at expense of environmental benefits. For instance, in the process of present large-scale afforestation for sand stabilization and of reclamation of desertified areas for grain production, attention should be paid to prevent environmental deterioration from drop of ground water table. However, in the specific operational process, efforts should be made to promote ecological and social benefits via economic results.


Status of combating desertification in China

It is evidence from the above analyses that the land desertification in China has led to a heavy loss of land resource, which is affecting sustainable economic development in farming-pastoral, pastoral, dry farming areas in the North China and hilly areas in the South China. The Chinese Government attaches very importance to combat desertification, so far substantial work has been done and certain achievements and experience have been gained. So it is very necessary to evaluate the status and existing problems of combating desertification in China, analyses examples and summarizes experience in combating desertified land in different types and formed under different natural conditions so as to provide scientific basis for the formulation of national action programs in combating desertification in China.



Gradual perfection in policy and management measures



Relevant legislation work has been quickened since the 1980s

As stipulates in Article 19 of Law of Environmental Protection of the People's Republic of China issued on 26 December 1989, ‘measures should be taken to protect eco-environment in exploiting and utilizing natural resources’; in Article 20, ‘people’s government at various levels should strengthen protection of agricultural environment, prevent soil pollution, land desertification, salinization, impoverishment, swamp, ground subsidence and prevent and control vegetation devastation, soil and water loss, water source exhaustion, species extinction as well as the occurrence and development of other phenomena concerning ecological disturbance.


Soil and Water Conservation Law of the People's Republic of China was reviewed and carried through at the Standing Committee of the National People's Congress on 29 June 1991. In this special law on prevention and control of soil and water erosion, aspects concerning principles on soil and water conservation, soil erosion prevention and supervision, soil erosion control, role of government and public in soil and water conservation, and legal obligations were stipulated in detail.
Item 1 of Article 19 of Forest Law of the People's Republic of China implemented on 1 January 1985 stipulates, ‘prohibit destroying forest for reclamation and destroying forest for quarrying, sand and earth mining as well as other actions related to forest destruction’.
Other relevant Laws can be listed as followings:


  • Grassland Law of the People's Republic of China implemented on 1 October, 1985.

  • Law of Mineral Resources of the People's Republic of China implemented on 1 October, 1986.

  • Land Management Law of the People's Republic of China issued on 29 December, 1988.

  • Law of Agriculture of the People's Republic of China issued and implemented on 2 July, 1993.



Gradual intensify management on combating land desertification


Relevant administration agencies concerning desertification control have been established in China, administering work to combat desertification from different aspects, such as the division in Department of Nature Conservation within NEPA with responsibility of administering work on land degradation/desertification control. For the sake of tackling land desertification problems in a comprehensive way, eco-environmental impact assessment of construction projects was strengthened and, work on ecological demonstration plots aiming at sustainable development in desertified areas was carried out. The Office of Sand Control was set up in Ministry of Forestry in the 1970s. In order to strengthen engineering construction of ‘Three North’ shelterbelts, the Bureau of Three North Shelterbelts was established under the ministry and corresponding institutions concerning desertification control and shelterbelts construction were also established in various relevant provinces and regions.
With regard to grassland operation and management, grassland administrative stations with a total staff of over 10,000 have been set up in major pastoral provinces, prefectures and counties throughout the country.

