Fjölrit RALA - 05.12.1999, Blaðsíða 108

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HUMAN DIMENSION OF LAND DEGRADATION IN CHINA
Population increase
Local statistical data for the Yulin County shows that the population increased by
250% from 1949 to 1982. The population density rose ífom 18 pers./km2 in 1949 to
43 pers./km2 in 1982 (He Peizheng 1988). The farmland available for each person de-
creased by about 100%.
A critical index of population pressure in different zones was provided during the
Conference of Arid Land Resources and Environment in 1977. The critical index of
population pressure was considered 20 pers./km2 in semi-arid zone, humid coeffícient
0.2-0.5.
At present, the population density of Yulin County has exceeded this critical index.
From now on, if population increases by a rate of 8.5%o annually, the total population
of Yulin County will increase by 39% in 2000. Farmland per capita will decrease
gradually. If forest damage and grassland to farmland changes increase together with
the population, land desertification will become more and more serious.
CONCLUSION
This study demonstrates that remote sensing technology and geographical information
systems can play a great role in land desertification investigation, monitoring land
changes, and as a tool for regional planning. If the multi-temporal remote sensing data
at optimum season are acquired, it is possible to establish a desertification analysis
model to study the cause of land desertification and predict the trend of its expansion
quantitatively.
References
He Peizheng 1988. Natural Resources of Yulin Prefecture. Xian Drawing and Mapping Press, China.
Ren Zhibi 1990. Remote Sensing Application on Grassland Investigations. Chinese Science and
Technology Publishing Press, Beijing.
She Hianhei 1981. Forest and Grassland Change during History Period in Middle Yellow River
Reach. Shaanxi Province Press, China.
Yang Zhongxin 1984. Afforestation Investigation in Yulin Prefcture. Shaahxi Province Publishing
House, China.