Study On The Optimal Spatial Allocation Of Cropland Occupation And Compensation And Its Impacts On The Loss Of Ecological Lands

Urbanization is the trend of historical development.It brings lots of vitality and power to the global economy,society and culture.At the same time,urbanization inevitably brings problems such as environmental degradation,cultivated land reduction and food security.In order to relieve the decrease of cropland,countries all over the world carry out different kinds of cropland protection policies.China,as the largest developing country,has the fastest urbanization rate and the largest population.To guarantee the food security,China has been implementing the strictest cropland protection across the world,for example The Basic Cropland Policy and Cropland Requisition and Compensation Balance Policy,to observe“1.8 billion mu”red line of the area of cropland.However,there is unexpectable situation happened,such as the phenomenon of“Occupation of high-quality cropland and Compensation of low-quality cropland”and the loss of ecological lands due to cropland compensation,which influences the ecological stability of the cropland compensation area.In March 2018,the General office of the State Council printed The Measures for The Overall National Management of Inter Province Cropland Compensation,which described the condition of inter province cropland compensation and created the basis of compensating cropland among provinces.Identifying the compensating area of cropland by a scientific and reasonable method has important meaning for food security,cropland protection and the ecological safety.This research chose China(main land)as the study area to explore the impacts of spatial allocation on cropland compensation and the loss of ecological lands from the perspective of“Occupation”and“Compensation”.Firstly,this research analyzed the historical situation of cropland occupation and compensation and the decrease of ecological lands due to cropland compensation from 2000 to 2015.Then based on the LANSCAPE(LAND System Cellular Automata model for Potential Effects)model,we developed four optimal scenarios:business as usual(BAU),optimization in compensation(BC),optimization in occupation(ZY)and optimization in compensation and occupation(BCZY)to allocate the spatial location of urban land and the compensated cropland and reduce the loss of ecological lands.The results indicated that:(1)There is a mismatch between the productivity of occupied and compensated cropland.The total land productivity of the compensated cropland on the northwest region is much higher than that on the east region.But this situation is becoming better.From 2000-2015,there are three provinces where the total land productivity of the compensated cropland is higher than the productivity of the occupied cropland,those are Xinjiang,Inner Mongolia,and Heilongjiang.The number of the province which meet the requirement of the Cropland Requisition and Compensation Balance Policy is3 from 2000-2005 but it increases to 7 on 2010-2015.(2)Cropland compensation causes a massive loss of ecological lands in China,among which grassland suffer the most loss.The quantities of ecological lands loss due to cropland compensation in 2000-2005,2005-2010,2010-2015 are 16873 km~2?5782km~2?16157 km~2,among which the quantities of grassland loss are 9212 km~2?2523km~2?7799 km~2,specifically.(3)The loss of ecological lands because of cropland compensation can be significantly reduced through allocating the spatial location of the compensated cropland.Only from the“Occupation”or“Compensation”side,the optimization efficiency is 0.0193 or 0.5621,while from the“Occupation”and“Compensation”side,it reaches to 0.5625.Considering the cost of policy implementation,this research recommends the focus should be the“compensation”side and suggests Shandong,Hebei,Henan,etc.as the area of compensating cropland because of their high land quality.