Major achievements in combating desertification in China


Following the UN Desertification Conference in 1977, the Leading Group Office on Environmental Protection under State Council (predecessor of Notional Environmental Protection Agency), in cooperation with the Chinese Academy of Sciences (CAS), entrusted the Institute of Desert Research, CAS and other units to carry out studies on desertification in China. Research results of various field teams and experimental stations as well as practical experience of local people were scientifically summarized. Then entrusted by international organizations of UNEP, FAO and ESCAP, over dozen training courses and seminars were jointly organized by NEPA and CAS, the areas covered including the North and South China. In addition, experts were sent to Ethiopia, Tanzania and Mali to give lectures or coordinate and guide work on desertification prevention and control. UNEP, CAS and NEPA set up an International Center for Research and Training on Desertification Control with assistance of the Institute of Desert Research in Lanzhou in 1987. Meanwhile, monitoring and mapping of causes and status of desertification in the North China and its trend of development was carried out systematically. Based on extensive investigations and studies on typical controlled areas, experiences of difference control models were summed up, a desertification combating system by combining prevention and control with development was proposed.
In order to quicken the pace in sandy desertification control in recent years, the centre government compiled Main Points on National Sand Control Project Planning in 1991- 2000, worked out plan target of combating 666.7 x 104 ha of desertified land within 10 years. So far, 20 key counties, 9 experimental districts and 22 demonstration bases related to national Sand Control project have been included in the national economic development program and in the progress of implementation. During the Eighth-Five-Year Plan period (1991-1995), 375.9 x 104 ha of land related to the project got controlled in a comprehensive way.
Up to mow, the first and second phase work concerning the Three North Shelterbelts system project has been completed. As a result, 1851 x 104 ha of land were forested with a forest coverage increased from 5.05 percent to 8.2 percent, more than 4 x 104 ha of ‘virgin land’ were turned into green woodland, 130 x 104 ha of sandy desertified land were transformed into farmland, grazing ground and orchard, 12 percent of the sandy desertified land were tackled and 10 percent of the sandy desertified land were put under control, over 1100 x 104 ha of farmland were protected with shelterbelts, 893 x 104 ha of grazing ground were rehabilitated, resulting in a grass yield increase of over 20 percent. Agricultural eco-environment of one third of the counties in the Three North shelterbelts tends to change toward a benign circulation. According to report from page 1 of China Forestry on 5 September 1996, the aerial sowing forest and grassland area for sand control reached 100 x 104 ha, they play a tremendous role in against wind and sand dune stabilization. In 1958, pilot project on aerial sowing to Sand Control was initiated in Yule of Shaanxi Province in China, and 1988, the results began to be used for extensive production, at an annual expansion rate of 70 x 104 ha, recently at 10 x 104 ha. Apparent ecological, social and economic benefits were gained.
According to stipulations of the Law of Grassland, Chinese government at various levels strengthened protection and management of grassland resources, strictly prohibited discriminatory reclamation, excavation and grazing, practiced the combination form of State, collective and individual, and quickened the pace in grassland rehabilitation and control of grassland degradation. Statistics revealed that aerial sowing grassland and artificial ameliorated grassland totaled 1175.7 x 104 ha and grassland fenced, 823.3 x 104 ha in the country. Remarkable achievements were obtained in 49 grassland and animal husbandry integrated demonstration projects organized by the State as focus of attention. Up to the end of 1994, artificial sown grassland area totaled 563.8 x 104 ha, opening up a new way development of livestock farming and eco-environmental protection in arid, desertified and soil eroded areas.
As the Chinese government attaches importance to soil and water conversation work, the desertification through water erosion (soil erosion) has been effectively controlled and eco-environmental and agricultural conditions have been improved. At present, 25 stretches of national key soil erosion control areas have been identified, water and soil conservation projects been carried out in 7 large river basins and mountains, rivers, farmland, forests and roads been tackled in a comprehensive way in more than 10,000 seriously eroded small catchments. Consequently, a total amount of 67 x 106 hm2 of soil eroded area was controlled, a great many water storage and water preserving projects were built, annual average soil loss was dropped by over 1.1 billion tons and water preserving and holding increased by 18 billion tons in the country. In soil erosion comprehensive control areas on the Loess Plateau, 15 x 106 hm2 were tackled, 30 percent of the eroded areas were controlled in different degrees and annual sediment delivery into the Yellow River reduced by over 0.3 billion tons. According to report from the article "Tremendous Changes Resulted from Soil and Water Conservation in China" carried on of Science and Technology Daily on 5 September 1996, since 1983 the State has selected 8 stretches of seriously eroded areas including Wuding River, Sanchuan Ruver, Huangpu River, upper reaches of Liuhe, Xingguo County, Dingxi County, reservoir area of Gezhouba and upper reaches of Yongding River from 7 major drainage basins of Yellow River, Haihe River, Liaohe River, etc. as key areas for soil erosion control. Up to now, satisfactory results have been gained in tackling problems concerning mountains, rivers, forests, farmland and roads in key areas under unified planning and in comprehensive way in light with the principle of bringing scale efficiency into play and tackling in continuous stretches. Within the 13 years, soil eroded area reduced by 33.2 x 104 hm2, forest and grassland area increased 239.8 x 104 hm2, per capita income in concerned areas exceeded 600 yuan, and over 1,500,000 people got rid of poverty.

