Transformation evaluation and differences evolution analysis of cultivated land functional in Guizhou Province in recent 40 years

Guizhou Province is located in the southeastern part of southwest China, and the capital city is Guiyang City. Terrain of the province is high in the west and low in the east. There are many plateau karst mountainous areas with large population living on the limited land resources where the quality of the cultivated land is extremely poor and the reserve resources are seriously insufficient. It is of significance to evaluate the function of cultivated lands in the area and to understand the status of the land functional transformation, in order to have a better management of the cultivated lands, and to make rational use of the land resources in a sustainable manner. This paper sorts out the agricultural polices and general farming situations in farmers of Guizhou Province since 1978. We constructed an evaluation index system, and calculated the index weigh and its function value by using entropy weight method ,to classify and evaluate the multi-function of the cultivated lands. This paper also studied the functions of cultivated lands on provincial, autonomous prefecture and local municipal scales, under different social and economic conditions. The research shows that, (1)The function of cultivated land in Guizhou Province showed a downward trend, with major changes occurred in 2000 to 2008 and in 2014 to 2015 respectively , with minor changes in the other years. The functional transformation started around 2006, and there were certain differences among the autonomous prefectures and various cities. The regions with rapid economic development were transformed in advance around 2004, while the regions with slower economic development were transformed in around 2012; (2)There were differences in spatial distribution of cultivated land function , which was mainly related to the combination of regional cultivated land pressure and economic development level. The regions with low tillage and low pressure and high GDP, such as Zunyi and Liupanshui cities, have the highest cultivated land functional value; the regions with high tillage and low pressure and high GDP, such as Guiyang City; the regions with high pressure and low GDP, such as Anshun, or the regions with low pressure and low GDP, such as Qiannan, have the lowest value; (3)As the quantity of cultivated land decreases, the population increases and the chemical load of cultivated land intensifies, it is suggested that we should pay more attention to the ecological protection of cultivated land, through reducing unreasonable practices such as exchanging excessive chemical inputs for food products, improving the basic land productivity of cultivated land, easing the pressure on cultivated land and food security crisis, and promoting sustainable agriculture development; (4) According to local conditions, it is suggested to choose appropriate agricultural development modes that may fit the local conditions, coordinate the relationship between the development of grain crops and planting and breeding industries so as to improve agricultural structures.