Analysis of changing use efficiency of cultivated land in town construction in China in the 1990s

To develop small town is one of the priorities of the national strategy for urbanization in China, and with the growth of the population in small town, large area of cultivated land is occupied during town construction in the 1990´s. Based on the Three-time TIM images of 1990,1995 and 2000, the author analyzes the dynamic variations of the areas of town construction land and cultivated land in 8 typical districts of China. Index Ccc (Coefficient of Changing use of Cultivated land), Cci (Coefficient of Construction land Increment) and Rcc (Ratio of occupied Cultivated land and Construction land increment) are built to analyze the dynamic characters of cultivated land, construction land and town population in town construction in each district. The results are as follows: In the 1990´s, the changing use efficiency of cultivated land is very high in Northeast district, Northwest district and Qinghai-Tibet Plateau district, but very low in North-China district. The changing use efficiency of cultivated land in 1995-2000 increases 56.4% by comparison with the period of 1995-2000, and the rise rates of the efficiency in Southwest district, Northwest drought district and Qinghai-Tibet Plateau district are the biggest, which are 2.48 times, 2.14 times and 1.7 times respectively, the one in North-China district rises smallest, so the difference of changing use efficiency of cultivated land in town construction among these districts are expanded more fin the 1990´s. The results also indicate that the improvements of changing use efficiency of cultivated land in town construction in 1995-2000 are results of the increase of the efficiency of construction land increment and Rcc being reduced together. But for different districts, the action degree of each factor is different. For Northeast district and North-China district, the fall of Rcc is the only factor that caused the improvement of changing use efficiency of cultivated land; For Qinghai-Tibet Plateau district and Southwest district, the increase of the efficiency of construction land increment in town construction is the only factor; For other districts, the improvements of changing use efficiency are results of these two factors, and for Loess Plateau district, the action degree of construction - land increment is bigger than the other while it is just reverse for the district of middle and lower reaches of Yangtse River; For South-China district and Northwest drought district, the action degrees of two factors are almost equivalent.