Major problems existing in combating desertification in China


Viewing generally in light with ‘Environmental Protection in China’, problems such as inadequate forest area, grassland degradation, land desertification, etc. still exist in China, therefore, further strengthening protection of eco- environment and biodiversity is still an important task confronting the Chinese government.

Legislation is incomplete and enforcement system of law is imperfect.

Except the Law of Soil and Water Conservation, which is a special law on soil and water loss (related to water erosion induced desertification) prevention and control, other relevant laws and regulations on desertification combating are scattered in many other laws. The urgent task is to make the Law of Combating Desertification and relevant specific stipulations to coordinate relations of resources development and desertification combating. Another serious problem is negligence of laws and regulations and enforcement system is imperfect.



The rate of desertification combating lags behind the rate of development


Since the founding of the People's Republic, work on combating various types of desertification has been carried out and greater achievements have been gained. However, in a long period of time, as no effective measures have been adopted to control artificial impacts and prevention has not been put on the No.1 position, though desertification development has been changed in reverse in partial areas, taking the country as a whole, the phenomenon of ‘combating in points but disrupting on entire area; combating while disrupting; and disrupting first followed by combating’ was very serious. The rate of desertification control lags behind the rate of development, and the desertified area is still expanding. In sandy desertification control, up to the end of 1988, the afforested area mainly for desertification control thus preserved covered 10 x 106 ha for the whole country, making 10 percent of the sandy desertified area have been controlled. However, the trend of desertified area expansion had not only been constrained but became aggravated.

Short of sufficient funds to combat desertification


China is a developing country, as economic growth exerts great pressure on funds, the State input to desertification combat is limited. What is more, because of severity in desertification extent, vastness in expand, and ‘too much debt owed’ in history, only substantial input is devoted can the problem be solved. Desertification usually occurs in poverty-stricken areas, hence non-governmental mobilization and accumulation of funds is also difficult in desertified areas. Shortage of funds to combat desertification in China, the same as in other developing countries in seriously desertified areas on the globe, has multiplied the difficulties in tackling the desertification problem.

Typical experience in combating desertification in the North China
With regard to content, the essence of desertification combating is to improve the degraded land conditions by rehabilitating productivity of the already desertified land, how to reverse the degradation process of the ongoing land desertification and how to prevent the development of the potential desertified land; and to make land resources being sustainably utilized and bring even greater benefits. Although the desertification has expanded in China as a whole for last decades, many efforts have reversed about 10 percent of the sandy desertified land in the North China and much more in the South. Some effective examples can be shown as following:

Hotan County of Xinjiang

Combating desertification around oasis in extremely arid region

Hotan Oasis, sandwiched in between Yurungkax River and Karakax River at southwestern margin of the Taklimakan Desert in Xinjiang, where annual average precipitation is only 34.8 mm with evaporation as high as 2564 mm. According to the natural conditions, the fundamental way combating sandy desertification is to set up sand-protecting plantation centered around the oasis and to stabilize oasis ecosystem by rational utilizing water resources of inland rivers. In this connection, the following measures are identified:




  1. Undertake new water conservancy projects. Making full use of water resources of Yarungkax and Karakax rivers had formed a complete irrigation system with trunk canals. As a result, small scale farming with irrigation system was realized for 80 percent of the cultivated land.




