Studies on Change and Driving Forces of the Cultivated Land use in Loess Pleteau——A Case of Longdong Region,Gansu

The change of cultivated land is core of regional land utilization change.It's change and change trend reflects basic state of society economy.The case is chosen in Longdong region which is one of typical mound county in Loess Plateau.. The changes characters,process and flow of the cultivated land in the representative region of Loess Plateau in the recent 50 years were analysis based on the GIS technology and statistical data.Mean while,using correlation analysis,principal component analysis methods the driven factors of the farmland changes in Longdong region in recent 17 years were also studied.The results indicated:(1) the changes of the total farmland in the Longdong region could be described as increased slowly at the first and decreased sharply and slowly in the middle and last from 1949 to 2002,and the per person farmland area reduced largely from 0.91 hm2 at 1955 to 0.18 hm2 at 2002;(2) The main flow of the farmland is construction land,forest and grassland and others,reclamation forest and grassland to farmland compensated the reduction of the farmland area in some extent;(3) Drought,precipitation dynamics and soil and water losses were the main natural driven factors of the farmland changes,the increasing of economics and population, city level and the advancement of science and technology were the main social economics driven factors of the farmland changes.The changes of farmland were relation to the state macro-policy,the farmland reduction was consistent with increased of social economics in temporal scale and accord with region economics develop difference in spatial scale.