The Change Of Cultivated Land And Its Influence On The Agricultural Economy In The Northeast Of Sanjiang Plain

In recent years,under the influence of climate warming and drived by comparing economic benefits,the distribution of cultivated land planting structure has changed significantly.Farmers have implemented projects which dry land turned into paddy field in areas with suitable conditions,and large areas of dry land have been converted into paddy field,achieving the idea of developing paddy field to increase production.Therefore,this paper analyzes the temporal and spatial characteristics of cultivated land in the northeast of Sanjiang Plain,the evolution law of cultivated land landscape pattern,and the influence of the change of cultivated land on agricultural economy.It is of great significance in scientific research and practice for optimizing the allocation of regional cultivated land resources and ensuring the national food security.Based on GIS spatial analysis method,this paper extracted the land use data of1986,1996,2005,2010 and 2016,using the transfer matrix of the cultivated land,the dynamic degree of cultivated land utilization,and kernel density calculation method to analyze the evolution characteristics of the northeast of the Sanjiang plain cultivated land,summarized farmland change characteristics and trends in the northeast of the Sanjiang plain from 1986 to2016;and based on the landscape pattern analysis software of Fragstats3.4,the cultivated land landscape pattern index based on patch type level was calculated in 5 periods of each city and county;based on the above analysis,qualitative and quantitative methods are used to analyze the impact of cultivated land change on agricultural economy.The correlation coefficient between cultivated land quantity and agricultural economic factors was calculated by using SPSS software and linear regression analysis method.The main contents and conclusions of this paper are as follows:(1)The analysis of temporal and spatial variation of cultivated land.The results suggested that:the area of farmland raised from 145.85×10~4hm~2 to 241.28×10~4hm~2 during 1950-1986,which the rate of reclamation is up to 65.76%,including the paddy field was increased by118.77×10~4hm~2,and dry land was decreased by 23.34×10~4hm~2.Paddy field has becomed the main type of cultivated land utilization.The new increased land was dry land mainly from woodland,grassland and unused land,those maximum contribution to new cultivated land was 53.72%、35.99%、53.01%.The transformation of the more obvious areas was Fujin City,Tongjiang City and Fuyuan County.(2)The analysis of landscape pattern change of cultivated land.The results suggested that:the index of aggregation degree and patch cohesion of dry land increased gradually,and the two indices of paddy field increased significantly in this region.At the early stage,dry land was in the concentrated distribution but with fewer paddy field;and at the last,showed a spatial distribution characteristics of dry land and paddy field which approaching equal quantity.The broken degree of paddy field showed a trend of fluctuation and rising.The paddy patch density raised from 0.01 to0.02,the paddy field fragmentation index raised from 0.34 to 7.27;The patch density and fragmentation index of dry land increased year by year,the patch density of those raised from 0.01to 0.02,and fragmentation index of those raised from 0.78 to 11.75.The patch shape of paddy field is more complex than that of dry land patch,and the disturbance degree of dry land is greater.The dominant position of cultivated land landscape changes from dry land to paddy field,the dominance degree of paddy field is strengthened continuously,and the dominance degree of dry land landscape type decreased.(3)The influence of the change of cultivated land on agricultural economy.The increase of cultivated land quantity,especially the increase of paddy field promoted the increase of agricultural output,the per capita net income of farmers and the grain yield.The linear regression analysis method is applied to the paddy field,dry land and agricultural economic factors,the results showed that the correlation coefficients between paddy field and agricultural economic elements were higher than those between dry land and agricultural economic elements.The projects which dry land turned into paddy field can promote the development of agricultural economy.This paper probes into the quantity of cultivated land,the composition of internal structure,the present situation and changes of the landscape pattern of cultivated land,and discussed the influence of a large number of dry land transformed paddy field on the agricultural economy.It provided a reliable basis for the sustainable development of the regional economy and the adoption of reasonable farming methods for cultivated land in this region.