  1. Built complete sand-protecting plantation and windbreak forest system centered around oasis. Forest reservation was adopted in the semi-fixed areas at the periphery of the oasis to preserve natural vegetation. A 358-kilometer-long trunk forest belt of the sand-protecting plantation and windbreak forest system, 100-300 m wide, was built encircling the fringe of the oasis. The woodland made of 40.2 % coverage in the oasis.




  1. Stabilize moving dunes and level individual dunes. For stretches of dunes, warping by diverting flood water was practiced on interdune lowland for woodland; and the dune surface was fixed by sand breaks made with reeds and wheat straw.

The adoption of above measures led to an environmental improvement, a drop of wind velocity over fields protected by forest grids by 25 percent and sand-bearing content in wind-drift sand by 40-60 percent in contrast to open space. Economic efficiency as also apparent. The total output of cereals, cotton and oil-bearing crops increased by 1.17, 1.16 and 2.31 times respectively, per unit area grain yield increased by 3.3 times and per capita income by 7.5 times in the county compared the case in the early 1990s with that of the end of the 1970s.


Yulin City of Shaanxi

Combating sandy desertification in western part of semi-arid farming-pastoral areas
Yulin City is situated in northern part of Shaanxi Province, where 70 percent of the annual precipitation (414.6-mm) is concentrated in July, August and September. It is one of the seriously desertified areas in China. In light with sandy desertification dominated by wind erosion, a ‘belt, patch and grid’ combined sand and windbreak system was recommended to be established.


  1. By using conditions of relative high ground water level and better water regimes in the interdune lowland within the desertified area to stabilize shifting sand; meanwhile, stabilized and semi-stabilized dunes were enclosed to facilitate plantation.




  1. Protection network dominated by narrow forest grids was established on dune encircled farmland distributing on river terraces and floodland of lake basins; along with measures such as enclose fixed and semi-fixed dunes to facilitate planting on the edges of floodland in combination with shrubby grass plantation, to form a farmland protection system.




  1. Aerial grass sowing in combination with artificial enclosure to facilitate plantation was adopted in vast expanse densely distributed with high moving dunes. The preservation rate is generally 40-50 percent; the highest may reach 70 percent.




  1. In areas abound in rich water resources, water diversion to disperse sand for soil amelioration was applied. As a result of transformation moving dunes along west bank of Yuxi River west of Yulin city into farmland or new urban district, the area of Yulin City in 1990s has been enlarged 8.5 times in comparison with in 1949.




  1. As a result of the adoption of aforementioned measures, the vast expanse of sandy desertified land was separated and encircled by green ecological breaks, forest coverage increased from original 1.8 percent to 37.6 percent in 1994, 3,400 km2 of shifting sands were stabilized, 1,000 km2 of farmland were protected with forest grids, over 660 km2 of farmland were added in desertified areas, 106 km2 of water surface of lakes or reservoirs in interdune floodland were used to raise fish, 1530 km2 of grazing ground were rehabilitated and improved. Both ecological and economic benefits were gained. For example, in Qinhe Township west of Yulin city, sandy desertified land decreased from pre-treatment 56 percent to post-treatment 13 percent in the 1990s and per capita income increased by 241.5 percent in 1995 than previous 10 years.


Naiman Banner of Inner Mongolia
Combating desertification in eastern semi-arid farming-pastoral area

As a huge ecological system, Horqin Steppe Region has varied conditions of eco-environment and complex relations between ecology, environment and human impact. Due to the unfavorable natural conditions, the eco-system is very fragile and it is much stable for grassland-livestock raising than drylands-farming. But along with the growth of population and development of cropping agriculture for the last 100 years, it is impossible to renew the original one again. Up to the present, the eco-system already has became a dry-land agricultural eco-system, which shares the cropping, animal husbandry and forestry as dominant composition and has much complex structure and function. Although the productivity is higher than before, the new eco-system is unstable. The process of desertification is the major result. So it needs great efforts to enable it reach a new stability for sustainable development.


