Research On The Allocation Of Ecological Land Increment In A Typical Black Soil Area Based On Cultivated Land Protection

The construction of ecological fertile farmland is the vital target on cultivated land protection in new period,and the key is to keep the scientific and reasonable amount and spatial structure of cultivated land and ecological land.Rapid urbanization in China has increased the land use confliction among social economic development,food security and ecological protection.Ecological land with a certain ecological value plays an important role in maintaining regional ecological security and promoting development of natural and social systems.Study on land use usually focused on the protection of cultivated land and to meet the demand of construction land during the economic growth period.However,serious problems of ecological security decline of cultivated land caused by the decrease of ecological land were apparently ignored.Land resource optimal allocation is an effective way to increase ecological land quantity and protect the quantity,quality and ecological security of cultivated land based on the research perspective of land ecological security.It is important means to improve regional ecological security,relief from social conflictions and accelerate sustainable development.Analyzing the coordination between ecological land and cultivated land and the ecological security status of cultivated land are the basis for the construction of ecological fertile farmland and environment protection in black soil area.This research chose Changchun City as the study area,which is a typical black soil area in northeast China.Then we analyzed serious environment problems and ecological risks caused by rapid economic development in this region and do the following researches respectively.The methods to analyze land use dynamic change were chosen to explore the spatial-temporal characteristics of land use,and the coordination degree and matching degree were calculated to analyze the coordination between ecological land and cultivated land.Based on this,landscape ecological risk and its driving factors were depicted and explored to describe land use state and level of ecological security in a typical black soil area by building a landscape ecological risk assessment model and using the geographically weighted regression method.At last,multiple constraints were added as different aspects that impacting ecological land expansion to simulate different scenarios of ecological land increment pattern,and to realize the optimal special allocation of ecological land.The conclusions can be summarized as follows:(1)The situation of land use change were dramatic during 1996-2015 in Changchun City,which showed significant features in rapid expanding of construction land and severe decrease of ecological land.Changes in 1996-2009 were more frequent than in 2009-2015.The cultivated land in study area changed with both loss and supplement that was influenced by protection policies.Human activities were the major factors affecting land use type conversion,and the transition types could be concluded as from cultivated land and ecological land to construction land and from ecological land to cultivated land.The internal changes in ecological land were relatively frequent that led to the land decrease and land fragmentation.(2)Coordination index and matching index were built to measure the coordination degree between ecological land and cultivated land.The results showed that spatial difference of coordination degree was not obvious in 1996-2009,but there existed distinct uncoordinated areas in the main urban area.The uncoordinated areas decreased during 2009-2015 and the spatial differentiation of coordination degree was significantly enhanced that expanded from the main urban area to outwards.The matching degree in the main urban area dropped dramatically as the most obvious area of change.Construction activities significantly affected relationships between ecological land and cultivated land,and the regional ecological security level tended to be uncoordinated.(3)This paper built the landscape ecological risk assessment model based on the landscape fragmentation index and vulnerability index,and discussed the tendency and spatial differentiation of regional landscape ecological risk.The results showed that landscape ecological risk increased obviously in 1996-2015,and changes were greater in 1996-2009 than in 2009-2015.The index based on grid cell showed that the level of landscape ecological risk was higher in forest region than in the cultivated area.However,the ecological risk level of cultivated land increased significant during the study period.In addition,ecological risk of ecological land was generally higher than cultivated and mostly distributed in Level II and Level III,while the region of Level ? and Level ? of ecological land was more than cultivated land.The level of cultivated land ecological risk decreased obviously and showed significant trends from Level ? to Level ? during study period.(4)By using the geographical weighted regression model,local regression analysis was carried out on the landscape ecological risk factors of ecological land and cultivated land.Impact factors on landscape ecological risk showed certain directional heterogeneity and spatial variability in geographic spatial distribution.The regression results of elevation,slope,proportion of residential area and residential area per square kilometer of cultivated land can better explain the ecological risk index of ecological land,while the regression coefficient of the proportion of residential areas changed greatest and the vegetation coverage changed in the minimum.The regression results of elevation,proportion of residential area,residential area per square kilometer of cultivated land and cultivated land per capita have relatively strong explanatory ability to the ecological risk degree of cultivated land,while the regression coefficient of the proportion of residential areas changed greatest and the vegetation coverage changed in the minimum as same as ecological land.Economic factors were still the most significant elements that impacting regional landscape ecological security.Natural factors and cultivated land resource conditions impacted ecological risk degree of ecological land a lot more than cultivated land,which indicated that the natural geographic elements and cultivated land structure has certain effect on the change of ecological land.(5)Landscape ecological security pattern,risk of cultivated land and suitability of urban sprawl reflected the different constraints on ecological land expansion process,and it showed that simulation results under multiple scenarios were superior to the simulation of a single process.The prime farmland protection area was added as a rigid constraint to limit ecological land expansion,which reflected the multiple protections on cultivated land quality,cultivated land quantity and ecological protection.Co-constrained by the preservation area of prime farmland,the optimal increment region,the appropriate increment region,the adjustable increment region and restricted increment region of ecological land increment allocation pattern occupied 1141.46km2,2629.11km2,1472.61km2 and 149.41 km2,respectively,accounting for 5.54%,12.77%,7.15%and 0.73%of the total area.The ultimate simulation results achieved the multiple protections on cultivated land and meet the need for regional ecological security and urban sprawl,which are helpful to promote the construction of ecological farmland and urban intensive development.