Research On Predictions Of Arable Land Quantity In County-Level Land-use Planning

The quantity and quality of arable land is a basic guarantee for food production.Chinese great population with few lands makes the contradiction between supply and demand of arable land become more prominent,thus the situation of arable land protection is more serious."National Land Use Planning Outline(2006-2020)" has proposed the control of land can be divided into binding indexes and expected indexes in terms of its nature.The expected indexes are the ones that expected to be reached primarily by guiding the action of market players;binding indexes are the ones that cannot be exceeded or have to be achieved within planning period.And they are achieved by strengthening the management in accordance with the law and providing services.Its includes the amount of arable land,basic farmland protection area,the scale of construction land in urban and rural areas,the size of occupation of arable land by new construction sites,obligated volume of finishing and reclamation of arable land and the size of the urban industrial land per capita.These six indexes highlight special protection of arable land.Four of them related to arable land itself.It makes the amount and layout of arable land play an important role in land-use planning,also makes the prediction of maintaining the amount of arable land play referential significance.Through the forecast of regional demand for arable land,it provides reference and basis for land utilization plan.This study reviewed previous researches on theories and practices about arable land protection and forecast.Then,it pointed out the shortcoming of these studies was that most of the researches regard the methods of prediction as the means of results obtaining,but lack of comparative study on practicality and limitations of the methods themselves.This study took Yongchuan district as an example to make an empirical research.Collected materials about land-use,socio-economic development from 1997 to 2005 and future development planning and synthesized previous research to predict the amount of arable land based on mathematical models and food security,and then made a comparison between both methods.By researched on the changing of arable land in Yongchuan(1997-2005),the declining of arable land area was found,whose reasons were returning farmland to forest,the adjustment of agricultural structure,occupied arable land by construction,and natural disasters.Prediction based on mathematic models was to develop related models according to Yongchuan arable land-use changing (1997-2005) data.Considering 'The Notice Of Returning Farmland to Forests Policy by State Council',some basic data was amendment,namely the impact of returning farmland to forest on arable land was excluded from consideration,which came to the basic data of arable land change, then proofed the rationality of arable land-use changing by studying the land utilization benefit. Then,the amount of arable land was got during planning period by subtracting arable lands which returned to forests in 1997-2006 from predicted result.This result was calculated by several mathematic models,which established based on excluding consideration on the function of arable land changes and time by returning to forests.Prediction method based on food security was used 'the smallest area of arable land per capita' model to forecast the demand for the land.Via quantitative and qualitative study on total population at the end of each year,food self-sufficiency rate,the annual per capita food demand,food production and multiple crop indexes,the proportion between food and cash crops,then the parameters of minimum arable land area was got,and the amount of the land during planning period was predicted.Through comparative analysis on these two kinds of prediction methods,we could draw a conclusion that both methods based on mathematical models and food security respectively were different with each other:The former made prediction by analyzing the change of arable land and it was primarily more thorough,meticulous,but for weak qualitative,the consideration on regional development in the past and future as well as policies is inadequate;the latter,unifying the investigated region itself,made a consideration on regional future food demand,and predicted the future amount of arable land in terms of food security,this method was good at qualitative analysis, but quantitatively weak.The common place of both methods was that their researching age had been limited to 1997-2005,for short researching period plus long forecasting time may exert bad influences on predicting accuracy.Generally speaking,both methods can complement with each other,because synthesizing the results of them could be able to weaken the deficiencies from single qualitative and quantitative research.Their even values were used as the final prediction results:In 2010,arable lands would be 64351.48hm~2 and 63073.31hm~2 respectively;and in 2020,arable lands would be 65620.63hm~2 and 64250.96hhm~2 respectively.The results of this paper can contribute to rational land-use and to the better prediction of arable land's demand in the future.