Many good results show clearly that land desertification could be controlled when some necessary measures have been token. Based on the analyses of eco-environmental, economic and social benefits between before and after desertified land had been brought under control in Xinglongzhao District, Naimanqi, as a good example, we try to evaluate the desertification control in Horqin Steppe Region. The area of Xinglongzhao District is about 53,000 ha, which was a fine pastureland until 1950s. But it was degraded because of over-cultivation, over-grazing and over-collection of fuelwood.
The desertified land had expanded to over 15,700 ha up to 1974, which resulted in the deterioration of the ecological environment, decrease of grain production and reduction of livestock output. The process of desertification hindered seriously the development of the local economy and the improvement of living standards of the people. Since 1976 the local government and masses implemented a project to combat desertification for improving the environment of production. This project has achieved success and the main targets are showed in Table 6.
Table 6: Effectiveness of combating desertification

in Xinglongzhao, Naiman (1974-1994)



Land type

1974

% of area

1994

% of area

Change

Desertland

15,700 ha

29.62

2,100 ha

3.96

86.62 %

Woodland

777 ha

1.47

25,840 ha

30.10

19 times

Farmland

4960 ha

9.36

6,900 ha

13.02

39.11 %

Other parameters -


Grain yeild

2,790 t

13,110 t + 10,320 t

+3.7 times

Unit grain yeild

562.5 kg/ha

1,900 kg/ha +

1,337.5 kg/ha



+2.4 times

Rangeland Capacity

124,200 sheep unit

152,200 sheep unit +

2,800 sheepunit



+22.5 %

Income/

person


80 yuan

1,120 yuan + 1,040 yuan

+13 times

The project has prevented the desertified land from spreading over more areas, which is very important since the prevention cost is much lower than the controlling one, as well as a large area of desertified land has been rehabilitated. It brought about a coordinated advance in economy, society and the environment, and made considerable headway on the ecological, economic and social benefits.

Desertification is a complex process caused by human impacts and natural factors. For a sustainable development in regions affected by the process, prevention and remedy of desertification is an arduous task which should and must be accomplished because of the human existence and can be accomplished since the effect of some theories and practices for combating desertification have been proved fully.

Hetian Town in Changding County of Fujian

Combating water erosion induced desertification in humid hilly areas

Hetian Town of Changding County, located at upper reaches of Dinghe southwest of Fujian, used to be known for its picturesque scenery over 100 years ago and became a representative of water erosion related desertification in hilly areas of southern as a result of human impact and natural erosion. In mid 1980s, eroded area accounted for 44.7% of the total land area, of which above moderate eroded area made up 78.9% of the total eroded area, including plane erosion, 34.5%, gully erosion, 15.8%, and heaving induced, 49.7%. They generally happened on badland, stony slopes and gravel landforms on low hills of 20-80 m high with dissection density, 0.25-0.30. in addition, sandified cultivated land also made up 4 percent of the affected farmland by accumulation of granitic weathered coarse sand due to flood scouring.


Water and soil erosion control has began as early as in the 1940s in Hetian. Since the founding of the People’s Republic, massive prevention and control was carried out following the principle of scientific experiment and research in combination with local peoples' practice. In order to popularize the mass movement in combating desertification, a number of demonstration plots aiming at different conditions were set up.


  1. As for stony slopes with topsoil being washed off, the Guanxintang Experimental Plot was set up at the upper reaches of Bashili River. The model of a vegetated cover consisting of various tree species (e.g. silk tree, Lespedeza bicolor, Amorpha fruticosa and Robinia pseudoacacia) planted in high density and with a mixture of forests and shrubs was developed. Observations indicated that soil erosion module dropped by 94.8 percent compared with pre-control, and soil organic matter increased 5 times.




