The comprehensive inventory and monitoring
of forest and other renewable natural resources
by means of
Remote Sensing data
in the 'Three Norths' shelter forest region*
Xu Guanhua
The Research Institute of
Forest Resource Information Technique
The Chinese Academy of Forestry
Introduction
The 'Three Norths' shelter forest region is situated in the northern part of China, 'Three Norths' is the abbreviation of the northwestern, northern and northeastern part of China, with a total area of 4,069,000 square kilometers, covering 42.4% of land area of China. The 'Three North's' area is the birthplace of the Chinese nation, with rich natural resources, and has experienced prosperities several times in the history of mankind. The area is pregnant with extremely great production potentials. In recent centuries, however, because of vicissitude in natural conditions and destruction by human activities, there has been extensive lack of the natural vegetation coverage. The forest coverage (including brushwood) is only 3.8%. It is the main forest-lacking and forestless area in China. The lack of vegetation coverage has caused droughts, sand blown by the wind, soil erosion and other natural calamities. The area of farmland and pastures that suffered from wind and sand damages amounts to 6,700,000 ha., and the desertized land has increased by 32,800,000 ha. In the past 30 years. Soil erosion has been extremely serious in the middle and lower reaches of the Yellow River, which causes the landform to be fragmented with crisscross gullies and ravines. Of the 1,600,000,000 tons of sand poured each year into the yellow Rover 80% derives from this region. The Yellow River bed is elevated 10cm each year, and so it has become the river above the ground. Natural calamities and destruction of ecological environment have seriously hindered the economic development of the area, and it is known as one of the backward regions of China..
In order to improve the ecological environment and to promote the economic development, the Chinese government began to establish shelter forest in this area in 1950s, and decided to construct the 'Three Norths' shelter forest system, known as the Green Great Wall, in 1970s. The orientation is to rationalize land utilization, to increase forest and pasture coverage, to develop shelter forest, to construct livestock bases and to realize self sufficiency in grain supply. The forest coverage is to be raised from 3.8% to 9.5%. The proportion of animal husbandry in productive value of agriculture is to be elevated from 16.9% to more than 30%. From the year 1978 till 1985, the investments made by the central and local
governments in the project have surpassed 460 million US dollars, and the afforested area reported to the central government has amounted to 6 million ha. At present, the economic managerial administration in urgent need of evaluating the practical economic and ecological benefits resulted from the huge investment, in the 'Three Norths' project, such as the actual survival rate of afforestation, the rebuilt pasture area, the improvement of soil erosion and desertification. At the same time, it also desire to make clear the results of the economic policies and technical measures adopted in recent years, so as to provide a reliable base for the drawing up and completion of further construction plans of the 'Three Norths' shelter forest system.
The Comprehensive Inventory and Monitoring of Forest and Other Renewable Natural Resources by Means of Remote Sensing Data in the 'Three Norths' Shelter Forest Region is one of the key national projects for scientific development during the Seventh Five-year Economic Plan ( 1986 - 1990). Its goal is to answer the above questions put forward by the central economic administration, and to develop the remote sensing techniques in the process, thus to achieve the practical application of space-born remote sensing techniques.
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* Xu Guanhua and Xu Jiyan are jointly in charge of the project
