The Relationship Between The Heterogeneity Of Farmland Landscape And The Proportion Of Non-arable Land In Changtu County

Landscape heterogeneity is the focus of landscape ecology research,and it is the basis of optimizing the allocation of resources and the structure and function of landscape.Farmland landscape is not only the product of human long-term management of land,but also the most basic material production department for human survival.The study of farmland landscape heterogeneity is helpful to maintain and improve the stability and efficiency of agricultural ecosystem and agricultural production,and provide a strong basis for the scientific layout of farmland and spatial effective management.Non-cultivated land is embedded in the farmland landscape,which is a general term for the natural and semi-natural habitats in the farmland system,such as woodland,garden,grassland,hedge,ditch,ridge,inland tidal flat,pit pond surface and river surface.Previous studies have shown that a high proportion of non-arable land landscape in farmland landscape can increase the heterogeneity and connectivity of farmland landscape.However,too much increase in the proportion of non-cultivated land obviously does not meet the development needs of cultivated land in China.Therefore,the research on the heterogeneity of non-cultivated land landscape can provide some reference for the rational layout of farmland landscape and land renovation in the future.Further discussion on the quantitative relationship between landscape heterogeneity and the proportion of non-cultivated land will not only help to optimize the structure and rational layout of non-cultivated land landscape in the future,but also help to find the proportion range of non-cultivated land suitable for the situation of our country.This paper selects Changtu County,a typical county in Northeast China,as the study area,using Arc GIS10.2,Fragstats4.2,GS+9.0,SPSS26 and other software,using GIS technology,landscape index method,semi-variation function method,correlation analysis method,data structure analysis method and curve fitting method to explore the corresponding relationship between farmland landscape heterogeneity and the proportion of non-cultivated land in the study area.First of all,the landscape types of Changtu County are divided based on GIS technology,and the index representing landscape heterogeneity is selected from the landscape level and type level to analyze the distribution characteristics of landscape heterogeneity in the study area.Secondly,non-cultivated land is selected and grided,the proportion of non-cultivated land in different scales is calculated,and the correlation between landscape index and the proportion of non-cultivated land is analyzed.Finally,the correlation and quantitative relationship between farmland landscape heterogeneity and the proportion of non-cultivated land are fitted.The main results are as follows:(1)At the landscape level,the degree of fragmentation of non-cultivated land in the study area is higher,the degree of mosaic is lower,the distribution of patches of the same type is more concentrated,the degree of diversification is better,the spatial connectivity of cultivated land is better,and the landscape heterogeneity is at a high level.On the type level,the fragmentation degree of other agricultural land and woodland is the highest,and the fragmentation degree of garden land and grassland is the lowest.The spatial connectivity of cultivated land is the best,the structure is the most compact,and the degree of fragmentation is the lowest.Cultivated land is the dominant landscape in the study area,and the proportion of garden land and grassland is the smallest.In terms of spatial distribution,the structure and quantity of non-cultivated land have a great impact on the spatial heterogeneity of farmland landscape.The heterogeneity in the eastern and western parts of the study area is high,and the main non-cultivated land landscape types are woodland,garden and grassland,while the overall spatial heterogeneity affected by the dominant landscape(mainly cultivated land)in the central part is relatively low.as a result,the heterogeneity of surrounding non-cultivated waters,other agricultural land and artificial woodland is not high.(2)In multi-scale,the landscape index and the proportion of non-cultivated land are significantly correlated in the selected scale.With the increase of the proportion of non-cultivated land,the landscape shape index(LSI),landscape separation index(DIVISION),Shannon diversity index(SHDI)and Shannon evenness index(SHEI)of diversity index increased rapidly at first and then slowed down,that is,the fragmentation index and diversity index were positively correlated with the proportion of non-cultivated land.The aggregation degree index(AI),spreading degree index(CONTAG)and patch adhesion index(COHESION)of connectivity index ii showed a decreasing trend,which was affected by the proportion of non-cultivated land,that is,there was a significant negative correlation between connectivity and the proportion of non-cultivated land.And with the decrease of the scale,the discrete space of landscape shape index(LSI)decreased,while the discrete space of other landscape index showed an increasing trend,while the change range of aggregation index(AI)and Shannon evenness index(SHEI)showed an increasing trend,while that of other landscape indexes showed a decreasing trend.(3)On the 5km scale,when the proportion of non-cultivated land is 20%,the increase of fragmentation index,connectivity index and diversity index slows down at the same time;on the 3km scale,only the increase of fragmentation index slows down when the proportion of non-cultivated land is 20%,and the inflection point of connectivity index and diversity index is at 30% of the proportion of non-cultivated land.On the 1.5km,1km and 0.5km scales,the inflection points of fragmentation index,connectivity index and diversity index are all at 30% of the proportion of non-cultivated land.Before the proportion of non-cultivated land reaches 20%,the growth of the area and types of non-cultivated land will also lead to the rapid growth of landscape heterogeneity;when it reaches the range of 20% of non-cultivated land and 30% of non-cultivated land,the growth trend of landscape heterogeneity gradually slows down,and the heterogeneity remains basically stable;after the proportion of non-cultivated land exceeds 30%,the sustained growth of the proportion of non-cultivated land will not significantly change the landscape heterogeneity.