  1. As for severely eroded red earth developed on granitic hill slopes, the mixed forest model dominated by Acacia mearnsii plus Robinia pseudoacacia and Amorpha fruticosa was developed. It functions as a temperature regulator to prevent high temperature hurt to plants because the maximum daily temperature variation was 17.9 oC inthe forest in summer and outside was 36.1 c. Contents of nitrogen and organic matter increased greatly due to nitron fixation of nodule bacteria of the plant and decomposition of fallen leaves.




  1. As for highly eroded barren terrains with dense gullies, a model of a multi-type, multi-layer vertical plantation system including afforestation, grass planting and fruit tree cultivation for prevention and control in combination with development was developed at Chiling. According to the model, grass was planted on hilltops, Acacia mearnsii was planted on hill slopes, fruit trees were planted at foothills and in places where water is available, and fishpond was opened. As to old and pinon pines remained on hill slopes, measures were taken to promote the growth of the trees. Fruit trees like peach, plum, hawthorn and kumquat were planted at the edge of forest belts. Economic crops like peanuts and citron daylily were interplanted. After treatment with this model, the amount of soil eroded reduced by 92 percent and soil organic matter increased 0.6 time.




  1. Low mountains and hills subjected to water erosion induced desertification were generally closed, after 5 years desertified area reduced by 14.3 percent. An important aspect to ensure implementation of desertification combating program is preferential policy formulation and strengthening organization and management. For instance, measures were taken to cope with coal supply and subsidies, popularize energy-saving cooking stove and build methane tanks. As a result, land pressure was reduced by firewood gathering, vegetation was protected and and combating results were consolidated. Meanwhile, propaganda was strengthened on law of environmental protection, forestry law, and law of soil and water conservation, relevant agencies concerning desertification combating were strengthen and perfected. With regard to organization and management, the measure of who made contributions in combating who gain was practiced, and responsibility system concerning combating and management was set up under contracts and in a planned way. Therefore, responsibility, rights and benefits were unified and combating, management and utilization were integrated. After adoption of aforementioned measures, the vegetation coverage increased from below 10 percent pre-treatment to over 50 percent and soil erosion module reduced from 5000-12,000 t/km2.a to 449-695 t/km2.a. Desertified area reduced from 26.2 percent to 21.6 percent and per capita income increased by 260 percent in 1990 than pre-treatment. Environment was also improved.


Tangbeihe in Xingguo County of Jiangxi Province
Combating water erosion induced desertification humid granitic hilly areas

Tangbeihe watershed in Xingguo County of Jiangxi Province, located to south of Xingguo, is a small tributary of Pingjiang River. The entire watershed is composed of coarse granites with loose weathered horizon ranging from several to dozens of meters andis liable to be eroded after vegetation destruction. Annual average precipitation is 1371.9 mm and is unevenly distributed with 73% concentrate in March to August. Except alluvial plains, the watershed is mostly composed of granite hills and their weathering product, i.e., red earth. Vegetation was seriously damaged due to afforestation, tea plantations at the expense of forests and firewood gathering. Most of the low mountains and hills in the middle and lower reaches were barren, subjecting to serious water erosion. in the watershed, 70.4% of the land were affected by soil erosion, 98% of the mountains were subjected to erosion. Of which badland and desertified stony slopeland occupied 58.1%, or 82.5% of the eroded area.


According to the actual situations, the following measures were taken.

Table 7: Effectiveness of combating desertification

in typical areas in China


Representative

Regions

Annual rainfall (mm)

Features of desertified

Land

A*

B *

C*

Pingchuan,

Linze County, Gansu



117

Dune mobilization around oases, sand dune enchroachment

56.4

9.4

154

Yaole Dianzi in

Naiman Banner

Inner Mongolia


360

Sandy grassland wind erosion, Dune mobilization and dune enchroachment in farming -pastoral area

77.0

25.0

126

Qinhe Township

Yulin,Shaanxi



415

Farmland surrounded by dunes on valley terraces and lake basin flats in semi-arid areas

