| With the continuous advancement of urbanization level and the rapid development of social economy,a large number of rural laborers in China have moved to urban areas.There is a phenomenon of cultivated land reclamation.in mountainous hilly areas,marginal areas and towns.To a certain extent,the continued spread of cultivated land reclamation in mountainous and hilly areas has adversely affected the remediation of mountainous land,the transfer of rural cultivated land,and the healthy development of the rural economy.At the same time,it is a certain extent threatened to food security As a region with widely distributed mountainous terrain in China,Sichuan Province has seen an increase in rural labor transfer and migrant workers in recent years,which has led to an increase in the area of cultivated land and wasteland.Zhongjiang County is a representative of large agricultural counties,has topographical conditions in which mountains,hills and plains are staggered.The total amount of cultivated land resources is large and the distribution areas are diverse.However,the phenomenon of cultivated land reclamation in the county is frequent,under the influence of many factors such as the restriction of natural conditions,the low efficiency of agricultural production and the adjustment of industrial structure.Therefore,it is urgent to fully grasp the characteristics of abandoned farmland and to find out the risk of land reclamation in Zhongjiang County.In this paper,the maps of abandoned land in Zhongjiang County were extracted by means of“star-machine-ground”synergy,and the comprehensive feature values were constructed by extracting the natural,human characteristics of abandoned farmland by means of landscape pattern index and topographic index;Based on the leading factors of the cultivated land reclamation,the structural equation model is used to construct the risk assessment system for cultivated land reclamation,and the natural waste risk value,the human wasteland risk value and the comprehensive waste risk value are measured.Finally,the risk of cultivated land reclamation is divided according to the comprehensive risk value.And put forward targeted measures for each risk zone.The main findings are as follows:(1)There are obvious natural eigenvalues for each influencing factor,the spatial distribution and correlation characteristics of human eigenvalues are significant.According to the analysis of natural eigenvalues,the plaque area is in the range of0.5~1hm~2,the average plaque shape index value(AWMSI)is in the range of 0~1.26,the average plaque shape fractal dimension(MPFD)is 0~1.31,and the edge density index is When the value(ED)is greater than 0.2,the incidence of wasteland is the highest;the topographic index value is greater than 1.5,the irrigation distance is within the range of 200-400m,and when the tillage distance is greater than 50m,the incidence of abandoned land is the highest,the cultivated land is also the most widely distributed;The less the cultivated land is distributed.The analysis of humanistic eigenvalues shows that the proportion of the employed population in the primary industry is generally high in the northwest and low in the southeast.In the northern towns,the area of cultivated land circulation is the highest.The townships along Huangpu Town,Yongtai Town,Tongji Town and Northeast Town are descending from south to west in a semi-circular direction,and the circulation level is lowest in the central region.Low;the effective irrigation rate is generally low in the southeast and low in the northwest.From the perspective of correlation,the proportion of the employed population in the primary industry,the area of cultivated land transfer,the multiple cropping index,the effective irrigation rate and the distribution of abandoned farmland showed a significant negative correlation.The higher the value,the less the distribution of abandoned farmland,on the contrary,the abandoned farmland the more distribution.(2)The contribution of each factor in the abandoned farmland is different,and the weight value of each factor is significantly different.The factors determining the value of each factor are sorted in order:farmland turn over area(0.2811)>topographic index(0.1795)>Edge density(0.1639)>Population in the primary industry(0.1460)>Irrigation distance(0.1459)>Average patch fractal dimension(0.1360)>Multiple cropping index(0.0905)>Trivening distance(0.0894)>Average shape index(0.0873)>Residential density(0.0842)>Effective irrigation rate(0.0520).The preliminary screening results of the influencing factors are obtained by the Geo-detector.In the natural factors,the irrigation distance and the density of the residential points are removed,and the human factors are not excluded because the integrity of the evaluation factors is considered.Based on the screening results,the structural equation model is used to construct the risk assessment system for cultivated land reclamation,and the weights of each factor are refined.The weight of cultivated land transfer area is the highest,and the factor weight is the minimum effective irrigation rate.The difference among other factors is obvious..(3)The risk of cultivated land reclamation in the county is mainly low-risk areas,followed by high-and medium-risk risks,and less risk-free areas.There are more risks and low-risk areas in natural reclamation,and less high-risk and low-risk cultivated land.The low-risk cultivated land is the most widely distributed,the risk-free zone and the medium-risk zone are ranked second,and the high-risk zone is the least distributed.In high-risk and medium-risk areas,the overall distribution of cultivated land shows a trend from scattered to concentrated distribution from northwest to southeast,mainly distributed in marginal areas or areas with poor natural conditions;comprehensive low-risk and risk-free areas of cultivated land are mainly Distributed in the flat dam area with low terrain and slope.In the high-risk area,the measures to integrate the plots with the plaque area less than 0.5 hm2 and the plots,and to arrange the plots with ED values less than 0.14 and AWMSI less than 1.26;In the areas with distances greater than 200m from the farmer,the construction of the farm roads should be planned reasonably;Cultivated land patches with a terrain index value greater than 1.5 are recommended to achieve ecological conversion directly through forest trees.The medium-risk area should speed up land remediation,and maintain the soil nutrient through the“drought-to-water”method for the cultivated land with a slope greater than10 degrees;improve the circulation mechanism;ensure that the farmland distribution is relatively wide in the 0~250m farming area,and the irrigation is relatively wide.The water source of the pit pond is sufficient within a range of 500m.Low-risk areas should focus on improving the level of machinery and cultivating characteristic agriculture.The main measures in the risk-free zone include maintaining the current status of farming and focusing on real-time monitoring. |
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