56.0

13.0

242

Zuocheng in

Yanjin,Henan



600

Dune and sandland in ancient yellow River beds and flooded splays of sub-humid area

48.6

2.7

178

Shibangou in

Baihe ,Shaanxi



799

Badland, stony slopeland and ground surface desertified by water erosion on mountains

21.7

4.7

335

Renli, Suining Sichuan

993

Purple sandatone and mudstone eroded hills

41.08

1.55

373

Xiadian,Dawu

Hubei


1150

Water eroded badland and stony slopeland on granitic gneiss hills

18.8

7.2

197

Dashan,

Hengnan,Hunan



1287

Sandstone and sandshale hills with badland and ston slopeland

54.9

7.6

86

Malinhe,Wuhua Guangdong

1443

Granitic hills dominated by badland and collapse erosion

64.6

9.5

98

Mengpuhe

Puding Guizhou



1450

Sand hill desertified limestone hilly areas

36.6

5.9

155

Fuling, Jixi Anhui

1534

Granitic hills dominated by badland

56.6

3.1

580

Tangbeihe

Xingguo


Jiangxi

1593

Granitic hills covered badland, ground surface broken subjected to be water eroded

82.4

7.2

272

WeishanNingx-iang, Hunan

1580

Granitic hills dominated by badland

45.8

3.5

230

HetianChang-ding, Fujian

1636

Granitic hills with badland and stony slopeland to be serious water eroded

26.2

21.2

260

  • A - Desertified land / total area (%) before combating desertification

  • B - Desertified land / total area (%) after combating desertification

  • C % of increase income/person between before and after combating desertification




  1. Build various types of field works for soil and water conservation so as to create conditions for quickening vegetation rehabilitation. For instance, bamboo joint contour trenches were mainly built on slopeland over 25 degrees, table land (terrace) with reversed gradient was mainly constructed on slopeland of 15-25 degrees, while level terraces were built on gentle sections of foothills.




  1. Select appropriate tree species and grass species for afforestation and allocate tree species properly. Native tree and grass species with high adaptability such as Pinus massoniana, Liquidambar formosana, Schima superba, Aleurites fordii, Quercus, and Lespedeza bicolor, were selected and good varieties of grass such as Staria vidiris, Paspalum thunbergii, were introduced. Fruit trees and firewood were normally planted above halfway up the mountains such as Pinus massoniana, Liquidamber formosana, Schima superba, Quercus and Lespedeza bicolor so as to form a multi-species, multi-layer and high density vertical structure. Economic forests and timer forests such as Aleurites fordii, Camellia oleifera, Cunninghamia lanceolata and Paulownia fortunei were planted below halfway up the mountains or at foothills.




  1. An essential guarantee to accelerate vegetation rehabilitation and combat desertification is to integrate combating with management and to practice forest reservation. After hillside enclosure and afforestation, vegetation coverage increased from less than 10 percent to 50-60 percent.




  1. An important measure to stop vegetation destruction is to provide solutions to domestic energy demand in rural areas. Such as to build methane tank, popularize fuel saving stoves and plant shrubs like Lespedeza bicolor and Arundo donax at four sides of the house for quick solution of firewood.

  2. After treatment, soil erosion was mitigated, desertified area dropped to 5.04% of the watershed area and per capita income increased 272%.



References

Wang Tao, 1998: Remote sensing monitoring and assessing sandy desertification: An example from the sandy desertification region of northern China, Quaternary Sciences, 2, 108-118

Wu Wei, 1997: Applying remote sensing data for desertification monitoring in the Mu Us sandy land, Journal of Desert Research, 17(4), 415-420

Zheng Du, 1998: A study on land degradation management and its regional defferentiation of China, Proceedings of Japan-China Workshop on Land evaluation of Prevention and remedies for Desertification, Tsukuba, Japan, 3-12



Zhu Zhenda, Liu Shu, 1989: Desertification and its Control in China, Beijing, Science Press




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